Building-Integrated Photovoltaic

Designs for Commercial and

Institutional Structures

A Sourcebook for Architects

Patrina Eiffert, Ph.D.

Gregory J. Kiss
Acknowledgements

Building-Integrated Photovoltaics for Commercial and Institutional Structures: A

Sourcebook for Architects and Engineers was prepared for the U.S. Department of

Energy's (DOE's) Office of Power Technologies, Photovoltaics Division, and the

Federal Energy Management Program. It was written by Patrina Eiffert, Ph.D., 

of the Deployment Facilitation Center at DOEís National Renewable Energy

Laboratory (NREL) and Gregory J. Kiss of Kiss + Cathcart Architects. 

The authors would like to acknowledge the valuable contributions of Sheila

Hayter, P.E., Andy Walker, Ph.D., P.E., and Jeff Wiechman of NREL, and Anne

Sprunt Crawley, Dru Crawley, Robert Hassett, Robert Martin, and Jim Rannels of

DOE. They would also like to thank all those who provided the detailed design

briefs, including Melinda Humphry Becker of the Smithsonian Institution, 

Stephen Meder of the University of Hawaii, John Goldsmith of Pilkington Solar

International, Bob Parkins of the Western Area Power Administration, Steve

Coonen of Atlantis, Dan Shugar of Powerlight Co., Stephen Strong and Bevan

Walker of Solar Design Associates, Captain Michael K. Loose, Commanding

Officer, Navy Public Works Center at Pearl Harbor, Art Seki of Hawaiian Electric

Co., Roman Piaskoski of the U.S. General Services Administration, Neall Digert,

Ph.D., of Architectural Energy Corporation, and Moneer Azzam of ASE Americas,

Inc.

In addition, the authors would like to thank Tony Schoen, Deo Prasad, Peter

Toggweiler, Henrik Sorensen, and all the other international experts from the

International Energy Agencyís PV Power Systems Program, TASK VII, for their

support and contributions.

Thanks also are due to staff members of Kiss + Cathcart and NREL for their 

assistance in preparing this report. In particular, we would like to acknowledge 

the contributions of Petia Morozov and Kimbro Frutiger of Kiss + Cathcart, and

Riley McManus, student intern, Paula Pitchford, and Susan Sczepanski of NREL.

On the cover: Architectís rendering of the HEW Customer Center in Hamburg, Germany,

showing how a new skin of photovoltaic panels is to be draped over its facade and forecourt

(architects: Kiss + Carthcart, New York, and Sommer & Partner, Berlin).

Building-Integrated Photovoltaics for Commercial and Institutional Structures
Building-Integrated Photovoltaics for Commercial and Institutional Structures 1

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Design Briefs

4 Times Square . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Thoreau Center for Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . .7

National Air and Space Museum . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Ford Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Western Area Power Administration . . . . . . . . . . . . . . . . . . . . . . .24

Photovoltaic Manufacturing Facility . . . . . . . . . . . . . . . . . . . . . . .28

Yosemite Transit Shelters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Sun Microsystems Clock Tower . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

State University of New York, Albany . . . . . . . . . . . . . . . . . . . . . .38

Navajo Nation Outdoor Solar Classroom . . . . . . . . . . . . . . . . . . . .40

General Services Administration, Williams Building . . . . . . . .42

Academy of Further Education . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45

Discovery Science Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

Solar Sunflowers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

Ijsselstein Row Houses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Denver Federal Courthouse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54

BIPV Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

BIPV Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

Appendix A: International Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . .71

Appendix B: Contacts for International Energy Agency 

Photovoltaic Power Systems Task VII—Photovoltaics in the 

Built Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77

Appendix C: Design Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78

About the Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
Introduction

Building-integrated photovoltaic (BIPV) electric power systems not only produce electricity, they

are also part of the building. For example, a BIPV skylight is an integral component of the building

envelope as well as a solar electric energy system that generates electricity for the building. These

solar systems are thus multifunctional construction materials.

The standard element of a BIPV system is the PV module. Individual solar cells are interconnected

and encapsulated on various materials to form a module. Modules are strung together in an

electrical series with cables and wires to form a PV array. Direct or diffuse light (usually sunlight)

shining on the solar cells induces the photovoltaic effect, generating unregulated DC electric

power. This DC power can be used, stored in a battery system, or fed into an inverter that

transforms and synchronizes the power into AC electricity. The electricity can be used in the

building or exported to a utility company through a grid interconnection.

A wide variety of BIPV systems are available in today's markets. Most of them can be grouped 

into two main categories: facade systems and roofing systems. Facade systems include curtain

wall products, spandrel panels, and glazings. Roofing systems include tiles, shingles, standing

seam products, and skylights. This sourcebook illustrates how PV modules can be designed as

aesthetically integrated building components (such as awnings) and as entire structures (such as

bus shelters). BIPV is sometimes the optimal method of installing renewable energy systems in

urban, built-up areas where undeveloped land is both scarce and expensive.

The fundamental first step in any BIPV application is to maximize energy efficiency within the

building’s energy demand or load. This way, the entire energy system can be optimized.

Holistically designed BIPV systems will reduce a building’s energy demand from the electric 

utility grid while generating electricity on site and performing as the weathering skin of the

building. Roof and wall systems can provide R-value to diminish undesired thermal transference.

Windows, skylights, and facade shelves can be designed to increase daylighting opportunities 

in interior spaces. PV awnings can be designed to reduce unwanted glare and heat gain. This

integrated approach, which brings together energy conservation, energy efficiency, building

envelope design, and PV technology and placement, maximizes energy savings and makes the

most of opportunities to use BIPV systems.

It is noteworthy that half the BIPV systems described in this book are on Federal buildings. This is

not surprising, however, when we consider these factors: (1) the U.S. government, with more than

half a million facilities, is the largest energy consumer in the world, and (2) the U.S. Department 

of Energy (DOE) has been directed to lead Federal agencies in an aggressive effort to meet the

government’s energy-efficiency goals. DOE does this by helping Federal energy managers identify

and purchase the best energy-saving products available, by working to increase the number and

quality of energy projects, and by facilitating effective project partnerships among agencies,

utilities, the private sector, and the states.

2 Building-Integrated Photovoltaics for Commercial and Institutional Structures
Because it owns or operates so many facilities, the U.S. government has an enormous number of

opportunities to save energy and reduce energy costs. Therefore, the Federal Energy Management

Program (FEMP) in DOE has been directed to help agencies reduce energy costs, increase their

energy efficiency, use more renewable energy, and conserve water. FEMP's three major work areas

are (1) project financing; (2) technical guidance and assistance; and (3) planning, reporting, and

evaluation.

To help agencies reach their energy-reduction goals, FEMP’s SAVEnergy Audit Program identifies

cost-effective energy efficiency, renewable energy, and water conservation measures that can be

obtained either through Federal agency appropriations or alternative financing. FEMP's national,

technology-specific performance contracts help implement cutting-edge solar and other renewable

energy technologies. In addition, FEMP trains facility managers and showcases cost-effective

applications. FEMP staff also identify Federal market opportunities and work with procurement

organizations to help them aggregate purchases, reduce costs, and expand markets.

All these activities ultimately benefit the nation by reducing building energy costs, saving taxpayers

money, and leveraging program funding. FEMP’s activities also serve to expand the marketplace 

for new energy-efficiency and renewable energy technologies, reduce pollution, promote

environmentally sound building design and operation, and set a good example for state and local

governments and the private sector. 

This sourcebook presents several design briefs that illustrate how BIPV products can be integrated

successfully into a number of structures. It also contains some basic information about BIPV and

related product development in the United States, descriptions of some of the major software design

tools, an overview of international activities related to BIPV, and a bibliography of pertinent

literature.

The primary intent of this sourcebook is to provide architects and designers with useful information

on BIPV systems in the enclosed design briefs. Each brief provides specific technical data about the

BIPV system used, including the system’s size, weight, and efficiency as well as number of inverters

required for it. This is followed by photographs and drawings of the systems along with general

system descriptions, special design considerations, and mounting attachment details.

As more and more architects and designers gain experience in integrating photovoltaic systems 

into the built environment, this relatively new technology will begin to blend almost invisibly into 

the nation’s urban and rural landscapes. This will happen as BIPV continues to demonstrate a

commercially preferable, environmentally benign, aesthetically pleasing way of generating

electricity for commercial, institutional, and many other kinds of buildings.

Building-Integrated Photovoltaics for Commercial and Institutional Structures 3
Close-up view of curtain wall illustrates that BIPV panels (dark panels) can be mounted

in exactly the same way as conventional glazing (lighter panels).

design briefs

4 design briefs: 4 Times Square

4 Times Square

Location: Broadway and 42nd Street, New York City, New York

Owner: Durst Corporation

Date Completed: September 1999

Architect & Designer: Fox & Fowle Architects, building architects; 

Kiss + Cathcart Architects, PV system designers

PV Structural Engineers: FTL/Happold 

Electrical Engineers: Engineers NY

Tradesmen Required: PV glazing done by shop labor at curtain wall fabricator

Applicable Building Codes: New York City Building Code

Applicable Electric Codes: New York City Electrical Code and National Electric Code

PV Product: Custom-sized BIPV glass laminate

Size: 14 kWp

Projected System Electrical Output: 13,800 kWh/yr

Gross PV Surface Area: 3,095 ft2

PV Weight: 13.5 lb/ft2

PV Cell Type: Amorphous silicon

PV Module Efficiency: 6%

PV Module Manufacturer: Energy Photovotaics, Inc.

Inverter Number and Size: Three inverters; two 6 kW (Omnion Corp.), one 4 kW (Trace Engineering)

Inverter Manufacturers: Omnion Corp. and Trace Engineering

Interconnection: Utility-Grid-Connected

Kiss + Cathcart, Architects/PIX08458
Description 

The tallest skyscraper built in New York

City in the 1990s, this 48-story office tower

at Broadway and 42nd Street is a somewhat unusual but impressive way to

demonstrate "green" technologies. Its

developers, the Durst Organization, want

to show that a wide range of healthy

building and energy efficiency strategies

can and should be incorporated into real

estate practices.

Kiss + Cathcart, Architects, are consultants for the building tower’s state-of-theart, thin-film BIPV system. Working in

collaboration with Fox and Fowle, architects for the base building, Kiss + Cathcart

have designed the BIPV system to function as an integral part of the tower's 

curtain wall. This dual use makes it one 

of the most economical solar arrays 

ever installed in an urban area. Energy

Photovoltaics of Princeton, New Jersey,

developed the custom PV modules to

meet rigorous aesthetic, structural, and

electrical criteria.

Traditionally, solar technologies have

been considered economical only in

remote areas far from power grids or in

areas with an unusually high amount of

sunlight. Advances in PV efficiency are

overturning these assumptions, allowing

solar electricity to be generated costeffectively even in the heart of the city. 

In fact, PV is the most practical means of

generating renewable electricity in an

urban environment. Further, BIPV can be

directly substituted for other cladding

materials, at a lower material cost than

the stone and metal it replaces. As the

first major commercial application of 

BIPV in the United States, 4 Times Square

points the way to large-scale production

of solar electricity at the point of greatest

use. The next major market for PV may

well be cities like New York that have both

high electricity costs and high-quality

buildings.

Special Design Considerations

The south and east facades of the 37th

through the 43rd floor were designated 

as the sites for the photovoltaic "skin."

BIPV was incorporated into the design

after the tower’s general appearance 

had already been decided upon, so the

design briefs: 4 Times Square5

BIPV panels have been

integrated into the

curtain wall instead of

conventional glass

spandrel panels on the

37th through the 43rd

floor.

The custom-made BIPV

panels are visible in this

sidewalk view from

Broadway. Kiss + Cathcart, Architects/PIX06457 Kiss + Cathcart, Architects/PIX08460
installation was made to harmonize with

the established design concept. 

PV System Configuration

The PV modules replace conventional

spandrel glass in the south and east

facades. There are four different sizes 

of modules, and they correspond to the

spandrel sizes established earlier in the

design process.

PV Module Mounting and

Attachment Details

The PV modules are attached to the building structure in exactly the same way that

standard glass is attached. The glass

units are attached with structural silicone

adhesive around the back edge to an aluminum frame. An additional silicone bead

is inserted between the edges of adjacent

panels as a water seal.

There is a separate electrical system for

each facade. Each system consists of two

subsystems, feeding two 6-kW inverters

and one 4-kW inverter. The larger inverters serve the two large-sized PV modules,

which have electrical characteristics that

are different from those of the smaller

ones. Using multiple inverters enables the

system to perform more efficiently. The

inverters are located in a single electrical

closet at the core of the building. The AC

output of the inverters is transformed

from 120 V to 480 V before being fed into

the main electrical riser.

6 design briefs: 4 Times Square

4 Times Square during construction

Kiss + Cathcart, Architects/PIX06458
design briefs Location: Presidio National Park, Building 1016, San Francisco, California

Owner: U.S. Department of Interior, National Park Service

Date Completed: May 1996

Architect & Designer: Tanner, Leddy, Maytum, Stacy

Structural and Electrical Engineers: Equity Builders

Tradesmen Required: Glaziers

Applicable Building Codes: California structural and seismic codes

Applicable Electric Codes: National Electric Code

PV Product: Roof-integrated, translucent glass-laminate skylight

Size: 1.25 kWp

Projected System Electrical Output: 716.4 kWh/yr/AC

Gross PV Surface Area: 215 ft

2

PV Weight: 8 lb/ft

2

PV Cell Type: Polycrystalline silicon

PV Efficiency: 11% cell, 7% module

PV Module Manufacturer: Solar Building Systems, Atlantis Energy

Inverter Size: 4 kW

Inverter Manufacturer and Model: Trace Engineering Model 4048

Interconnection: Utility-Grid-Connected

design briefs: Thoreau Center for Sustainability7

Thoreau Center for Sustainability

Presidio National Park, Building 1016

Atlantis Energy, Inc./PIX04779

The first application for

integrating photovoltaics

into a Federal building is the

skylighted entryway of the

Thoreau Center in Presidio

National Park.
Description

The Greening of the Presidio demonstrates the impact of successful partnerships between the private and public

sector. The Thoreau Center for Sustainability is a historic building, located in the

National Historic Landmark District of the

Presidio in San Francisco, California. The

goal of transforming this historic building

into an environmentally responsive structure produced an opportunity to apply

principles of sustainable design and

architecture and educate the public about

them. Within this building rehabilitation

project, materials selected for the renovation included recycled textile materials,

recycled aluminum, recycled newsprint,

recycled glass, and wood grown and 

harvested sustainably.

The environmentally friendly strategy

included reducing energy consumption

through a Demand Side Management

(DSM) Program with the local utility company, PG&E. The building has a highly efficient direct/indirect lighting system with

translucent office panels to allow inner

zones to borrow daylight from the perimeter. The building is heated by an efficient

modular boiler and is cooled by natural

ventilation. The BIPV system is a highly

visible sustainable building feature. The

demonstration of this power system by

DOE FEMP, the National Renewable

Energy Laboratory (NREL), and numerous

private-sector partners illustrates that

BIPV is a technically and economically

valuable architectural element for 

designers.

The skylit entryway of the Thoreau Center

for Sustainability at Presidio National

Park was the first demonstration in the

United States of the integration of photovoltaics into a federal building. Laminated

to the skylight glass are photovoltaic cells

that produce electricity and also serve 

as a shading and daylighting design element. Atlantis Energy provided custommanufactured PV panels and the system

design and integration for this project.

The firm was joined by construction 

specialists who made it possible to 

transform this historic building into an

environmentally responsive structure.

The solar electricity generated in the 

PV system in the skylight offsets power

provided by the utility, thereby conserving

fossil fuels and reducing pollution.

Converting the DC electricity to AC, the

system can produce about 1300 watts

during periods of full sun. The system 

is fully automatic and requires virtually 

no maintenance. Like other PV systems,

it has no moving parts, so this solar 

generating system provides clean, quiet,

dependable electricity.

The entry area into the Thoreau Center is

a rectangular space with a roof sloping

slightly to the east and west. The roof is

constructed entirely of overhead glazing,

similar to a large skylight. PV cells are

laminated onto the 200 square feet of

available overhead glazing to produce

approximately 1.25 kW of electricity under

standard operating conditions. The PVproduced DC electric power is converted

to high-quality AC by a power-conditioning

unit (inverter). After it is converted, the

power enters the building to be consumed

by the building’s electrical loads.

Special Design Considerations

Design and construction issues for the 

relatively small Thoreau Center system

were similar in many ways to issues

involved with designing and constructing

much larger systems. The panels for this

project were custom-manufactured by

Atlantis Energy to meet the esthetic

requirements of the architect. The square,

polycrystalline PV cells are spaced far

enough apart from one another to permit

daylighting and provide pleasant shadows that fall within the space. The amount

of daylight and heat transfer through

these panels was considered in determining the lighting and HVAC requirements

for the space. The panels themselves

were constructed to be installed in a standard overhead glazing system framework.

The system is installed above seismiccode-approved skylight glazing. The daylighting and solar gains through the PV

modules mounted above the skylight system do affect the building lighting and

HVAC loads, but the modules do not also

serve as the weathering skin of this building envelope. Originally, the design called

for the PV modules to replace the skylight

units. But during design approval, local

building code authorities were uncertain

whether the modules could meet seismic

code requirements. So the alternative

design, stacking the skylights and the

modules, was used instead.

To ensure that the glazing used in manufacturing the PV panels was acceptable

according to Uniform Building Codes

8 design briefs: Thoreau Center for Sustainability

The PV arrays produce electricity and serve as a daylighting design

element.

Lawrence Berkeley Laboratory/PIX01052
design briefs: Thoreau Center for Sustainability 9

This schematic drawing shows how the PV modules were attached above the conventional skylight glazing.

02527226m
(UBC), building code issues were

addressed. Special arrangements were

made with the local electrical utility to

ensure that the grid-tied system would

meet safety requirements. Finally,

installing the system required coordination between the panel supplier, electrician, glass installer, and Presidio facilities

personnel.

PV System Configuration 

The BIPV glazing system consists of 24 PV

glass laminates. The spacing of the cells

within the modules allows approximately

17% of the sunlight into the entryway,

reducing the need for electric lights. The

modules consist of 6-mm Solarphire

glass, 36 polycrystalline silicon PV cells,

an ethylene-vinyl acetate coating, a

translucent Tedlar-coated polyester backsheet, and two sealed and potted junction

boxes with a double pole plug connector.

The PV cells are laminated in a 6-cell x 6-

cell matrix. The minimum spacing

between cells is 1.25 cm (1/2 in.). The

dimension of each module is 81 cm x

94 cm (32 in. x 37 in). The gross area of

the entire structure is 18.8 m2 (200 ft2).

The power produced by the system is converted to high-quality AC electricity and

supplements power supplied to the building by the utility. The system is rated at

1.25 kW. Each of the 24 PV modules generates 8.5 V of DC power at approximately

5.5 amps. Six modules per sub-array are

connected in series to feed the sine-wave

inverter, which is configured to 48 V and

rated at 4,000 W capacity.

PV Module Mounting and

Attachment Details

Structural upgrades were made to accommodate the additional weight of the PV

system. These added about $900 to the

total cost, for structural components.

10 design briefs: Thoreau Center for Sustainability

This drawing shows how the photovoltaic skylight array was arranged. The total array area is 20.6 square meters. 02527228m
design briefs

design briefs: National Air and Space Museum 11

National Air and Space Museum

Location: Dulles Center, Washington, DC

Owner: Smithsonian Institution

Date Completed: Construction begun in 2000, scheduled for completion in 2003

Architect & Designer: HOK, Building Architects; Kiss + Cathcart Architects, PV System Designers; 

Satish Shah, Speigel, Zamel, & Shah, Inc. 

Structural Engineers: N/A

Electrical Engineers: N/A

Tradesmen Required: Building tradesmen

Applicable Building Codes: BOCA, Metropolitan Washington Airport Authority

Applicable Electric Codes: National Electric Code

PV Product: Various BIPV systems

Size: To be determined for BIPV curtain wall, facades, and canopy

Projected System Electrical Output: 15.12 kWh for the canopy system

Gross PV Surface Area: 223 m

2 for the canopy system

PV Weight: 5 lb/ft

2 for the canopy system

PV Cell Type: Polycrystalline cells, amorphous silicon film for various systems

PV Efficiency: Systems will range from 5% to 12%

PV Module Manufacturer: Energy Photovoltaics, Inc., for the 

canopy system

Inverter Number and Size: To be determined

Inverter Manufacturer & Model: To be determined

Interconnection: Utility-Grid-Connected

Project Overview:

Axonometric

PV Canopy

PV Curtain Wall

02527218m

The BIPV installations at the

entryway will demonstrate

different BIPV systems and

technologies, such as thin

films and polycrystalline

solar cells.
Description

The National Air & Space Museum

(NASM) of the Smithsonian Institution is

one of the most-visited museums in the

world. However, its current building on

the Mall in Washington, D.C., can accommodate only a fraction of NASM’s collection of historical air- and spacecraft.

Therefore, a much larger expansion facility is planned for a site adjacent to Dulles

Airport. Since the new facility will exhibit

technologies derived from space exploration, the use of solar energy, which has

powered satellites and space stations

since the 1950s, is especially fitting for

this new building.

Kiss + Cathcart, Architects, are under 

contract to the National Renewable

Energy Laboratory as architecturalphotovoltaic consultants to the

Smithsonian Institution. Working with 

the Smithsonian and HOK Architects, 

Kiss + Cathcart is identifying suitable

areas for BIPV, selecting appropriate 

technologies, and designing the BIPV 

systems. For DOE FEMP, a partner in the

project, a primary goal is to demonstrate

the widest possible range of BIPV applications and technologies in one building.

Construction should begin in 2000. 

The NASM Dulles Center will serve as 

an exhibit and education facility. Its 

core mission is to protect the nation’s 

collection of aviation and space-flightrelated artifacts. It will also house the

preservation and restoration workshops

of the Air and Space Museum.

The center’s design includes a large,

hangar-style main exhibition space that

will allow visitors to view the collections

from two mezzanines as well as from

ground level. It is estimated that more

than 3 million people will visit the center

annually to view aircraft, spacecraft, and

related objects of historic significance,

many of which are too large to display at

the National Air and Space Museum in

Washington, D.C. The facility will set new

12 design briefs: National Air and Space Museum

Plan view of BIPV installation at entry areas
design briefs: National Air and Space Museum 13

The south- and west-facing facades of the entry hall will be glazed with polycrystalline glass laminates.
standards for collections management

and the display of large, 20th-century

functional objects.

Smithsonian staff are evaluating the integration of a number of grid-connected

BIPV systems into the building. The NASM

Dulles Center will be a very large structure

(740,000 ft2), with commensurate energy

and water requirements. As part of its

educational mission, the museum plans

to exhibit hardware that points to the 

historic use of photovoltaic (PV) power

systems in space; the museum would 

also like to demonstrate how that technology can be used today in terrestrial

applications such as BIPV. To this end, 

the Smithsonian is evaluating the highly

visible application of BIPV at this facility

to meet a portion of its energy requirements. In this way, two objectives will be

met: (1) reduce the amount of energy

required from the power grid, especially

during peak times, and thus conserve

energy and save operational funds, and

(2) demonstrate the use of PV in a highly

visible context in a much-visited Federal

facility.

