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V57;197l /Comparison measured and computer-pre TA43S .U58 V57;1978 C.I NBS-PUB-C 1975

Q NBS BUILDING SCIENCE SERIES 57

U.S. DEPARTMENT OF COMMERCE / National Bureau of Standards

1

Comparison of

Measured and Computer-Predictecf

Thermal Performance of

our Bedroom Wood-Frame Town

-TA.

.U58

NO. 52

1978
The Building Science Series

'I'he Building Science Series disseminates technical information developed at the National Bureau of Standards on

building materials, components, systems, and whole structures. The Series presents research results, test methods, and performance criteria related to the structural and environmental functions and the durability and safety characteristics of building elements and systems. These publications, similar in style and content to the NBS Building Materials and Structures Reports (1938-59),

are directed toward the manufacturing, design, construction, and research segments of the building industry, standards organizations, and officials responsible for building codes. The material for this Series originates principally in the Center for Building Technology of the NBS Institute

for Applied Technology. The publications are divided into three general groups: Building Systems and Processes; Health, Safety and Comfort; and Structures and Materials. For further information regarding these publications

please contact the Scientific and Professional Liaison Section, Center for Building Technology, Institute for Applied Technology, National Bureau of Standards, Washington, D.C. 20234.

[See mailing list announcement on last page |
Comparison of Measured and

Computer-Predicted Thermal Performance

of a Four Bedroom Wood-Frame Townhouse

B. A. Peavy, D. M. Burch,

F. J. Powell, and C. M. Hunt

Building Environment Division

Institute for Applied Technology

National Bureau of Standards

Washington, D.C. 20234

Sponsored byDepartment of Housing and Urban Development

451 7th Street, S.W. Washington, D.C. 20410

and

National Bureau of Standards Washington, D.C. 20234

U.S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts, Director

Issued April 1 975
Library of Congress Cataloging in Publication Data

Main entry under title:

Comparison of Measured and Computer-Predicted Thermal

performance of a Four Bedroom Wood-Frame Townhouse. (NBS Building Science Series; 57) Sponsored by U.S. Dept. of Housing and Urban Development

and National Bureau of Standards.

Supt. of Docs. No.: C 13.29/2:57

1. Wooden-frame houses—Heating and ventilation. 2. Woodenframe houses—Air conditioning. 3. Wooden-frame houses—Testing. 4. Wooden-frame houses—Thermal properties. I. Peavy, Bradley A. H. United States. Dept. of Housing and Urban

Development. HI. United States. National Bureau of Standards.

IV. Series: United States. National Bureau of Standards. Build- ing Science Series; 57. TA435.U58 No. 57 [TH7341] 690'.08s [697] 74-20830

National Bureau of Standards Building Science Series 57

Nat. Bur. Stand. (U.S.), Bldg. Sci. Ser. 57, 62 pages (Apr. 1975) CODEN: BSSNBV

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1975

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

(Order by SD Catalog No. C13.29/2:57). Price 11.20. Stock Number 0303-01364
Contents

Page

1. Introduction 1

2. Prediction and evaluation analysis 2

3. Description of the test house 4

4. Instrumentation and transducers 10

5. Experimental methods and conditions 13

5.1. Simulated outdoor weather cycles 13

5.1.1. Macon, Georgia 13

5.1.2. Kalamazoo, Michigan (Battle Creek) 15

5.2. Simulated occupancy 16

5.3. Internal mass of test house 20

5.4. Performance of HVAC system components 21

5.4.1. Air distribution system 21

5.4.2. Air cooling unit 22

5.4.3. Gas-fired furnace 22

5.5. Thermal and physical properties 24

5.6. Description of tests 26

5.6.1. Description of winter tests 26

5.6.2. Description of other tests 26

6. Results and discussion , 27

6.1. Winter heating tests 27

6.2. Summer cooling test 31

6.3. Fall test 32

6.4. Comparison summary of predicted and measured energy consumption 33

6.5. Pull-down test 33

6.6. Nighttime setback tests 34

6.7. Steady-state winter test 36

6.8. Temperature distribution during winter tests 38

6.9. Mean radiant temperature 41

6.10. Humidity analysis 42

7. Conclusions 44

8. Nomenclature and conversion factors 44

9. References 46 Acknowledgment 46 Appendix A — Air infiltration measurements on the four-bedroom townhouse 47 Appendix B — Interior noise levels in the four-bedroom townhouse 51 Appendix C — Mathematical simulation of the test house 55

III

Comparison of Measured and Computer- Predicted Thermal

Performance of a Four- Bedroom Wood- Frame Townhouse

B. A. Peavy, D. M. Burch, C. M. Hunt, and F. J. Powell

Measurements of the dynamic heat transfer in a four-bedroom townhouse were made under controlled conditions in a large environmental chamber to explore the

validity of a computer program developed at NBS, labelled NBSLD, for predicting

heating and cooling loads and inside air temperatures. This study was supported jointly b> the Department of Housing and Urban Development and the National Bureau of Standards, and is a part of a broader research program supported by both agencies to improve performance test procedures and criteria for housing.

The test house was a factory-produced four-bedroom townhouse of modular

design and of lightweight (wood) construction. Tests were performed with simulated

outside summer, winter, and fall diurnal temperature cycles. The inside temperature was maintained at about 75 °F. Also during the tests, the activities of a six-member

family were simulated. The time-varying energy requirements were measured, and these values were compared with computer predicted values. For example, the disparity between

predicted and measured daily heating energy requirements averaged 3.1 percent with a maximum departure of 4.9 percent for five tests. The computer program NBSLD was

experimentally validated for predicting the peak heating and coohng loads and the energy requirements for the test house. The air leakage of the house was measured by a tracer gas technique over a range of outdoor conditions, and algorithms were developed to account for its effect on heating loads and energy requirements.

Separate tests were also performed to investigate the energy savings achieved

by night temperature setback. An 8-h 9 °F setback from 75 °F produced an 11 percent

diurnal savings in energy for an average nighttime temperature of 20 °F and a 9 percent

savings in energy was achieved for the same setback when the average nighttime

temperature was 2 °F.

Key words: Air leakage measurement; building heat transfer; computer programs; dynamic thermal performance; heat flow analysis; heating and cooling loads; temperature predictions; thermal analysis; thermostat setback; transient heat flows.

The indoor thermal environment of a building

is influenced by the weather, by the thermal

behavior of the walls, roof, and floor, by heat- producing occupancy-related activities and

especially by the mechanical, electrical and

service systems that must function to provide

control of heating and cooling devices that serve to make living spaces more habitable. To provide a functional and habitable indoor thermal environment for occupants within a building requires

careful consideration of the properties and

performance of the materials that comprise the

1. Introduction building envelope together with careful design,

specification and installation of its mechanical

and electrical systems.

The building materials and systems taken

together are a major cost of the building in-place. In addition, the operating and maintenance costs

for a building such as fuel and power for heating,

cooling, and lighting plus labor costs can make the

long-term investment large. A small impact in any

of these areas can pay long-term dividends and

at the same time help our nation conserve its energy resources.

In order to accomplish savings, it is necessary

that the architect and engineer be provided with

1
reliable techniques and methods for predicting

and evaluating the energy utilization for the

building. An energy analysis should be capable of providing hourly, daily, and seasonal system

performance data and it must preferably be

based on dynamic conditions reflecting the

changing patterns of weather and climate and

the time-dependent interactions within the

building itself. Such an approach requires a very

large number of calculations. The digital

computer allows an engineer to rapidly and inexpensively calculate: (a) energy requirements with

consideration of operating costs, (b) heating and

cooling load profiles for equipment design or

selection and operation, (c) information needed to rapidly evaluate a large number of options in the

design process, (d) optimum energy utilization and (e) the need for zoning in large buildings.

The Thermal Engineering Systems Section at NBS has developed a comprehensive

computerized mathematical model called National

Bureau of Standards Load Determination Program

[1],' NBSLD, which when taken with simulations

of the building's mechanical and electrical systems and economics routines allows a complete

energy analysis.

Computer programs usually contain

engineering approximations that require

experimental verification before being adopted for wide-scale use. In addition, the performance data on building materials and elements, design

weather data and boundary conditions at surfaces need specific definition to assure accuracy of predicted results. An example is the

lack of reliable data on air infiltration rates into

buildings which may account for as high as onethird of the heating or over 40 percent of the

cooling load for a building. A previous study [2] was completed on an experimental masonry

building where the fabric of the building was

altered to determine the thermal response of the

building and to validate the computer program

NBSLD when used on heavyweight construction.

This study, cosponsored by the Department of Housing and Urban Development (HUD) and the

National Bureau of Standards (NBS), explores the

actual dynamic flow of heat into and out of the

fabric of a hghtweight building made of wood and

the resulting temperature patterns of the indoor air and the structure itself when the indoor air

• Figures in brackets indicate the literature references on page 46.

temperature was controlled by a thermostat. The

objectives of this study were: (1) to measure timevarying heating and cooling energy consumptions

for a full-scale test house subjected to changing

simulated weather patterns in the laboratory and

to compare these values with corresponding

computer-predicted values, and (2) to experimentally measure the internal environment with

respect to temperature distribution, air infiltration, mean radiant temperature, relative humidity,

and the performance of the heating and coohng

system. Experiments were performed under

controlled conditions in a large (70,000 ft^) environmental chamber at NBS capable of controlling temperature and humidity over the

range -50 to 150 T.

For the series of tests discussed in this paper,

a full-scale house was purchased using the

performance specifications developed by NBS

for HUD Operation BREAKTHROUGH. The four- bedroom townhouse of lightweight (wood) construction was factory produced in three modules or

units. It was transported to NBS on flat-bed

trailers and installed in the environmental

chamber. The first floor consisted of two modules

and contained the kitchen, dining room, living room, two bedrooms and a bathroom. The second

floor (third module) consisted of two bedrooms and

a bath and was placed above the module

containing the kitchen. The townhouse was

designed to be the end unit of a row of townhouses. The house was suitably furnished for a family of six. During the tests normal living

activities of a family of two adults and four

children were simulated. Weather patterns for the summer and winter of cold and warm climates were imposed on the house.

In conjunction with the experimental phases

involving thermal performance, two other

significant experiments were performed on the

test house. The first experiment was concerned

with the air infiltration rate. The method,

procedure, and results are contained in appendix

A of this paper. The second experiment involved a

series of noise level measurements and the

method, procedure, and results are presented in appendix B.

2. Prediction and Evaluation Analysis

In using the NBS Load Determination

Computer Program, it is necessary to provide as

2
input the outdoor weather conditions, the

construction details of the building (such as a layer

by layer description and the heat transfer areas of the exterior facing walls, roof, and floor, its orientation, etc.), and the building operating

schedule for equipment, lighting, and occupancy.

The algorithms of the computer program operate on this input data in such a manner as to predict

either inside air temperature or heating and

cooling loads. A simplified flow chart of the

computer program is given in figure 1. The

computer algorithms used in NBSLD are given in detail in [1]. In summary, the prediction procedure

contains:

Item 1. Derived expressions for converting

outside environmental conditions

and weather elements, such as dryand wet-bulb temperature, incident

solar radiation, wind velocity, etc., into forms useful for quantifying the

heat transfer phenomena.

