Economics of 

Energy Effective Lighting for Offices

Energy Effective Lighting accomplishes the dual objectives of being efficient while meeting the needs of the space 

occupants. The USDOE Federal Energy Management Program is committed to saving energy and improving workspaces for

Federal workers at the same time.

In recent years there has been a steadily increasing tide of concern about lighting quality 

in addition to energy efficiency. Conscientious Federal energy managers, energy services 

companies, and utility providers have learned from experience that lighting is a double-edged

sword. It represents the most significant energy savings opportunity of all the building 

energy systems, and also has a profound and direct impact on the occupants of the buildings,

for better or for worse.

FOR BETTER

Energy-efficient lighting can also be energy effective, but only if thoughtful and careful 

decisions are made. From a conceptual perspective, it stands to reason that reducing glare

and gloom are likely to have positive impacts on occupant satisfaction and performance. It is

the challenge and responsibility of those who make lighting decisions in Federal buildings to

optimize the well-being and performance of the Federal workforce where possible as well as

to save energy and money.

FOR WORSE

The most common lighting fixture in Federal office buildings is the lensed 2x4, which 

is the least appropriate lighting technology for most modern open plan office 

environments. Additionally, some of the most frequent energy-efficient lighting 

installations can result in problems. In some cases specular reflector retrofits can

reduce the visual comfort of the workers and decrease brightness at the walls.

THE NEW STANDARD OF PRACTICE

Federal specifications are based on the standards and 

recommended practices of the Illuminating Engineering

Society of North America. The year 2000 brings a new IESNA

Lighting Handbook, 9th edition, that sets new standards and

fundamentally changes lighting specification practices. The

long-standing illuminance selection table has been replaced

with a matrix that prioritizes design issues, and it has 

significant implications for Federal lighting projects. In offices

the most important design characteristics are brightness 

(luminance) of the room surfaces, reflected glare, and direct

glare. Notably, horizontal illuminance is no longer the highest

priority. Federal lighting guidelines will be updated to meet the

IESNA standard of practice.

ECONOMIC IMPACT OF

LIGHTING ON FEDERAL

PRODUCTIVITY

If energy effective relighting were

accomplished in Federal office buildings,

the benefit would extend above and

beyond the energy savings. The mean

value of improved productivity from

effective relighting in the Federal sector

has been estimated at $1.64/SF per 

year, with a total annual value of $640

million. While productivity improvements are not typically introduced into a

payback scenario, these tremendous

potential benefits indicate that all 

reasonable effort should be made to

provide Energy Effective Lighting using

Federal life cycle cost guidelines.1

1 See inside center column.

Sun Microsystems,

Mountain View, CA

ECONOMICS

Fortunately it is economically feasible to meet the dual objectives

of new standards and energy efficiency at the same time. In fact,

it is possible to actually improve the workplace environment for

the Federal workforce and increase the value of the building stock

as well. This brochure has been developed to help achieve the

optimum balance between the factors discussed above. As with all

energy conservation measures in the Federal sector, economics are

at the core of how decisions will be made with respect to lighting

energy effectiveness. In years past quality lighting equipment was 

out of reach because of higher costs, but the falling costs of new

technologies has shifted the balance favorably. In most cases it will

be cost-effective to use new equipment in a relighting design

instead of simply retrofitting the components of aging and less

appropriate lighting technologies. The design cases that follow

show that it is now possible to provide Energy Effective Lighting

using new and more appropriate technologies and with excellent

payback scenarios. 

Brightness on the room

surfaces is one of the top

three priorities for office

lighting in the new standards. Indirect lighting is

one way to accomplish

this. Alternatively, when

using recessed fixtures, be

sure to locate them close

to the walls, or use a wall

washing system as well. 
Base Case Design

Lensed 2x4s, (4) T12 lamps, magnetic ballast.

Until recently, the most common lighting system installed in office buildings employed four fluorescent lamps in a recessed troffer with an acrylic

lens. A typical layout is shown here, with fixtures on 8’ by 8’ centers.

Many installations will be found using 34 watt T-12 lamps and “energy

saving” magnetic ballasts,

operating at around 2.0 W/SF or

more. Older installations may

employ standard magnetic 

ballasts and 40-watt lamps,

increasing power density to 2.6

W/SF or more.