Five BIPV subsystems could be demonstrated at the new NASM facility, including

the south wall and skylight of the entry

"fuselage," the roof of the restoration

hangar and space shuttle hangar, the

facade of the observation tower, and

awning canopies. The entry fuselage 

figure clerestory windows will be a highly

visible way of demonstrating PV to visitors approaching the center. Once in the

entryway, visitors would also see the 

patterns of shadow and light the fritted

glass creates on the floor, thus focusing

visitors attention on the PV. Labels,

exhibit material, and museum tour staff

could further highlight the PV arrays and

call attention to the energy savings being

realized. PV would also be used to power

some exhibit material exclusively. The

related exhibit materials could highlight

the many connections between PV and

the field of space exploration and utilization, as well as today’s construction and

building industry.

14 design briefs: National Air and Space Museum

BIPV Canopy detail 1:10

Canopy:

Structural Details

BIPV Canopy - section 1:60

02527219m

Thin-film BIPV glass

laminates will function

as the canopy.
design briefs: National Air and Space Museum 15

Fuselage detail illustrates patterns of polycrystalline glazing.
16 design briefs: National Air and Space Museum

Curtain wall details indicate how mullion channels will act as electrical conduits.
design briefs: National Air and Space Museum 17

The canopy plan and perspective demonstrate how shading and power output are combined in one architectural

expression.
18 design briefs: National Air and Space Museum

Curtain walls typically will be 16 polycrystalline solar cells per panel, laminated between two clear glass panes.
design briefs

design briefs: Ford Island 19

Ford Island

Building 44, Pearl Harbor Naval Station

This illustration is a view of the building from the southwest corner; the dark areas

represent the photovoltaic standing-seam metal roofing material.

Location: Honolulu, Hawaii

Owner: U.S. Navy, Department of Defense, and Hawaiian Electric Company

Date Completed: September 1999

Architect & Designer: Victor Olgyay, Fred Creager, and Stephen Meder, University of Hawaii, School of 

Architecture

Structural Engineers: Hawaiian Electric Co.

Electrical Engineers: Hawaiian Electric Co.; Peter Shackelford, Renewable Energy Services, Inc., system integrator

Tradesmen Required: Roofers, electrical contractors

Applicable Building Codes: Uniform Building Code

Applicable Electric Codes: National Electric Code

PV Product: Integrated standing seam metal roof

Size: 2.8 kW DC

Projected System Electrical Output: 9,720 kWh per month

Gross PV Surface Area: 571 ft

2

PV Weight: 4 lb/ft

2, with the roof

PV Cell Type: Multijunction amorphous silicon

PV Module Efficiency: 5%-6%

PV Module Manufacturer: Uni-Solar

Inverter Number and Size: One, 4-kW

Inverter Manufacturer and Model: Trace SW 4048PV 

Interconnection: Utility-Grid-Connected

02527213m
Description

A partnership consisting of the U.S. Navy,

Hawaiian Electric Co. (HECO), the

University of Hawaii, the U.S. DOE Federal

Energy Management Program (FEMP),

and the Utility PhotoVoltaic Group (UPVG)

was created in order to design and install

a 2-kW, grid-intertied, BIPV retrofit system using the Uni-Solar standing seam

metal roofing product and to monitor its

performance for one year. The University

of Hawaii School of Architecture designed

and administered the project and a local

utility, HECO, funded it. Additional construction cost support was supplied by

FEMP, NREL, and the Navy. The utility and

the Navy determined the site, and the

installation date was scheduled for the

third quarter of 1998 (Figure 1). HECO was

designated to be the client for the first

year, after which the Navy will assume

ownership of the system.

The tropical location (21° North) and the

site’s microclimate make it an ideal location for PV installations. Project planners

expected an annual daily average of

5.4 peak sun hours and 20 to 25 in.

(57 cm) of annual rainfall. This project, at

this particular site, will also be testing the

limits of the products used in the installation. Monitoring the performance of the

PV system, the McElroy metal substrate,

and the Trace inverter in a tropical marine

environment will provide valuable performance information to guide the future

development and use of these products.

The total cost of this project was $92,000.

This included design, procurement, roof

removal and BIPV installation, and a year

of monitoring.

Special Design Considerations

The context of this project is the naval

industrial site at Pearl Harbor Naval

Base.The site contained a 90 ft x 52 ft

(27.4 m x 15.8 m) open-wall boathouse

structure. The existing roof of the structure was made of box rib metal on trusses

(Figure 2) in gable form, divided longitudinally on its east-west axis. The south

20 design briefs: Ford Island

In this illustration, the dark areas represent amorphous

silicon laminates on standing seam metal roofing panels.

02527214m

The array in mid-installation is shaded only by cloud cover.

PIX08475
slope provides a 90 ft x 26 ft (27.4 m x

7.9 m) surface at a 5° incline. This half 

of the roof measured approximately

2,340 ft2 (217 m2). The box rib roofing

was removed from the entire south-facing

slope, and new standing seam pans,

including 24 of the Uni-Solar SSR 120

photovoltaic standing seam panels,

replaced the original roofing.

Integrating the new metal roofing with 

the existing roof posed several design

and construction challenges. In addition,

the longest panel that Uni-Solar could

provide is 20 ft (6.09 m) and the required

run is 26+ ft (8 m). This shortfall required

overlapped joints to be used on the ends

of the panels and additional purlines 

to be welded for support. Full-length,

standing-seam panels and non-PV panels

were set in an alternating pattern with 

the PV modules. This arrangement

allowed the full-length pans to add

strength over the required lap joint of 

the shorter PV units.

The length limitation of the Uni-Solar 

panels was a design deficiency of the 

Uni-Solar product; unless new PV-tometal laminating processes are developed, this product will be substantially

limited in metal roofing applications.

Joining the panels to extend their length

not only increases material and labor

costs, it also provides opportunities for

water penetration and corrosion. The

"galvalum" coating is cut away everywhere the panel is modified. This exposes

the steel of the standing seam panel to

the marine environment. Therefore,

McElroy, Uni-Solar’s metal roof supplier,

will not warranty the product for marine

applications.

In addition, to match the paint of the

existing structure, McElroy required a

minimum order to custom-paint the new

roof panels. Therefore, about one-third

more roofing panels had to be purchased

than were needed, and this increased the

overall project cost. The extra panels

turned out to be useful, however, since

many were damaged during transport to

Hawaii.

The part of the roof to be retrofitted spans

a dock area below. This presented staging

challenges for the roofing and electrical

contractors. Along with restricted access

to the military base and the need to take a

bridge to the site, the location of the roof

added to the complexity and costs of the

project. And the harsh marine environment could have a corrosive effect on the

array and its components.

PV System Configuration

The system is rated at 2.175 kW AC

(2.8 kW DC). The estimated system output is 9,720 kWh per month. The building

is not independently metered. It is fed by

the Pearl Harbor grid, to which HECO supplies power. The estimated demand of the

building is about 12000 kWh per month.

The energy generated by the PV system

will feed but not meet the average loads

of this building.

PV Module Mounting and

Attachment Details

Integrated connection follows standard

metal seam roof attachment process.

Notched PV panels are secured to non-PV

panels with metal fasteners.

design briefs: Ford Island 21

This illustration shows how the notched BIPV standing-seam components

overlap the regular roofing panels.
22 design briefs: Ford Island

Junction box at ridge, viewed from below

PIX08478

Junction box at ridge, viewed from above

PIX08480

Additional electrical junction boxes were required over

potted terminals and raceways at the ridge, before the

ridge cap was installed.

PIX08477

Workers install short lapped roofing pans at BIPV

module sections.

PIX08476
design briefs: Ford Island 23

The part of the roof containing BIPV spans a dock area, as shown in this illustration.

02527289m
design briefs

24 design briefs: Western Area Power Administration

Western Area Power Administration

Elverta Maintenance Facility, Phases I and II

Phase I 

Location: Elverta, California 

Owner: U.S. Department of Energy (DOE) Western Area Power Administration

Date Completed: May 1996

Architect & Designer: DOE Western Area Power Administration, PowerLight Corporation

System Integrator: PowerLight Corporation

Structural Engineers: DOE Western Area Power Administration

Electrical Engineers: DOE Western Area Power Administration

Tradesmen Required: Roofers, electrical contractors

Applicable Building Codes: Standard California building codes

Applicable Electric Codes: National Electric Code

PV Product: PowerGuardTM BIPV roof tiles

Size: 40 kW DC

Projected System Electrical Output: 70,000 kWh/year

Gross PV Surface Area: 5,400 ft

2

PV Weight: 4 lb/ft

2

PV Cell Type: Polycrystalline silicon

PV Efficiency: 12%

PV Module Manufacturer: Solarex

Inverter Number and Size: 8 inverters, 6 kW each

Inverter Manufacturer: Omnion Corp.

Interconnection: Utility-Grid-Connected

PIX08451

A 38-kW BIPV system supplements a 

40-kW system installed in 1996.

Phase I

Phase II
Description

Staff in the Department of Energy’s

Western Area Power Administration 

Sierra Nevada Region (SNR) have had two

main goals for SNR's photovoltaic (PV)

program: (1) promote PV systems as a

renewable energy resource, and (2) do 

so in a cost-effective manner. In support

of these goals, SNR has incorporated 

PV panels into the roofs of buildings in

Elverta and Folsom, California. The building-integrated systems will repay investments in them by extending roof lives,

reducing maintenance costs, generating

electric power, and reducing the buildings' cooling requirements.

In Phase I, a 40-kW building-integrated

photovoltaic system was installed at

SNR's Elverta Maintenance Facility. The

Sacramento Municipal Utility District

(SMUD) funded the PowerLight Corp.

PowerGuard® system, while Western 

contributed funds equivalent to the cost

of replacing the facility roof. Funding was

also provided by the Utility Photovoltaic

Group (UPVG) through TEAM-UP, with

support from the U.S. Department of

Energy.

With a power capacity of 40 kW peak DC

and an annual energy output of more 

than 70,000 kWh/year, the PV systems

have significant environmental benefits.

Phase I prevents the emission of

2,300 tons of carbon dioxide, 8.7 tons 

of nitrogen oxides and 16.4 tons of sulfur

dioxides; these emissions would be the

result if fossil fuels were burned to 

generate the same amount of electricity.

Because this system is designed to have 

a life expectancy of 20 years, the cumulative benefits for the environment are

many.

Special Design Considerations

PowerGuard PV tiles were used to reroof

the building, saving on the cost of conventional roofing material. The patented

PowerGuard tiles incorporate high-efficiency polycrystalline silicon cells from

Solarex. Site conditions were favorable

for this sytem: 38° latitude; a dry, sunny

climate throughout most of the year; and

no shading. The system features horizontal tiles and tiles with an 8° southerly tilt

for greater annual energy production. In

addition to generating clean renewable

energy, the lightweight system provides

R10 roof insulation for improved building

comfort and membrane protection for

extended roof life. Installation took only

7 days to complete once the building's

old roof was replaced with a new singleply membrane roof.

PV System Configuration

A 40-kW PowerGuard building-integrated

PV system was installed at the Elverta

Maintenance Facility in Western's Sierra

Nevada Region to function as both a roof

and solar electric photovoltaic (PV) power

plant. Phase I modules were installed in

parallel strings containing 56 modules per

string (7 series, 8 parallel).

design briefs: Western Area Power Administration 25

A view of the rooftop of the Elverta facility after the PV system installation.

A PowerLight rooftop PV system is installed on Western’s facility in

Elverta, California.

PIX08452 PIX08450
PV Module Mounting and

Attachment Details

The panels are designed to interlock

using a tongue-and-groove assembly.

Panels with 3/8-in. concrete topping,

instead of PV modules, are set among 

the PV panels to allow working access

throughout the roof. Along the edges 

of the PVarray, a steel ribbon links the

modules together, in order to connect

everything structurally.

26 design briefs: Western Area Power Administration 

The temperature curves show how the PV-integrated roof compares with various roofs without solar electric

systems. Roof-integrated PV with integral insulation reduces a building’s heat load as much as 23°C. The

measurements were derived from sensors placed in representative roof specimens.

02527230m

Workers carry PV modules with attached foam backing in preparation for

rooftop mounting. Smaller panels with concrete topping were also

installed as a walking surface.

PIX08453
Description 

This 38-kW BIPV system supplements the

Phase I system. Both systems completely

cover the Elverta roof and are the largest

PV application of its kind in the United

States. Phase II is totally funded and

owned by Western. The PV systems utilize

thin-film amorphous silicon technology.

The DC output from the PV modules is

converted to 240 V AC by means of a 

custom-built 32-kW Trace inverter, and

then stepped up to 480 V, three-phase 

AC by a 45-kVA transformer for direct 

connection to the building's service

panel. Besides replacing grid power, the

Powerlight system protects the roof 

membrane, which extends its life. The roof

system also provides R10 insulation to

reduce cooling and heating loads, thereby

decreasing energy consumption.

Special Design Considerations

The flush roof design provides excellent

insulation as well as electricity, as shown

in the graph comparing roof temperature

data.

PV System Configuration

The Solarex modules were installed in

254 parallel strings, with three Solarex

modules in series per string. The modules

produce 43 watts each. The APS modules

were installed in 22 parallel strings with

12 modules in series per string. The APS

modules produce 22 watts each.

PV Module Mounting and

Attachment Details

Same as those for Phase I.

design briefs: Western Area Power Administration 27

The illustration shows how the layers in the roofs provide above-average

insulation as well as a good base for the PowerGuard PV system.

Roofing

Membrane

Solar Electric

Panel

Styrofoam®

Insulation

Substrate Roof Deck 02527234m

Phase II 

Location: Elverta, California 

Owner: U.S. Department of Energy (DOE) Western Area Power Administration

Date Completed: June 1998

Architect & Designer: DOE Western Area Power Administration, PowerLight Corporation

System Integrator: PowerLight Corporation

Structural Engineers: DOE Western Area Power Administration

Electrical Engineers: DOE Western Area Power Administration

Tradesmen Required: Electrical and building contractors

Applicable Building Codes: Standard California building codes

Applicable Electric Codes: National Electric Code

PV Product: PowerGuardTM BIPVroof tiles

Size (kWp): 38 kW DC

Projected System Electrical Output: 67,500 kWh/year

Gross PV Surface Area: 9,900 ft2

PV Weight: 5 lb/ft2

PV Cell Type: Thin-film amorphous silicon

PV Efficiency: 4%-5%

PV Module Manufacturer: Solarex (762 modules) and APS (264 modules)

Inverter Number and Size: One 32-kW AC

Inverter Manufacturer and Model: Trace Technologies

Interconnection: Utility-Grid-Connected

Phase I

Phase II
design briefs

28 design briefs: Photovoltaic Manufacturing Facility

Photovoltaic Manufacturing Facility

Location: Fairfield, California

Owner: BP Solar

Date Completed: 1993

Architect & Designer: Kiss Cathcart Anders, Architects

Structural Engineers: Ove Arup & Partners

Electrical Engineers: Ove Arup & Partners

Tradesmen Required: Glaziers, electricians

Applicable Building Codes: BOCA and California Title 24

Applicable Electric Codes: National Electric Code

PV Product: Glass laminates as curtain wall spandrel, skylight, and awning

Size: 9.5 kWp 

Projected System Electrical Output: 7.9 kW 

Gross PV Surface Area: 1,975 ft

2

PV Weight: 3 lb/ft

2

PV Cell Type: Amorphous silicon

PV Efficiency: 5%

PV Module Manufacturer: APS

Inverter Number and Size: 6 kW

Inverter Manufacturer: Omnion Corporation

Interconnection: Utility-Grid-Connected

Views looking north (top) and south show how BIPV is integrated into both the facade and the

canopy that runs the length of the building.

PIX08446 PIX08449
Description

Completed in 1993, this 69,000-ft2 manufacturing facility houses a new generation

of production lines tailored to thin-film 

PV technology. The building also incorporates into its design several applications

of thin-film solar modules that are prototypes of BIPV products.

The heart of the project is a 22.5-ft-high

BIPV glass cube containing the factory’s

control center and visitor facilities. This

cube is perched on the second floor, and

half of it is outside of the manufacturing

building, emphasizing its status as an

independent element and a prototype

that demonstrates BIPV in a typical commercial building. The cube’s PV cladding,

the solar entrance canopy, and the translucent BIPV skylight provide more than

enough energy to power the control 

center’s lighting and air-conditioning 

systems.

The production floor and warehouse

space are housed in a tilted-up concrete

shell with a steel intermediate structure

and a timber roof. Glass blocks embedded

as large-scale "aggregate" in the outside

walls provide a pattern of light in the interior during the day and on the exterior at

night. Mechanical service elements are

contained in a low, steel-framed structure

on the north side of the building. The

entry court is paved in a pattern of tinted

concrete and uplighting that represents

an abstracted diagram of solar energy

generation.

Special Design Considerations

In addition to providing a working product

development test bed for BIPV systems,

the project serves an educational function

for public and private groups. The

lobby/reception area provides display

space for products and research. A pattern cast into the paving in front of the

main entry combines a sun path diagram

with a representation of the photovoltaic

effect at the atomic level. The control

room/cube also serves an educational

design briefs: Photovoltaic Manufacturing Facility 29

Interior view shows how BIPV is

used with vertical and sloped

glazing.

PIX08447

This office interior view demonstrates the quality of light transmitted

by the approximately 5% translucent BIPV panel skylight.

PIX08448
30 design briefs: Photovoltaic Manufacturing Facility Sectional view shows office “cube” and factory. PV skylight Parapet beyond Built-up roofing Tapered insulation Metal deck Scupper & D.S. beyond Steel beam Aluminum curtain wall PV glass Elevator bulkhead beyond Oriented strand board Stainless steel panel Footing beyond Elevator pit beyond Steel stair beyond Expanded metal panel Steel guardrail Plastic coated wire Parapet beyond Built-up roofing, min. slope 1/4" per 1'-0" to drain Wood frame roof - See structural dwgs Glu-lam beam Braced frame beyond glass Aluminum frame Vision glass GWB Steel column Wainscot Concrete base @ column Concrete slab Spread footing beyond - see structural dwgs Integral duct Flashing PV awning Concrete walk Receptionist's booth, see sheet A39 D.1 REFER TO MECHANICAL DWGS FOR ALL MECHANICAL LOCATIONS Vision glass, tempered glass, type B, typ. Plywd panels

2'-6" 5'-0" 5'-0" 5'-0"

2'-6"

8'-4 1/4" 1'-9"

2'-6"

7

A39

6

A16

C 5'-0"

C

CCCC

2'-7" 12'-4 3/4" 3A37

5

A37

6

A37

2

A37

Vision glass, tempered type D typ.

4

A37

02527210m
design briefs: Photovoltaic Manufacturing Facility 31 The PV awning provides a sunscreen. PV panel Panel connection below Purlin below Panel wiring points typ. Light fixture below (25' O.C.) Curved Stainless panel below Vertical Stainless stiffener 3352.8 2743.2 3 Awning Plan 1/2" = 1'0" 6 Axonometric NTS PV panel Purlins Frame Bracing rods Light fixture Stainless steel awning assembly above slab above slab 1 Awning Section 1/2" = 1'0" 381 381 152.4152.4 381 1066.8 381 914.4 533.4 533.4 914.4 381 3505.2 1828.8 Typ. braced bay (see A06-A07 for locations) Typ. awning bay (see A06-A07 for locations) East end bay (West end opposite hand) eq. eq. typ. PV spacing See structural drawings for frame dimensions 1,2 A40 14 15 C 330.2 406.4 508 typ. PV connection point spacing 914.4 02527206m
32 design briefs: Photovoltaic Manufacturing Facility

Built-up roofing, min. slope 1/4" per 1'-0" to drain

Tapered insulation

Metal deck

Steel beam

Aluminum curtain wall

PV glass

Expanded metal pane

Plastic coated wire

Steel guardrail

REFER TO MECHANICAL DWGS FOR

ALL MECHANICAL LOCATIONS

Flashing

8

REFER TO SHT. A/20 FOR LOCATIONS OF

WALL OPENINGS AT TILT-UP PANELS

7

+15'-0"

T.O.Mezz.

+0'-0"

T.O.Slab

+25'-0"-26'-8"

T.O.Frame varies

+27'-8"

T.O.Conc. tilt-up wall

+35'-2 1/2"

T.O.Cube

7.9 7.8 7.2 7.1 6.8 6.5 1'-9" 8'-4 1/4" 7'-6"

Plywood interior finish panels

Vision glass tempered glass type D, typ.

1 Section looking south through cube

Scale: 1/4"=1'-0"

12'-4 3/4" 2'-7"

7

A37

8

A37

9

A37

12'-4 3/4" 22'-9 1/2"

PV skylight

02527208m

Sectional view indicates skylight configuration and curtain-wall facade.
function; a raised platform allows groups

of visitors to view the control equipment,

and beyond it, the production line.

Computerized monitoring equipment displays the status of the PV systems as well

as information regarding building HVAC

and lighting energy use, exterior ambient

conditions, insolation, and other data.

Wherever possible, the PV systems are

designed to do double duty in terms of

energy management by reducing heat

gain while providing power. The curtain

wall and skylight are vented, eliminating

radiant heat gain from the modules and

enhancing natural ventilation in the cube.

The awning is designed to shade the row

of south-facing windows that open into

the production area and employee

lounge. The cube curtain wall integrates

PV modules with vision glass in a 

standard pressure plate curtain wall 

framing system, modified to be selfventilating. The system is intended to 

be economical and adaptable to new 

construction or retrofit.

PV System Configuration

The PV module is a nominal 2.5 ft x 5.0 ft,

a-Si thin-film device rated at 50 Wp stabilized. The PV system contains 84 full-size

modules mounted on the awning, 91 modules installed in the curtain wall, and 8 in

a skylight. The curtain wall modules are

installed in custom sizes as required by

architectural conditions. The system has 

a total capacity of 7.9 kW; because of the

varying orientations of the modules, the

peak output is 5 kW. Despite the hot local

climate, the power consumed by the cube

for cooling and lighting never exceeds

3.5 kW, producing a surplus of PV power

which is directed into the main building

grid.

PV Module Mounting and

Attachment Details

Standard PV modules are 31 in. x 61 in.

but can be produced in custom sizes as

required to fit the framing requirements of

the curtain wall. One unique feature is

that the modules are glass-to glass laminated products. The modules are installed

with an insulated inner liner, which forms

a plenum for ventilation. Heat radiated

into the curtain wall plenum is vented to

the outside by natural convection through

holes drilled in the horizontal mullions. In

some cases, the hollow vertical mullions

are used as ducts to direct the warm air

upward.

The skylight panels are standard modules

that transmit approximately 5% of the

sunlight through the laser scribe lines.

The PV modules are supplemented by

clear glazing units to increase light transmission. Another unique feature of this

BIPV system is that the skylight is vented

to remove heat gain from the modules. 