Item 2. A comprehensive system of mathematical expressions or algorithms for solving dynamic heat

transfer problems dealing with

conduction, convection, and thermal

radiation. These algorithms apply to heat transfer as related to walls,

windows, roofs, floors, surrounding

earth, and the internal mass of a building such as the furniture, partitions, and equipment.

Item 3. Expressions for air infiltration and

ventilation rates based on information

given in the literature and on current experimental work.

Item 4. Algorithms for the time-dependent

thermal interactions taking place

within a building, such as human

occupancy, occupancy related

activities, and process heat generating functions.

For this work the algorithms of Item 1 were

not needed because the outdoor air temperatures

as a function of time were purposely defined,

controlled and measured in the laboratory. The

algorithms for Item 2 employ the Response Factor method which predicts one-dimensional heat flow

in building components by utilizing the superposition principle in such a manner that the overall thermal response of a component at a selected

time is the sum of the responses caused by many

individual temperature or heat flux pulses during

previous time steps. The theory and applications

of this method are discussed in detail in appendix C. These algorithms were used

extensively for the prediction aspects of this paper. For Item 3, infiltration of air from the

outside to the inside was considered to be

approximated by the simple relationship

I = A + BM + CW

where / is the air change rate, AT is the

temperature diffence between the inside and

outside air temperature, W is the outside air velocity, and A, B, and C are constants. Values

for A, B, and C are given in [4] and were also determined experimentally on the test house. For

Item 4, algorithms were developed for determining

the heat generation due to the time-dependent

activities of occupants and related processes.

WEATHER

DATA

INPUT

BUILDING MATERIAL DATA

OPERATING SCHEDULE

DATA

' WEATHER

ALGORITHMS

TIME-DEPENDENT HEAT CONDUCTION ALGORITHMS

AIR INFILTRATION ALGORITHMS

OCCUPANT

RELATED ALGORITHMS

INDOOR TEMPERATURE

HEATING/

COOLING LOADS

Figure 1. Simplified flow chart of NBS load determination computer program. For the test house, safe, rehable and

comfortable heating and cooling control should

be provided for all occupied spaces. To attain

these conditions certain performance guidelines or

criteria were established and then the house was

measured in the laboratory. In general, these

criteria are that the heating, ventilating, and air- conditioning system should provide:

1. Adjustable automatic means for control of temperature in the house to within ± 2 °F at the

point of control for any indoor temperature

between 65 and 80 °F at any time subject only to the capacity of the system to maintain a given

temperature setting.

2. Interior temperature distribution such that the difference in air temperature measured 5 ft 3
above the floor in the center of any two habitable rooms of the unit does not exceed 4 °F.

3. Air velocities within the occupied zones

should not exceed 45 fpm with the system idle or operating. The occupied zone is defined as the

region within a space between the 3-in and the

6-ft level above the floor and more than 2 ft from

walls or fixed air-conditioning equipment.

4. Interior air temperature distribution such

that the difference between any two air temperatures measured simultaneously within

the occupied zones of all habitable rooms in the

unit does not exceed 12 °F at any environmental

load within design limits.

3. Description of the Test House

The test house was a factory-produced four- bedroom townhouse of modular design and of lightweight (wood) construction. A sketch of the

test house in the environmental chamber is shown

in figure 2. The particular townhouse studied in

Figure 2. Test house the Environmental Chamber.

this report was the left end dwelling of a row of townhouses and was constructed from three

modular units. Two modules composed the first floor and contained the kitchen, dining area, utility room, living area, and two bedrooms separated

by a fuU bath. (See first floor plan, fig. 3.) The

second floor module contained two bedrooms and

a second fuU bath with a stairway from the kitchen

to the hallway connecting the bedrooms. (See

second floor plan, fig. 4.) The floors of the living area, dining area, and the four bedrooms were

carpeted. All other floor areas were finished with

LEGEND

• THERMOCOUPli STRING

G GLOBE THBIMOMETK

H HUMIDITY TRANSDUCER W OUTSIDE AIR TC

C CRAWL SPACE Affi It

3/16 = 1'-0"

Figure 3. First floor plan of test house.

asphalt tile. As received from the factory, the

townhouse was equipped with a refrigerator, an

electric range, an 80-gal electric hot water heater,

a gas-fired furnace, and electric air-conditioning

equipment. Elevation plans of the townhouse are shown in figures 5 through 8. The total floor area

of the townhouse was about 1200 ft^. The townhouse was manufactured m

Pennsylvania and transported about 200 miles on flat-bed trailers to NBS. It was assembled over

a 2-ft-high crawl space in a high-bay environmental laboratory of approximately 70,000 ft^ in volume. Figure 9 shows the three modules on flat- bed trailers upon arrival at NBS, and figures 10 and 11 show the assembly process. In this laboratory the temperature and relative humidity can be controlled over the ranges -50 to 150 °F and 15 to 85 percent, respectively. Temperatures

and relative humidities can be changed as a function of time using cam-operated controllers. 4
The floor of the laboratory is undisturbed earth

suitable for placing building foundations.

LEGEND

• THERMOCOUPLE STRIN6 G GLOBE THERMOMETER

H HUMIDITY TBANSOJCEfi W OUTSIDE AIR TC

BEDROOM #4

T1-0" X n-v

GH

BEDROOM #3 c-r X n-i

18

PARTT WALi

3/16- = 1'-0"

Figure 4. Second floor plan of test house:

Figure 5. Front elevation of test house.

Typical construction details of the townhouse

are shown in figures 12 and 13. The construction

of the external walls from the outside to the inside was: 5/8-in-thick redwood veneer plywood siding

running vertically, 3 1/2 in of glass fiber batt insulation with a vapor barrier placed between

nominal 2- by 4-in wood studs, and 1/2-in-thick

gypsum board nailed directly to the studding. The

inside surfaces were painted. The floor above the

crawl space consisted of 7 1/2 in of glass fiber

insulation with a vapor barrier placed between

nominal 2- by 8-in wood joists covered with 5/8-in

plywood sheeting on top and nominal 1/4-in

wood composition fiber board on the bottom. The

floors in the kitchen, utility room, halls, and

bathrooms were finished with 1/16-in-thick asphalt

565-603 O - 75 - 2
Figure 7. Rear elevation of test house.

tile and the remainder of the floor area was

covered with 1/4-in nylon carpet. The construction

materials of the roofs from the outside to the

inside were: 1/8-in asphalt shingles, 1/16-in asphalt

roofing felt, 1/2-in plywood sheathing, 5 1/2 in of glass fiber batt insulation with vapor barrier

placed between nominal 2- by 6-in joists, and 1/2- in gypsum board nailed to the underside. The

ceiling was painted.

The windows consisted of brown anodized

aluminum frames and sash, with 1/8-in window

panes, storm windows and screens. A typical

window detail is shown in figure 14. There were

five double-hung windows, 59-in high by 35-in

wide, one for each of the four bedrooms and one

in the living area. The hving area had three

Figure 8. Side elevation of test house showing space for party wall for adjacent unit.
Figure 11. Third module placed into laboratory.

double-hung windows, 71-in high by 34-in wide

placed in a row to form a picture window. The

kitchen had a casement window, 34-in high by 35-

in wide. The double front door contained two

insulating glass units each 63-in high by 23-in

wide. The rear door was solid. Each bathroom had

a ventilating fan but no window.

The test house was assembled over a foundation and five piers constructed from two

courses of mortared cinder-concrete blocks. The

foundation and piers were constructed over a

reinforced concrete footing. A detailed

illustration of the foundation, piers, and footings is given in figure 15. The earth crawl space floor was

covered with a 10-mil polyethylene ground cover

vapor barrier. The equipment for heating, cooling, and

distributing air was located in the left side of the

living area closet and consisted of a gas-fired

furnace, cooling coil, and forced air blower. A

schematic of this equipment is shown in figure 16. A humidifier was added by NBS.

The thermostat was located on the hall wall between the living room and utility closet at a height of 5-ft 4-in above the floor. This thermostat

also contained manual switches for heating,

cooling, and fan-only operation.

The gas furnace was rated at 75,000 Btu h"' input and 60,000 Btu h'' output at the bonnet. The

air conditioning equipment had a listed capacity of 24,000 Btu h''. The condensing unit was located

in an interior cabinet under the kitchen window

with the outdoor coil projecting through the

wall. A wetted-drum type domestic humidifier,

shown in figure 17, was attached to the plenum of the air distribution system.

SHINGLES

ROOFING FELT

1/2" PLYWOOD SHEATHING

INSULATION

2" X 6" ROOF JOISTS

1/2" DRYWALL

SHINGLES ROOFING FELT

1/2" PLYWOOD SHEATHING

INSULATION

2" X 6" ROOF JOISTS

1/2" DRY WALL

2" X 4" PLATES

6/8" PLYWOOD SIDING INSULATION

2" « 4" STUDS

1/2" DRY WALL

ENLARGED DETAILS

@ 3"-r-o"

BUILDING SECTION

3/16 = 1'-0"

Figure 12. Typical construction details of walls and roof of test house.
SECTION 5, PARTY WAU

SCALE: I" = V - O

'

Figure 13. Typical construction details of floor and party

wall of the test house. After several tests with operation of the gas

furnace, the system was modified for electric heating by the installation of three resistance

heating elements in the plenum above the cooling

coils. Each element was rated at 3460 W for 208-V

operation. The voltage supplied to two of the

elements was controlled by a variable

transformer for varying the electric heat output. Figure 14. Typical window detail showing storm sash installed.

FOUNDATION SECTIONS

1 w = r-o"

PIER-FOOTING SECTION FOUNDATION WALL SECTION

Figure 15. Detail sections offoundation pier and footings.

8
The air distribution system consisted of a common return (fig. 16), located in the hallway

between the living room and the utility closet, with

a circulating blower forcing air through the gas furnace into the distributing ducts and to the

registers. There was one supply register located in each room located about 7 ft above the floor except for one low-wall register in the smaller

upstairs bedroom.

Since interior furnishings will have an effect on the thermal behavior of a house, the test house was fully furnished with 3300 lb of furniture,

draperies, and other household accessories

including a stacked clothes washer and dryer, and

a dishwasher. In addition, a garbage disposal unit was connected to the drain of the kitchen sink. Figures 18 through 20 show the furnishings of the

house.

AIR OUTLET

Figure 16. Schematic of gas-fired furnace, cooling coil, and

forced air blower.

MOTOR-COOLING

FAN BLADE

Figure 17. Wetted drum type humidifier.

Figure 18. Photograph showing living room furniture.

Figure 19. Photograph showing the furniture in bedroom number 1.

Gas, electric energy, and water were metered.

Sewage and waste water from the townhouse were

fed into a sump from which it was pumped

selectively into either an aerobic sewage treatment

facility which was located above grade directly in the chamber or to a sanitary drain. Treated water

from the aerobic system was subsequently fed into the sanitary drain.

9
Figure 20. Photograph showing the kitchen and its appliances.

For expelling exhaust furnace flue gases a 12- in diam flexible hose was run from the flue gas

stack located on the roof to the laboratory outdoor

exhaust system. A photograph showing the flexible hose installation is shown in figure 21. The clothes dryer in the utility room was

vented to the outside by running a flexible hose

from the dryer through the wall space above the

kitchen cabinets to the exterior wall at the end of the kitchen.

Figure 21. Photograph of the flexible hose installation for

flue gas exhaust.