Option 1 • Retrofit

(2) T8 lamps, specular reflector, new lens, electronic ballasts,

standard ballast factor.

The simplest improvement is to retrofit the existing troffers. In this case,

the interior of the fixtures will be stripped of lamps, ballast, and sockets,

and a specular reflector with sockets and ballast for two lamps will 

be installed. The lens should be replaced and the fixture cleaned. The

resulting design will save at least 60% of the energy of the base system.

While this will be the cheapest retrofit and will offer the fastest payback,

unfortunately it fails to improve the quality of the overall lighting system,

and does not meet the IESNA recommended practice. This system has a

low Visual Comfort Probability of 50, indicating that one-half of the 

population is likely to experience discomfort from glare.

Option 2 • Retrofit

(2) T8 lamps, parabolic 

louver doorframe, white

reflector, electronic ballasts,

high ballast factor.

For an additional cost of about

$25 per fixture, you can improve the retrofit by upgrading from a lens to

a parabolic louver. The existing troffer is raised up, and the new louver

doorframe is placed over the opening. The troffer then sits on top of the

frame. In this case a high reflectance white reflector is recommended. The

energy savings will be the same as for the basic retrofit, but now you will

gain the shielding of the parabolic louver needed for open office areas.

Because parabolic fixtures have a more downward distribution, it is

important that the existing layout have the fixtures located within 3’ of

the walls to avoid scallops and darkness at the tops of the walls. In a 

situation where new fixtures are prohibited because of asbestos or code

wiring upgrade constraints, this retrofit can reduce glare without installation of new fixtures. 

Option 3 • Relighting

2x4 parabolic fixtures, (2) T8 lamps, 12-cell semi-specular louver,

electronic ballasts, standard ballast factor.

This design replaces lensed fixtures with parabolic troffers using (2) T8

lamps in an existing 8x8 layout. The layout is advantageous because most

workstations end up with a fixture overhead providing relatively even 

OPEN PLAN DESIGNS

WHAT ARE SEMI-IN

Semi-indirect fixtures have a primarily

uplight distribution, but they have a small

amount of downlight usually through a

luminous element in the housing such as

perforated metal. The brightness in the

housing reduces their contrast against the

bright ceiling and makes them an excellent

solution for visual comfort and aesthetics.

Other features include:

It is not advisable to perform only lighting

energy conservation measures in a 

building. Since lighting usually offers the

most cost-effective energy savings, it is

important to address other efficiency

improvements at the same time. Building

analyses should consider performing 

energy conservation measures of the other 

building systems at the same time as the

lighting. Often HVAC impacts of reduced

lighting energy use can result in additional

savings. If expensive equipment such as

chillers are not replaced when savings are

available from a relighting project, it 

can make it difficult to cost justify the 

measures alone at a later time.

DEEP ENERGY SAVINGS

LIGHTING SYSTEM OPTIONS

The lensed troffer has been the workhorse of office lighting for over 60 years. Unfortunately the brightness of the 

plastic lens can create problems in the modern open plan office environment because of the prevalence of Visual Display

Terminals (computer monitors). Even with the significant improvements in VDT screens, the lensed troffer does not meet

the IESNA recommended practice for office lighting. This presents a significant challenge in Federal 

buildings because of the prevalence of this outdated technology. The designs below have been created to meet the 

following objectives:

■ Meet the new standards of practice by avoiding reflected and overhead glare and creating brightness on the 

room surfaces.

■ Wherever possible replace lensed troffers with lighting technologies such as parabolic troffers or semi-indirect 

fixtures.

■ All proposed designs meet Federal life cycle cost requirements and have a Savings to Investment Ratio > 1.

WHEN RELIGHTING

The economic information included in this

brochure is based on typical conditions.

There are some conditions that change the

economics enough that it becomes less 

feasible to obtain new fixtures, and 

component retrofit becomes the best

option. If your project has one or more of

the following constraints, you should 

re-evaluate the payback considering the

additional costs:

8x8 Layout BASE

CASE & OPTION

1

OPTION 2 & 3

■ Because of long-term deterioration of

lighting equipment, a fixture older than

15 years should almost always be

replaced rather than retrofitted.

■ Walls and ceilings should be light colored wherever possible to save energy

and improve lighting quality. 