The awning panels are bolted through the

steel tube awning structure to aluminum

channels epoxied to the encapsulating

glass. This is the attachment used in typical field-mounted arrays.

design briefs: Photovoltaic Manufacturing Facility 33
design briefs

34 design briefs: Yosemite Transit Shelter

Yosemite Transit Shelters

The transit shelter prototype makes use of both high-tech and low-tech materials, combining

locally forested lumber with BIPV panels.

02527238m

Location: Yosemite National Park, California

Owner: U.S. Department of Interior, National Park Service

Date Completed: Scheduled for system completion in 2001

Architect & Designer: Kiss + Cathcart, Architects

Structural Engineers: Ove Arup & Partners, Structural Engineers

Electrical Engineers: None; design overview provided by inverter manufacturer

Tradesmen Required: Standard Contractor/Carpenter and Electrician

Applicable Building Codes: National Park Service, self-regulating

Applicable Electrical Codes: National Park Service, self-regulating

PV Product: Amorphous silicon glass panels

Size: 560 Wp per transit shelter

Projected System Electrical Output: 1.15 MWh/yr

Gross PV Surface Area: 112 ft

2

PV Weight: 3.375 lb/ft

2

PV Cell Type: Amorphous silicon

PV Efficiency: 6%

PV Module Manufacturer: Energy Photovoltaics, Inc.

Inverter Numbers and Size: 1 kW

Inverter Manufacturer: Advanced Energy Systems

Interconnection: Optional—Grid-Connected or Stand-Alone
Description

Yosemite National Park is one of the most

treasured environments in the United

States – and also the site of serious vehicular traffic congestion. The National Park

Service is working to reduce traffic and

pollution in Yosemite by expanding the

shuttle bus service and introducing electric shuttle buses. This necessitates an

infrastructure of combined weather shelters and information boards at the new

shuttle stops.

Funded by DOE FEMP, Kiss + Cathcart,

Architects, is under contract to NREL to

design a prototypical bus shelter incorporating BIPV panels. The park will begin

installing the first of 19 new shuttle stops

in the summer of 2000. The shelters that

are near existing electrical lines will send

the power they generate into the utility

grid system serving Yosemite; the more

remote shelters will have battery storage

for self-sufficient night lighting.

Special Design Considerations

The design mandate for this project is to

balance a sense of the rustic historical

building style of the Yosemite Valley with

the frankly technological appearance of

BIPV systems. The overall structure is 

a composite of heavy timber and steel

plates that serves two purposes: accommodating heavy snow loads with minimum structural bulk and projecting an

appearance that is rustic from a distance

but clearly modern in a close-up view. 

The structural timbers (unmilled logs 

from locally harvested cedar) are split 

in half, and the space between them is

used for steel connections, wiring, and

mounting signage. The BIPV roof structure is made of a single log cut into eight

separate boards.

A shallow (10°) tilt was chosen for the PV

roof. A latitude tilt of approximately 37°

would provide the maximum annual output in an unobstructed site; however, a

shallower angle is better suited to

Yosemite because of the considerable

shading that occurs at low sun angles in

the valleys, especially in winter. A steeper

slope would also have made the shuttle

stop much taller, significantly increasing

structural loading and demanding a heavier structure. This was determined to be

undesirable in terms of both appearance

and material use. 

PV System Configuration

Fourteen semitransparent, 40-W thin-film

modules make up the PVsystem for each

shelter. Power is fed to a single inverter.

Some systems will be grid-connected and

some will be stand-alone with batteries

for backup.

PV Module Mounting and

Attachment Details

The PV roof of the shelter is not designed

to be watertight like the roof of an

enclosed building. Instead, it is designed

to be waterproof so that water does not

drip through the roof in normal weather

conditions. Therefore, the PV modules are

overlapped (shingled) slightly along the

center seam, and sheet metal gutters are

inserted at the seam between the rough

wood rafters and the modules.

design briefs: Yosemite Transit Shelter 35

Yosemite National Park

Dave Parsons, NREL/PIX00923
design briefs

36 design briefs: Sun Microsystems Clock Tower

Sun Microsystems Clock Tower

North-facing view of

the clock tower at Sun

Microsystems facility.

ASE Americas, Inc./PIX07044

Location: Burlington, Massachusetts

Owner: Sun Microsystems

Date Completed: October 1998

Architect & Designer: HOK Architects and ASE Americas, Inc.

Structural Engineers: Whiting-Turner Contracting Co.

Electrical Engineers: Enertech Engineering

Tradesman Required: Glaziers, electricians

Applicable Building Codes: Uniform Building Code

Applicable Electrical Codes: National Electric Code Section 620

PV Product: BIPV curtain wall

Size: 2.5 kWp

Projected System Electrical Output: 2.5 kWp

Gross PV Surface Area: 827 ft

2

PV Weight: 8.3 lb/ft

2

PV Cell Type: Polycrystalline silicon manufactured by ASE Americas, Inc.

PV Efficiency: 12.8%

PV Module Manufacturer: Pilkington Solar International

Inverter Number and Size: One 2.5 kWp inverter

Inverter Manufacturer and Model: Omnion Power Corp.

Interconnection: Utility-Grid-Connected
Description

ASE Americas recently provided the

design, PV panels, and electronic equipment needed to power an 85-ft high clock

tower on Sun Microsystems' new 1 million

ft2 campus in Burlington, Massachusetts.

The architects who designed the building

included both electrically active and electrically inactive glass panels on four sides

of the tower. The electrically active panels

incorporating PV modules were used on

the east and west sides. A diffuse light

pattern washes around the edges of the

solar cells in the inside of the tower to 

create a soft look in the interior. The clock

tower load is primarily a nighttime load.

Energy from the PV array goes into the

building by day, and the clock tower

draws power at night from the building's

electrical grid. This could be the first use

of dual-glazed, thermally insulated PV

panels in a U.S. building structure.

Special Design Considerations

The PV panels were custom designed to

match the dimensions of the Kawneer

Series 1600 mullion system used on the

four sides of the clock tower. They were

fabricated as dual-glazed, thermally 

insulating panels with a glass-cell-glass

laminate as the outer surface and a

frosted glass sheet as the inner surface.

Some of the panels were required to wrap

around the clock, so three different basic

shapes were designed with round cusps

cut out of the corners to match the curvature of the round, 7.5-ft-diameter clock.

Two rectangular shapes were required so

the panels were vertically arranged to

match the floor levels. 

PV System Configuration

The PV modules are connected in series

and feed electricity into an inverter that

converts the 2.5 kW DC power to AC.

PV Module Mounting and

Attachment Details

Eight electrically active panels were fuly

wired and interconnected through an

inverter and transformer into the building

wiring as a utility-interactive system.

These systems are the simplest and most

economical way to install a PV power

source. There are no batteries in this type

of system, since the system draws power

from the building's electrical grid.

design briefs: Sun Microsystems Clock Tower 37

Pilkington Solar International’s

project leader, John Goldsmith, is

shown with the integrated curtain

wall on the south and west faces 

of the clock tower.

East view of the clock tower shows BIPV installation.

ASE Americas, Inc./PIX07042

ASE Americas, Inc./PIX07045
design briefs

38 design briefs: State University of New York, Albany

State University of New York, Albany

Looking southeast

at the Center for

Environmental

Sciences and

Technology

Management

Location: Albany, New York

Owner: State University of New York, Albany

Date Completed: Summer 1996

Architect: Cannon Architects

Electrical Engineer: Cannon Architects

Solar Consultant: Solar Design Associates, Inc.

Tradesmen Required: Beacon Sales Corporation, roofing contractors

Applicable building codes: New York State Building Code and ANSI Z97.1

Applicable electrical codes: National Electric Code

PV product: Kawneer 1600 PowerWallTM 

Size: 15 kWp

Project System Electrical Output: 19,710 kWh / yr.

Gross PV Surface Area: 1,500 ft

2

PV Weight: 1.93 lb / ft

2

PV Cell Type: Polycrystalline silicon

PV Cell Efficiency: 12%

PV Module Manufacturer: Solarex

Inverter Number and Size: AES 250 watt

Inverter Manufacturer and Model: Advanced Energy Systems Micro Inverter

Interconnection: Utility-Grid Connected

Gordon Schenck/PIX084
Description

For the new Center for Environmental

Sciences and Technology Management

(CESTM) at the State University of New

York in Albany, Cannon Architects developed an energy-conscious design strategy. This strategy included the integration

of solar electric systems into both the

building and the project site as landscape 

elements. The building incorporates

15 kWp of custom PV modules in buildingintegrated sunshades that support the 

PV modules while reducing cooling loads

and glare on the south facade. The PV

modules feature module-integrated

inverters.

Special Design Considerations

This system was the first of its kind in the

United States to tie together more than

2 kW of AC modules, and the first to use

the AC module platform for a sunshade.

AC modules proved to be far more effective than a typical single inverter, given

the different light levels on the modules

over the course of a day.

PV System Configuration

There are two different system configurations in the CESTM solar system. The 

sunshade portion consists of 59 pairs of

framed Solarex MSX 120 modules. Each

pair is connected to its own accessible AC

micro-inverter. The inverters are installed

inside the building for ease of service. The

landscape portion consists of 18 pairs of

Solarex MSX 240 modules. An AC microinverter is attached to the underside of

each pair.

PV Mounting and Attachment

Details

Solarex provided framed PV modules that

were modified to incorporate the AES

micro-inverters. Most of the modules

were mounted in an aluminum strut, 

creating a solar sunshade. The rest of the

modules were mounted above ground,

along a curved pathway at the main

approach to the building. The building’s

sunshades use standard extrusions from

the Kawneer curtain wall system, the

Kawneer 1600 PowerWallTM. This custom

configuration provided structural support

to the modules.

design briefs: State University of New York, Albany 39

Close-up view of photovoltaic sunshade

Gordon Schenck/PIX08464
design briefs

40 design briefs: Navajo Nation Outdoor Solar Classroom

Navajo Nation Outdoor Solar Classroom

Each new BIPV structure at the Seba Dalkai School will serve as an open-air classroom

supported by timber columns in a concrete foundation.

Location: Seba Dalkai, Navajo Reservation, Arizona

Owner: Seba Dalkai Boarding School

Scheduled Completion Date: Fall 1999

Architect: Kiss + Cathcart, Architects

Electrical Engineer: Energy Photovoltaics, Inc.

Solar Consultant: Kiss + Cathcart, Architects

Tradesmen Required: Electricians, laborers

Applicable Building Codes: Standard building codes

Applicable Electrical Codes: National Electric Code

PV Product: Energy Photovoltaics EPV-40 modules

Size: 4.0 kWp

Projected System Electrical Output: 5,818 kWh/yr

Gross PV Surface Area: 625 ft

2

PV Weight: 3.75 lb/ft

2

PV Type: Amorphous silicon

PV Efficiency: 6%

PV Module Manufacturer: Energy Photovoltaics, Inc.

Inverter Number and Size: Four 2.5 kW inverters

Inverter Manufacturer: Trace Engineering

Interonnection: Stand-Alone System

02527276m 02527274m
Description

The Seba Dalkai Boarding School, a

Bureau of Indian Affairs school on the

Navajo Reservation in Arizona, is constructing a new K-8 facility to be completed in 2001. Funded by DOE FEMP, this

facility will incorporate a BIPV system

capable of producing approximately

4.0 kW of electricity.

The school is currently housed in a 

traditional hogan and in a stone facility

built in the 1930s. These will remain and

be juxtaposed with a new school facility.

The photovoltaic component of this 

project will mediate between the old and

the new, and it will add a structure that

clearly expresses solar technology and

BIPV principles. Funded by DOE FEMP,

this structure will serve as an outdoor

classroom and as part of the school’s

HVAC circulation system. It will also be a

hands-on laboratory for educating people

about BIPV systems and training them in

system installation.

Special Design Considerations

The installation is designed to minimize

the cost of the support structure while

incorporating sustainable construction

materials. Within an enforced simplicity,

the design attempts to establish a connection with Navajo building traditions.

PV System Configuration

The design includes two 25-ft x 25-ft,

open-sided, timber-framed structures.

Each one supports 2.88 kW of semitransparent PV modules, and each one

includes two Trace 2.5-kW inverters plus

batteries for three days’ worth of energy

storage. Each structure will function as an

open-air classroom.

PV Mounting and Attachment

Details

The PV modules are attached with aluminum extrusions fixed with silicone to

the back of the glass (four per module).

Each aluminum channel is 12 ft long. The

channels are supported on a grid of rough

timber beams, which in turn are supported by timber columns on concrete

foundations.

design briefs: Navajo Nation Outdoor Solar Classroom 41

The design attempts to establish a connection with Navajo building traditions.

02527275m
design briefs

42 design briefs: General Services Administration, Williams Building

General Services Administration, Williams Building

The nine-story Williams Building in Boston 

(at right in photo above) has a new BIPV roof

(bottom, lower right photo) rather than a

conventional one.

Location: 408 Atlantic Avenue, Boston, Massachusetts

Owner: U.S. General Services Administration

Date Completed: September 30, 1999

Project Developers: Enron Energy Services and U.S. General Services Administration

Electrical Engineer: PowerLight Co.

Solar Consultant: PowerLight Co.

Tradesmen Required: Electricians and roofers

Applicable Building Codes: Standard building codes

Applicable Electrical Codes: National Electric Code, Boston Electric Interconnection Guidelines, and IEEE

Specifications

PV Product: PowerLight, using ASE Americas, Inc., solar panels

System Size: 37 kW DC, 28 kW AC

Projected System Electrical Output: 50,000 kWh/yr

Gross PV Surface Area: Approx. 3,800 ft

2

PV Weight: 4 lb/ft

2

PV Cell Type: Amorphous silicon

PV Efficiency: 12%

PV Module Manufacturer: ASE Americas, Inc.

Inverter Number and Size: 1 30 kVa 

Inverter Manufacturer: Trace Engineering

Interconnection: Utility-Grid-Connected

PIX08465

PIX08474
Description 

In this project, a regularly scheduled roof

replacement was upgraded to the installation of a building-integrated photovoltaic

roof. The BIPV roof is installed on the

Williams Building in downtown Boston.

The U.S. Coast Guard is the leading tenant

of this 160,000-ft2 building, which sits on

Rowe’s Wharf at 408 Atlantic Avenue, near

the city’s financial district.

In addition to the new PV system for the

roof, the building is also switching from

district steam to on-site gas boilers. Two

75-kW Teco-gen co-generation units are

also being added, as well as a highefficiency chiller, more efficient lighting,

and upgraded, more efficient motors.

Special Design Considerations

The building is located on a wharf, so the

design must take into account not only

the water but also 140-mile-per-hour wind

conditions at the site.

After a site review, including a review of

the wind conditions, the contractor

decided to use a PowerLight RT photovoltaic system. The RT system was chosen

for its cost-effectiveness when extreme

roof penetrations are required (for example, with penthouses, skylights, and HVAC

frames).

PV System Configuration

This system produces 37 kWp DC and

28 kW AC. Its 372 PV panels are connected in sets of 12. Each panel has a

maximum output of 100 watts. 

PV Mounting and Attachment

Details

A metal raceway, ballast, and anchoring

system is used. It was also necessary to

add rigid insulation for thermal protection.

The PowerLight RT system is fastened to

the roof along its perimeter using epoxyembedded anchors set into the concrete

deck. These use pitch pans and a raceway

for moisture protection. The system

allows water to flow under the

PowerGuard to existing roof drains. It

should not be necessary to add new

drains.

A harness from the panels goes through

two conduits into attic space located

above the eighth floor. Part of the attic

needed additional metal decking.

design briefs: General Services Administration, Williams Building 43 PIX08473 PIX08472 PIX08471 PIX08470

View of the new BIPV roof on

the Williams Building, during

and after construction

Pavers are in foreground, PV array is in background on

the rooftop.

Wiring for the rooftop installation

Paul King, DOE Boston Regional Office FEMP

liaison, surveys the installation work.
44 design briefs: General Services Administration, Williams Building

The plan for the roof of the Williams Building included a rooftop BIPV system consisting of 372 solar panels.02527263m

Co-funded by the DOE FEMP Renewable Energy

Program, this BIPV application illustrates how the

technology can be introduced into complex roof spaces.

Jeff Ansley, PowerLight Corporation/PIX08461

Shading from other buildings is not a problem at this

site, which is in urban Boston.

Jeff Ansley, PowerLight Corporation/PIX08466
design briefs

design briefs: Academy of Further Education 45

Academy of Further Education

The Academy of Further Education under construction in Herne, Germany

Location: Herne, North Rhine-Westphalia, Germany

Owner: EMC, Ministry of Interiors of North Rhine-Westphalia, City of Herne

Date Completed: May 1999

Architect & Designer: Jourda et Perraudin Architects, HHS Architects

Structural Engineers: Schleich, Bergermann and Partner

Electrical Engineers: HL-Technik

Tradesmen Required: Glaziers, electricians

PV Product: BIPV roof

Size: 1 MWp

Projected System Electrical Output: 750,000 kWh/yr

Gross PV Surface Area: 10,000 m

2

PV Weight: 130 kg per each 3.2 m

2 module

PV Cell Type: Polycrystalline and monocrystalline silicon

PV Efficiency: 12.8% to 16%

PV Module Manufacturer: Pilkington Solar International, Cologne

Inverter Number and Size: 600, 1.5 kW

Inverter Manufacturer and Model: SMA, Kassel

Interconnection: Utility-Grid-Connected

PIX08454
Description

As part of the International Construction

Exhibition, Emscher Park, the site of a former coal mine in Herne, Germany, is being

used for a new purpose. A comprehensive

urban development plan is providing the

district of Sodingen with a new centerpiece: the Academy of Further Education,

Ministry of Interior, North RhineWestphalia.

The large glass hall incorporates not only

the Academy but also a hotel, library, and

administrative municipal offices. The

glass hall is multifunctional. It protects

the interior from harsh weather and uses

solar energy both actively and passively

by producing heat as well as electric

power.

Special Design Considerations

Approximately 3,180 multifunctional roof

and facade elements are the core of the

solar power plant. With a total area of

10,000 square meters, most of the roof

and the southwest facade is covered by

photovoltaics, making this system the

largest building-integrated PV power

plant in the world. It produces approximately 750,000 kWh of electric power 

per year. This is enough to supply more

than 200 private residences. About

200,000 kWh is used directly by the

Academy building, and the remaining

550,000 kWh is fed into the public power

grid in Herne.

PV System Configuration

The Optisol photovoltaic elements were

produced by Pilkington Solar at a site in

Germany. The PV system consists of solar

cells embedded between glass panes.

Daylighting needs were taken into

account in designing the roof- and facadeintegrated system. The PV modules have

areas of 2.5 to 3.2 square meters and an

output of 192 to 416 peak watts each. This

makes them larger and more powerful

than most conventional solar modules.

Direct-current electricity is converted to

230 V alternating current by means of 

a modular inverter. This is made up of

roughly 600 decentralized string inverters

and allows optimal use of the incident

solar radiation.

Mounting and Attachment

Details

The building-integrated photovoltaic 

panels are set into aluminum mullions

like skylights. The rooftop panels are

positioned at an angle to capture as much

of the incident sunlight as possible.

46 design briefs: Academy of Further Education

An inside view of the Academy building as construction progressed

This photo shows how the PV panels are angled to capture the sunlight

shining on the roof.

PIX08455 PIX08456
design briefs: Academy of Further Education 47

Rooftop view shows placement of insulation and PV panels.

PIX08457
design briefs

48 design briefs: Discovery Science Center

Discovery Science Center

Architect’s rendering

of the Discovery

Science Center Cube

in Santa Ana,

California

Location: Santa Ana, California

Scheduled Completion Date: November 1999

Architect & Designer: Arquitectonica for the cube, Solar Design Associates for the PV system

Structural Engineers: Advanced Structures, Inc.

Electrical Engineers: Solar Design Associates, Inc.

Tradesmen Required: Electricians

Applicable Building Codes: Building Administrators Code Administrators International (BOCA)

Applicable Electrical Codes: National Electric Code 

PV Product: Thin-film photovoltaic system

Size: 20 kWp

Projected System Electrical Output: 30,000 kWh/yr

Gross PV Surface Area: 4,334 ft

2

PV Weight: 3 lb/ ft

2

PV Cell Type: Thin-film technology

PV Efficiency (%): 5.1 %

PV Module Manufacturer: BP Solarex Inverter Number and Size: 4

Inverter Manufacturer and Model: Omnion 2400, Model 5015

Interconnection: Utility Grid-Connected

Solar Design Associates, Inc./02527271
Description 

This solar electric system, located in

Santa Ana, California, boasts one of the

world's largest building-integrated thinfilm applications to date. The PV-covered

surface of the cube is tilted at 50° for 

maximum visual impact and optimal solar

harvest. BP Solarex's Millennia modules

cover the entire 4,334-ft2 top of the cube

The thin-film modules are treated as an

architectural glazing element, replacing

what would have been a glass canopy.

They produce up to 20 kW of DC electricity

at mid-day and 30,000 kWh of electrical

energy per year, which is enough to run

four typical homes. 

The solar energy system is connected 

to the Discovery Science Center's main

utility line. When the solar system produces energy, it feeds the energy to the

Science Center, displacing conventional

utility power. When the solar system 

produces more electricity than the

Science Center needs, the excess electricity is "exported" to the utility, thereby

effectively spinning the electric meter

backwards.

design briefs: Discovery Science Center 49

The view from inside the cube

Solar Design Associates, Inc./02527277m
design briefs

50 design briefs: Solar Sunflowers

Solar Sunflowers

These Solar Sunflowers

track the sun to produce

electricity.

Location: Napa, California

Date Completed: N/A

Architect & Designer: Solar Design Associates, Inc.

Structural Engineers: Solar Design Associates, Inc.

Electrical Engineers: Solar Design Associates, Inc.

Tradesmen Required: Electricians

Applicable Building Codes: Building Officials Code Administrators International (BOCA)

Applicable Electrical Codes: National Electric Code

PV Product: BP Solarex

Size: 36,000 Wp

Projected System Electrical Output: N/A

Gross PV Surface Area: 3,456 ft

2

PV Weight: 3.4 lb/ ft

2

PV Cell Type: Polycrystalline

PV Efficiency: 11.1%

PV Module Manufacturer: BP Solarex

Inverter Number and Size:6

Inverter Manufacturer and Model: Omnion Series 2400, Model 6018

Interconnection: Utility-Grid-Connected

PIX08468
Description 

Nestled atop a hillside in Northern

California, 36 Solar Electric Sunflowers

represent an elegant combination of art

and technology. The clients requested an

unconventional and artistic installation.

They got just that.

Just like a sunflower, the Solar Electric

Sunflowers look and act like nature's own

variety. Making use of a two-axis tracking

system, the sunflowers wake up to follow

the sun's path throughout the day,

enabling the system to produce enough

energy for eight to ten homes. 

design briefs: Solar Sunflowers 51

Solar electric sunflowers resemble nature’s own.