4. Instrumentation and Transducers

Ambient air and surface temperatures were

measured with 24-gage copper-constantan

thermocouples. Thermocouple strings, suspended

by 3/16-in diam polycarbonate rods, were placed

at the geometric center of each room and 2 ft from

and horizontally centered in front of each of the

windows. The locations of the thermocouple

strings are numbered 1 through 19 and depicted

with solid circles on the floor plans of figures 3

and 4. Six thermocouples were attached to a rod

and located at 3, 30, 60, 72, and 84 in above the

floor, and 3 in below the ceiling. Due to the low

ceiling in the utihty room, it was necessary to omit

the thermocouple 3 in below the ceiling.

Ambient air thermocouples also were placed 3 in

in front of the seven air supply griUs and 3 in in front of the thermostat for the furnace system. In

addition, ambient air temperature thermocouples were placed 3 in in front of the wall, roof, and

floor in the plane A-A of the hving area (see floor plan of fig. 3). The floor and ceiling thermocouples were placed 30 in from the west wall, and

the wall thermocouple was placed 60 in from the

floor. The ambient air thermocouples of the

thermocouple strings in the geometric center of the hving area, kitchen, downstairs bathroom, and

the bedrooms, along with those 3 in in front of the

air supply grills, the furnace thermostat, the

wall, roof, and floor were referenced to the ice

point (32 °F) by connecting these thermocouples to a thermoelectric ice-point reference system. The

other ambient air temperature thermocouples were

referenced to a uniform-temperature reference

junction maintained at approximately room

temperature. The temperature of the reference

junction or zone box was in turn referenced to 32

°F.

Globe thermometers were used to measure the mean radiant temperature (MRT) at the geometric

center of the living room, den, kitchen, and four

bedroom areas at the 30-in level above the floor. The locations of the globe thermometers are shown

with the symbol G on the floor plans of figures 3 and 4. A globe thermometer consisted of a 6-in diam hollow copper sphere with a thermocouple

supported in the center. The outside surface of the

spheres were painted with matte-black paint, so as

to absorb most of the long wave thermal radiation

emitted from the inside surfaces of a room. A

cross section of a globe thermometer is shown in figure 22.

Four thermocouples were placed in the crawl

space 6 in below floor joists. The location of the

crawl space thermocouples are depicted with the

symbol C on the floor plan of figure 3. Outside

10
r-DIA. COPPEB SPHEffi

( COATID W/FIAT BLACK PAINT |

COPPER-CONSTANTAN THERMOCOUPLE

Figure 22. Cross section through globe thermometer.

ambient air temperature thermocouples were

placed 1 ft from external surfaces of the

townhouse. An attempt was made to locate these

thermocouples in the geometric center of wall

heat transfer surfaces. The outside air thermocouples for the walls are depicted with the symbol

W on the floor plans of figures 3 and 4. Outside

air temperature thermocouples were also placed

in the geometric center and 1 ft above each of the

three roof sections. Those in front of the waUs on

the first floor were placed 6 1/2 ft above the

ground, while those for the second level walls were

located 15 1/2 ft above the ground. The thermocouples in front of the bay window of the living room were located 9 1/2 ft above the ground.

Thermocouples were attached with aluminum

adhesive tape at the center of the upper section of the double-hung windows. One of these thermocouples was placed on the inside surface of the

inside pane and the other was located on the

outside surface of the outside pane. For the bay

window in the hving room only the center doublehung window was instrumented with thermocouples. An identical thermocouple pair was

placed on the lower section of the window in the

den portion of the living area. For the casement

window in the kitchen the thermocouple

placement was identical, except that the thermocouple pair was placed on the right section of this

window. For the door in the living room an inside

and outside thermocouple pair was attached to one of the glass panes. In addition, for the doublehung windows in the master bedroom and the center one of the living room, thermocouples were placed on glass surfaces within the air space

formed by the double panes.

In a normal field apphcation another

townhouse would be attached to the test house

studied in this report. The area of contact for the

adjoining unit is shown with broken line B-B

labeled party wall on the floor plans of figures 3

and 4. This surface should be maintained very

nearly adiabatic, since the indoor air temperatures for the two townhouses are normally

maintained approximately equal. The presence

of the adjoining townhouse was simulated with the contact surface area (12-ft wide and 20-ft high)

maintained at approximately 75 °F. The

construction, shown in figure 13, consisted of 15

heating panels of 5/8-in thickness. The layer of

heating panels were placed over a 2-in layer of polystyrene board-type insulation covered with a

6-in layer of polystyrene insulation and a 3/8-in

plywood cover. The surface temperature of the

heating panels facing the townhouse was

maintained at 75 °F within a 4 °F band by con- troUing the electrical energy supplied to the

heating panels. The sensing element of a thermostat was two thermocouples attached to the inside surface of the heating panels. These

thermocouples were horizontally centered and

placed 8 and 13 ft from the bottom edge of the

simulated party wall. The temperature of the

simulated party wall was measured with eight

thermocouples. Four of these thermocouples were attached to the redwood siding (two were

placed 8 ft from the bottom edge and 3 ft from

either side edge of the simulated party wall. The

other two were placed directly above the former at the 13-ft level). The other four thermocouples were placed in the same locations as the previous

four thermocouples but on the other side of

insulation in contact with the heating panel.

Relative humidity transducers were placed in the geometric center of the living room, kitchen,

bathrooms, and bedrooms at the 60-in level above the floor. These humidity transducers

produced a millivolt output signal proportional to the relative humidity. The temperature of the

return air for the heating and cooling equipment

11
was measured by a network of four thermocouples which were connected electrically in

parallel. In addition, a network of eight thermocouples was placed in the air outlet above the

cooling coils to measure the temperature of the

air distributed to the rooms. The air delivery rate

of the furnace blower was determined with a vane anemometer. An aluminum duct was placed in front of the return air supply before it entered the

grill, to make air velocity measurements. A grid

network of four thermocouples was mounted in the flue that protruded from the roof of the house.

A sample of the flue gas was continuously pumped

from a tap in the flue pipe at the second floor level

to an infrared gas analyzer which continuously

registered the percent carbon-dioxide content.

An adequate indoor humidity level was

maintained in the house during winter testing

periods by the operation of a humidifier

connected to the plenum of the furnace. Warm air from the plenum was drawn into the humidifier

by its self-contained blower. This heated air was

forced through a sponge-like media pad which

rotated slowly in a bath of water to constantly add

moisture to the dry air. Moisture-laden air was

then returned into the plenum and was dis- tributed to the test house. Water was supplied to the humidifier by a tank located in the secondfloor linen closet. The amount of water used by

the humidifier during a given time period was

determined by measuring the difference in water

level in the supply tank at the beginning and end

of a time period. The water level in this tank was

measured with a static pressure transducer that generated a millivolt signal proportional to the water level in the tank.

Six heat flow meters were placed on inside

surfaces to measure heat flow through external

building components. Each heat flow meter was masked with a 2-in-wide circular commercial gum

rubber border having approximately the same

thickness as the heat flow meter. A 6-in diam and

1/8-in thick commercial gum rubber cover was

secured to the top of the masked heat flow meter. The purpose of the mask and cover was to eliminate fluctuations in the milhvolt output due

to local variations in the air flow in the vicinity of the heat flow meter. Two of these meters were

placed in plane A-A (fig. 3) on the wall of the den

60 in above the floor. One of these was located over a wooden stud and one was placed over the

space between wooden studs. Two other pairs of heat flow meters were placed on the roof and floor

at corresponding locations in the plane A-A and

30 in from the west wall. The heat flow meters

consisted of a 2.0-in diam, 0.13-in thick, circular

disk made of tan polyvinylchloride filler material, each having an embedded thermopile.

The millivolt signal generated by the thermopile is proportional to the heat flow through the circular

disk. The heat flow meters were calibrated in an

8-in guarded hot plate apparatus conforming with

the requirements of Standard Method of Test ASTM C177.

Six thermocouples v/ere glued to the inside

surfaces in the plane A-A just above each of the

heat flow meters. In addition, six thermocouples were attached to the outside surface of the

building at corresponding locations.

The volume of natural gas consumed by the

furnace in the townhouse was measured with a

calibrated domestic gas meter that was specially

modified, so that the passage of 1 ft^ of gas caused

an electric pulse to be generated. This was

accomplished by placing an excitation voltage across a micro-switch that rode on a cam shaft of the metering circuit. The temperature and

pressure of the gas at the inlet to the gas meter were also monitored, so that the volumetric con- sumption of gas could be corrected for changes in density. The gas temperature was measured with a thermocouple placed inside a tube that protruded into the gas stream. The pressure of the gas was metered with a static pressure gage. The gross electric energy supplied to the

house was measured using a calibrated 3-wire

watt-hour meter equipped with an impulse generator.

The impulse generator was a photoelectric device

which generated a pulse for each revolution of a disk inside the meter.

The transducer signals were fed into a data

acquisition system which in turn recorded these

signals on punched cards at selected time

intervals. The gas and electric pulses were

totalized and also fed into this data acquisition

system.

The individual electric energy consumption of the furnace blower, refrigerator, electric range, washer and dryer (and humidifier), air conditioner,

and hot water heater were monitored with singlephase Wh meters mounted on the east wall of the kitchen. The difference between the gross energy

12
and the sum of the energies supplied to the above

circuits was equal to the energy for the Hghts,

kitchen and bathroom blowers, radio, and

disposal.

Air velocities in excess of 80 fpm were measured with conventional vane and hot wire

anemometers. Both of these instruments were

calibrated in a wind tunnel. For velocities below 60

fpm, a low velocity anemometer utilizing a vibrating hot-wire probe was used. The low

velocity anemometer used in this study was cali- brated by its manufacturer.

5. Experimental Methods and Conditions

Prior to and during tests performed, certain

guidelines and conditions were established for laboratory testing. For example, in the laboratory

it was not planned to obtain time dependent data on the effects of outside conditions of wind, rain, snow, and incident solar radiation upon the house.

These variables were handled in the weather

portion of the predictive NBSLD computer

program. Also, it is planned to expose this house

to natural weather conditions at the NBS site at the conclusion of laboratory tests. In the following

sections the experimental methods and conditions used are set forth for a comparison of the

laboratory testing results and computer

predictions.

5.1. Simulated Outdoor Weather Cycles

The outdoor conditions used for testing of the

house were taken from Weather Bureau data for two locations-Macon, Ga. and Kalamazoo, Mich,

where similar models of the test house have been

installed. Winter and summer data were chosen to include recommended outdoor design conditions as given in the ASHRAE Handbook of Fundamentals, and include sol-air temperatures. The solair temperatures were computed using the

algorithms of [5], and were averaged by weighting

the areas of the exposed surfaces.

In order to obtain an area-averaged sol-air temperature, it was assumed that the two large

sloping roof areas faced west. The areas for the

various orientations are:

North facing wall East facing wall

South facing wall

West facing wall

West facing roof South facing roof

339.0 ft^ 512.0 ft^ 282.0 ft^ 485.5 ft^ 887.5 ft^ 78.0 ft^

The values of the ratio of the absorptance of surfaces, a, to the coefficient of heat transfer, ho, were 0.2 and 0.3 for the wall and roof areas,

respectively. These values were derived from

comparative temperature measurements made

on materials of the house and materials of known

absorptance that were exposed to solar radiation on the grounds of NBS.