■ Direct glare from overly bright lamps

and reflectors can cause significant visual discomfort. T5 lamps are best used in

indirect wall washing fixtures rather

than open downlights so the lamps are

not exposed directly to the eyes.

■ When there are high partitions in the

open plan office, problematic shadows

can occur and a tighter spacing layout

IMPORTANT CO

8x8 Layout

BASE CASE

Watts/Square Foot 1.97

Average Illuminance, footcandles 65

Total Initial Cost/SF N/A

Annual Own and Optg Cost/SF $0.69

Simple Payback (years) N/A

Federal Savings to Investment Ratio N/A

OPTION 1

Watts/Square Foot .77

Average Illuminance, footcandles 51

Total Initial Cost/SF $1.12

Annual Own and Optg Cost/SF $0.33

Simple Payback (years) 3.1

Federal Savings to Investment Ratio 5.6

OPTION 2

Watts/Square Foot 1.01

Average Illuminance, footcandles 51

Total Initial Cost/SF $1.42

Annual Own and Optg Cost/SF $0.41

Simple Payback (years) 5.0

Federal Savings to Investment Ratio 3.2

OPTION 3

Watts/Square Foot .77

Average Illuminance, footcandles 46

Total Initial Cost/SF $1.84

Annual Own and Optg Cost/SF $0.32

Simple Payback (years) 4.9

Federal Savings to Investment Ratio 3.1

Federal offices constitute 36% of t

but house a disproportionate 6

The high density of workers in Fe

any effects that the physical enviro

1, 2 “Potential Productivity Benefits from High Qua

Proceedings of 1998 ACEEE Summer Study on E

for an Energy-Efficient Economy, Washington, D
Option 1 • Retrofit

(2) T8 lamps, specular reflector, new lens, electronic ballast, 

low ballast factor.

Similar to the Open Plan Office Option 1, retrofitting the lensed fixtures with

new components is the most common solution. A low ballast factor (.75-.80)

keeps the power density low while still providing adequate light levels. In 

private offices, lensed fixtures do not create reflected glare in VDT screens,

but the overhead glare can create discomfort and reduce satisfaction.

Base Case

Two 2x4 lensed troffers, (4) T12 lamps, magnetic ballasts 

This illustrates typical baseline conditions. Two lensed troffers in an 8’x12’

private office will provide adequate brightness on the walls and desktop, 

but can create an uncomfortable sensation of overhead glare for the 

occupants. Some offices may only have one 2x4 troffer which is inadequate

with respect to uniformity and wall brightness. NDIRECT FIXTURES?

1 recent trends in lighting equipment costs

have made these fixtures surprisingly

affordable with the use of steel housing, 

2 they are inexpensive to install because

they are pendant mounted and they

require a feed only at one end of the

run. Ceilings must be at least 8’-6” to

allow for an indirect lighting solution.

G DOESN’T WORK

■ Asbestos in the ceiling

■ Very low labor costs

■ Wiring upgrade required by code

■ Certain seismic considerations

■ Prior retrofit to T8 with electronic 

ballasts.

Option 4 • Relighting

New 2x4 parabolic fixtures, (2) T8 lamps, 12-cell semispecular louver, electronic ballasts, standard ballast factor.

It is also possible to employ parabolic fixtures on 8’x10’ centers. With 

a new fixture layout it becomes possible to ensure adequate wall 

brightness. This design should not be used if high partitions are in the

space. If the original layout is 8x10, this design will have a better payback

than what is estimated below because rewiring costs will be reduced. The

system has a high Visual Comfort Probability of 85, indicating that 85%

of the population is likely to find the lighting system visually comfortable.

Option 5 • Relighting

10’-0” on center layout, 3-lamp semi-indirect pendant mounted

fixtures, electronic ballasts, low ballast factor.

Modern sheet-metal indirect and semi-indirect fixtures using T-8 lamps

can be suspended from ceilings that are 8’-6” high or greater. The 

typical row spacing is 10’-0” on center. A low ballast factor (.75-.80)

keeps the power density low while still providing adequate light levels.

Using (2) T8 lamps per fixture and rows combining three or more fixtures,

it is possible to implement high quality, modern office lighting within

Federal payback criteria. 