PIX08467
design briefs

52 design briefs: Ijsselstein Row Houses

Ijsselstein Row Houses

Fourteen planned new row-house units in the Netherlands demonstrate the aesthetic use of

building-integrated photovoltaics: front (above) and back views.

Location: Ijsselstein Zenderpark, Ijsselstein, The Netherlands

Date Completed: Scheduled for completion in late 2000

Architect & Designer: Han Van Zwieten, Van Straalen Architecten, co-designer; Gregory Kiss, Kiss + Cathcart 

Architects, co-designer

Structural Engineers: N/A

Electrical Engineers: N/A

Tradesmen Required: Building tradesmen

Applicable Building Codes: Dutch Building Code

Applicable Electrical Codes: Dutch Electrical Code

PV Product: Standard-size BIPV glass laminate panels

Size: 1.6 kWp per housing unit

Projected System Electrical Output: 1150 kWh/year per housing unit

Gross PV Surface Area: 30 m

2 per housing unit

PV Weight: 3.75 lb/ft

2

PV Cell Type: Amorphous silicon, both opaque and 15% translucent

PV Efficiency: 6% 

PV Module Manufacturer: EPV

Inverter Number and Size: N/A

Inverter Manufacturer and Model: N/A

Interconnection: Utility-Grid-Connected

02527269m 02527270m
Description

This Dutch-American design collaboration

is intended to develop a new standard in

Europe for moderately priced housing

with integrated solar electric systems. The

first phase consists of 14 row-house units,

each with its own grid-connected BIPV

array. As part of a highly ordered "new

town" development adjacent to the city

center of Ijsselstein, these units conform

to strict space and budget guidelines 

as well as to advanced standards of PV

integration.

The overall design is a composition of

brick volumes and two-level, woodframed sunrooms. The latter are partially

clad in opaque and translucent PV units,

and they are raised and staggered to 

maximize solar exposure. The sunroom

volumes are wood-paneled on the sides

facing north.

The Netherlands is home to some of the

most advanced PV systems in the world.

However, before this project began, little

work had been done on integrating solar

arrays into the prevailing Dutch architectural idiom of abstract cubic forms. The

Ijsselstein row houses demonstrate how

photovoltaics can be a fully participating

element in the design, rather than just 

an applied system. Amorphous silicon

modules in particular are generating very

positive responses among many Dutch

architects, who perceive them as looking

much more like an architectural material

than polycrystalline panels do.

Special Design Considerations

In marked contrast to the United States,

The Netherlands favors residential design

that is largely modern and rational in

character. The ubiquitous pitched roofs 

of North American houses (which provide

convenient mounting surfaces for PV

arrays) were considered aesthetically

undesirable at Ijsselstein. However, at

higher latitudes with low sun angles, vertically mounted BIPV panels can generate

power at output levels competitive with

those of optimally angled panels. The

design takes advantage of this by using

standard-sized units as glazing and 

exterior enclosure combined in a simple

wooden frame wall. 

Extensive computer modeling studies

were done to ensure that the complex

massing of the row houses works to provide maximum solar exposure for each

unit’s array and minimum shadowing of

BIPV surfaces by adjacent units. 

Given that BIPV glass is a major cladding

component for the sunroom elements,

excessive interior heat loss or gain was 

a significant design consideration. The

adjacent stair serves as a convection

chimney that actually uses the heated 

air produced in the sunrooms to draw air

currents through the entire row house,

cooling it in warm weather. Cold weather

conditions are addressed simply by 

providing a suitable layer of insulation

between the cladding and the interior 

finish. 

PV System Configuration

A 1.6-kW, grid-connected BIPV system is

part of each row house. Each system will

be individually metered, and there is no

battery storage.

PV Module Mounting and

Attachment Details

Standard PV modules are set into a wood

framing system, which can be either sitebuilt or prefabricated. The opaque units

are set as typical single glazing, using

minimum-profile glazing stops and caulk.

The translucent panels are incorporated

into double-glazed window units. The 

horizontal members of the wood frame

have an absolute minimum exposed

depth to prevent shadowing. The vertical

members, which are not as likely to interfere with solar exposure, have a raised

profile.

design briefs: Ijsselstein Row Houses 53 M.K.M.K.

rooster

Sample floorplans for row-house units

02527268m
design briefs

54 design briefs: Denver Federal Courthouse

Denver Federal Courthouse

The U.S. Court House expansion in Denver will be a showcase for sustainable building design.

Location: Denver, Colorado 

Owner: U.S. General Services Administration

Date Completed: Scheduled for completion in 2002

Architect & Designer: Anderson Mason Dale (Architects); Hellmuth, Obata, & Kassabaum, St. Louis 

(Designers); Architectural Energy Corporation (Energy Consultants)

System Integration: Altair Energy (PV Consultant)

Structural Engineers: Martin/Martin, Inc.

Electrical Engineers: The RMH Group, Inc.

Tradesman Required: Building tradesmen/glaziers

Applicable Building Codes: Uniform Building Code (1997)

Applicable Electric Codes: National Electric Code (1999)

PV Product: Custom-sized BIPV glass laminate

Size: 15 kWp (roof); 3.4 kWp (skylight)

Projected System Electrical Output: 20,150 kWh per year (roof); 4,700 kWh per year (skylight)

Gross PV Surface Area: 172 m

2 (roof); 59 m2 (skylight)

PV Module Weight: 4,661 kg (roof); 2,749 kg (skylight)

PV Cell Type: Single- or polycrystalline silicon

PV Efficiency: 10% or greater

PV Module Manufacturer: Pilkington Solar

Inverter Number & Size: One 20-kW and one 3.4-kW inverter

Suggested Inverter Manufacturers: Trace Technologies, Trace Engineering, Omnion

Interconnection: Utility-Grid-Connected

02527279m
Description

The United States Courthouse Expansion

in Denver, Colorado, consists of 17 new

courtrooms and associated support

spaces for an additional 383,000 ft2

(35,600 m2). The U.S. General Services

Administration (GSA) approached the

expansion of this Federal Courthouse in

downtown Denver as a showcase building

for sustainable design. One of the GSA’s

project goals was to "use the latest available proven technologies for environmentally sensitive design, construction, and

operation. It should set a standard and be

a model of sustainable design." Another

goal was to create a building that would

remain usable for its 100-year lifespan.

The design projects an image of respect

and reflects the city’s rich architectural

heritage. The 11-story structure houses 

six floors of district courts, two floors of

magistrate courts, offices for the United

States Marshal, a jury assembly area, 

and a special proceedings courtroom.

Anderson Mason Dale P.C. is the architect

of record, and HOK served as the design

architect.

Recalling a traditional town square 

courthouse, the two-story pavilion is an

arrangement of two geometric forms

under a large horizontal roof. It is the 

frontispiece of the entire composition. 

An open peristyle colonnade supports 

the roof and transparently encloses the

entrance lobby and the drum-shaped

secured lobby. As a series of vertically 

oriented rectangular planes, the 

courthouse tower caps the structure 

with an open framework and a floating

horizontal roof of photovoltaic panels.

With technical assistance provided by

FEMP, the project’s sustainable design

consultant, Architectural Energy Corporation of Boulder, Colorado, and the design

team developed the building’s overall 

sustainable design strategies. The building achieves a high level of energy efficiency through a combination of

strategies that seek first to reduce building energy loads as low as possible and

then to satisfy the remaining reduced

design briefs: Denver Federal Courthouse 55

This chart summarizes the BIPV system design:

Component Orientation Effective Size Annual

Area (m2) (kW) kWh

Roof area Horizontal 173.4 13.9 23,300

Lobby skylight Horizontal 63.6 4.4 7,400

Photovoltaics will be integrated into the top roof louver of the tower and into a skylight above the lobby rotunda. 02527278m

Standard

 Skylight

Glazing

Insulated

Photovoltaic

Glass

02527294m
loads through state-of-the-art, highefficiency mechanical and electrical systems and renewable energy sources. The

unique attributes of the Denver climate,

sunny skies and low humidity, are used

throughout the design to minimize energy

consumption. The resulting building is 

a visible expression of sustainability

through features that work together in 

an integrated energy-efficient system. 

The improved building envelope allows

substantial reductions in energy use for

lighting, ventilation, and cooling. These

reductions, along with the energy generated from the BIPV system, will make the

annual operating energy costs of the new

courthouse 43% lower than those of a

building designed according to Department of Energy standards for energy 

efficiency (10 CFR Part 436, which is

based on ASHRAE 90.1-1989). 

Energy savings were calculated by constructing a simulation model of the building that meets the minimum requirements

of the Federal Energy Standard (10 CFR

Part 435). This minimally compliant building (the base building) was the baseline

from which energy savings were calculated. A comparison of the simulated

annual energy costs for the base building

and the proposed design is shown below.

Local materials, such as precast concrete

and native stone, have been incorporated

into the exterior cladding system. The

building will have a steel frame with recycled material content. Most of the flooring

materials in the building are made from

recycled or native sources, including

native stone, cork, or recycled plastics.

Low-impact landscaping is used to minimize water use, reduce the "urban heat

island" effect, and provide an attractive

outdoor space. Low-flow lavatory faucets

and water closets will be used throughout

to minimize water use. All interior finish

materials were carefully selected on the

basis of their impacts on the environment

and occupants.

The building is crowned by a series of

glazing-integrated PV modules incorporated into the top horizontal roof louver of

the tower and the skylight element above

the cylindrical volume of the secure lobby

rotunda. This bold architectural statement

expresses both energy efficiency and

adaptation to climate. The glazingintegrated PV array at the top horizontal

roof louver of the tower is composed of

crystalline cells covering approximately

87% of the visible glazing area. This is

intended to be a highly visible element of

the building’s architecture, recognizable

from many places around the city.

The cylindrical volume of the secure lobby

rotunda culminates in an insulated BIPV

glass skylight using crystalline cells covering approximately 60% of the visible glazing area; it provides necessary shading

while generating power for the building

and making a statement about alternative

energy sources. Perimeter skylights

around the outside of the rotunda are

laminated glass. Setting the tone for 

other special places within the building, 

a perforated metal scrim ceiling diffuses

this light.

The BIPV panels provide electricity during

daylight hours, reducing the building’s

peak electricity requirements. Direct current from the BIPV system is fed into the

building’s electrical system via a DC to AC

power-conditioning unit. Since the system

is utility-interconnected, battery storage

is not necessary. Estimated total energy

production from the two systems is

approximately 25,000 kWh per year, or

about 2% of the building’s total annual

electrical consumption.

The new U.S. Federal Courthouse expansion lends an optimistic, forward-looking

image to the City of Denver while making

a strong case for sustainable design.

Inside the courthouse, the design will 

project a bright, airy appearance. "Green"

design features also improve the work

environment, which can lead to increases

in employee productivity and satisfaction.

By investing in improved materials and

systems, and using an integrated, environmentally conscious design approach,

the GSA will reduce environmental

impacts as well as long-term operating

costs. Because the courthouse expansion

has been designated a "demonstration

project" by GSA, it will be used to influence future courthouse design projects.

Special Design Considerations

The basic laminated BIPV glazing panels

are a compilation of square polycrystaline

cells measuring 125 mm x125 mm. The

manufacturing process varies the density

and coverage of these cells within the

BIPV panel to accommodate the design

intent. This ability to custom-design individual BIPV panels allowed the design

team to specify skylight panels to be more

light transmissive, thereby providing

ample illumination of the lobby rotunda,

and to design the roof louver panels with

greater opacity, thereby providing

increased power capabilities.

The laminated BIPV glazing panel of the

skylights allows the phototvoltaic system

to be responsive to indoor safety and

security requirements. Condensation concerns also required that the skylight’s

BIPV panels be integrated into an insulated glazing element.

In addition, the inside glass pane is laminated with a milk-white, PVB (polyvinyl

butyral) inner layer to diffuse direct sunlight and obscure the less visually appealing side of the crystalline cells from view.

PV System Configuration

A one-line electrical schematic is given 

for the two photovoltaic systems. The

photovoltaic modules are wired in series

and parallel to meet the voltage and current input requirements of the power 

conditioning unit (PCU). To simplify the

wiring between the PV array and the PCU,

combiners are installed near the array.

The array combiners include reverse 

current protection, surge protection, 

and series string fusing, and they provide

a convenient place for testing and

troubleshooting the PV array.

DC and AC disconnects enable proper 

disconnection and protection for the PCU.

Depending on whether the output of the

PCU is compatible with utility voltage and

grounding requirements, an external (to

the PCU) isolation transformer may be

needed. A utility-required relay mechanism provides over- and under-frequency

protection and over- and under-voltage

protection. The utility disconnect is a

redundant measure required by the utility

to ensure that the PV system will not

56 design briefs: Denver Federal Courthouse
backfeed utility lines that are not meant

to be energized. The PCU has an antiislanding feature that is the first line of

defense against undesired backfeed 

onto the utility grid. The point of interconnection can be made in any electrical 

distribution panelboard with the proper

voltage and current ratings.

Because the BIPV arrays are located in

different places on the building, each

array will be equipped with its own data

acquisition system. The data acquisition

systems will measure and record four

parameters that can be used to scrutinize

the performance of the BIPV systems.

These parameters are the four required 

by the Utility Photovoltaic Group (UPVG)

for its monitoring and rating program.

This may also make the PV systems 

eligible for cost-sharing with UPVG. The

following measurements and sensors 

will be employed:

(1) Plane-of-array global solar irradiance

(W/m2) will be measured with a Licor

pyranometer mounted on the array.

(2) Wind speed (m/s) will measured with

an NRG systems cup anemometer

mounted near the array.

(3) Ambient temperature (°C) will be 

measured with a thermistor inside 

a radiation shield mounted near the

array.

(4) PV system AC power/energy output

(kW/kWh) will be measured with a

standard accumulating energy meter

with a special pulse output device.

This device will be located near the

PCU.

The data from the two data acquisition

systems will go to a central computer via

standard telephone wire. The computer

will probably be in a busy area, such as

the special proceedings lobby, to help

educate the general public about BIPV

systems. The computer will have customdesigned software for displaying the data

in a "cockpit" format (i.e., with graphic

elements such as dials and strip charts).

Both real-time and archived data will be

available on this display, along with 

educational screens. 

PV Module Mounting and

Attachment Details

The glazing-integrated PV modules will 

be shipped to the site individually with

terminals for making electrical connections. Because the skylight installer will

mount the modules into the mullions and

make the electrical connections, the electrical connections must be very simple.

Electrical terminals are located on the

panel edges so they are concealed by 

the mullion system. Traditional modules

have a junction box mounted on the back.

Special plug-and-socket connectors will

enable easy one-wire connections to be

made between adjacent modules. The

mullions will be constructed so that individual modules may be removed for

repairs.

design briefs: Denver Federal Courthouse 57

Insulated 

Photovoltaic 

Glass

Standard 

Skylight 

Glazing

02527292m

Tower 

BIPV

Roof 

Louver

02527293m

These drawings show the position of BIPV modules on the skylight and the tower roof louver.
BIPV Basics

Photovoltaic Technologies

A French physicist, Alexandre Edmond

Becquerel, was the first to record his

observation of the photovoltaic effect

(photo denotes light and voltaic denotes

the generation of electricity) in the 19th

century. Since then, many scientists

have worked to develop energy technologies based on this effect. It is a

process in which electricity is generated

in the boundary layers of certain semiconductor materials when they are 

illuminated. Todayís photovoltaic semiconductor materials include silicon,

gallium arsenide, copper indium diselenide, cadmium sulfide, and cadmium 

telluride.

Photovoltaic materials are classified as

either crystalline, polycrystalline, or

thin-film in form. These classifications

represent the three major PV technologies. These are the building blocks for

today's commercial PV products, 

which include consumer electronics

(such as a solar-powered calculator or

watch), remote electric power systems,

utility-connected power systems, and

building-integrated systems.

One of these PV materials, silicon, is

highly abundant; it constitutes more

than 25% of the Earth's crust. Silicon is

used in more than 90% of all PV applications, including building-integrated

photovoltaics or BIPV. Silicon solar

technologies can be grouped in these

three basic areas: single-crystal silicon,

polycrystalline silicon, and thin-film 

amorphous silicon. The primary distinctions among the three technologies

are their sunlight-to-electricity conversion efficiency rates, the methods by

which they are manufactured, and their

associated manufacturing costs.

The efficiency of each BIPV product 

is specified by the manufacturer.

Efficiencies range from as low as 5% 

to as high as 15%ñ16%. A technology's

conversion efficiency rate determines

the amount of electricity that a commercial PV product can produce. For

example, although thin-film amorphous silicon PV modules require less

semiconductor material and can be less

expensive to manufacture than crystalline silicon modules, they also have

lower conversion efficiency rates. Until

these conversion efficiencies increase,

58 BIPV Basics

Cell

Module

Panel

Array

02527265m

PV Cells

PV cells are the basic building blocks

of PV modules. They are made of semiconducting materials, typically silicon,

doped with special additives. Approximately 1/2 volt is generated by each

silicon PV cell. The amount of current

produced is directly proportional to

the cell’s size, conversion efficiency,

and the intensity of light. As shown in

the figure below, groups of 36 seriesconnected PV cells are packaged

together into standard modules that

provide a nominal 12 volt (0r 18 volts

@ peak power). PV modules were 

originally configured in this manner 

to charge 12-volt batteries. Desired

power, voltage, and current can be

obtained by connecting individual PV

modules in series and parallel combinations in much the same way as 

batteries. When modules are fixed

together in a single mount they are

called a panel and when two or more

panels are used together, they are

called an array. (Single panels are also

called arrays.)

Photovoltaic device 02527264m

Light

energy

Electrical

energy p-Type

semiconductor

n-Type

semiconductor

The Photovoltaic Effect

Sunlight is composed of photons—discrete units of light energy. When photons

strike a PV cell, some are absorbed by the semiconductor material and the energy 

is transferred to electrons. With their new-found energy, the electrons can escape

from their associated atoms and flow as current in an electrical circuit.

PV arrays require no care other than occasional cleaning of the surfaces if they become

soiled or are used in dusty locations. However,

they must be kept clear of snow, weeds, and

other sources of shading to operate properly.

PV cells are connected in series, so shading

even one cell in a module will appreciably

decrease the output of the entire module.
more amorphous silicon modules will

be required to generate the same

amount of electric power produced by

other silicon-based PV modules.

Continuing research and development

in thin-film silicon should increase its

conversion efficiencies.

An important architectural consideration is aethetics, and PV modules do

differ in appearance. Single-crystalline

PV modules are dense blue (almost

black), with a flat, uniform appearance.

Polycrystalline modules are multicolored, having a variety of sparkling blue

tones. Thin-film amorphous silicon

modules are a reddish-brown to black;

the surface may appear uniform or

nonuniform, depending on how the

modules are made. Consequently, 

typical system colors are blues, browns,

and black. However, some PV manufacturers can fill special orders for colors such as gold, green, and magenta.

These color variations will result in

some loss in performance efficiencies.

BIPV Systems

PV applications for buildings began

appearing in the United States and elsewhere in the 1970s. Aluminum-framed

PV modules were connected to, or

mounted on, buildings that were usually in remote areas without access to

an electric power grid. In the 1980s, 

PV module add-ons to roofs began

being demonstrated. These PV systems

were usually installed on utility-gridconnected buildings in areas with centralized power stations. In the 1990s,

BIPV construction products specially

designed to be integrated into a building envelope became commercially

available.

Internationally, the past decade has

ushered in a myriad of BIPV demonstration buildings and other structures.

In both new projects and renovations,

BIPV is proving to be an effective 

building energy technology in residential, commercial, industrial, and institutional buildings and structures.

BIPV systems are considered to be 

multifunctional building materials, 

and they are therefore usually designed

to serve more than one function. For

example, a BIPV skylight is an integral

component of the building envelope, 

a solar energy system that generates

electricity for the building, and daylighting element.

The standard element of a BIPV system

is the PV module. Individual solar cells

are interconnected, encapsulated, laminated on glass, and framed to form a

module. Modules are strung together 

in an electrical series with cables and

wires to form a PV array. Direct or diffuse light (usually sunlight) shining on

the solar cells induces the photovoltaic

effect, generating unregulated DC electric power. This DC power can be used,

stored in a battery system, or fed into

an inverter that transforms and synchronizes the power into AC electricity.

The electricity can be used in the building or exported to a utility company

through a grid interconnection.

BIPV systems are made up of BIPV 

construction materials and balance-ofsystem (BOS) hardware. The BOS hardware is composed of cabling, wiring,

and structural elements that hold 

the modules in place, as well as 

BIPV Basics 59

02527266m

Schematic of a typical stand-alone PV system

PV array

Lightning

protection

Source

combiner

with DC

string

disconnects DC

UI

DC/AC

inverter

AC

disconnect

Utility service

connection

kWh

meter

Electrical

distribution

panel

AC to all

loads

AC

02527267m

Block diagram of a utility-interactive PV system
grid-metered connections, fault protectors, a power conditioning unit

(inverter), and an electricity storage

system (usually batteries), as needed.

Demonstrations of BIPV systems have

greatly increased people's awareness 

of the potential of BIPV products. This 

is especially true for members of the

building profession and construction

trades. At the same time, the PV industry has gained experience in designing,

manufacturing, and installing BIPV

systems. The current challenge for the

industry is to penetrate the commercial

construction market. This is being

achieved through new linkages

between PV manufacturers and the

building materials manufacturing

industry.

The economics and aesthetics of BIPV

systems are optimized when PV is 

integrated into the building during preliminary design stages. In order to be

effective, BIPV products should match

the dimensions, structural properties,

qualities, and life expectancy of the

materials they displace. Like standard

construction glass, cladding, and roofing materials, they can then easily be

integrated into the building envelope. 

Design Issues

Beyond comfort and aesthetics, BIPV

design considerations encompass both

environmental and structural factors.

Environmental factors include a structure's solar access as well as average

seasonal outdoor temperatures at the

site, local weather conditions, shading

and shadowing from nearby structures

and trees, and the site's latitude, which

influences the optimum BIPV system

orientation and tilt. Structural factors

include a building's energy requirements, which influences the size of the

system, and the BIPV system's operation and maintenance requirements.

These factors must all be taken into

account during the design stages, when

the goal is to achieve the highest possible value for the BIPV system. Some of

the major design considerations unique

to solar energy systems are solar access,

system orientation and tilt, electrical

characteristics, and system sizing.

Solar access ó Solar access, the incidence of solar radiation (insolation)

that reaches a PV surface at any given

time, determines the potential electrical

output of a BIPV system. Solar 

radiation data for sites in the United

States can be obtained from the

Department of Energy's National

Renewable Energy Laboratory (NREL).

The data are available in publications

such as the Solar Radiation Data Manual

for Flat-Plate and Concentrating Collectors

and the Solar Radiation Data Manual for

Buildings (call (303) 275-4363 to request

copies) or online from the Renewable

Resource Data Center (http://rredc.

nrel.gov). Statistical estimations of

average daily insolation levels for specific locations are commonly used in

the BIPV design process and measured

as kilowatt-hours per square meter per

day (kWh/m2/day).