In addition to the winter and summer days

where only heating or cooling is needed, it was

decided to pick a day in either the spring or fall when outside conditions might indicate that both

heating and cooling may be needed in a diurnal

cycle. For this, a search of Weather Bureau data was made to find days where the daily change in dry-bulb temperature was more than 35 °F and the

maximum temperature was greater than 75 °F. These conditions were satisfied for many days in the fall for Macon, Ga., but rarely occurred for Kalamazoo, Mich.

5.1.1. Macon, Georgia

From the ASHRAE Handbook of Fundamentals, the winter design (99%)

temperature is 23 °F and the summer design (1%)

dry-and wet-bulb temperatures for Macon, Ga. are 98 °F and 80 °F, respectively.

From Weather Bureau data covering the 10-yr

time period from January 1, 1949 to December 31,

1958, there were 25 winter days when the

temperature dropped below the design

temperature of 23 °F for two or more hours. The

lowest temperature recorded during this time

period was 11 °F on February 17, 1958. December 18, 1953 was picked as a design

day where the average dry-bulb temperature from

midnight to 8 a.m. was slightly less than 23 °F. The pertinent weather data for this day are shown

in figure 23 and the sol-air temperatures for the

various orientations of walls and roofs are

plotted on figure 24. The sol-air temperatures were computed from the algorithms given in the

ASHRAE Procedure for Determining Heating and

13

565-603 O - 75
Cooling Loads for Computerized Energy

Calculations [5]. Figure 24 shows that the

nighttime air temperature for the roof areas is below the design temperature. This effect is due to nighttime sky radiation to cloudless skies.

40- 1 1 < 1 —1—^ 1-

rifiCON. GEORGIA / \

1

35-

OECEMBER 18. 19S3 06/ \

30- / ^ "

^

U- 25-

ERflTURi 20- \ / / ^ \ /

^ \

a.

iz — y

1 5-

10- f \ NINO SPEED X

Q- H-

: - .

WIND

SPEED,

CLOUD

AMOL 5-

0- 1

CLOUO fini ^

1 ^ 3 6 9 12 15 18 21 24

TIME OF DRY. HOURS

Figure 23. Weather data for Macon, Georgia, December 18, 1953.

120

100-

60

40

20

CD klEST SLOPING ROOF O SOUTH SLOPING ROOF a UEST HfiLL + ERST URLL X SOUTH UflLL O NORTH HFILL

MACON, GEORGIA DECEMBER 18, 1953

9 12

TIME OF DfiY 15

HOUR

21 24

Figure 24. Computed sol-air temperature for various orienta- tions— Macon, Georgia, December 18, 1953.

Assuming that the two large sloping roof areas

of the test house face west, an area average of the

sol-air temperatures of figure 24 gives the sol-air temperature with time as shown in figure 25. This

is the outdoor air temperature cycle used in heating tests for the house.

S 30

Figure 25. Area averaged sol-air temperature for Macon,

Georgia, December 18, 1953.

From the Weather Bureau data for this same

10-yr period, there were 40 summer days when the

dry-bulb temperature exceeded the design

temperature of 98 °F for two or more con- secutive hours. The highest temperature recorded

for this time period was 106 °F on June 28, 1954. June 30, 1952 was picked as a design day where

the coincident dry- and wet-bulb temperatures were equal to the design values of 98 °F and 80 °F,

respectively, for the hours of 2 and 3 p.m. The

pertinent weather data for this day are shown in figure 26 and the sol-air temperatures for the

100-

nflCON. GEORGln

95-

JUNE 30. 1952

90-

Q_ _ / ^ ^ \

\

75- \

^ ^ ^ ^ ^ _ /

UINO SPEED /~

q:<i 5-

in _

WIND CLOUC

o

f

\ CLOUD fiMT r \

1 ! 1 9 12

TIME OF DAY. 15HOURS

21 24

Figure 26. 14

Weather data for Macon, Georgia, June 30, 1952.
various orientations of walls and roofs are plotted on figure 27. The area-averaged sol-air temperatures are shown in figure 28. This is the outdoor

air temperature cycle used in cooling tests for the

house.

190

170

150

^ 130-

1 logo

70-

a UEST SLOPING ROOF O SOUTH SLOPING ROOF MACON, GEORGIA « NEST NULL JUNE 30, 1952 + EAST HBLL X SOUTH UflLL O NORTH URLU

9 12 15

TIME OF DRY. HOURS

21 24

Figure 27. Computed sol-air temperature for various orientations, Macon, Georgia, June 30, 1952.

which the maximum and minimum temperature was 81 and 40 °F, respectively. The sol-air temperature for surface orientations is shown in figure 30 and the area averaged sol-air temperature

is given in figure 31. This is the outdoor air temperature cycle used in the fall season tests for the house.

90

F 60

nncoN. GEORcra 0CT08ER 25. 1952

6 9 12 15 18 21 24

TInE OF DfiY. HOURS

Figure 29. Weather data for Macon, Georgia, October 25, 1952.

140

130-

120-

1 loss 100-

9 12 15

TIME OF DAY. HOURS

Figure 28. Area averaged sol-air temperature, Macon, Georgia, June 30, 1952.

From the Weather Bureau data for this same

10-yr period, there were 96 days during

September, October, and November when the

daily change in dry-bulb temperature exceeded 35

°F and the maximum temperature was greater

than 75 °F. The largest daily change in temperature was 45 °F. A plot of dry- and wet-bulb

temperature and wind speed for October 25, 1952

is shown in figure 29. This was a cloudless day for

170

150-

^ ISOno

S 90

70-

50

30

MACON, GEORGIA OCTOBER 25, 1952

Q UEST SLOPING ROOF O SOUTH SLOPING ROOF A WEST WALL + EAST HHLL X SOUTH WALL © NORTH NRLL

6 9 12 15

TIME OF OHY. HOURS 18 21 24

Figure 30. Computed sol-air temperature for various orientations, Macon, Georgia, October 25, 1952.

5.1.2. Kalamazoo, Michigan (Battle Creek)

From the ASHRAE Handbook of Fundamentals, the winter design (99%)

temperature is 1 °F and the summer design (1%)

dry- and wet-bulb temperatures for Kalamazoo,

Mich, are 92 and 76 °F, respectively.

15
From Weather Bureau data covering the 6-yr

period from January 1, 1949 to December 1, 1954,

there were 12 winter days when the temperature

dropped below the design temperature of 1 °F

for 2 h or more. The lowest temperature recorded

during this time period was -12 °F on February 2, 1951. December 22, 1951 was picked as a design

day where the average dry-bulb temperature from

midnight to 8 a.m. was approximately 1 °F. Using the same procedure as given for Macon,

Ga., the variation of the sol-air temperature with

time is shown in figure 32. This is the outdoor air temperature cycle used in heating tests for the

house.

From the Weather Bureau data for this same

6-yr period there were 23 summer days when the

dry-bulb temperature exceeded the design

temperature for two or more consecutive hours.

The highest temperature recorded during this time

period was 99 °F on June 20, 1953 and September

2, 1953. July 25, 1949 was picked as a design day

and the area averaged sol-air temperatures are shown in figure 33. This is the outside air temperature cycle used in the cooling tests for the house.

60

120

110

100

6 9 12 15

Tine OF DHY. HOURS

21 24

u. 50-

40-

30-

20-

10

KfiLflnnzGO. niCH

OECEHBER ZZ. 1951

9 12 15

TInE OF OflY. HOURS

Figure 32. Area averaged sol-air temperature for Kalamazoo,

Michigan, December 22, 1951.

1 30-

u. 120-

KALAMAZOO, MICH JULY 25,1949

9 12 15

TIME OF DRY, HOURS

Figure 31. Area averaged sol-air temperature, Macon, Georgia, October 25, 1952.

Figure 33. Area averaged sol-air temperature, Kalamazoo,

Michigan, July 25, 1949.

5.2. Sitnulated Occupancy

To achieve realistic conditions for the

operation of the townhouse while under test, it was necessary to simulate the occupancy and

activities of a family living in the house. The

diurnal activities of a family as a series of events

in conjunction with an outside weather cycle

may have a significant effect on the heating and

cooling load of a building. The release of heat to the house from metabolic processes and by the use

of lights and appliances and the increase in air infiltration rates by door and window openings

are the dynamic considerations for thermal

performance.

16
Because there are no published representative

schedules of activities for occupants of residences and the characteristics of family

activities vary widely from geographic and other

considerations, the simulated occupancy and

activity schedules used in conjunction with tests on the four-bedroom townhouse are based on

assumptions set forth by the authors. The

occupants are assumed to be a family of six,

composed of a father, mother, two girls (ages 12 and 16), and two boys (ages 6 and 8). Activities for each member of the family are detailed in the

following paragraphs, so as to be consistent with

"assumed" typical family living patterns for both

winter and summer conditions.

Detailed activities of family members for winter conditions are shown in table 1. Specifically, this schedule is based on the children

attending school, the father going to work and

the mother performing household tasks.

Activities for a summer condition are shown in table 2. The children are assumed to be at home

during a greater portion of the summer daytime

hours rather than attending school.

Table 1. Winter daily living pattern for occupants of test house

Father

0000 - 0700

0700 - 0715

0715 - 0730

0730 - 0800

0800 - 1800

1800 - 1830

1830 - 1900

1900 - 2230

2230 - 2245

2245 - 2400

Mother

Sleeps Uses upstairs bathroom

Dresses in master bedroom

Eats breakfast At work

Enters house and relaxes in living room

Eats dinner Miscellaneous activities in living room

Uses upstairs bathroom

Sleeps

0000 0630 Sleeps 0630 0645 Uses upstairs bathroom

0645 0700 Dresses in master bedroom

0700 0730 Prepares breakfast 0730 0800 Eats breakfast 0800 0815 Cleans off dining room table and prepares breakfast for 0815 0830 Prepares children for school 0830 0900 Cleans up after breakfast 0900 0930 Washes and dries clothes 0930 1000 Vacuums downstairs

1000 1015 Cleans downstairs bathroom

1015 1100 Washes and waxes kitchen

floor 1100 1200 Relaxes in living room

1200 1215 Eats quick lunch

1215 1230 Cleans up lunch

1230 1500 Goes shopping

1500 1730 Tending to needs of children 1730 1830 Prepares dinner

1830 1900 Eats dinner

1900 1930 Cleans up dinner

1930 2245 Miscellaneous activities in living room

2245 - 2300 Uses upstairs bathroom

2300 - 2400 Sleeps

Girl - 16 0000 - 0700 Sleeps 0700 - 0715 Uses downstairs bathroom

0715 - 0730 Dresses in her bedroom

0730 - 0800 Eats breaktast 0800 - 0830 Prepares for school in her bedroom

0830 - 1530 At school 1530 - 1730 Miscellaneous activities in living room

1730 - 1830 Helps prepare dinner

1830 - 1900 Eats dinner 1900 - 1930 Dinner clean up in kitchen 1930 - 2030 Studies in bedroom

2030 - 2200 Miscellaneous activities in Hving room

2200 - 2230 Uses downstairs bathroom

2230 - 2400 Sleeps

Girl - 12 0000 - 0715 Sleeps 0715 -- 0730 Uses downstairs bathroom

0730 -- 0800 Eats breakfast 0800 -- 0830 Dresses in bedroom and gets ready for school 0830 -- 1530 At school 1530 -- 1600 Miscellaneous activity in living room