The additional benefits of

worker satisfaction and overall workplace improvements

will generally make this an

excellent choice.

8x10 Layout OPTION

4

O

10’-0” on Center Layout

PTION

5

may be required. If direct fixtures are

used, is it especially important to ensure

that fixtures are located directly over the

workstations. 

■ If your general lighting level is less than

40 footcandles in the task areas, task

lighting should be used. In addition to

undercabinet task lighting, compact 

fluorescent desk and table lamps may be

used.

■ Use controls to reduce hours of 

operation and adjust lighting levels.

Depending on the space usage and 

technologies, the use of controls could

save significant energy over time.

ONSIDERATIONS

OPTION 4

Watts/Square Foot .99

Average Illuminance, footcandles 56

Total Initial Cost/SF $1.85

Annual Own and Optg Cost/SF $0.39

Simple Payback (years) 6.2

Federal Savings to Investment Ratio 2.5

OPTION 5

Watts/Square Foot .85

Average Illuminance, footcandles 47

Total Initial Cost/SF $2.16

Annual Own and Optg Cost/SF $0.36

Simple Payback (years) 6.5

Federal Savings to Investment Ratio 2.3

BASE CASE

Watts/Square Foot 2.85

Average Illuminance, footcandles 60

Total Initial Cost/SF N/A

Annual Own and Optg Cost/SF $0.82

Simple Payback (years) N/A

Federal Savings to Investment Ratio N/A

OPTION 1

Watts/Square Foot .98

Average Illuminance, footcandles 44

Total Initial Cost/SF $1.62

Annual Own and Optg Cost/SF $0.33

Simple Payback (years) 3.3

Federal Savings to Investment Ratio 6.0

BASE

CASE & 1

Lensed 2x4

PRIVATE OFFICE DESIGNS

he Federal building square footage 

66% of the Federal employees.

ederal office buildings magnifies 

onment has on labor productivity.2

“With each lighting project,

we have a crucial opportunity to improve lighting

conditions for the Federal

workforce. Attention to

lighting quality is clearly 

a win-win approach that

has the potential to raise

morale and productivity

while simultaneously 

reducing operating costs

and meeting our energy

efficiency goals.”

Lisa Heschong, 

Instructor FEMP Lights Web Course,

Partner, Heschong-Mahone Group

lity Lighting in Federal Buildings,” L. Harris et.al, 

Energy Efficiency in Buildings. American Council 

D.C.

illumination. This design has the advantage of providing an all new lighting system that meets quality recommendations. The system has a high

Visual Comfort Probability of 85, indicating that 85% of the population

is likely to find the lighting system visually comfortable.
WEIGHING THE OPTIONS

One of the things that makes lighting especially challenging and rewarding at the same time

is that every application is different. Generalizations are useful, but should always be viewed

in the context of the particular application. Based on the typical assumptions made for this

analysis, Option 3 is a good open plan choice. The payback is less than 5 years, the fixtures

are new, glare is reduced, and the power density is very low at .77 W/SF. When using the 

existing layout, the fixtures may not be close enough to the walls to avoid scallops and the

cave effect. In this situation, adding a wall washing system can solve the problem. Wall 

washing fixtures are available in all types — such as a linear fluorescent system, compact 

fluorescent wall washers (cans), and 2’-0” wide fixtures using T5 lamps. The addition of wall

washers to the design may make the parabolic design economically comparable to the 

indirect solution.

For private offices the clear winner is Option 4, which has a lower payback than the retrofit

solutions at 2.5 years. This low payback is achieved because of the reduction from two 

fixtures to one, which is acceptable because of the diffuse distribution that is characteristic of

indirect lighting. If there is a high concentration of private offices in your lighting project, it

may be economical to expand the indirect solution into the open plan and conference room

areas as well.

In some cases project constraints make it impossible to obtain new fixtures and retrofit

becomes the only option. For the best retrofits, make an effort to reduce glare with the use

of white reflectors or by using lenses that are thicker or designed to reduce lamp image. Also

consider adding dimming ballasts and controls in the perimeter zones to take advantage of

the daylight.

Option 4 • Relighting

4’-0”semi-indirect pendant mounted fixture, (3) T8 lamps,

high ballast factor (1.1-1.2)

This is the only private office design in which one fixture is acceptable.