System Orientation and Tilt ó To maximize solar access and power output,

the physical orientation of the BIPV

system and the tilt angle of the array

should be considered relative to the

geographical location of the building

site. As a general rule of thumb, BIPV

installations north of the equator perform optimally when oriented south

and tilted at an angle 15 degrees higher

than the site latitude. Conversely, BIPV

installations south of the equator perform best when oriented north and

tilted at an angle 15 degrees lower than

the site latitude. The orientation and 

tilt may vary from this formula when 

a BIPV system's particular seasonal 

performance must be optimized. For

example, a system might be designed 

to produce maximum power output

only in the summer months in order 

to reduce peak electricity costs for airconditioning loads; thus, the system

should be installed at an optimum 

orientation and tilt for summer power

output.

Demonstrations have shown that a system installed at a tilt angle equivalent

to the site latitude produces the greatest

amount of electricity on an annual

basis. In comparison to a system's performance at latitude angle, annual 

performance losses for vertical facade

systems can be as high as 30% or more.

In contrast, annual performance losses

for horizontal installations can be as

high as 10%, in comparison to those of

systems installed at latitude angle.

Electrical Characteristics ó The pertinent electrical characteristics of a PV

module or array are summarized in the

relationship between the current and

voltage. The amount and intensity of

solar insolation controls the current (I);

the temperature of the solar cells affects

the voltage (V) of the PV module or

array. Module I-V curves that summarise the relationship between the

current and voltage are furnished by

manufacturers. I-V curves provide

information designers need to configure systems that can operate as close 

to the optimal peak power point as 

possible. The peak power point is measured, under standard testing conditions (STC), as the PV module produces

its maximum amount of power when

exposed to artificial solar radiation of

1000 W/m2.

System Sizing ó Choosing a BIPV type

and sizing a system have three main

components: energy loads, architectural

or aesthetic considerations, and economic factors. To determine the desired

power rating of a BIPV system for a

building, the electrical requirements of

the building should first be evaluated.

The optimum power rating of the system can be calculated and sized, based

on the portion of the building's electricity that will be supplied by the BIPV

system. For example, an autonomous or

off-grid building may require a large

system with battery storage capabilities

to provide 100% of the building's electricity requirements; a building owner

desiring to reduce demand charges will

require a small system that produces

electricity only during peak utility

charge hours.

Architecturally, the size of the BIPV 

system is physically limited to the

dimensions of the building's available

surface area. The balance between the

60 BIPV Basics
amount of power required and the

amount of surface area available can

determine the type of PV technology

that will be used. Each technology has

an associated range of output in watts

per square foot or per square meter and

cost per watt. For example, systems

made of amorphous silicon require a

larger surface area but cost less than

equivalent systems composed of singlecrystal solar cells. Therefore, in projects

that have a limited budget but include a

large south-facing facade surface area,

amorphous silicon can be the most suitable BIPV technology.To achieve the

appearance of a uniform surface area,

less expensive "mock" or imitation PV

panels can also be provided by the

manufacturer.

Once the building energy load requirement is determined, the watt-hour

method can be used to design the electrical system. An evaluation of seasonal

climatic conditions and variations (temperature and solar insolation) and the

available surface area will determine

the number of modules that will satisfy

the voltage and current requirement 

of the load. After that, corresponding

inverter requirements and BOS requirements can be specified. Currently, PV

specialists, system integrators, and 

consultants provide electrical sizing

information, assessments, and recommendations. However, BIPV manufacturers are increasingly providing full

turn-key services for large systems 

for commercial buildings, and prepackaged, standardized, residential systems

are being sold by distributors. For more

information on software tools for optimizing PV systems, see Appendix B.

Electrical and Safety Issues

Electrical issues primarily involve the

performance and reliability of the

inverters. The variety available for

BIPV systems include single inverters,

master-slave inverter configurations,

modular inverters, and parallelindependent or string inverters. A

BIPV system is most vulnerable to a

single-point failure where the power

generated from the BIPV array must be

transformed and synchronized through

the inverter from DC to AC power and

then fed into the building or an electric

utility system. If the inverter fails, the

entire system malfunctions.

Today, most inverters are highly reliable. However, the practice of relying

on only one inverter for a BIPV system

in a commercial building is problematic. When BIPV systems are made 

up of a large series of interconnected

strings, there is a technical difficulty in

determining where a system has failed.

This is akin to the problem people had

with old-fashioned Christmas tree

lights. When one light malfunctioned,

the entire string went down, and each

bulb had be tested to determine the

source of the problem.

A BIPV system designed so that multiple inverters work together ensures

greater system reliability. If one inverter

malfunctions or requires maintenance,

it can be disconnected from the array

and the BIPV system can still operate. 

A cascading hierarchy "master-slave"

configuration includes one master

inverter and multiple slave inverters

that operate together for maximum 

efficiency

Modular, "micro," or "mini" inverters

allow each module to be tested (each

has its own address) through the use 

of a power line carrier signal injected

into the building's electrical distribution system. This way, each unit's 

performance can easily be evaluated.

Modular inverters also enable PV to 

be integrated into complex, geometric

building designs.

Modular inverters are desirable for

commercial buildings because they

operate independently. Shading one

module will not interrupt the power

output of the whole array. In single or

multiple inverter systems, a number 

of modules are connected in series to

achieve the voltage needed by the

selected inverter. Shading any one

module in this series can negate the

output of the entire string. 

One design issue related to the modular

inverter is whether it will last the 

lifetime of the PV module. If the

inverter has a lifetime of only 5 years

and the BIPV facade lasts 25 years,

replacing the modular inverter has an

associated periodic cost, and access

needs to be anticipated and designed

into the project.

The string inverter is the second 

generation of inverters for buildings. 

In Europe, one string inverter with the

nominal power of 750 watts can connect as many as 10 PV modules in a

series and be connected anywhere in

the building's electricity distribution

system. The flexibility, reliability, and

increased efficiency offered by string

inverters may further reduce the cost 

of BIPV systems.

New AC modules are being equipped

with individual AC mini-inverters

mounted on the backs of the PV panels.

They are at the early commercial stages

of development in the United States

and Switzerland. One benefit of these 

is that they eliminate the need in the

building for the high-voltage DC

wiring associated with other BIPV 

systems.

In regard to electrical safety issues, 

it is important to note that lightning,

ground faults, and power line surges

can cause high voltages in otherwise

low-voltage BIPV systems. National

and international electric code regulations and building codes are being

amended to include PV technologies

and address fire and safety issues concerning BIPV design, installation, and

maintenance.

Codes and Standards

The national model codes historically

have been composed of three primary

organizations: the International

Conference of Building Officials

(ICBO), Building Officials Code

Administrators International (BOCA),

and the Southern Building Code

Conference International (SBCCI).

These organizations have collaborated

to create one umbrella organization, 

the International Code Conference

(ICC). The ICC has begun the process 

BIPV Basics 61
of writing one model code, the International Building Codes. These codes

began development in 1996, and the

entire group will be published by the

year 2000. Although these codes must

be adopted by each municipality to

have any authority, they will be the

most up-to-date ones that can be

adopted after the year 2000. This is a

major step toward a unifying model

code, reducing the duplication and

diversity of the previous three code

bodies. The change process for all ICC

codes will occur annually until 2003

and at three-year intervals after 2003.

To date, these codes do not refer specifically to BIPV systems, leaving compliance to the discretion of local building

inspectors. If BIPV is the structural

equivalent of a current building material, only specific code provisions or

compliance required for the structural

equivalent will be necessary. However,

the typical crystalline PV cell adds

weight to the traditional building 

product relative to a thin filmed glazing, and this may require closer evaluation by code officials. Because of their

multifunctional nature, BIPV systems

must also comply with the National

Electric Code (NEC), which addresses

PV power systems but not BIPV 

specifically.

Local codes vary by state and municipality, and some covenant-controlled

communities regulate the appearance

of buildings for architectural aesthetics

and homogeneity. This may affect decisions about the suitability of BIPV systems. Furthermore, a few communities

in the United States have developed

zoning ordinances relative to solar

access laws that could affect BIPV systems and structures that may shade

solar systems.

Residential Energy Codes ó The Model

Energy Code (MEC) has been published by the Council of American

Building Officials (CABO). The MEC is

no longer being updated, and is being

replaced by the International Energy

Conservation Code (IECC). The CABO

requirement for one- and two-family

dwellings is being replaced in the year

2000 by the International Residential

Code. The CABO document is not

being updated at this time, and changes

will need to be made to the IRC. The

change process for both the IECC and

IRC will occur annually until 2003 and

at three-year intervals after 2003.

Commercial Codes & Products ó DOE

supports commercial energy codes,

especially ASHRAE 90.1, by helping to

develop them and by providing tools

and resources that make the codes 

easier to use. The COMcheck-EZTM

materials were developed to simplify

and clarify commercial and high-rise

residential building energy code

requirements. The materials include

easy to use IBM-compatible software;

compliance guides for envelope, lighting, and mechanical requirements; and

prescriptive packages for county-based

climate zones. Forms and a checklist 

are included to document compliance.

All COMcheck-EZ materials can be

downloaded at no cost. If you download any material, please register with

the program so you will be notified of

upgrades (online, see http://www.

energycodes.org/comm/comm.htm).

Federal Building Codes ó The current

Federal code for low-rise residential

energy efficiency (10 CFR Part 435, 

sub-part C) can be obtained online (see

http://www.access.gpo.gov/nara/cfr/

cfr-retrieve.html#page1). DOE has been

updating this code. The proposed rulemaking for the Energy Efficiency Code

for new Federal Residential Buildings

was published in the May 2, 1997, edition of the Federal Register. A printed

copy of the rulemaking can be obtained

in Federal Register Volume 62, Number

85, pages 24163-24209, or at the online

address above.

The proposed rule is based on the 1995

version of the Model Energy Code, but

it contains more stringent envelope

requirements and rules related to radon

control and backdrafting from fossilfuel-burning appliances. DOE has been

preparing the final rule based on comments received on the proposed rule

and expects to issue it in 1999. DOE 

is also preparing a code compliance

package known as FEDcheck to assist

users in understanding and complying

with the code. For more information,

contact Stephen Walder, DOE, 202-

586-9209, or Robert Lucas, Pacific

Northwest National Laboratory, 

509-375-3789 (online, see http://www.

energycodes.org/federal/federal.htm). 

DOE has also prepared a third edition

of its Building Standards and Guidelines Program catalogue. This catalogue

is one of many services that promote

the adoption, implementation, and

enforcement of residential and commercial building energy codes. One of

the primary goals of the program is to

provide products and services that

make it easy for builders, architects,

designers, building code officials, and

state energy officials to implement

building energy codes.

The catalogue features many products

that will quickly and efficiently implement the requirements of the Model

Energy Code; the American Society 

of Heating, Refrigerating, and AirConditioning Engineers and Illuminating Engineering Society of North

America Standard 90.1-1989; and the

Federal Performance Standards for

New Commercial and Multi-Family

High-Rise Residential Buildings.

In addition to the catalogue, the

MECcheck and COMcheck-EZ compliance tools and manuals may be downloaded at no cost from the Building

Standards and Guidelines Web site at

http://www.energycodes.org/. For

more information, or to place an order,

call the U.S. Department of Energy

Building Standards and Guidelines

program hotline at 1-800-270-CODE

(online, see http://www.energycodes.

org/news/catalog.htm).

State Energy Codes ó The status of

each stateís building energy codes is

current as of September 1997. The list is

likely to become less accurate in time,

however, as states adopt new codes.

Thus, there will be continual updates.

Printed copies of the State Building

Codes Database are available for $15 by

calling 1-800-270-CODE. To view the

62 BIPV Basics
status of a particular stateís energy

codes, select a state from the list online

(see http://www.energycodes.org/

states/ states.htm). The status of the

state energy codes can be found at

http://www.bcap.com .

Maintenance

PV has no recurring fuel costs, and it 

is promoted as a simple energy technology that is durable and relatively maintenance-free because it has no moving

parts. However, designers should

ensure that BIPV installations allow

easy access for inspecting, repairing,

and replacing components. Maintenance costs can be divided into two categories: preventive and failure-related.

Preventative maintenance can ensure

the performance of a BIPV system.

Shadowing on the PV array caused 

by the natural or built environment

reduces system output. Sunlight

reflects off expanses of sand, snow, 

ice, and other light surfaces, and can

increase output by reflecting additional

solar energy onto arrays. However,

other structures, trees, and bushes near

a BIPV system can inhibit solar access

and thus reduce system performance.

This is in turn detrimental to the 

economic performance of the system.

In the case of building retrofits, landscaping can often shade parts of a roof

and limit solar access, so landscape

architecture must be considered, and

trees must be trimmed periodically.

The electrical performance of a BIPV

system can also be affected by accumulations of dirt on the modules. In most

locations, normal rainfall removes the

layers of dust and pollution that can

accumulate on the outer surface. Where

there is little rainfall, occasionally

spraying the system with water from 

a standard garden hose to remove 

dirt and debris is adequate but not 

required.

The performance of a BIPV system can

decline if it is located in a particularly

dirty urban environment. Layers of

grime, caused by fuel exhaust and other

emissions, can accumulate on a system.

This exhaust can combine with sunbaked atmospheric dust to reduce the

amount of light that can reach the 

modules and thus reduce system performance. Such systems may require

periodic cleaning with chemical agents

to maximize the system's electrical output. Consequently, system designers

must ensure adequate access to the 

system to perform these maintenance

activities.

Failure-related maintenance involves

repairs and replacements associated

with poor performance or failures of

the BIPV system. This can be covered

under traditional and extended 

warranties.

Warranties

BIPV systems are generally covered 

by a limited 12-month replacement

warranty that guards against defects

and ensures system repair and product

replacements or an optional full refund

of the purchase price. In case of an accident, such as a fire, ancillary damage to

a BIPV system may be covered by a

conventional building insurance policy.

Currently, the major PV manufacturers

offer power production warranties for

as long as 10, 20, and 25 years. These 

manufacturers will replace the power

output lost from modules that fail to

produce at least 80% of the minimum

power output specified on the back of

the module. This warranty dates from

the sale of the product to the original

purchaser and is generally nontransferrable. Other suppliers also offer

optional warranties on roofing through

service and maintenance contracts.

BIPV Products

These are the types of BIPV systems

commercially available:

Facade systems ó The BIPV system is

designed to act as an outer skin and

weather barrier as part of the building

envelope. An example is a BIPV system

used for rainscreen overcladding. Glass

BIPV products are typically used as

facade systems.

Atrium systems ó BIPV is a glass element that provides different degrees 

of shading and can be designed to

enhance indoor thermal comfort as 

well as daylighting.

Awning and Shading systems ó A variety of PV materials can be mounted

onto a facade in aesthetic manner to

serve as awnings.

Roofing systems ó The BIPV system 

displaces conventional roofing materials such as tiles, shingles, and metal

roofing.

The cost of a BIPV system depends 

on the type of system and the PV 

technology used in manufacturing it.

Currently, only a few U.S. manufacturers produce custom and standardized

BIPV products. For commercial and

institutional structures and buildings,

the two primary types of BIPV products, facades and roofing materials, are

available for both new construction and

refurbishment projects.

BIPV Facade Systems ó BIPV facade

systems include laminated and patterned glass, spandrel glass panels, and

curtain wall glazing systems. These

BIPV products can displace traditional

construction materials. Laminated glass

is a standardized BIPV product. It is

composed of two pieces of glass with

PV solar cells sandwiched between

them, an encapsulant of ethylene-vinyl

acetate (EVA) or another encapsulant

material, and a translucent or colored

tedlar-coated polyester backsheet. It

can also be made with only one piece 

of glass and a tedlar backsheet.

Architects can specify the color of the

tedlar backsheet.

Spandrel panels are the opaque glass

used between floors in commercial

glass building facades. A glazed curtain

wall is a non-load-bearing exterior wall

suspended in front of the structural

frame and wall elements. Patterned or

fritted glass is semitransparent with

distinctive geometric or linear designs.

BIPV Basics 63
Some companies sell custom-made

BIPV glazing products, available in any

size or dimension and consisting of any

PV technology (crystalline or thin film).

The architect can indicate the spacing

between solar cells, which will determine the power supply and also permit

the design of passive solar features by

regulating the amount of daylighting

allowed to enter into the builiding.

These products can be used in any commercial glazing application. Standard

and custom products are available in

many sizes (as large as 1.3 m x 1.7 m)

and in a range of thicknesses (0.5 mm 

to 2.5 mm glass).

Curtain wall laminates are available for

both AC and DC power. The AC panel

has its own mini-inverter attached to

the back of the laminate. The AC

PowerWallô operates with current at

maximum power with 2.0 amps (A)

and 110 volts (V). The DC PowerWallô

operates at maximum power with 3.5 A

and 68.4 V. The PowerWallô generates

250 watts (W) under standard test 

conditions (STC).

BIPV Roofing Systems ó Roofing systems include BIPV shingles, metal 

roofing, and exterior insulation roof

systems. These BIPV products can displace traditional construction materials.

Flexible thin-film amorphous silicon

BIPV shingles can replace asphalt 

shingles. This BIPV product is nailed to

the roof deck, very much the way that

traditional asphalt shingles are attached

to a roof. This technology was designed

as a 2-kilowatt peak (kWp) BIPV system for the Southface Energy Institute

in Atlanta, Georgia. Also available 

are fiber cement PV roofing shingles

measuring 16 in. (40 cm) by 12 in.

(30 cm) by 1/4 in. (0.6 cm) and weighing 5 pounds (2.27 kg). Crystalline silicon cells are laminated to fiber cement

roofing shingles and are rated at 11 W

of power output under STC. 

64 BIPV Basics

Figure 1. AC PV modules, Solar Design Associates

Solar Design Associates, Inc./PIX04472

Figure 2. Architectural PV glazing system, Innovative

Design, Inc.

Figure 3. PV-integrated modular homes, Fully

Independent Residential Solar Technology, Inc.

FIRST, Inc./PIX03612

Figure 4. Rooftop PV systems, Energy Conversion

Devices, Inc.

Tim Ellison, ECD/PIX04473 PIX08462
BIPV metal roofing can replace an

architectural standing seam. The thinfilm amorphous silicon PV material is

laminated directly onto long metal

roofing panels. The BIPV metal roofing

panels, with edges turned up, are laid

side by side and a cap is placed over the

standing edges to form a seam. These

metal panels can be installed by a traditional roofer followed by an electrician.

As an exterior insulation BIPV roof system, PV laminates are attached to polystyrene insulation, and it provides

thermal insulation rated R-10 or R-15. 

It rests on the waterproof membrane

without penetrating or being mechanically fastened to the building. In an

interlocking tongue-and-groove assembly, the panels are weighed down by

pavers that surround the system to 

provide access for maintenance and

repairs. Channels or raceways are

designed to provide access to the electrical connections. This technology can

be used to redo the roof of an existing

building, as demonstrated by the New

York Power Authority on a community

center in Tuckahoe, New York.

Additionally, the PV portion of the

product can be tilted up to 12° to help

optimize the system's orientation.

This system can be installed on builtup and single-ply membranes of flat

commercial roofs and typically weighs

4 lb/ft2 versus 10 lb/ft2 for a conventional aggregate ballast roof. Any PV

technology can be applied in this process and will provide power according

to its solar cell and system efficiency

rating.

The manufacturer claims that this 

product extends normal roof life by

protecting insulation and membranes

from ultraviolet (UV) rays and water

degradation. It does this by eliminating

condensation because the dew point 

is kept above the roofing membrane.

BIPV Product Development

Since the early 1990s, the U.S. Department of Energy's (DOE's) Photovoltaics: Building Opportunities in the

United States (PV:BONUS) program

has brought together PV and building

product manufacturers in a coordinated

effort to develop PV roofing shingles,

facade glazing, and curtain wall products for buildings and other structures.

Today there is a recognizable commercialization trend toward standardizing

BIPV construction products. In the long

run, product standardization will be an

essential element in reducing the cost 

of manufacturing BIPV systems. The

following section on new construction

materials for buildings was extracted

from a paper written by Sheila J.

Hayter, P.E. (NREL) & Robert L. Martin

(DOE). This paper, titled "Photovoltaics

for Buildings, Cutting Edge PV," was 

presented at the UPEX conference in

1998. Below is the section on Building

Opportunities in the U.S. for Photovoltaics (PV:BONUS).

The U.S. Department of Energy demonstrates its commitment to supporting

new PV-for-buildings technologies by

awarding Cooperative Agreement

funding to U.S. manufacturers and

organizations for product development. These agreements are within the

Building Opportunities in the U.S. for

Photovoltaics (PV:BONUS) program.

The objective of the PV:BONUS program is to develop technologies and to

foster business arrangements that integrate photovoltaics or hybrid products

into buildings cost-effectively. Costeffectiveness, either through design;

integration (i.e., components, system,

and/or building integration); dedicated

end-use applications; or technology

bundling (i.e., PV/thermal hybrids) is 

a major factor in selecting PV:BONUS

projects. DOE is interested in products

that can replace commercial building

products and be installed without the

necessity for specialized training. The

ultimate goal of the PV:BONUS program is market demonstrations of commercially viable products that lead to

manufacturer commitments to pursue

production and sales.

In 1993, the U.S. Department of Energy

awarded cooperative agreements for

five PV:BONUS projects. The success 

of this initial effort resulted in DOE

funding additional projects in 1997

under a second program known as

PV:BONUS Two.

PV:BONUS (June 1993 – May 1999). The

five projects originally funded by the

PV:BONUS program have all been successfully installed in demonstration

projects, and most are now commercially available to the buildings industry. These new technologies include the

following.

ï AC photovoltaic module and curtain

wall application (Figure 1)

ï Architectural PV glazing system

(Figure 2)

ï Dispatchable PV peak-shaving 

system

ï PV-integrated modular homes

(Figure 3)

ï Rooftop BIPV standing-seam systems

(Figure 4).

AC Photovoltaic Module and Curtain

Wall Application. The product developed for this PV:BONUS project was a

large-area PV module with a dedicated,

integrally mounted, direct-current (DC)

to alternating-current (AC) power

inverter (Figure 1). The module is

designed to be integrated into the 

vertical facades and sloped-roof 

construction of residential, commercial,

or institutional buildings. Large spaces

between the PV cells can be incorporated into the module design to allow

direct sunlight to transmit through the

module. The building designer can use

this feature to enhance daylighting and

provide passive solar heating to the

space adjacent to the modules. Solar

Design Associates, Inc., led development efforts for this project. Other team

members included Mobil Solar Energy

Corp., New England Electric, New 

York Power Authority, Pacific Gas and

Electric, Kawneer, Maryland Energy

Administration, and Baltimore Gas 

and Electric.