1600 -- 1830 Plays outside 1830 - 1900 Eats dinner 1900 - 1930 Miscellaneous activities in family room

1930 - 2030 Studies in bedroom

2030 - 2130 Miscellaneous activities in living room

2130 - 2200 Uses downstairs bathroom

2200 - 2400 Sleeps

17
Table 1. Winter daily living pattern for occupants of test /ioj«e — Continued

Boy -- 6 0000 - 0745 Sleeps 0745 - 0800 Uses upstairs bathroom

0800 - 0825 Dresses in bedroom

0815 - 0830 Eats breakfast 0830 - 1530 At school 1530 - 1700 Comes home from school and

plays outside 1700 - 1830 Miscellaneous activities in living room

1830 - 1900 Eats dinner

1900 - 1930 Miscellaneous activities in

living room

1930 - 2030 Studies in bedroom

2030 - 2100 Uses downstairs bathroom

2100 - 2400 Sleeps

Boy - 8 0000 - 0645 Sleeps 0645 - 0700 Uses upstairs bathroom

0700 - 0730 Dresses and prepares for school in bedroom

0730 - 0800 Miscellaneous activities in

living room

0800 - 0830 Eats breakfast 0830 - 1530 At school 1530 - 1700 Comes home from school and

plays outside 1700 - 1830 Miscellaneous activities in living room

1830 - 1900 Eats dinner

1900 - 1930 Miscellaneous activities in

living room

1930 - 2030 Studies in bedroom

2030 - 2100 Uses upstairs bathroom

2100 - 2400 Sleeps

Table 2. Summer daily living pattern for occupants of test house

Father I20U 1 OOA 1230 Eats lunch 0000 - 0700 bleeps 1 QAA IdUU Cleans up lunch

0700 - 0715 Uses upstairs bathroom ioOU 1600 lakes children to communi

0715 - 0730 Dresses in master bedroom swimming pool 0730 - 0800 Eats breakfast 1600 1700 House cleaning in downstai 0800 - 1800 At work bedrooms

1800 - 1830 Enters house and relaxes in 1700 1730 Relaxes in living room and

living room to the needs of the chUdi

1830 - 1900 Eats dinner 1730 1830 Prepares dinner

1900 - 2100 Sitting outside 1830 1900 Eats dinner 2100 - 2230 Miscellaneous activities in 1900 1930 Cleans up dinner

living room 1930 2100 Sits outside with husband

2230 - 2245 Uses upstairs bathroom 2100 2245 Miscellaneous activities in 2245 - 2400 Sleeps living room

2245 2300 Uses upstairs bathroom Mother 2300 2400 Sleeps 0000 - 0630 Sleeps Girl 16 0630 - 0645 Uses upstairs bathroom 0000 0700 Sleeps 0645 - 0700 Dresses in master bedroom 0700 0715 Uses downstairs bathroom

0700 - 0730 Prepares breakfast 0715 0730 Dresses in her bedroom

0730 - 0800 Eats breakfast 0730 0800 Eats breakfast 0800 - 0815 Cleans up in kitchen and 0800 0830 Grooms herself in bedroom

prepares breakfast for boys 0830 1200 Visits a girls friend 0815 - 0830 Tends to the needs of the 1200 1230 Eats lunch

children 1230 1300 Helps mother clean up

0830 - 0900 Cleans up breakfast 1300 1600 Goes swimming

0900 - 0930 Washes and dries clothes 1600 1830 Goes bicycle riding with 0930 - 1000 Vacuums upstairs friends 1000 - 1015 Cleans upstairs bathroom 1830 1900 Eats dinner

1015 - 1100 House cleaning in living 1900 1930 Helps mother with after room dinner clean up

1100 - 1130 Relaxes in living room and tends 1930 2200 Goes out on a date

to the needs of the children 2200 2230 Uses downstairs bathroom

1130 - 1200 Prepares lunch 2230 2400 Sleeps

18
Table 2. Summer daily living fjaUern Jor occupants of test /lou.vp— Continued

Girl - 12 0000 - 0715 Sleeps 0715 - 0730 Uses downstairs bathroom

0730 - 0800 Eats breakfast 0800 - 0815 Cleans up dining room

0815 - 0830 Grooms herself in bedroom

0830 - 1200 Visits a girl friend 1200 - 1230 Eats lunch

1230 - 1300 Cleans up lunch in kitchen 1300 - 1600 Swimming at community pool 1600 - 1830 Plays outside 1830 - 1900 Eats dinner

1900 - 1930 Cleans up dinner

1930 - 2100 Plays outside 2100 - 2130 Miscellaneous activities in living room

2130 - 2200 Uses downstairs bathroom

2200 - 2400 Sleeps

Boy - 6 0000 - 0745 Sleeps 0745 - 0800 Uses upstairs bathroom

0800 - 0815 Dresses in bedroom

0815 - 0830 Eats breakfast 0830 - 1200 Plays outside 1200 - 1230 Eats lunch

The metabolic heat production rates assumed

for members of the family are given in table 3, where the rates are dependent upon age and type

of activity: sleeping, sitting, and moderate work.

The rates for the adults are taken from the

available literature, and the rates for other

family members are proportional to assumed

body surface areas. Where the metabolic rates include both sensible and latent heat, the

simulation was made for the total as sensible heat

by placing arrays of electric lights at appropriate

locations throughout the house. Each array was

adjusted so that heat given off by the bulbs would

simulate the net metabolic heat produced for occupancy of the room at the appropriate time

of day.

Table 3. Metabolic heat production

rates [Btu A"')

Activity Family Member

Level Father Mother Girls Boys

Sleeping 250. 250. 187.5 125.

Sitting 400. 400. 300. 200. Moderate work 660. 660. 495. 330.

1230 - 1300 1 IC^cllCS lUl o W 1 III 1111 llg, 111 bedroom

1300 - 1600 vjucb lu i^uiii 111 uiiiiy swiiiiming

1600 - 1830 Plays outside 1830 - 1900 Eats dinner 1900 - 2030 1. lay Q \j\A\.si\X\Z 2030 - 2100 \Jo(3o UUWIIdlallo k) cLviii III 2100 - 2400

Boy - 8 0000 - 0645 Sleeps 0645 - 0700 Uses upstairs bathroom

0700 - 0730 L'lc&acb 111 utjurooiii 0730 - 0800 iviiaL,CiiallCULIs IVl 1 Cr'f^i 1 3 n^/\ll C a/^fiiritidQ in dCllVllieb in living room

0800 - 0830

0830 - 1200 Plays outside 1200 - 1230 rate liinr^n 1230 - 1300 Xrn^narf^C icjjdico fr^T* CiA/immin/v in lui 3 w iiiiiiiiiig, in bedroom

1300 - 1600 Swirns in fominiinitv r»r» aI 1600 - 1830 Plays outside 1830 - 1900 Eats dinner 1900 - 2030 Plays outside 2030 - 2100 Uses downstairs bathroom

2100 - 2400 Sleeps

The heat released by appliances and

equipment is the most significant occupancyrelated heat producing activity of the operating

schedule. Energy release rates for the various

appliances are summarized in table 4. The energy release rates were experimentally

determined by operating each appliance and

measuring energy consumption with watt-hour

Table 4. Energy release rates for operating appliances, Btu h~'

Hot water heater 10410. Refrigeration 575. Clothes washer

(average during cycle) 618. Dish washer 2100. Range, oven 2790. Range, burner 1025. Television

(simulated by lights) 1708. Clothes dryer 5464. Instrumentation

(continuous) 437. Vacuum sweeper 1810.

19
meters. For the clothes dryer it was determined

that about 15 percent of the energy consumed was

released to the house and the remainder was

vented to the outside.

Without hot water usage, the average heat

loss from the hot water heater was about 590

Btu h"' or 5.6 percent of the electrical heat input

to the heater when operating continuously. This

average heat input was determined for a 66-h

period with the room air at about 75 °F and the water temperature maintained at 140 °F.

For the tests discussed in this paper, the

heat release to the house by the hot water heater was assumed to be 600 Btu h"' without hot water

usage and 1100 Btu h~^ when hot water was being

used where the additional heat is lost in the hot water pipes. The remaining heat consumed in heating the water was assumed to be lost to the

sanitary drain.

The procedure followed in performing an

operating schedule was to simulate the activities for the family members. The location of the

occupants were traced throughout the house. The

rooms of the house were equipped with arrays of electric lights for simulating body heat. Each array was continuously adjusted so that the heat given

off by the bulbs would simulate the net metabohc

heat produced by the occupants of the room. In

similar manner, the doors were opened and closed

and the fixtures and the appliances were

operated, so as to be consistent with the

particular daily living pattern.

The net daily energy inputs for the winter

operating schedule are given in figure 34. The

finely shaded area corresponds to the net body

heat produced by the occupants, the cross-hatched

area represents the heat release from the

appliances, and the unshaded area depicts the

energy given off by the electric lights. A morning

peak of about 7000 Btu h"i occurs between 7 and 8

a.m., and an evening peak of about 7500 Btu h'^

takes place during the nineteenth hour. The

evening peak represents approximately one-fifth

of the total energy supplied to the house. The net

daily water consumption and net daily hot water

usage are approximately 232 and 83 gal,

respectively. The energy inputs for simulated summer operating schedule are plotted in figure

35. The uniformly distributed energy given off by

the instrumentation was omitted from this

graph, since it is not really an integral part of the

daily living pattern.

ENERGY INPUTS OF

WINTER OPERATING SCHEDULE

I I LIGHTING

g???! OCCUPANCY

- EQUIPMENT O DOOR OPENINGS (D®

10 12 14 16 18 20 22 24 Figure 34. Energy inputs for simulated winter operating

schedule.

TIME, HOURS

Figure 35. Energy inputs for simulated summer operating

schedule.

5.3. Internal Mass of Test House

The mathematical model used in the

computer program for predicting the thermal

behavior of the townhouse treated the structure

as an equivalent one room space. The heat

exchange between adjoining rooms was negligible, owing to the very small temperature gradient across internal room partitions. All material inside

20
the shell of the structure acted as an internal mass, which absorbed and rejected heat as the

temperature of the inside air fluctuated.

The wall partitions consisted of 2- by 4-in wood studs (placed 16 in on center) covered with

1/2-in gypsum board on both sides. The face area

of one side of the internal waU partitions was

approximately 1098 ft^. The floor partitions from the floor of the

upper module to the ceiling of the lower module

consisted of 1/4-in carpet, 5/8-in plywood, 9-in wood equivalent through members (taken to be 16

in on center), and 1/2-in gypsum board. The fact area of one side of the internal floor partitions was

approximately 417 ft^. The interior furnishings consisted of portable

furnishings (such as furniture) and fixed

furnishings (such as plumbing, heating and

cooling ducts, range, refrigerator, cabinets,

closets, hot water heater, furnace, bathroom

fixtures, and the staircase). The portable

furnishings were weighed on a scale, and their

weight was 3182 lb. The weight of the fixed

furnishings was estimated to be approximately

5000 lb. The net weight of interior furnishings was

8182 lb. Since the interior furnishings consist of a

variety of materials of many differnt shapes and

sizes, it was not practical to model them in an

exact fashion. The effect of the interior furnishings was simulated in the computer program with an equivalent mass of wood. The face area and

thickness of this equivalent mass were first estimated and then adjusted in the analysis as a

result of a time-temperature plot of a puU-down

test, so that the measured thermal mass effect agreed with the predictions of the computer

program and thus could be later applied in per- formance tests.