A single 3-lamp uplight provides extremely uniform and comfortable

light. Because general light levels tend to be about 35 footcandles, a

task light is suggested. This solution works well when conditions 

prohibit recessed fixture options and can be used to replace 

wraparounds, strip lights, and other surface-mounted low quality

lighting solutions. Even when a task light is included in the energy

consumption calculation, the payback (2.7 years) and SIR (7.9) are

better than the component

retrofit of the existing

lensed fixtures. This is an

excellent solution from

both an efficiency and

quality perspective.

Option 2 • Retrofit

(2) T8 lamps, white reflector, parabolic louver door frame,

electronic ballast, standard ballast factor.

This design is also a retrofit design, but with the use of a parabolic

louver door frame (see Open Office Option 2). In order to have

acceptable lighting quality using retrofit parabolic louvers, the 

existing layout must have the fixtures located close to the walls to

avoid the gloomy “cave effect.” Because the louver door frame is

not designed for the original optics of the existing 

troffer, the efficiency is

reduced and task lighting

may be necessary.

Option 3 • Relighting

2x4 parabolic fixtures, (2) T8 lamps, 12-cell semi-specular

louver, electronic ballasts, standard ballast factor. 

If installing new fixtures, parabolic troffers produce light of acceptable quality and improved appearance. However, it is important to

use more than one fixture and spread them so as to illuminate 

the walls.

CAVEATS

The design guidance provided here is

suitable for most conditions. However,

the application of lighting technologies

varies depending on the occupants 

of the space and the tasks to be performed. Following are some important

caveats regarding the proposed designs:

■ As eyes age they need more light.

Occupants over the age of 45 should

be offered a task light to supplement

the general lighting levels. For those

who need more light, the undercabinet task lights are not always 

sufficient. Consider the use of a compact fluorescent task lamp that sits on

the desktop with an adjustable arm.

■ Visually demanding tasks require

more light. If the visual task is one

with very small font size or low 

contrast conditions, then the footcandle allowances should increase.

■ Use lighting design professionals for

challenging or unusual relighting 

projects. Look for professionals who

have credentials indicating a specialty

in lighting. People with an “LC” 

credential have demonstrated an 

ability to apply fundamental lighting

principles and techniques in the

NCQLP Lighting Certification exam.

People with an “IALD” credential are

lighting design specialists who have

been recognized for their experience

and design expertise by the 

peer review of the International

Association of Lighting Designers.

MORE INFORMATION

For additional information on Federal

Lighting, visit the DOE FEMP web site 

at www.eren.doe.gov/femp to find 

additional FEMP Lights products such as:

■ Federal Lighting Guide

■ Energy Effective Lighting Checklist

■ Energy Effective Lighting Video

■ Web-based FEMP Lights training

course

Additional lighting resource 

information can be found at the 

following web sites: 

Illuminating Engineering 

Society of North America:

www.iesna.org

International Association 

of Lighting Designers:

www.iald.org 

National Council on Qualifying the

Lighting Professions:

www.ncqlp.org 

Lighting Research Center 

at Rensselaer Polytechnic Institute:

www.lrc.rpi.edu 

Inter.Light, Inc.:

www.lightsearch.com 

Lighting.Com:

www.lighting.com

National Lighting Bureau:

www.nlb.org 

OPTION 2

Watts/Square Foot 1.12

Average Illuminance, footcandles 37

Total Initial Cost/SF $2.05

Annual Own and Optg Cost/SF $0.36

Simple Payback (years) 4.4

Federal Savings to Investment Ratio 4.0

OPTION 3

Watts/Square Foot 1.12

Average Illuminance, footcandles 42

Total Initial Cost/SF $2.66

Annual Own and Optg Cost/SF $0.34

Simple Payback (years) 5.5

Federal Savings to Investment Ratio 3.0

OPTION 4

Watts/Square Foot .98

Average Illuminance, footcandles 36

Total Initial Cost/SF $1.36

Annual Own and Optg Cost/SF $0.28

Simple Payback (years) 2.5

Federal Savings to Investment Ratio 8.6

OPTION 2 & 3

Parabolic 2x4s

OPTION

4

4’-0” Semi-Indirect

TECHNICAL QUESTIONS?

Send email to Carol.Jones@pnl.gov