Architectural PV Glazing System. A

system of matching building facade

glazing products including opaque,

BIPV Basics 65
semitransparent, and clear units was

developed. A large-area, thin-film PV

module option was available for the

opaque and semitransparent units. The

system was incorporated into the overhead glazing of a demonstration project

in an Applebeeís Neighborhood Grill

and Bar in Salisbury, NC (Figure 2). The

designers placed a high-absorptance

metal pan approximately 1 in. (2.5 cm)

below the back of the panel to increase

effectiveness for solar heating of the air

behind the panels. Fans operated by the

PV system drew the heated air through

an air-to-water heat exchanger to

reduce the restaurantís energy demand

for producing hot water. Drawing hot

air off the back of the PV panels also

increased the operating efficiency of 

the panels. Although the manufacturer

of the PV panels and leader of this

PV:BONUS team, Advanced Photovoltaic Systems (APS), is no longer in

existence, the PV technology the company developed continues to be used

by the PV industry. Innovative Design

partnered with APS to design the

Applebeeís system.

Dispatchable PV Peak Shaving

System. A fully integrated dispatchable

peak-shaving system for commercial

applications was designed for this

PV:BONUS project. The focus of the

project was to reliably control the PV

system output for a prescribed length

of time by including battery storage

with the PV system. The dispatchable

system made it possible to displace a

load greater than the arrayís output

during peak demand periods. This feature is especially important in commercial buildings where the peak demand

period often extends beyond the period

of peak power production of the PV

system. Delmarva Power and Light

Company was responsible for this

PV:BONUS effort.

PV-Integrated Modular Homes.

Installing residential photovoltaic systems onto homes constructed in a factory along with other energy-efficient

features result in reducing the total 

construction cost of the manufactured

homes to be comparable to typical sitebuilt homes (Figure 3). The objective of

this PV:BONUS project was to design 

a line of modular solar homes that

include photovoltaic power. To meet

this objective, it was necessary to minimize construction costs of the home so

that the higher cost of the PV system

could be absorbed into the overall cost

of the home. The effort was lead by

Fully Independent Residential Solar

Technologies, Inc. (FIRST, Inc.), a 

non-profit organization teamed with

Bradley Builders and Avis America 

(a builder of manufactured homes).

Rooftop Photovoltaic Systems. The

result of this PV:BONUS project was

the development of residential and

light-commercial PV-integrated roofing

materials. These amorphous-silicon

modules are manufactured either to

resemble asphalt shingles or to be laminated onto metal standing-seam roof

modules (Figure 4). One of the goals of

the project was to develop a product

that required no special training to

install the PV-roof on actual buildings.

These products have been tested in

demonstration projects and are now

commercially available. The leader 

of this development team, Energy

Conversion Devices, Inc., worked 

with United Solar Systems Corp., the

National Association of Home Builders,

Solar Design Associates, Inc., and a

number of utility companies, construction companies, government agencies,

and educational institutions to design,

manufacture, and test this product.

PV:BONUS Two (September 1997 – early

2000s). PV:BONUS Two activities are

being carried out in three phases. Phase

I was the concept development and

business planning phase. Prototype

systems will be developed and tested 

in Phase 2, the product and business

development phase. Product demonstration and marketing will occur in

Phase 3. It is expected that viable products will be offered commercially during Phase 3. Participation in Phases 2

and 3 depend on the accomplishments

of the previous phases.

The U.S. Department of Energy

awarded 17 Phase I cooperative 

agreements. These project areas were

divided into four categories: 1) glazing

products; 2) roofing materials; 3) PV/

thermal (PV/T) hybrid systems; and

4) other related projects (inverter technology, fire retardancy investigations,

and development of a "mini-grid"). 

At the completion of Phase I, seven of

these projects were selected for continued Phase II funding. Phase II is currently under way and the following

projects are being pursued:

ï PV-powered electrochromic windows

ï Thin-film PV product line

ï Hybrid PV/thermal collector

ï Ballast-mounted PV arrays

ï PV string inverters

ï Field-applied PV membrane

ï PowerRoofTM 2000.

PV-Powered Electrochromic Windows.

Sage Electrochromics, in conjunction

with Solarex, proposes to develop and

commercialize photovoltaic (PV) powered electrochromic (EC) "smart windows." EC windows control the amount

of sunlight and solar heat by dynamically switching between darkened and

clear states and anywhere in between.

They provide an opportunity to realize

energy savings and reduce peak 

electrical demand in buildings. The

low-power DC voltage required to

power the EC window glazing will be

supplied by PV solar cells incorporated

in the double-pane insulating glass unit

(IGU) so that no external hard-wired

connections are needed.

Thin-Film Photovoltaics. With the 

support of subcontractors Kawneer,

Solar Design Associates, Inc., and

Viracon, Solarex will develop buildingintegrated photovoltaic products using

tandem-junction amorphous silicon

modules. Major objectives of the program include: 1) developing a commercial photovoltaic curtain wall module

(Spandrel Module); 2) developing a

commercial photovoltaic sunshade for

curtain walls (PowerTint Window); 

and 3) developing a light-transmitting

66 BIPV Basics
photovoltaic module and incorporating

it into the curtain wall product.

Hybrid Photovoltaic/Thermal

Collector. Solar Design Associates, Inc.,

United Solar Systems Corporation, 

and SunEarth, Inc., propose to design,

develop, demonstrate, manufacture

and commercialize a hybrid flat-plate

photovoltaic/thermal (PV/T) collector

to deliver both electricity and thermal

energy. The PV/T collector design 

will employ a liquid thermal transfer

medium and closely resemble conventional flat-plate solar thermal collectors

in size, appearance, installation, and

function. However, in place of the 

normal thermal absorber plate, it will

employ a PV element of triple-junction

amorphous silicon alloy solar cells

made with United Solar's proprietary

UNI-SOLAR technology, in which the

material and thermal characteristics 

are well suited for combined PV/T

applications.

Ballast-Mounted PV Arrays. Ascension

Technology will develop analytic and

experimental capabilities for quantifying the balance between driving (wind,

seismic) forces and the restraining

(gravitational/frictional) forces that

must exist for the ballast-mounting

approach to succeed. Ascension

Technology has already developed a

ballast-mounting system for PV arrays.

The system is applicable for both new

and retrofit construction on flat or

nearly flat roofs, typically on commercial buildings.

PV String Inverters. Advanced Energy

Systems, Inc., proposes to design and

manufacture a low-cost string inverter

system (SIS), which will minimize the

cost of the BOS components (i.e., the

inverter and the PV output circuit

wiring). The SIS is an inverter and 

associated wiring that is designed to

operate with a single string of photovoltaic (PV) modules. By using a single

string, the need for an expensive stringcombiner is eliminated. The paralleling

of multiple strings is accomplished by

the utility or AC side of the system,

which can result in inexpensive installation costs.

Field-Applied PV Membrane. United

Solar Systems Corp., in collaboration

with Energy Conversion Devices, Inc.,

the National Association of Home

Builders, Phasor Energy, Arizona Public

Service, Southern California Edison

Co., Southern Cal Roofing, ATAS

International, Elk Corp., and San Diego

Gas & Electric intend to develop a 

field-applied, flexible photovoltaic 

(PV) membrane product for the 'builtenvironment." UNI-SOLAR PV Roll

Membrane is a

flexible PV laminate designed for a

range of market

applications, such

as covered parking

structures, "flat"

roof commercial

buildings, architectural and structural metal roofing

(including new

construction and

retrofit, flat, and

curved roofs),

facades, prefabricated stress skin

panel production,

and fabric roofing systems. The 

UNI-SOLAR PV Membrane will be

shipped directly to the site for field

application or to a building product

company for integration with its own

products. The membrane uses United

Solar Systems Corp.ís multijunction 

a-Si stainless steel PV cells laminated 

in flexible UL-approved 

materials.

PowerRoofTM 2000. PowerLight

Corporation, in cooperation with

AstroPower, Solarex, BP Solar, and

Siemens Solar, proposes to develop an

innovative building-integrated PV 

roofing system called PowerRoofTM

(Figure 6). PowerGuardÆ is the first

core product in the PowerRoof family

and has been successfully developed

under prior programs. The PowerRoof

2000 proposal targets the development

of two next-generation core PowerRoof 

building products, HeatGuardTM and

PowerThermTM. Each builds upon the

proven technological approach of the

PowerGuard solar electric roofing 

system.

Other PV for Buildings Products on

the Market and on the Horizon.

Building designers have shown great

interest in the new PV-for-buildings

systems, as indicated by the number of

participants in BIPV workshops for

architects sponsored by DOE, the

American Institute of Architects (AIA),

and other organizations. In general,

BIPV Basics 67

Figure 5. PV sunshades at the State

University of New York, Albany

Solar Design Associates, Inc./PIX06429

Figure 6. PowerLight roof on Tuckahoe Community

Center

Power Light Coproration/PIX04471
building designers want PV systems

that can be integrated into the building

envelope and blend well with other

building envelope components and

materials. Many of the products that

have been or are being developed with

assistance from the PV:BONUS

Program meet these criteria.

New products such as transparent 

thin-film PV modules, for which the

designer can specify the transmissivity,

are expected to become commercially

available in the near future. The

designer will be able to specify both

view glass and curtain wall PV 

modules, so that the entire facade of 

a building can be clad in PV. Manufacturers predict that the price of these

PV modules will be close to that of

high-end glass products, making it 

easier for designers to justify the cost 

of PV.

Designers are beginning to integrate

photovoltaics into sunshade building

components. Sunshades are used to

reduce the direct solar gain into a building, which also reduces the building

cooling loads (Figure 5). The angle of

the sunshade can also be set to optimize

the output of the PV/sunshade system.

Several PV-roofing products are 

now commercially available. One 

crystalline-silicon-cell product replaces

traditional roofing materials and is 

usually used in new construction.

Other products are designed to be used

in flat-roof commercial retrofit applications. They include an insulated unit

with PV integrated into the top layer

and a roof membrane product with PV

integrated into the membrane.

The cutting-edge PV products discussed in this paper are only an example of what is available or expected to

become available for buildings applications. This is not an exhaustive list,

however. 

Source: Sheila J. Hayter, P.E., and

Robert L. Martin, "Photovoltaics for

Buildings, Cutting Edge PV," presented

at the Utility PV Experience Conference

& Exhibition, October 1998.

68 BIPV Basics
BIPV Terminology 69

BIPV Terminology

Building-integrated photovoltaics (BIPV) is a relatively recent new application of

photovoltaic (PV) energy technologies. These are some of the basic terms used in

describing PV technologies, BIPV products, and their uses:

Antireflection coating ó a thin coating of a material that reduces light reflection

and increases light transmission; it is applied to the surface of a photovoltaic cell.

Balance of System (BOS) ó Non-PV components of a BIPV system typically

include wiring, switches, power conditioning units, meters, and battery storage

equipment (if required).

Bypass diode ó a diode connected across one or more solar cells in a photovoltaic

module to protect these cells from thermal destruction in case of total or partial

shading of individual cells while other cells are exposed to full light.

Conversion efficiency ó Amount of electricity a PV device produces in relation 

to the amount of light shining on the device, expressed as a percentage.

Curtain wall ó an exterior wall that provides no structural support.

Encapsulant ó Plastic or other material around PV cells that protects them from

environmental damage.

Grid-connected ó Intertied with an electric power utility.

Inverter ó Device that transforms direct-current (DC) electricity to alternatingcurrent (AC) electricity.

Module ó Commercial PV product containing interconnected solar cells; 

modules come in various standard sizes and can also be custom-made by the 

manufacturer.

PV array ó Group or string of connected PV modules operating as a single unit.

PV laminate ó Building component constructed of multilayers of glass, metal or

plastic and a photovoltaic material.

PV solar cell ó Device made of semiconductor materials that converts direct or 

diffuse light into electricity; typical PV technologies are made from crystalline,

polycrystalline, and amorphous silicon and other thin-film materials.

Solar access ó Insolation incidence of solar radiation that occurs on a PV 

systemís surface at any given time; it determines the potential electrical output 

of a BIPV system.

Stand-alone ó Remote power source separate from an electric utility grid; a

stand-alone system typically has a battery storage component.
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70 Bibliography
Appendix A:

International Activities

"Building with Photovoltaics — The Challenge For Task VII Of The IEA PV Power Systems

Program" by T. Schoen1, D. Prasad2, P. Toggweiler3, P. Eiffert4 and H. S ̄rensen5

1: Ecofys Energy and Environment, P.O. Box 8408, NL-3503 RK Utrecht, 

2: National Solar Architecture Research Unit, UNSW, Sydney NSW 2052, Australia, 

3: ENECOLO, Lindhofstrasse 13, CH-8617 Mˆnchaltorf, Switzerland 

4: National Renewable Energy Laboratory, Center for Energy Analysis and 

Application, 1617 Cole Blvd, Golden, CO 80401, USA, 

5: Esbensen Consulting Engineers, Teknikerbyen 38, DK-2830 Virum, Denmark

Abstract

On January 1, 1997, a new Task started within International Energy Agencyís Photovoltaic

Power Systems (IEA PVPS) Program: Task VII. The objective of Task VII is to enhance the architectural quality, the technical quality and the economic viability of PV systems in the built environment and to assess and remove non-technical barriers to their introduction as an

energy-significant option. The value of building integration for the introduction of grid-connected PV is recognized around the world. Rooftop programs, aiming at large-scale application

in the next century, are carried out in many countries. In order to reach this widespread application, however, cost reductions still are essential. BIPV research and development should therefore focus on achieving these cost reductions, by optimizing integration concepts, by

developing new building products and by the development of standardized products.

Building-integrated PV does more than offer perspectives for the next century. PV systems are

installed today by building owners who appreciate the added value of solar roofs and facades,

and who are willing to pay a premium for PV. This market potential must be captured and

assisted. From the research and development side, this can be done by focusing on architectural

issues and on non-technical barriers that impede short-term market penetration. The work in

Task VII concentrates on all these aspects. The Task VII research and development strategy is to

enhance systems technologies, to work on the architecture of building integrated PV, and to

assess and remove non-technical barriers that impede the widespread application of PV in the

built environment.

Note: One ECU is approximately equivalent to one U.S. dollar.

Appendix A: International Activities 71
INTRODUCTION

It is generally expected that in the next

century, photovoltaics will be able to

contribute substantially to the mainstream power production, even though

PV now is up to five times more expensive than grid power.

In densely populated areas, such as

major parts of Europe, Japan and the

US, large-scale realization of systems

will only be possible through distributed PV systems in the urban environment since no land is available for the

installation of ground-based systems.

Rooftop programs in Japan (70,000+),

US (1,000,000) and Europe (1,000,000)

illustrate the worldwide attention given

to building-integrated PV.

Integration of PV into buildings offers

cost advantages that make this concept

attractive for urbanized regions as well

as for less densely populated areas with

sufficient unoccupied land available.

PV installations can be installed on 

surfaces of buildings and along roads

or railways, with the possibility to 

combine energy production with other

functions of the building or nonbuilding structure. Compared with

large-scale, ground-based PV power

plants, cost savings through these combined functions can be substantial, e.g.,

in expensive facade systems where

cladding costs may equal the costs of

the PV modules.

Additionally, no high-value land is

required, and no separate support

structure is necessary. Electricity is generated at the point of use. This avoids

transmission and distribution losses

and reduces the utility company's 

capital and maintenance costs. 

Following the advantages of building

integration, more and more countries

view distributed PV as a power source

with a large potential for the future and

are correspondingly starting to construct and operate building-integrated

PV systems on a large scale [1].

THE COSTS OF BIPV

Figure 1 gives the breakdown of the

average costs for building-integrated

PV systems, though estimates vary

from country to country.

As can be seen in this figure, the costs

for building integration currently range

from 30% to 50% of the total system

costs. Reduction of module costs will

enlarge the need for attention to optimal building integration, i.e., reducing

the costs for substructures, mounting

and wiring to the absolute minimum.

In order to achieve widespread application of PV as a competitive power

source, PV electricity must be produced

at the level of 0.05 to 0.10 ECU per kWh

(5¢ to 10¢). From Fig. 1, it can be seen

that even for Italy, this would require

cost reductions by a factor 3 to 4. In the

Netherlands, cost reductions by a factor

10 or more are required.

Here is where the major challenge 

lies for R&D programs in the field of

BIPV: cost reductions are essential for

large-scale introduction of buildingintegrated PV systems. R&D should

focus on these cost reductions.

PV FOR THE FUTURE — 

PV FOR TODAY

In addition to cost reduction opportunities as previously mentioned (such as

replacement of building materials and

avoidance of land use), building integration offers interesting cost benefits.

If PV systems are installed as decentralized power systems on buildings, and 

if net metering is used for selling back

surplus power to utilities, PV electricity

will only have to be produced at consumer tariff prices, ranging from 0.10 to

0.20 ECU per kWh. For the Netherlands

this implies required cost reductions 

by a factor of 3 to 5. For Italy, cost

reductions by a factor of 2 to 3, or in 

the optimistic scenario, a 50% cost

reduction would be sufficient for 

market introduction.

Given the cost reductions that have

been achieved by BIPV R&D programs

in the last five years, it can be estimated

that these cost reductions will be

reached within only a few years, indicating that BIPV will rapidly become

interesting and competitive. 

PV, well integrated into the architectural design of the building, can

enhance the aesthetics of the building

and give the property owner a 'green'

and self-sufficient image. Owners of

commercial buildings are increasingly

more interested in installing PV systems as a high-value feature of their

property. Projects are being realized

with limited or no government support

at all, indicating that cost reductions of

a mere 25% to 50% are sufficient for

opening up the market.

The housing market is increasingly sensitive for this 'added value' of the PV

system; house owners are willing to

pay a premium price for a PV-clad

house, thereby generating additional

funding for the PV system.

The AC module system seems to be

very attractive for this type of application. Property developers in the

Netherlands have shown interest in

introducing PV systems consisting of

4 AC modules on a regular basis in the

building programs, if the prices are

reduced to 5 ECU ($5) per Wp. This

makes PV a technology not just for the

future but also for today.

The challenge of national programs as

well as international actions, such as

Task VII, is to assist these emerging

markets by developing photovoltaics

into a cost-effective and clean power

source, available for application in distributed systems of utilities, builders,

and cities of the future as well as today.

R&D should therefore not only address

long-term developments for large-scale

application as a bulk power source, but

also short-term application as competitive feature of the built environment.

The integration of PV into architecture

and the building market are important

issues in such an R&D strategy.

72 Appendix A: International Activities
Upscaling of the near-term BIPV market will, moreover, be possible only if

non-technical barriers that impede the

application of BIPV are addressed and

dealt with successfully. The major barrier to overcome here could well be the

involvement of builders and building

owners in the design and implementation of building integrated PV. R&D, 

as well as pilot and demonstration 

projects, should work on the achievement of this involvement as well as 

on the removal of other non-technical

barriers such as the lack of information,

confidence, or appropriate financing

mechanisms.

R&D STRATEGIES FOR

TASK VII

In recognition of the potential of 

building-integrated PV to the development and introduction of photovoltaics,

IEA's PV Power Systems Program in

January 1997 launched a new task: Task

VII - PV in the Built Environment.

The objective of Task VII is to enhance

the architectural quality, the technical

quality, and the economic viability of

PV systems in the built environment

and to assess and remove non-technical

barriers to its introduction as an

energy-significant option. This objective reflects the R&D strategies mentioned earlier.

The primary focus of Task VII is on the 

integration of PV into the architectural

design of (roofs and facades of residential, commercial, and industrial) buildings and other structures in the built

environment (such as noise barriers,

parking areas, and railway canopies).

Also important are the market factors,

both technical and non-technical, that

need to be addressed and resolved

before wide adoption of PV in the built

environment will occur. 

Essential for the success of Task VII is

the active involvement of urban planners, architects, building engineers, 

and the building industry. Task VII is

very keen on the collaboration between

these groups and PV system specialists, 

utility specialists, the PV industry, 

and other professionals involved in

photovoltaics. 

The joint effort will consist mainly of

the evaluation and development of

innovative concepts for the integration

of PV into the built environment, the

demonstration of integration concepts,

contribution to the development of

standards and guidelines, and the

study of economic aspects and other

market factors that impede the widespread application of PV in buildings.

In brief, Task VII will work on R&D in

the following fields: 

(1) BIPV technologies

(2) PV and architecture

(3) Non-technical barriers

BIPV Technologies

The technologies that are now available

for the integration of PV into buildings

are, in general, too expensive for largescale introduction. Cost reductions 

are thus still essential. They can be

achieved by carefully redesigning the

PV support structure, and by integrating the PV system into well-known

building components such as the prefabricated roof or the structural-glazing

facade. 

Development of standardized

PV/building units

The development of low-cost, flat roofmounting elements such as the Sofrel

[3] show that, through careful redesign

of substructures from the low-cost

point of view, cost reductions up to 

50% are possible for substructure and

mounting costs. A similar strategy

could be applied in the development of

mounting structures for sloped roofs

and facades. PV facades in general still

use tailor-made solutions, suitable only

for custom-made modules, requiring

case-by-case engineering and installation by specialists, which lead to highquality but high-price solutions.

For new buildings, integration of standard PV modules into low-cost, everyday cladding systems is required,

whereas for existing buildings, low-cost

add-on systems offer good cost perspectives. In order to make mounting

concepts suitable for application in the

vast number of existing buildings with

a poor energy balance, add-on systems

should include extra thermal insulation

layers.

Appendix A: International Activities 73

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

NL NL IT IT

PV electricity costs, ECU/kWh

 (U.S. $/kWh) 8

7

6

5

4

3

2

1

0

PV costs, ECU/Wp

 (U.S. $/Wp)

Mounting and

installation

Substructure

Cabling

Inverters

Modules

02527250m

(NL = Netherlands; IT = Italy.)

Figure 1. Overview of BIPV system costs in ECU/Wp (left) and the resulting 

PV electricity costs in ECU/kWh (right), for different countries and

calculation methods (optimistic: maximum performance ratio, low interest

rate; pessimistic: average performance ratio, high interest rate). 

Note: Currently, the ECU is equivalent to one U.S. dollar.
Integration of PV modules and

cells into standard building

materials

The integration of PV into well-known

building materials, such as roof tiles, 

is under way. Attention to these developments around the world shows the

cost reduction potential of this R&D

path.

Optimal tuning of PV modules to existing building materials can result in substantial reduction of mounting and

substructure costs. In the end, these

costs might be fully omitted through

the integration of PV cells into building

materials. Similar attempts are being

made in the field of stand-alone PV systems, where PV cells are being integrated into bus shelters, vessels, and

other applications.

Integration of PV into

prefabricated building elements

This R&D path is especially suitable 

for countries where the prefabricated

buildings and building components are

commonly used (e.g., the Netherlands,

Japan). Preliminary research indicates

that cost reductions up to 50% (compared with that of today's technology)

through prefabrication are possible [4].

PV and Architecture

Market enhancement requires acceptance of PV by builders, architects, and

users. Full integration into architecture

is therefore essential.

The physical characteristics of PV products for integration in buildings must

meet architectural requirements for

color, size, and 

materials. Products that meet these

requirements are being developed

around the world. Cells are available 

in different colors and textures; modules can be produced to the designerís

specification.

These developments have certainly

assisted the creation of high-end, highquality examples of building-integrated

PV. They are thus very important to the

introduction of BIPV.

It should, however, be noted that the

application of custom-made PV products has economic consequences. The

costs of modules can go down substantially if they are produced in bulk. At a

production level of 500 MWp per year,

costs of less than 1 ECU ($1) per Wp are

achievable with today's technologies

[5]. This cost level will not be reached

with tailor-made modules produced 

on a smaller scale.