5.4. Performance of HVAC System

Components

In order to perform prediction and evaluation

analyses of the test house, it was necessary that the performance characteristics of the

components of the HVAC (heating, ventilating and

cooling) systems be determined. In some cases it was necessary to make adjustments to components to obtain a performance as set forth in the criteria or guidelines. The following sections

describe the procedure and testing.

5.4.1. Air Distribution System

In an attempt to obtain uniform temperature

conditions in all rooms for both the heating and

cooling conditions, it was necessary to balance

the air distribution system by controlling the air delivery rate to each room by adjustments to the

respective supply register dampers. Prior to each

cyclic test, the system was operated and temperatures were measured at the center of each

room. Damper adjustments were made. Time was

allowed for the system to stabilize at a given condition and the process was repeated until a fairly

uniform condition was achieved. To obtain

nearly uniform temperature conditions for the

winter heating cycles it was necessary to close

off the registers in the two upstairs bedrooms. For

the summer cooling cycles, the registers in the

upstairs bedrooms were fuUy open.

The forced air blower of the air distribution

system had two speeds. Operation of the blower at high speed occurred for summer cooling and

"fan-on only" conditions that are obtained from

manual switches located above the thermostat

control. The low speed occurred during heating or furnace operation. Subsequent to the balancing of the system, air flow rates were determined at the

air return for both the high and low speeds. The

procedure for testing was to place an aluminum

extension duct (fig. 16) in front of the return air register to confine the air flow prior to entering the

register so that velocity measurements could be

made. Air velocities were measured with a vane anemometer at the center of 12 subareas of the

duct. The velocity readings were numerically

integrated across the field of flow to give air flow rates. Air flow rates for high and low speeds were 1050 and 800 ft^ min"^, respectively.

Velocity measurements at various locations

within the house were made with two instruments.

One instrument was a hot-wire anemometer

capable of measuring velocities above about 75

ft min^', and the other a hot-wire low velocity

anemometer for velocities below 60 ft min"'. The

various locations include the velocities at supply

registers, around the globe thermometers, the

occupied zone, living room windows, and at cracks

at the bottom of the doors.

For velocities at the supply registers, velocity scans were made with the sensing element 2 in from the register. With a low-speed fan operation

565-603 O - 75 - 4
the average velocities in feet per minute were

living room, 878; family room, 415; kitchen, 678

bedroom 1, 320; bedroom 2, 355; bedroom 3, 226

bedroom 4, 166; bathroom 1, 326; and bathroom 2, 116. A velocity scan was made of the occupied

zone which is defined as the zone from 3 in to 6 ft above the floor and 2 ft from the wall. With lowspeed fan operation, no velocities exceeding 45

ft min~^ were found. With high speed operation,

two locations had velocities exceeding 45 ft min~', one at the 6-ft level between the living and family room and 2 ft from the wall with the supply

register of the family room, and the other 5 in from the floor and 2 ft from the entrance to bedroom 4. The velocities were 60 and 90 ft min"'

for these locations, respectively.

Scans were made near the surface of the

globe thermometers indicating that velocities were less than 10 ft min"' with and without fan

operation.

At the center of the middle window in the

living room, velocity measurements were made

for 1/2-, 1- and 2-in distances from the window.

For a thermostated inside temperature of 75 °F

and an outside temperature of 20 °F, the velocity

of the air (in ft min"^) flowing down the window was

the air flow was 1004 cfm, the average room air temperature and relative humidity was 74.1 °F

and 33.4 percent, respectively, and the average

outside air temperature was 94.3 °F. There was no

condensate from the cooling unit. For these

conditions the cooling capacity of the unit was

22,900 Btu h-'.

The rate of electric energy consumption of the refrigeration unit was 3452 W, and that by

the blower of the air distribution system was 504

W. The coefficient of performance for the

refrigeration unit and the total system was 1.97

and 1.69, respectively, for the conditions of the

test.

5.4.3. Gas-Fired Furnace

A test was performed on the gas furnace to determine its efficiency under intermittent

operation. The heat delivered to the house, q, by

the furnace was computed for each operation of the forced air blower by the relation

(1) where

distance from window, in 1/2

12

fan off fan on 30-60 ± 60

15-40 45-50

0-20 20-30

Velocity measurements were also made 2 in from and at a level with the nominal 1/16-in cracks

at the bottom of the doors. Average velocities were

40 ft min~>

5.4.2. Air Cooling Unit

A test was performed on the cooling unit

supplied with the test house to determine the

cooling capacity. With the unit operating continuously, readings were taken of air temperatures

at the inlet and outlet of the unit, air velocities at the return of the air distribution system, relative

humidities, pertinent watt-hour meters and air temperatures at the inlet and outlet of the con- denser of the cooUng unit. The air temperature

difference across the cooling unit was 21.1 °F,

p = density of the air, Ibm ft~^ V = air delivery rate, ft^ min~'

Cp = specific heat of air, Btu lb"' °F~'

r, = supply air temperature, T

T, = return air temperature, °F

t — time, h

L ~ total time for blower operation, h

For the test, the return and supply air temperatures were recorded every 20 s for three

heating cycles, for which 18 ft^ of gas was

consumed. Figures 36 and 37 show the results for one of these cycles. The gas input energy was

18,360 Btu with a higher heating value of 1020

Btu ft"^ for the gas. The integral was evaluated for each blower on cycle, giving a net heat delivery of 11,788 Btu. The resulting efficiency is

11788 X 100

18360

64.2 percent

22
TIME-MINUTES

Figure 37. Temperature and carbon dioxide content offlue gas during cycle of burner on and burner

off time.

23
The above calculated efficiency is defined for heat supplied to the air distribution system when

the blower is operating and does not account for heat that may be transferred to the system by

gravity effects when the blower is not operating.

This would indicate that the calculated efficiency

is low, but intuitively the gravity effects would

at best make a very small increase.

An evaluation was made of the heat flowing

up the furnace stack when the furnace and blower were not operating. Of the 52 min of three cycles,

the blower and furnace were not operating for 35.5 min. In another determination, the pilot light

consumed 1.5 ft' h"^ for the off condition. If it could be assumed that during furnace operations

the efficiency was 80 percent, then the flues losses

during these periods are 0.2 X (18 - 1.5 X 35/60) X

1020 = 3491 Btu. This leaves 18,360 - 11,788 -

3491 = 3081 Btu which must be accounted for by

flue losses during the time when the furnace is not

operating. During this period, the average

temperature of the flue gases was about 145 °F

and the average velocity at the exit to the flue was

550 ft min"^ For a 51 °F crawl space temperature the heat loss to the flue during the 35.5 min is 2883 Btu which for this rough calculation indicates an unaccounted for 198 Btu and a possible increase

in the efficiency to 65.2 percent.

Another rough estimate of the efficiency of the gas furnace with intermittent operation can

be made from the tests where gas and electric heating were used (simulated Kalamazoo weather

cycle). For these tests the heating load was fairly constant during the period from 0000 to 0600. For

the electric heating test, the average energy input was 22,050 Btu h"' with a temperature difference

between inside and outside of 74 °F; for the gas heating test the values were 32,100 Btu and

71 T, giving a value for efficiency as

5.5. Thermal and Physical Properties

The thermal and physical properties of the

building materials needed for use in the computer

program were obtained from available literature and are presented in the following table.

Table 5. Thermal and physical properties

Thermal Specific

conductivity heat Btu h-' Density Btu lb-'

It r

IK ft-3 ID tt F-i r

Gypsum board .12 58. .26 Glass fiber insulation .023 2.0 .22 Plywood .08 34. .38 Roofing felt .046 63. .35 Asphalt shingles .084 73. .2 Wood member .07 26. .38 Redwood .07 25.5 .387 Nylon carpet .07 20. .21 Wood fiber board .028 15. .34 Asphalt tile .09 80. .21

The coefficients of heat transfer at the inside

and outside surfaces were the most difficult of the numerous parameters to define for this experimental work. Values given in literature are usually determined from steady-state conditions whereas these test conditions were dynamic and the coefficients vary with

orientation of surfaces, direction of heat flow,

temperature of surface and air motion at the

surfaces. Values for the surface coefficients of heat transfer at the various surfaces (except for windows) were selected as shown in the follow- ing table and used in the computer program as constants for the time period of a test.

Table 6. Selected heat transfer coefficients, Btu h-' ft-2 F-i

22,050 X 71 X 100

32,100 X 74 = 65.9 percent.

For computer predictions of the total energy

requirements a value of 65 percent for the

efficiency of the gas-fired furnace under

intermittent operation was used.

Inside Surface Outside Surfaces

Wall Roof

Floor

1.10 1.64

1.08

1.47 2.00

1.10

In general, these values are based on a value

of 0.9 for the radiation component of heat transfer and time-averaged temperature differences

24
between surfaces and adjacent air. Reasonable

variations in these coefficients as high as 20

percent have shown a negligible effect on results from the computer program, due to the fact that the thermal resistance of surface films is generally comparatively small.

The above statement is not true for the

double-pane windows used in all tests because the

surface films comprise a larger portion of the

overall thermal resistance due to the relatively

high thermal conductance of the two window

glasses. Because temperature measurements were made on the inside and outside of all windows, it

is possible to determine an average thermal

transmittance for the windows, if the thermal

conductance of the glass and airspace can be

reasonably estimated.

Several measurements were made to determine the thicknesses of the glass and

airspace. The thickness of the airspace was 0.2 in and that for the glass was 0.125 in. Due to the

small thickness of the airspace, the convective

effect was assumed negligible and the heat transfer due to conduction was taken to be 0.74 Btu h"^

ft'^ F"'. The conductance of the airspace is the sum of the conduction, convection, and radiation

components, or

C. = 0,74 +.00617 (Hsr-)' (2)

where is the average temperature of the

airspace. The thermal conductance of the two

panes of glass and airspace as series resistance is given from the relationship

C

"

C. ^ 4 (3)

The air-to-air thermal transmittance is then

calculated from the relationship

(4)

where the subscripts / and o are inside and outside

conditions, respectively, the subscript w refers

to window surfaces, and the subscript a refers

to air temperatures. Values of U were calculated

for the eight window systems of the test house for each scan of several tests and averaged on an area

basis. A plot of the results of these calculations

against air temperature difference between

inside and outside shows some scatter but seems

to indicate that the thermal transmittance for the windows is invariant with the temperature

difference. An average value of thermal trans- mittance f/ = 0.46 Btu h~' ft ^ was used for the computer predictions. For the computer program, the heat capacity

effects of the doors, windows, and window panes

were assumed to be negligibly small and only the

thermal resistance of these components were

used. The thermal resistance for doors was

calculated by series resistance using surface heat

transfer coefficients for walls from table 6. The

thermal transmittance of the aluminum window

frames was assumed to be 0.65 Btu h"' ft"^ F"',

where the resistance to heat flow through the

framing material is assumed to be negligibly

small.The areas used for computing heat flows

through the building components were the inside areas of each of the components. These areas and their respective calculated thermal trans- mittance are summarized in table 7 below.