The challenge for the PV R&D community, together with architects and

builders, is to develop high-quality

integration concepts that can make 

use of the low-cost potential of bulkproduced modules.

As a first activity, Task VII has dealt

with the evaluation of existing BIPV

projects. The result is a list of architectural quality criteria for BIPV projects

(please see Table 1).

Using these criteria in the design of

new projects and integration concepts

based on standard modules can

enhance the architectural quality of

BIPV without introducing high-cost

(custom-made) products.

Non-Technical Barriers

As mentioned above, a number of nontechnical barriers exist that impede 

the implementation of PV in buildings.

Assessment and removal of these barriers will result in enhancement of both

the near-term and the long-term PV

market. A preliminary listing of barriers

has been prepared by

Task VII. Task VII will

work on the analysis of

these market barriers,

followed by recommendations for their

removal.

As can be expected, 

budgetary constraints

are the main barrier. 

The removal of other

barriers, however, 

will most certainly help

overcome this prime

barrier. A number of R&D actions are

discussed here.

Development of 

financing schemes

The availability of appropriate financing mechanisms in Germany and

Switzerland has been shown to have a

major impact on the introduction of PV.

In Germany, rate-based incentives have

led to a substantial increase in the PV

market, with annual growth figures

larger than ever (1996: 3 MW;1997:

10 MW) [6].

The assessment of such financing

schemes, tailored to the specific needs

of individual countries, will be one of

the key activities of Task VII.

Integration into the 

building process

If PV is to become a well-accepted technology readily available for architects,

the building industry, and property

owners, integration concepts will have

to meet regular building quality standards. This can be achieved by fully

integrating the PV system into building

materials and by integrating the construction process of BIPV systems into

the building construction process.

Building integration must include integration into the contractual framework

and the organizational structure of

building projects.

Building integration also must include

integration into the regular quality

schemes for building components. 

74 Appendix A: International Activities

Table 1: Architectural criteria for the review of

PV buildings and integration products

• Natural integration and visually acceptable

• Architecturally pleasing and visually pleasing

• Good composition between materials and colors

• Fit the grid, harmony, composition

• Appropriately links with the context of the project

• Well-engineered and designed

• Innovative new design
PV will be largely accepted by builders,

architects, and end-users only if the

quality of BIPV systems fully meets the

requirements of everyday construction

elements.

The development of such quality

schemes is a part of the work of Task

VII as well as an import issue of the

European BIPV programs. As an example, the Joule PRESCRIPT project aims

at the development of guidelines and

pre-standards for the testing and certification of building-integrated PV [7].

Training and education

PV can be included in building projects

only if architects and principals have

sufficient knowledge about PV technologies and appropriate design tools

to assist them.

Design tools can range from planning

instruments to tools for shaping and

sizing the PV systems. Planning instruments are required to ensure that PV is

taken into account from the very start

of the building process, where the first

decisions have a major impact on the

ways to include PV in the building (e.g.,

the orientation of the building). Tools

for shaping and sizing of the PV system

can range from intricate software packages (linked to the overall energy

design tools) to easy aids as an irradiation disk.

R&D is required in both energy planning and the design and sizing of PV

systems, within the overall design of

the energy system of the building.

Concerning education, 'PV at schools'

programs have proven to be successful

in a number of European countries [8].

In order to teach the architects,

builders, and occupants of the future

how to work with PV, integration of PV

into educational programs at all levels

is important. A follow-up of national

activities at the European level could

enhance this process.

FINAL REMARKS

The aforementioned R&D directions are

reflected in the projected activities of

Task VII. It can, therefore, be concluded

that Task VII can contribute to the further development and implementation

of PV in the Built Environment. The

success of Task VII will of course

depend on the effectiveness of the 

international collaboration and on 

the contributions of the participating

countries to the overall framework of

the Task.

The coming five years will show if

Task VII can achieve its challenging

objective. All experts in the countries

participating in Task VII are requested

to closely follow the task and, where

appropriate, collaborate in its work.

REFERENCES

[1] Palz, W., and Van Overstraeten, R.

(1995). Strategic Options for PV

Development in Europe. In:

Proceedings of the 13th EC

Photovoltaic Energy Conference,

883–886.

[2] Barnes, H. (ed) (1997). Photovoltaic

power systems in selected IEA 

member countries. EA Technology,

Capehurst Chester, UK.

[3] Toggweiler, P., Ruoss, D., Roecker, C.,

Bonvin, J., Muller, A., and Affolter, P.

(1997). Sofrel flat roof system and first

installation. In: Proceedings of the

14th EC Photovoltaic Energy

Conference, 701–704.

[4] Boumans, J.H. and Schoen, T. (1996).

Prefab Energy-roof — trends and

developments. Ecofys, Utrecht, the

Netherlands.

[5] Bruton, T.M, e.a. (1997). A study of the

Manufacture of 500 Wp p.a. of

Crystalline Silicon Photovoltaic

Modules. In: Proceedings of the 14th

EC Photovoltaic Energy Conference,

11–16.

Appendix A: International Activities 75

Figure 2: The National Association of Home Builders 21st Century

Townhome at the National Research Home Park in Bowie, Maryland, USA;

it is one of the Task VII projects to be evaluated.

Tim Ellison, ECD/PIX04473
[6] Gabler, H., Heidler, K., and Hoffmann,

V.U. (1997). Market Introduction of

Grid-Connected Photovoltaic

Installations in Germany. In:

Proceedings of the 14th EC

Photovoltaic Energy Conference,

27–32.

[7] Van Schalkwijk, M., Hoekstra, K.J.,

Schoen, T., and Van der Weiden, T.C.J.

(1997). Quality Assurance of PV

Integration in Buildings: Experiences

from Practice and Future Outlook. In:

Proceedings. of the 14th EC

Photovoltaic Energy Conference,

1616–1619.

[8] Nordmann, T. (1995). The Swiss 1 MWp

PV-School Demonstration Program. In:

Proceedings of the 13th EC

Photovoltaic Energy Conference,

894–897.

76 Appendix A: International Activities
Australia

Deo Prasad

d.prasad@unsw.edu.au

Austria

Reinhard Haas 

haas@risc.iew.tuwien.ac.at

Canada

Per Drewes 

Per.Drewes@hydro.on.ca

Denmark

Henrik Sorensen 

esbensen@inet.uni-c.dk

Germany

Hermann Laukamp 

helau@ise.fhg.de

Netherlands

Henk Kaan 

kaan@ecn.nl

Bert Middelman

middelman.bert@enw.emswitch.nl

Tjerk Reijenga 

tjerk@bart.nl

Tony Schoen 

T.Schoen@ecofys.nl

Spain

Nuria Martin 

chivelet@dec.ciemat.es

Sweden

Mats Andersson 

mats.andersson@mbox10.swipnet.se

Switzerland

Christian Roecker 

Roecker@LESOsun1.epfl.ch

Peter Toggweiler 

enecolo@.active.ch

United Kingdom

David Lloyd Jones 

1014572375@compuserve.com

Donna Munro 

dkm@hga.co.uk

Paul Ruyssevelt 

par@hga.co.uk

United States

Patrina Eiffert

Patrina_Eiffert@nrel.gov

Steven Strong

Sjstrong@solardesign.com

Appendix B: Contacts for International Energy Agency Photovoltaic Power System Task VII 77

Appendix B:

Contacts for International Energy Agency

Photovoltaic Power System Task VII —

Photovoltaics in the Built Environment
Appendix C:

Design Tools

Dru Crawley, DOE Program Manager for Building Energy Tools, has established a Building

Energy Software Tools Directory. This directory is available on the Internet online; see

http://www. eren.doe.gov/buildings/tools_directory/.

Software building design tools are divided into categories that include Energy Simulation,

Utility Evaluation, Energy Economics, Atmospheric Pollution, Envelope Systems, Solar Climate

Analysis, Codes and Standards: Development and Compliance, and Load Calculations. The

software tools described in this section may be particularly useful to those designing buildings

and other structures into which photovoltaic power systems are integrated. 

78 Appendix C: Design Tools
AWNSHADE

This program calculates the unshaded

fraction of a rectangular window for

any given solar position coordinates

relative to the window. Calculations are

made for window shading configurations, including awnings, with or without side walls or overhangs of arbitrary

dimensions above the window.

Awnshade can also calculate the

unshaded fraction for a sequence of

solar positions. It calculates the effective unshaded fraction of diffuse sky

irradiance or illuminance incident on

the window, assuming uniform sky

radiance/luminance, and the effective

ground-reflected unshaded fraction. It

can handle cases in which shadows of

the side of the awning/overhang cross

the top of the window.

Audience: This is for architects, building

designers, building energy performance simulators.

Expertise Required: Basic understanding

of building shading geometry.

Input: User-friendly I/O screens,

describing geometry of windows,

awnings, and vertical side fins.

Output: Results can be printed directly

to a printer, saved to a print file, or

saved to files formatted for importing

into graphic plotting programs.

Strengths: Outputs a table of unshaded

fractions for a range of incident sun

directions.

Weaknesses: No fancy graphics of window shadows or their movement across

the window.

Availability: Awnshade version 2.0 is

available from the contact at a cost of

$45 (including shipping and handling).

Contact: 

Joanne Stirling, Document Sales Office

Florida Solar Energy Center

1679 Clearlake Road

Cocoa, Florida 32922-5703

Telephone: 407- 638-1414

Facsimile: 407-638-1439

E-mail: joann@fsec.ucf.edu

Online: http://www.fsec.ucf.edu

BEES 

A powerful technique for selecting costeffective, environmentally preferable

building products, BEES (Building for

Environmental and Economic Sustainability) is based on consensus standards. The Windows-based decision

support software, aimed at designers,

builders, and product manufacturers,

includes actual environmental and economic performance data for a number

of building products.

BEES measures the environmental performance of building products by using

the environmental life-cycle assessment

approach specified in the latest versions

of ISO 14000 draft standards. All stages

in the life of a product are analyzed:

raw material acquisition, manufacture,

transportation, installation, use, 

recycling, and waste management.

Economic performance is measured

using the American Society for Testing

and Materials (ASTM) standard lifecycle cost method, which covers the

costs of initial investment, replacement,

operation, maintenance, repair, and 

disposal. Environmental and economic

performance are combined into an

overall performance measure using the

ASTM standard for Multi-Attribute

Decision Analysis. For the entire BEES

analysis, building products are defined

and classified according to the ASTM

standard classification for building 

elements known as UNIFORMAT II.

Audience: This is for designers, specifiers, builders, product manufacturers,

researchers, and policy makers.

Expertise Required: None; there were

more than 500 users in the first 6

months of availability, both in the U.S.

and abroad. 

Input: The user sets relative importance

weights for (1) synthesizing six environmental impact scores (global warming, acid rain, nutrification, resource

depletion, indoor air quality, solid

waste) into an environmental performance score; (2) discounting future

costs to their equivalent present value;

and (3) combining environmental and

economic performance scores into an

overall performance score. Default 

values are provided for all of this

Windows-based input.

Output: Summary graphs depicting 

life-cycle environmental and economic

performance scores for competing

building product alternatives. Detailed

graphs are also available, depicting

scores for the six environmental

impacts underlying the life-cycle environmental performance score, and

depicting first and future costs underlying the life-cycle economic performance

score. Graphs are live in the sense that

alternative graph types (pie graph, bar

graph, etc.) may be displayed; rows and

columns may be moved; colors, labels,

and other display attributes may be

customized; and graphs may be

printed.

Computer Platform: Windows 95 or

higher personal computer with a 486 

or higher microprocessor, 32 megabytes

or more of RAM, at least 10 megabytes

of available disk space, and a 3.5-in.

floppy diskette drive. The programming language is CA Visual Objects.

Strengths: The program offers a unique

blend of environmental science, decision science, and economics. It uses 

life-cycle concepts, is based on consensus standards, and is designed to be

practical, flexible, and transparent. It is

practical in its systematic packaging of

detailed, science-based, quantitative

environmental and economic performance data in a manner that offers 

useful decision support. It is flexible 

in allowing tool users to customize

judgments about key study parameters.

It is transparent in documenting and

providing all the supporting performance data and computational 

algorithms.

Weaknesses: It includes environmental

and economic performance data for

only 24 building products covering 

12 building elements.

Availability: BEES 1.0 software and

printed documentation available free 

of charge through the EPA Pollution

Prevention Information Clearinghouse

at 202-260-1023 or via e-mail,

Appendix C: Design Tools 79
ppic@epamail.epa.gov. BEES was

developed by the NIST Green Buildings

Program with support from the EPA

Environmentally Preferable Purchasing

Program.

Contact:

Barbara C. Lippiatt 

National Institute of Standards and 

Technology 

Office of Applied Economics 

100 Bureau Drive, Stop 8603

Gaithersburg, Maryland 20899-8603

Telephone: 301-975-6133 

Facsimile: 301-975-5337

E-mail: BLippiatt@nist.gov 

Web: http://www.bfrl.nist.gov/oae/ 

bees.html

BLAST

This program performs hourly simulations of buildings, air handling systems, and central plant equipment in

order to provide mechanical, architectural, and energy engineers with accurate estimates of a building's energy

needs. The zone models of BLAST

(Building Loads Analysis and System

Thermodynamics), which are based on

the fundamental heat balance method,

are the industry standard for heating

and cooling load calculations. BLAST

output may be utilized in conjunction

with the LCCID (Life Cycle Cost in

Design) program to perform an economic analysis of the building, system,

and plant design.

Audience: Mechanical, energy, and

architectural engineers working for

architectural-engineering firms, consulting firms, utilities, Federal agencies,

research universities, and research laboratories.

Expertise Required: High level of computer literacy not required; engineering

background helpful for analysis of airhandling systems.

Input: Building geometry, thermal characteristics, internal loads and schedules, heating and cooling equipment

and system characteristics. Readable,

structured input file may be generated

by HBLC (Windows) or the BTEXT 

program.

Output: More than 50 user-selected, 

formatted reports printed directly by

BLAST; the REPORT WRITER program

can generate tables or spreadsheetready files for more than 100 BLAST

variables.

Strengths: PC Format has Windows

interface as well as structured text

interface; detailed heat balance algorithms allow for analysis of thermal

comfort, passive solar structures, high

and low intensity radiant heat, moisture, and variable heat transfer coefficients Ê none of which can be analyzed

in programs with less rigorous zone

models.

Weaknesses: High level of expertise

required to develop custom system and

plant models.

Availability: Software prices range from

$450 for an upgrade package to $1500

for new installations. This package 

contains complete sources, almost 400

weather files, numerous documents

about using BLAST as well as documentation (all on CD ROM). Contact

the Building Systems Laboratory for

additional information.

Contact: 

Building Systems Laboratory

University of Illinois

1206 West Green Street

Urbana, Illinois 61801

Telephone: 217-333-3977

Facsimile: 217-244-6534

E-mail support@blast.bso.uiuc.edu

Online: http://www.bso.uiuc.edu

BUILDING DESIGN ADVISOR

This provides a software environment

that supports the integration of multiple building models and databases

used by analysis and visualization

tools, through a single, object-based

representation of building components

and systems. Building Design Advisor

(BDA) acts as a data manager and

process controller, allowing building

designers to benefit from the capabilities of multiple analysis and visualization tools throughout the building

design process. BDA is implemented as

a Windows-based application. The 1.0

version has links to a Schematic

Graphic Editor and two simplified 

simulation tools, one for daylight and

one for energy analyses.

Audience: Architects and engineers

working in early building design

phases.

Expertise Required: Knowledge of

Windows applications; there are at least

200 users.

Input: Graphic entry of basic building

geometry and space arrangements.

Default descriptive and operational

characteristics can be edited by user.

Output: User-selected output parameters displayed in graphic form, including 2-D and 3-D distributions.

Computer Platform: PC-compatible,

Windows 95/98/NT, 30 megabytes of

hard disk space; the programming 

language is C++.

Strengths: It allows comparisons of multiple design solutions with respect to

multiple descriptive and performance

parameters. It also allows the use of

sophisticated analysis tools from the

early, schematic phases of building

design, and does not require the user to

have in-depth knowledge to use linked

tools for energy, daylighting, and other

analyses.

Weaknesses: Version 1.0 is linked to 

simplified tools for daylight and 

energy analyses.

Availability: Version 1.0 is available at

the Web site below.

Contact:

Konstantinos Papamichael 

Lawrence Berkeley National 

Laboratory 

Mail Stop 90-3111 

1 Cyclotron Road 

Berkeley, California 94720

Telephone: 510-486-6854 

Facsimile: 510-486-4089

E-mail: K_Papamichael@lbl.gov 

Web: http://kmp.lbl.gov/BDA

80 Appendix C: Design Tools
CLIMATE CONSULTANT

This program graphically displays climate data in dozens of categories useful

to architects. These include temperatures, wind velocity, sky cover, percent

sunshine, psychrometric chart,

timetable of bioclimatic needs, sun

charts, and sun dials showing hours

when solar heating is needed and when

shading is required. The psychrometric

analysis recommends the most appropriate passive design strategy as outlined in Givoni, Man, Climate and

Architecture (ref. date). It also develops

the kind of data incorporated in Watson

and Labs, Climatic Design (ref. date).

Audience: Architects, students of 

architecture.

Expertise Required: Intended to be selfinstructional, the program requires

only basic familiarity with computers

and architectural vocabulary.

Input: Typical Meteorological Year

(TMY) weather data in short format.

Output: Graphic plots of weather data.

Strengths: Highly graphic, user-friendly.

Weaknesses: Requires weather data in

TMY weather data format.

Availability: Not copy protected; sharing

is encouraged. It is most easily aquired

by copying a disk or by downloading

off the Web; otherwise, users can send a

check to the technical contact for $35,

payable to the Regents of the

University of California.

Contact: 

Professor Murray Milne

Department of Architecture and Urban 

Design

Box 951467

University of California at Los Angeles

Los Angeles, California 90095-1467

USA

Telephone: 310-825-7370

Facsimile: 310-825-8959

E-mail: Milne@ucla.edu

Online: http://www.aud.ucla.edu/ 

energy-design-tools 

DOE-2 

This is an hourly, whole-building

energy analysis program calculating

energy performance and life-cycle cost

of operation. It can be used to analyze

the energy efficiency of given designs

or the efficiency of new technologies.

Other uses include utility demand-side

management and rebate programs,

development and implementation of

energy efficiency standards and compliance certification, and training a new

corps of energy-efficiency-conscious

building professionals in architecture

and engineering schools.

Audience: Architects, engineers in private A&E firms, energy consultants,

building technology researchers, utility

companies, state and Federal agencies,

and university schools of architecture

and engineering.

Expertise Required: A high level of computer literacy is required; a 5-day session of formal training in basic and

advanced DOE-2 use is recommended.

There are 800 user organizations in 

the United States and 200 user organizations internationally; user organizations consist of 1 to 20 or more

individuals.

Input: Hourly weather file plus

Building Description Language input

describing geographic location and

building orientation, building materials

and envelope components (walls, windows, shading surfaces, etc.), operating

schedules, HVAC equipment and controls, utility rate schedule, building

component costs. The program is available with a range of user interfaces,

from text-based to interactive/graphical windows-based environments.

Output: Twenty user-selectable input

verification reports, 50 user-selectable

monthly/annual summary reports, and

user-configurable hourly reports of 700

different building energy variables. 

Computer Platform: PC-compatible; Sun;

DEC-VAX; DECstation; IBM RS 6000;

NeXT; 4 megabytes of RAM; math

coprocessor; compatible with UNIX,

DOS, VMS; the programming language

is FORTRAN.

Strengths: Detailed, hourly, wholebuilding energy analysis of multiple

zones in buildings of complex design; it

is widely recognized as the industry

standard.

Weaknesses: A high level of user knowledge and computer literacy is required. 

Availability: The cost is $300 to $2000,

depending upon the hardware platform

and software vendor.

Contact:

Fred Winkelmann 

Lawrence Berkeley National 

Laboratory 

Mail Stop 90-3147 

1 Cyclotron Road 

Berkeley, California 94720

Telephone: 510-486-5711 

Facsimile: 510-486-4089

E-mail: FCW@gundog.lbl.gov 

Web: http://gundog.lbl.gov

EMISS

This software generates a file of local

air-pollution emission coefficients. It 

is used with the BLCC life-cycle cost

program to estimate reductions in emissions associated with energy conservation projects. Three types of emission

factors are currently included: carbon

dioxide, sulfur dioxide, and nitrous

oxide. Emissions factors are specified

separately for six different end-use

energy types: electricity, distillate and

residual fuel oil, natural gas, liquid

petroleum gas, and coal. It is distributed in connection with the BLCC 

life-cycle cost program to several thousand users.

Audience: Federal energy managers 

and energy coordinators; engineers 

and architects; budget analysts and

planners.

Expertise Required: None required.

Input: Regional or local emissions factors or fuel-specific end-use data.

Appendix C: Design Tools 81
Output: Preformatted tables of computed emission factors by type of fuel.

Strengths: Emission factors for fossil

fuels can be regionalized or localized.

Program contains state-specific electricity emission factors and U.S. average

sulfur content of fossil fuels as default

data. A users guide is included as file

with program.

Weaknesses: The quality of the emissions

factors depends on the user's knowledge of the factors that contribute to

these emissions.

Availability: Free to Federal agencies

through the Energy Efficiency and

Renewable Energy Clearinghouse, 

1-800-DOE-EREC (363-3732).

Contact: 

Linde Fuller

National Institute of Standards and 

Technology

Office of Applied Economics

Building 226, Rm B226

Gaithersburg, Maryland 20899

Telephone: 301-975-6134

Facsimile: 301-208-6936

E-mail: Sieglinde.Fuller@nist.gov

Online: http://www.eren.doe.gov/ 

femp/ 

ENERGY-10

This is a design tool for smaller residential or commercial buildings (e.g., those

that are less than 10,000 square feet in

floor area) or buildings that can be

treated as one- or two-zone increments.

The software performs a whole-building energy analysis for 8760 hours 

per year, including dynamic thermal

and daylighting calculations. It is

specifically designed to facilitate the

evaluation of energy-efficient building

features in the very early stages of the

design process.

Audience: This is for building designers,

especially architects; HVAC engineers;

utility companies; university schools 

of architecture and architectural 

engineering.

Expertise Required: A moderate level of

computer literacy is required; two days

of training are advised.

Input: Only four inputs are required to

generate two initial generic building

descriptions. Virtually everything is

defaulted but modifiable. User adjusts

descriptions as the design evolves,

using fill-in menus, including utilityrate schedules, construction details,

materials.

Output: Summary table and 20 graphical outputs are available, generally

comparing current design with base

case. Detailed tabular results are also

available.

Strengths: Fast, easy-to-use, accurate.

Automatic generation of base cases 

and energy-efficient alternate building

descriptions; automatic application of

energy-efficient features and rankordering of results; integration of daylighting thermal effects with thermal

simulation; menu display and modification of all building-description and

other data.