Table 7. Areas and thermal transmittances of building components

Thermal

transmittance

Building

components

Area

ft^

Btu h-'

ft-2 F-I

Roof Insulation

joist

734.3

83.7

.045 .110

Walls Insulation stud

1108.8

166.1

.063 .138

Carpet floor Insulation

joist

468.2

54.3

.033 .086

Tile floor Insulation

joist

247.7

28.8

.034

.087

Windows 137 .46

Doors 36.4 .20

Aluminum

framing 21 .65

Party wall Insulation stud

208.8

31.2

.019

.022

25
5.6. Description of Tests

The following sections give a brief, identi- fying description of the principal tests performed

on the test house. For most tests, it was necessary

to maintain cyclic temperature patterns for a period of 2 to 3 days before a final set of data was

taken. This conditioning period was deemed

sufficient to eUminate transient heat flows

thereby giving only heat flows that occur in a steady periodic condition. The temperatures

occurring in the crawl space are an exception to

this, because they are affected by the temperature of the earth below. A discussion of this will be found in another section.

A complete set of data for each test consisted

of recording the digital output from analog

signals of 241 sensing elements (thermocouples,

etc.) every 30 min for the duration of a test. The

recorded data was fed into a data reduction

computer program to process the data into

temperatures, relative humidities, etc. The

converted data was then transferred to magnetic

tape for use in analyses, and plotting as temperature and heat flow patterns.

5.6.1. Description of Winter Tests

A summary of the tests performed on the test house that simulate winter conditions is given in the following table.

Table 8.

Simulated

Outside temp. Range Type of occu- Test weather cycle T heating pancy

1 Kalamazoo 1 - 38 Electric yes

2 Kalamazoo 1 - 38 Gas yes

3* Kalamazoo 1 - 38 Electric no

4 Macon 27 - 65 Gas yes

5* Macon 20 - 65 Electric no

6 BSS 45 17 - 70 Electric no

7 Steady state 28 Electric no

Night temperature setback test.

The outdoor temperature patterns for Kalamazoo and Macon were the corresponding

averaged sol-air temperature cycles defined in section 5.1. The cycle termed "BSS 45" is shown

in the section on discussion for test 6 and refers

to a simulated outdoor weather cycle used in tests

on an experimental masonry building [2]. Simulated occupancy of tests 1, 2, and 4 refers to a winter operating schedule as defined in section

5.2. Tests with no simulated occupancy were

performed without the heat generating loads due to appliances and lighting. For tests employing

electric resistance heating, both the combustion

air inlet and the chimney flue were sealed.

Tests 3 and 5 were special purpose tests for determining the reduction of energy usage due

to "nighttime setback" of the thermostat.

Generally these tests were performed for four

identical diurnal cycles in which during two of the

cycles the thermostat control was moved from a

setting of 75 to 65 °F for a period of 8 h and then

reset to 75 °F again. During the other two cycles

the thermostat setting was unchanged. The

difference in the readings for the energy con- sumption during the appropriate time periods gives

the reduction in energy consumption due to "nighttime setback."

For the steady-state test 7, the outdoor air temperature was maintained continuously at about 28 °F for a 4-day period. The rate of heat

output of the electric resistance heating elements was

adjusted to provide a continuous operation of the

heaters and fan and an indoor temperature of about 75 °F. The purpose of this test was to provide information concerning the thermal

transmittance of the house and its components

in order to corroborate thermal property values

used in the prediction analysis.

5.6.2. Description of Other Tests

Three additional tests were performed;

namely, a pull-down test, a summer cooling test, and a fall test. A pull-down test (test 8) is defined

as a test for which the inside air temperature

reduction of a test house is obtained in response to a sudden decrease in the outside air temperature.

The lower level outdoor temperature is maintained

for a prolonged period of time and the

temperature inside the house drops as heat is lost.

Tests 9 and 10 were performed with simulated

occupancy schedules. Test 9 was a summer

cooling test using the outside air temperature

cycle computed for the Kalamazoo design

condition of figure 33. Test 10 was a fall test using

the outside air temperature cycle computed for the Macon condition of figure 31.

26
6. Results and Discussion

In the following sections, results and

discussion are presented for various aspects of 10 tests, such as the comparison of measured

and computer-predicted heating and cooling

loads, performance characteristics of the

heating, ventilating system, and special purpose

tests-pull-down, steady-state and nighttime

setback of the thermostat.

6.1. Winter Heating Tests

For the winter tests 1, 2, 4, and 6, the test house was exposed to a dynamic daily sol-air temperature cycle, while the interior of the test house was maintained at approximately 75

by the operation of its furnace system. During

these tests the rate of energy input to the furnace

system and the rate of electrical input energy

(other than heating energy) were measured, and

these values were compared to corresponding

predicted values of the NBSLD program. For tests

1, 2, and 4 the activities and occupancy of a six member family were simulated with the operating schedule described in section 5.2. Test 6 was

performed without simulated occupancy.

The measured indoor temperature, obtained

by averaging the temperatures sensed by the

indoor air thermocouples located on the

thermocouple strings of the center of the rooms,

contained many fluctuations due to the inter- mittent operation of the furnace system. It was,

therefore, necessary to apply a harmonic analysis

to these sets of data. By maintaining only the first four terms in the resulting series, a smoothed

variation of inside air temperature with time was

obtained for each of these sets of data. The

outside air and the crawl space temperatures

needed for the analysis were obtained by averaging the temperatures sensed by the outside air thermocouples and crawl space thermocouples,

respectively.

In test 1, the test house was exposed to a Kalamazoo winter design day (sec. 5.1.). The

measured daily variation in the outside air, crawl

space air, and the inside air temperature is given

in figure 38. For this test the test house was

heated with electric resistance heating elements

located in the warm air outlet of the furnace

system. A comparison between the measured and

1 I I

1 KALAMAZOO-WINTER, ELECTRIC HEAT

INSIDE AIR

CRAWL SPACE

12 16 TIME, HOURS

Figure 38. Measured daily variation in the outside, crawl space and the inside air temperature for test I.

calculated rate of energy input to the furnace

system is given in figure 39. The agreement

between the measured and predicted peak heating

energy input rates is very good. The predicted

peak value is 4.5 percent higher than the

measured value. A comparison between the

measured and predicted rate of electrical energy

input (other than heating energy) is given in figure

40. This is the electrical energy required for the

Hghting, equipment, and simulating the heat

release of the occupants. Since exact values for the hourly electrical energy consumption for Hghting, equipment, and occupancy were fed into

the NBSLD program, difference, between these

o

g 30

Si! 10

KALAMAZOO WINTER

ELECTRIC HEAT

ELECTRIC HEATING ENERGY

MEASURED

PREDICTED

TIME, HOURS

Figure 39. A comparison between the measured and calculated

rates of energy input to the furnace system for test 1.

27
1 1 I 1 - KALAMAZOO-WINTER

ELECTRIC HEAT

1

ELECTRICAL ENERGY ( ENERGY

DTHER THAN HEATING

r V /\

.' / \ \

1 \\ / \ \\/ ^ \

1 \y / 1 \

\A ' 1 \ V 1 \

1 1 \

^

1

1 MEASURED /j \

1 PREDICTED M

\ 1

,' 1 1

J 1

\ \ 1 M

\\ —U* n //^

\\ /

! —

4- / \ //

\\ /

\ \ , ;/

^\ \ J

\""\

\ \ /

1 1 1 1 1 8 12 16 TIME, HOURS

20 24

Figure 40. A comparison between the measured and calculated

rates of electrical energy input (other than heating energy) for test 1

two electrical input rate profiles should be

attributed to the predictive capability of the

mathematical model used to calculate energy for hot water heating. The mathematical model

contains algorithms for converting hot water

consumption into energy requirements for hot

water heating. A comparison between the

measured and predicted rate of total energy input

to the test house is given in figure 41. Test 2 was identical to test 1, except that the

test house was heated with its gas-fired furnace

system, instead of electrical heaters. The

measured daily variations in the outside air, crawl

space air, and the inside air temperatures for

this test are given in figure 42. A comparison

KALAMAZOO WINTER

ELECTRIC HEAT

TIME, HOURS

between the measured and predicted rates of energy input to the furnace system are pre- sented in figure 43. For the case of a gas-fired

furnace system, the NBSLD program calculates

the rate of gas energy input by dividing the heating

load by the efficiency of the gas furnace system.

The efficiency of the gas furnace system was

determined by laboratory measurements to be

0.65, and this value was used in the computer

program. A comparison between the measured and

predicted rates of electrical energy input (other

than heating energy) is given in figure 44, and a comparison between measured and predicted rates

of total energy input to the test house are pre- sented in figure 45.

KALAMAZOO WINTER GAS HEAT

CRAWL SPACE

12 TIME, HOURS

Figure 42. Measured daily- variation in the outside air, crawl space air, and the inside air temperature for test 2.

1 1 1 1 KALAMAZOO, WINTER

40 GAS ENERGY INPUT

U/H H

cc /

/

/

0001 30 \Nr'"^^ A /

RATE- \ \ '^vA / V \, ' 7 \ /

20

^^v /

INPl

>-o

trUJz

w

10 MEASURED

GAS

n

PREDICTED

1 1 I I I 12 TIME, HOURS

Figure 41. A comparison between the measured and calculated

rates of total energy input to the test house for test 1. Figure 43. A comparison between the measured and calculated

rates of energy input to the furnace system for test 2.

28
20 KALAMAZOO WINTER

GAS TEST

ELECTRIC ENERGY INPUT

100 I 1 1 1 1 MACON - WINTER GAS HEATING

80 -

^ ' INSIDE AIR 75.9 -

li. »_ 60

iij IT

/~\" CRAWL SPACE AIR — — \ ^ .. —

< / \--OUTSIDE AIR S 40 S

UJ

1-

20

n 1 1 1 1 1 12 16 TIME, HOURS TIME - HOURS

Figure 44. A comparison between the measured and calculated

rates of electrical energy input (other than heating energy) for test 2.

Figure 46. Measured daily variation in the outside air, crawl space air, and the inside air temperature for test 4.

KALAMAZOO WINTER GAS HEAT

TOTAL ENERGY INPUT

MEASURED

PREDICTED

? 16

o: 8 -

1 I MACON - WINTER

MEASURED

PREDICTED

TIME, HOURS

12 16 TIME, HOURS

Figure 45. A comparison between the measured and calculated

rates of total energy input to the test house for test 2. Figure 47. A comparison between the measured and calculated

rates of energy input to the furnace system for test 4.

For test 4 the test house was heated with its gas furnace system and exposed to a Macon design

day temperature cycle. Measured daily variations

for this test are given in figure 46. Comparisons

between measured and predicted values for the

rates of energy input to the furnace system, rates

of electrical energy (other than heating energy),

and rate of total energy input to the test house are

given in figures 47, 48, and 49, respectively.