Weaknesses: Limited to smaller buildings and HVAC systems that are most

often used in smaller buildings.

Contact:

Passive Solar Industries Council

Suite 600

1511 K Street, NW

Washington, DC 20005

Telephone: 202-628-7400

Facsimile: 202-393-5043

Online: http://www.psic.org/ 

energy10.htm

FRESA

This is a first-order screening tool to

identify potentially cost-effective applications of renewable energy technology

on a building and facility level. FRESA

(Federal Renewable Energy Screening

Assistant) is useful for determining

which renewable energy applications

require further investigation. Technologies represented include active

solar heating, active solar cooling, solar

hot water, daylighting with windows,

daylighting with skylights, photovoltaics, solar thermal electric (parabolic dish, parabolic trough, central

power tower), wind electricity, small

hydropower, biomass electricity (wood,

waste, etc.), and cooling load avoidance

(multiple glazing, window shading,

increased wall insulation, infiltration

control). Life-cycle cost calculations

comply with 10 CFR 436. 

Audience: Building energy auditors.

Expertise Required: Must be able to

gather summary information on building and installation energy use patterns; intended for use by trained

auditors; results should be interpreted

by someone familiar with the limitations of the program. 

Input: Summary energy load data; solar

and wind resource data provided in a

database indexed by ZIP code; biomass

and solid waste resource data must be

gathered by the auditor. 

Output: Annual cost and energy savings; life cycle economics; a red flag if

an option is viable; viable options

ranked by savings-to-investment ratio. 

Strengths: Establishes consistent

methodology and reporting format for

a large number of audits in varying

locations and with varying building 

use types; sophisticated analyses of

technology performance and cost 

while keeping data requirements to a

minimum. 

Weaknesses: Provides only first-order

screening, to focus design; requires

more detailed feasibility analyses on

applications most likely to be cost-effective; requires high level of knowledge

about energy audits and the limitations

of the program; not suitable for general

use.

Availability: Available from the technical

contact.

82 Appendix C: Design Tools
Contact: 

Andy Walker, Ph.D.

National Renewable Energy Laboratory

1617 Cole Boulevard

Golden, Colorado 80401

Telephone: 303-384-7531

Facsimile: 303-384-7411

E-mail: Andy_Walker@nrel.gov

Online: http://www.eren.doe.gov/ 

femp/techassist/softwaretools/

softwaretools.html

IDEAL

This software is designed to read electronic data records of facilitiesí electrical energy use; the data records are

compiled by electric utility companies

and normally used internally only for

billing purposes. Upon request, the 

utility will release the data to the customer for analysis purposes. These 

data records are formatted in more than

25 distinct file types identified thus far.

IDEAL (Interval Data Evaluation and

Analysis of Load) translates all these

formats into a common database and

produces informative graphs and

reports to assist the user, the energy

management team, or consultants in

quickly identifying periods of serious

power mismanagement. Extensions to

the basic program will perform power

bill calculations, time-of-use analysis,

temperature and humidity plots, and

optimum standby generator sizing and

run times. 

Audience: Industrial and large commercial accounts who have electronic

metering on their electrical power service (typically, loads with more than

500 kilowatts demand, and virtually all

with time-of-use metering).

Expertise Required: No special expertise

required.

Input: Data file, normally obtained from

the electric utility company, which

includes interval recordings of power

usage. Program requires data to be an

ASCII-formatted data file on diskette.

Output: Both detailed and summary

reports of facility electrical usage. More

than 70 preformatted graphs visually

depict power usage by day, week, or

month. Variables include kilowatts at 

a minimum and may include kilovars

and kilovolt-amperes, if the source data

file contains this information. 

Strengths: Identifies, by time of day,

periods of excessive power demand

and consumption. Also useful in benchmarking a facility's power usage before

energy measures are implemented and

tracking the results after implementation. Ability to immediately utilize

more than 25 data formats without

prior conversion of the data by the user.

Weaknesses: Limits analysis to monthby-month studies. Can produce records

suitable for greater-than-one-month

analysis using conventional spreadsheets. Must use DOS sequences for

printing reports and graphs.

Availability: Download demos from 

the Web to determine suitability to task.

Price negotiable based on number of

copies; list price $1,000.

Contact: 

John D. Helms

PC Application Systems

4310 Twin Pines Drive

Knoxville, Tennessee 37921-5143

Telephone: 423-588-7363

Facsimile: 423-584-1350

E-mail: john_helms@msn.com

Online: http://ourworld.compuserve.

com/homepages/john_helms/

PV-DesignPro

This program simulates photovoltaic

system operation on an hourly basis for

one year, based on a user-selected climate and system design. PV-DesignPro

is recommended for designs that

include battery storage, which can be

either stand-alone systems with generator backup or utility-interconnected

systems. The purpose of the program 

is to aid in photovoltaic system design

by providing accurate, in-depth information on the likely system power 

output and load consumption, backup

power needed during system operation, and the financial impacts of

installing the proposed system. The

program CD-ROM includes a climate

database of 239 locations in the continental United States, Alaska, Hawaii,

Puerto Rico, and Guam and a Worldwide Hourly Climate Generator

Program that generates hourly climates

for 2,132 global locations from monthly

data. The SolarPro 2.0 solar water heating program is also included. Six types

of panel surface tracking are incorporated into the program: fixed slope and

axis, tracking on a horizontal east-west

axis, tracking on a horizontal northsouth axis, tracking on a vertical axis

with a fixed slope, tracking on a northsouth axis parallel to the Earth's axis,

and continuous tracking on two axes.

Panel shading information can also be

input. 

Audience: This program is for PV system design professionals, architects,

engineers, energy offices, universities,

and students.

Expertise Required: Knowledge of electrical design, PV basics.

Input: Windows 95-based interface;

uses the electrical system load by hour

for weekdays, weekends, and holidays;

requires panel type from database,

number of parallel connections and

series strings of similar panels; battery

backup charging parameters; AC

inverter requirements; and climate file.

Output: Solar Fraction charts by month,

battery states of charge by month (maximum, average, minimum), annual 

performance table (energy produced,

necessary backup, and states-ofcharge), prospective cash-flows of purchased and sold energy, system costs,

costs of backup energy, prices of sold

energy, maintenance and replacement

costs, and the estimated life of the system. A rate of return is calculated, as

well as an overall price per kWh of the

system and payback years.

Strengths: Most information needed for

PV designs is included in databases.

Weaknesses: Resistive loads, such as

water pumping with a motor only, 

cannot currently be modeled.

Appendix C: Design Tools 83
Relatively high level of PV expertise

recommended.

Availability: CD-ROM, $149.00 + $10.00

shipping and handling. Price includes

Worldwide Hourly Climate Generator

1.0 program and SolarPro 2.0 solar

water heating program. See Web site 

or call for more information.

Contact: 

Mike Pelosi

PV-DesignPro Software

P.O.Box 1043

Kihei, Maui, Hawaii 96753

Telephone: 808-879-7880

Facsimile:

E-mail: MPelosi@maui.net

Online: http://www.maui.net/ 

~sandy/PV-DesignPro.html

Quick BLCC

This program is used to set up multiple

project alternatives for life-cycle costing

analysis in a single input file. The Quick

BLCC (Quick Building Life-Cycle Cost)

program provides a convenient method

for solving relatively simple LCC problems that require finding the lowest

LCC design alternative among many

mutually exclusive alternatives for the

same project. Input data files are transferrable to BLCC for more detailed

analysis. 

Audience: Federal energy managers 

and energy coordinators; engineers 

and architects; budget analysts and

planners.

Expertise Required: Familiarity with 

present-value concept is helpful. 

Input: Initial investment costs; baseyear annual energy costs; maintenance,

repair, and replacement costs; time

period. 

Output: Preformatted tables of input

data summary and LCC and comparative analyses results. Exportable data

files. 

Strengths: Ideal for preliminary economic evaluation of multiple design

alternatives. Users guide is included as

file with program.

Weaknesses: No private-sector tax analysis included.

Availability: Free to Federal agencies

through the Energy Efficiency and

Renewable Energy Clearinghouse, 

1-800-DOE-EREC (363-3732).

Contact: 

Linde Fuller

National Institute of Standards and 

Technology

Office of Applied Economics

Building 226, Rm B226

Gaithersburg, Maryland 20899

Telephone: 301-975-6134

Facsimile: 301-208-6936

E-mail: Sieglinde.Fuller@nist.gov

Online: http://www.eren.doe.gov/ 

femp/techassist/softwaretools/

softwaretools.html

SOLAR-2

This software plots sunlight penetrating through a window with any 

combination of rectangular fins and

overhangs. It also plots an hour-byhour, three-dimensional suns-eye view

"movie" of the building. It prints annual

tables of the percentage of the window

in full sun, radiation on glass, and other

data. 

Audience: This is for architects, students

of architecture, building managers, and

knowledgeable homeowners.

Expertise Required: Intended to be selfinstructional, it requires only basic

familiarity with computers and architectural vocabulary.

Input: Window, overhangs, and fins

geometry.

Output: Graphic plots, tables.

Strengths: User-friendly, highly graphic.

Weaknesses: Allows only rectangular

shading elements.

Availability: Not copy protected; sharing

is encouraged. The software is most

easily aquired by copying a disk or by

downloading off the Web; otherwise,

users can send a check to the technical

contact for $35, payable to the Regents

of the University of California.

Contact: 

Professor Murray Milne

Department of Architecture and 

Urban Design

Box 951467

University of California at Los Angeles

Los Angeles, California 90095-1467

Telephone: 310-825-7370

Facsimile 310-825-8959

E-mail: Milne@ucla.edu

Online: http://www.aud.ucla.edu/ 

energy-design-tools

Florida Solar Energy Center

1679 Clearlake Road

Cocoa, Florida 32922-5703

Telephone: 407-638-1414 

Facsimile: 407-638-1439

E-mail: joann@fsec.ucf.edu

Online: http://www.fsec.ucf.edu

SOLAR-5

This program displays 3-D plots of

hourly energy performance for the

whole building or for any of 16 different components. SOLAR-5 also plots

heat flow into and out of thermal mass

as well as indoor air temperature, 

output of the HVAC system, cost of

electricity and heating fuel, and the 

corresponding amount of air pollution.

It uses hour-by-hour weather data. It

contains an expert system to design 

an initial base case building for any 

climate and any building type, which

an architect can copy and redesign.

Contains a variety of decision-making

aids, including combination and comparison options, color overlays, and bar

charts that show for any hour exactly

where the energy flows. 

Audience: This is for architects, students

of architecture, building managers, and

knowledgeable homeowners.

Expertise Required: It is intended to be

self-instructional, with built-in help

options; requires only basic familiarity

with computers and with architectural

vocabulary.

84 Appendix C: Design Tools
Input: From only four pieces of data 

initially required (floor area, number of

stories, location, and building type), the

expert system designs a basic building,

filling in hundreds of items of data; the

user can make subsequent revisions,

usually beginning with overall building

dimensions, window sizes, etc.

Output: Dozens of different kinds of

three-dimensional plots, tables, and

reports. For example, displays heat gain

or loss for more than a dozen different

building components; shows heat flow

into and out of the thermal mass of the

building, as well as the output of the

heating and air conditioning systems;

displays air temperatures (outdoors or

indoors) and air change rates; predicts

the cost of heating fuel and electricity.

Strengths: Intended for use during 

the very earliest stages of the design

process (when most critical energy

decisions are made); extremely user

friendly and rapid, calculating a full

year using TMY data in less than a

minute on a 486 MB machine.

Weaknesses: Not intended for complex

mechanical system design or equipment sizing.

Availability: SOLAR 5.4 is the most

recent public release, updated in

September 1997. It writes out its own

users manual. Not copy protected;

sharing is encouraged. Most easily

aquired by copying a disk or by downloading off the Web; otherwise, users

can send a check to the technical contact for $35, payable to the Regents of

the University of California.

Contact: 

Professor Murray Milne

Department of Architecture and 

Urban Design

Box 951467

University of California at Los Angeles

Los Angeles, California 90095-1467

Telephone: 310-825-7370

Facsimile: 310-825-8959

E-mail: Milne@ucla.edu

Online: http://www.aud.ucla.edu/ 

energy-design-tools

SOMBRERO

In designing both active (domestic hot

water, photovoltaics) and passive solar

energy systems, shading of collectors 

or windows by other objects plays an

important role. SOMBRERO provides

quantitive solutions to these problems.

It calculates geometrical shading coefficients, which can be used either directly

for visualization or as quantitative

input to other thermal simulation 

programs. 

Audience: Architects, engineers for thermal simulations of buildings or solar

plants.

Expertise Required: Basic knowledge of

geometry and solar radiation.

Input: Three-dimensional objects are

built up by their boundary planes. Up

to 300 plane areas with 12 points each

can be treated. Objects like houses and

trees are predefined and described by

parameters like height, width, and

position in space. Single planes are

described by their vertex-points in the

two-dimensional co-ordinate system

related to the plane itself (in case of 

rectangles simply by their length and

height) and positioned by indication 

of azimuth, elevation, and origin in the

three-dimensional space. Time steps 

for simulation can be selected freely.

Foliage of trees and reflection factors 

of the ground can be given as monthly

schedules.

Output: Values of the daily course of

geometrical shading coefficients are 

calculated hourly. 

Computer Platform: MS-DOS 5.0 

and MS-Windows 3.1 or better; PCcompatible system with VGAcompatible graphic-board (at least 

640 x 480 pixels); about 5 MB free 

space on hard disk. The programming

language is Delphi.

Strengths: Easy to handle.

Weaknesses: Unknown.

Availability: A demonstration version

can be downloaded free; it expires

5 days after it is first started up. The full

version sells for $230.

Contact:

Prof. Dr.-Ing. F.D. Heidt 

Building Physics and Solar Energy 

University of Siegen 

Siegen, 57068

Germany

Telephone: +49 271-740-4181 

Facsimile: +49 271-740-2379

E-mail: heidt@physik.uni-siegen.

d400.de 

Web: http://nesa1.uni-siegen.de

SUN POSITION 

The program calculates time series of

sun angles (such as solar altitude and

solar azimuth) for a given location and

outputs them as text files that can be

imported into spreadsheets and solar

energy analysis programs. Sun Position

is highly customizable; it can calculate

angles for one specific day, once a

month for one year, once a week, daily,

etc., and in a given day calculate the

angles once a day, hourly, every 15 minutes, etc. Its primary purpose is to assist

architects and solar designers.

Audience: Architects, passive solar

designers, PV and solar thermal energy

system designers.

Expertise Required: Understanding of

fundamentals of sun angles (see

www.crest.org/staff/ceg/sunangle/

for an introduction to sun angle 

concepts).

Input: The user inputs the geographical

location, the frequency of the data

desired, and the output format desired;

the program has a graphical user 

interface.

Output: The output is text files consisting of tables of sun angle data; the 

specific sun angles, format of the data,

etc., are specified by the user.

Computer Platform: Windows and

Macintosh; the programming language

is MacroMedia Director.

Strengths: Best for people performing

analyses of buildings or solar energy

Appendix C: Design Tools 85
systems over a year who need to know

solar altitude and azimuth angles for

their analysis.

Weaknesses: While Sun Position can

compute individual sun angles (i.e., at

one specific time instead of throughout

the year), it would be more efficient to

use the internet SunAngle calculator for

single calculations.

Availability: Free.

Contact:

Christopher Gronbeck 

Seattle Energy Works 

1020 NE 68th Street 

Seattle, Washington 98115

Telephone: 206-729-5260 

Facsimile: 206-522-5051

E-mail: ceg@energysoftware.com 

Web: http://www.energysoftware.

com

SUNSPEC

This software calculates clear-sky direct

beam and diffuse-sky solar spectral

irradiances and the sum of these two

spectra for sun positions and atmospheric conditions specified by the user.

Sunspec also calculates the spectral

irradiances from the direct beam, diffuse sky, or ground reflections that are

incident on an arbitrarily tilted plane.

Sunspec integrates these spectra to

determine the total irradiances, 

illuminances, and luminous efficacies

for each component.

Sunspec offers the user a menu of typical atmospheric conditions to choose

from and follows this with detailed

editing screens permitting the user to

change any input parameter. The input

parameters include values for ozone

concentration, water vapor, turbidity,

ground reflectance (albedo), solar altitude and azimuth angles, and tilted

plane altitude and azimuth angles.

Sunspec includes a loop option permitting repeated calculations at different

solar positions for the same atmospheric conditions. It also has an option

for outputting solar spectral data files

that can be read by the Window 4 program, which calculates the solar optical

and heat transfer properties of windows in buildings.

Audience: This is for architects, building designers, fenestration energy 

performance simulators, atmospheric 

scientists, and others interested in

determining the spectrum of radiation

from the sun and sky.

Expertise Required: Basic understanding

of solar geometry.

Input: User-friendly I/O screens, solar

position, atmospheric conditions.

Output: Results can be printed directly

to a printer, or saved to a print file or to

files formatted for importing into

graphic plotting programs.

Strengths: Provides a solar spectrum

data file with columns for wavelength,

direct normal, direct horizontal, direct

tilted, diffuse horizontal, and diffuse

tilted spectral irradiances, as well as the

global (both direct and diffuse) versions

of these. Also outputs the integrated

total irradiances in W/m2 and the total

integrated illuminances in lux for all

these beams.

Weaknesses: Current menu of typical

atmospheric conditions is limited. It

does not yet have the latest version of

the SMARTS algorithm and is not as

user-friendly as a planned future 

version.

Availability: Sunspec 1.0 is available

from the contact at a cost of $35 

(including shipping and handling).

Contact:

Joanne Sterling, Document Sales Office

Florida Solar Energy Center

1679 Clearlake Road

Cocoa, Florida 32922-5703

Telephone: 407- 638-1414

Facsimile: 407-638-1439

E-mail: joann@fsec.ucf.edu

Online: http://www.fsec.ucf.edu

TRNSYS

This modular system simulation software includes many of the components

commonly found in thermal energy

systems as well as component routines

to handle input of weather or other

time-dependent functions and output

of simulation results. TRNSYS

(TRaNsient SYstem Simulation

Program) is typically used for HVAC

analysis and sizing, solar design, building thermal performance, and analysis

of control schemes. 

Audience: Engineers, researchers, and

architects. 

Expertise Required: None to use standard

package; FORTRAN knowledge is helpful for developing new components 

Input: TRNSYS input file, including

building input description, characteristics of system components and manner

in which components are interconnected, and separate weather data (supplied with program). Input file can be

generated by graphically connecting

components. 

Output: Life-cycle costs, monthly 

summaries, annual results, histograms,

plotting of desired variables (by time

unit), online variable plotting (as the

simulation progresses).

Strengths: Because of its modular

approach, the program is extremely

flexible for modeling a variety of thermal systems at different levels of 

complexity; supplied source code 

and documentation provide an easy

method for users to modify or add

components not in the standard library;

extensive documentation on component routines, including explanation,

background, typical uses and governing equations; supplied time step, 

starting, and stopping times allow

choice of modeling periods. Version

14.2 moves all the TRNSYS utility programs to the MS Windows platform

(95/NT), including a choice of graphical drag-and-drop programs for creating input files, a utility for easily

creating a building input file, and a 

program for building TRNSYS-based

applications for distribution to

nonusers. Web-based library of additional components and frequent downloadable updates are also available. 

86 Appendix C: Design Tools
Weaknesses: No assumptions about the

building or system are made (although

default information is available) so the

user must have detailed information

about the building and system and

enter this information into the TRNSYS

interface.

Availability: Version 14.2, Commercial,

$4000; Educational, $2000. Free demonstration diskette and information are

available from the technical contact.

International distributors are located 

in Germany, France, Belgium, and

Sweden in addition to two distributors

in the United States.

Contact: 

TRNSYS Coordinator

Solar Energy Laboratory

University of Wisconsin

1500 Johnson Drive

Madison, Wisconsin 53706

Telephone: 608-263-1589

Facsimile: 608-262-8464

E-mail: trnsys@sel.me.wisc.edu

Online: http://sel.me.wisc.edu/

trnsys/download.htm

Appendix C: Design Tools 87
Patrina Eiffert, Ph.D.

Dr. Eiffert is a project leader in the National

Renewable Energy Laboratoryís (NRELís)

Deployment Facilitation Center. NREL is a U.S.

Department of Energy (DOE) national laboratory. 

As a Deputy Team Leader within NRELís Federal

Energy Management Program (FEMP) team, Dr.

Eiffert has had experience managing projects that

assist in implementing renewable energy in the

Federal sector. Primary activities range from conducting economic feasibility analysis and design

studies through assessment and exploration of 

alternative financing mechanisms. Dr. Eiffert leads

national activities under the Save with Solar: Federal

Participation in the Million Solar Roofs Initiative on

behalf of DOE FEMP.

Additionally, Dr. Eiffert co-represents the United

States in the International Energy Agency,

Photovoltaic Power Systems (PVPS) Task VII, 

Photovoltaics in the Built Environment, along with

Steven Strong of Solar Design Associates. In this

position, as an internationally recognized expert in

Building Integrated Photovoltaics (BIPV), Dr. Eiffert

leads the effort to develop International Guidelines

for the Economic Evaluation of BIPV and is the

Activity Leader for Subtask 3: Non-technical

Barriers.

Dr. Eiffert completed her doctorate in Architecture

on building-integrated photovoltaics at Oxford

Brookes University Post-Graduate Research School

in the United Kingdom. Dr. Eiffert has authored

many articles and publications related to renewable

energy systems and programs and is a guest lecturer

at universities across the country.

Patrina Eiffert

NREL, M.S. 2723

1617 Cole Blvd.

Golden, CO 80401-3393

Gregory J. Kiss

Mr. Kiss, a specialist architect, has been a principal of

Kiss + Cathcart since 1984. His work has focused on

the integration of solar technologies into architecure

and product design, and has included built projects

research and education. Kiss + Cathcart have won a

number of awards and invited competitions, including top prizes in every solar-architecture competition

since 1992. Kiss + Cathcartís projects range from

first-of-a-kind photovoltaic buildings in Port Jarvis,

New York, and Fairfield, California, to major PV

buildings projects in progress at Four Times Square

in Manhattan, New York; in Yosemite National Park;

and in Hamburg, Germany.

Research by the firm has included three studies on

building-integrated photovoltaics commissioned 

by NREL. In conjunction with Energy Photovoltaics

of Princeton, New Jersey, Kiss + Cathcart has developed several BIPV construction products, including

large-area lamiations for facades and skylights. The

firm is also developing custom patterned, semitransparent PV panels for building use.

Consulting activities include the Whitehall Ferry

Terminal project in New York and solar housing in

Winslow, Arizona, as well as the projects listed in 

the design briefs in this book.

Kiss + Cathcart designed "Under the Sun," a major

exhibition of solar design and architecture at the

Cooper Hewitt, National Design Museum,

Smithsonian Institution. The exhibit is an investigation of the design implications of the solar future;

it was originally held in one of the most prestigious

garden sites in the United States. This is now a 

traveling exhibit.

Gregory J. Kiss

150 Nassau Street, Top Floor

New York, NY 10038

88 About the Authors

About the Authors
89

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