For test 6, the test house was exposed to an

outside air temperature cycle (fig. 50) similar to that used for tests on an experimental masonry

building (test 10, BSS 45 [2]). Heating was accomphshed with electric heaters. This test was

performed without simulated occupancy, so that the rate of heat loss from the test house was equal

to the rate of total energy supplied to the house. A

comparison between measured and predicted heat

loss rate for test 6 is shown in figure 51. Also shown

in this figure is the time-varying heat loss rate that

is calculated by a steady-state procedure (see

equation (5) given below). A phase difference

between measured and predicted heating load was

observed as the heat loss rate decreased to a mini29
mum. This phase difference was also observed in tests on an experimental masonry building [2]. It was pointed out in reference [2] that steadystate procedures may predict maximum heat

loss rates that are too high, since these methods

do not take into account the dampening effect caused by the thermal mass of a building. The

maximum heat loss rates for tests 1, 2, 4, and 6 were calculated by the steady-state relation:

q = {T,-TJ[lU^A^+ 1.08F]

+ {T,-T,)XU^^ (5) where

q = heat loss rate, Btu h"^ U = thermal transmittance, Btu h~' ft~^ F"' A = surface area, ft^ = inside air temperature, °F = minimum outside sol-air temperature, °F = crawl space temperature, °F = air infiltration rate, ft^ min"'

20

1 1 1 1 MACON - WINTER

1

ELECTRICAL ENERGY INPUT

16

|-~ MEASURED

l' 1 PREDICTED

12

8

1 / 1 \ y \ \ 1/

4

\ \ r

/

n 1 1 1 1 12 TIME, HOURS

20

Figure 48. A comparison between the measured and calculated

rates of electric energy input (other than heating energy) for

test 4.

The subscript n refers to the building components

such as walls and windows, and the subscript m

refers to the components of the floor as given in table 7. Air infiltration rates were based on the

results given in appendix A. These steady-state

I

I MACON - WINTER

TOTAL ENERGY INPUT

MEASURED

PREDICTED

12 16 TIME, HOURS

Figure 49. A comparison between the measured and calculated

rates of total energy input to the test house for test 4.

I r

TEST 6

AIR TEMPERATURES

12 16 TIME OF DAY, HOUR

Figure 50. Measured daily variations in the outside air, crawl

space air, and the inside air temperature for test 6.

heat loss rates are compared to corresponding

values calculated by the NBSLD computer

program and corresponding measured values in table 9. The measured heat loss rates were taken

ABLE 9. Maximum heat loss rates, BtU h~

Test Steady-state NBSLD Measured

no. procedure method values

1 27,422 27,310 26,080

2 25,767 25,600 24,100* 4 16,193 15,697 14,950* 6 20,514 17,950 17,400

•Based on efficiency of .65 for gas-fired furnace

30
to be equal to the total amount of heat released

inside the test house at the time of the maximum

heat loss rate.

HEAT LOSS RATE COMPARISONS

0 4 8 12 16 20 24

TIME OF DAY, HOUR

Figure 51. A comparison between the measured rates of heat

loss for test 6 to the corresponding values by NBSLD program and steady-state procedures.

6.2. Summer Cooling Test

Test 9 was a summer cooling test where the

outside air temperture varied in a manner

similar to the sol-air temperature calculated for the Kalamazoo summer condition described in section 5.1.2. The average inside, outside and

crawl space temperatures for this test are shown

in figure 52, and the rate of condensate

collection is showji on figure 53. The average

relative humidity in the house was about 42

percent, being somewhat higher in the evening

hours when baths and showers were used. The

dew point temperature of the outside air was

maintained at about 62 °F, except for the period

from 1000 to 1600 where it was maintained at about 71 °F. For the time period from 1130 to 2130 the

cooling system was operating continuously for which the power consumption of the air conditioning unit was about 3978 W (13,578

Btu h"'). The air temperatures entering and

leaving the condenser coil averaged 99 and 140 °F,

respectively, during this time period. An

140

120

60

1 1 1 SUMMER COOLING TEST

1 1

OUTSIDE AIR

/

_ / INSIDE AIR

-

/ CRAWL SPACE N

^"""""^r 1 1 1 1 0 4 8 12 16 20 24

TIME, HOURS

Figure 52. Measured daily variation in outside, inside crawl

space air temperature for test 9.

1 1 1 1 r SUMMER COOLING TEST CONDENSATE COLLECTION RATE

0 4 8 12 16 20 24

TIME HOURS

Figure 53. Condensate collection rate for test 9.

approximate value for heat removed by the evaporator of 20,000 Btu h~' was determined from

temperature drop across the evaporator,

condensation and heat from the blower. This gives

a coefficient of performance for the refrigeration

unit of 1.47. This gives a considerably lower value than the

value of 1.97 previously stated for a test performed

on this unit. During that test the power

consumption was 3452 W and the entering and

leaving condenser temperatures were 97 and 125

°F, respectively. This indicates for the summer

test that the condenser was operating at a much

higher temperature and, therefore, at a reduced

efficiency. A rule of thumb calculation for the

31
coefficient of performance would be 1.97 X

(3452/3987)' = 1.48, which is close to the value

derived from the approximate heat balance.

For the summer operating condition described

in section 5.1.2. and using a coefficient of performance of 1.47, the computer predicted

energy use by the cooling equipment is shown in figure 54 as well as that measured during the test. For the time period 1200 to 2200 the predicted

values lie below the measured curve. An

explanation for a portion of this discrepancy may

be an unaccounted for heat gain to the kitchen

area from the refrigeration compressor and

condenser unit that was located in a closet in the

kitchen. Noticeably high air temperatures were

recorded in the vicinity of this unit.

6.3. Fall Test

MACON

FALL TEST

OUTSIDE AIR

TIME OF DAY - HOUR

Figure 55. Measured daily variation in inside, outside, and

crawl space air temperatures for test 10.

The outdoor air temperature for test 10 varied

in a manner similar to the sol-air temperature

calculated for the Macon fall condition described

by figure 30. The average inside, outside and

crawl space temperature are shown in figure 55. Tests were performed concurrently with this test involving the use of the plumbing system of the

house. For this reason, the operating schedule was

as shown in figure 56, which reflects an

increased usage of the washer, dryer, and

dishwasher and an increase in door openings. But

to a high liberation of water vapor from the

washer, dryer, and dishwasher, the condensation

collection rate was as high as 3 Ib/h during the

daytime hours.

SUMMER COOLING TEST ENERGY USE BY COOLING EQIPMENT MEASURED

PREDICTED

TIME, HOURS

Figure 54. Energy consumed by air cooling equipmentfor test 9.

I I LIGHTS

OCCUPANCY

EQUIPMENT

O DOOR OPENINGS

HEAT GENERATION

FALL OPERATING SCHEDULE

0 4 8 12 16 20 24

Figure 56. Operating schedule for Macon fall {test 10).

During this test, only the air cooling unit was

used. It was not deemed necessary to use the

heating unit because the inside air temperature

did not drop below 69 °F at night. Shown in figure

57 is the computer predicted energy use by the air cooling equipment as well as that measured during

the test. As in the summer cooling test, the

predicted values lie below the peak measured

value and appear to be out of phase as is also shown in the winter heating tests.

32
0 4 6 12 16 20 24 TIME OF DAY- HOUR

Figure 57. Energy consumed by air cooling equipment for test 10.

6.4. Comparison Summary of Predicted

and Measured Energy Consumption

Of particular interest is the capability of the

NBSLD program to predict maximum heating

and cooling loads, since these values are used to select appropriately sized heating and cooUng

equipment. Also of interest, is the capability of the

NBSLD program to predict daily heating and

cooling energy requirements, so that energy

consumption for heating and cooling may be

determined.

Comparisons between measured and

calculated maximum heating and cooling energy

consumption for the computer validation tests are summarized in table 10.

From table 10, it can be seen that NBSLD

predicted maximum heating and cooling

consumption rates within a difference of 9.2

percent from the measured values. The average

difference for predicting maximum energy input

rates was 2.9 percent. In predicting daily energy

requirements the maximum difference was 8.2

percent, whereas the average difference was 4.5

percent.

6.5. Pull- Down Test

In the pull-down test the townhouse was

maintained at a constant chamber air temperature of 77 °F for 3 days to obtain a uniform

temperature throughout the house. The chamber

air temperature was reduced from 77 to 33 °F in 3 h and maintained at 33.6 °F for an additional 93 h. Inside the house the blower of the air distribution system was operated continuously to provide

mixing of the inside air. The internal heat

generation rate by the blower and instru- mentation located inside the house was constant at 685 W or 2339 Btu h"^ The temperature inside

the house decreased as the house lost heat to the

chamber air. Figure 58 is a plot of the measured values for the inside, outside, and crawl space

temperatures. The measured inside air temperature at any instant of time was obtained by

averaging temperatures recorded from thermocouples located at the geometric center of the rooms. Two days were required to reduce the

inside air temperature from 77 to 53 °F and an

additional 2 days were required to drop the

temperature from 53 to 49 °F. The slow decrease

Table 10. Comparison summary of predicted and measured energy consumption

Maximum heating/cooling energy Daily heating/cooling energy consumption, Btu/hr consumption, Btu per day

Test Predicted Measured % difference Predicted Measured % difference

Heating Test 1 23,400 22,600 -t- 4.0 434,000 436,000 - 0.5 Heating Test 2 35,700 32,700 -t- 9.2 684,000 652,000 -t- 4.9 Heating Test 4 20,300 20,400 - 0.5 319,000 327,000 - 2.5 Heating Test 6 18,000 17,400 -1- 3.4 273,000 286,000 - 4.3 Summer cooling test 13,600 13,600 0.0 201,100 219,100 - 8.2

Fall test 10,950 11,000 - 0.45 107,300 100,650 + 6.61

33
in temperature is attributed to decreased temperature difference between inside and outside, to the large amount of internal mass (interior walls,

floors, and furnishings) which release heat at a slow rates and to the crawl space temperature

which in latter portions of the test was greater

than the inside air temperature indicating that heat was flowing into the house from the crawl

space. The earth below the crawl space takes a long time to come into equilibrium with the

outside air temperature and is therefore able to maintain the crawl space at a temperature above

the outside temperature for fairly long periods of time. This was observed for all tests. An initial computer prediction for the pulldown test assumed that the air infiltration rate was constant at 0.75 air changes per hour and that

the internal furnishings (8200 lb) was simulated

by an equivalent weight of wood 2-in-thick with

a surface area of 1892 ft^. The results for the initial prediction are shown in figure 58. Subsequent

testing (app. A) showed that air infiltration behaved by the relation.

LU 60

PULL -DOWN TEST

EXPERIMENTAL VALUES

INSIDE AIR TEMPERATURE • CRAWL SPACE TEMPERATURE

INITIAL PREDICTION- CORRECTION FOR AIR INFILTRATION

CORRECTION FOR INTERNAL MASS

OUTSIDE

32 48 64

TIME, HOURS

Figure 58. Measured and predicted temperatures for pull- down (test 8).

function is applied. From the results of the pulldown test, the thermal time constant for the test house is approximately 24 h.

7 = 0.117 + 0.0108 Ar (6)

where AT is the temperature difference between

inside and outside. With this correction, the

predicted temperature variation is also shown on

figure 58. This indicates that the thermal mass

was coming into thermal equilibrium with the

inside air at too fast a rate. The agreement shown

on figure 58 was found by assuming an equivalent weight of wood with 1.5 ft thickness with a surface area of 210 ft^ From the thermal point of view a building can

be defined by thermal behavior parameters such

as the equivalent thermal resistance of the

building or the thermal time constant of the

building as a whole. As a parameter, the thermal

resistance defines the ability of the building to restrain heat flows with an applied temperature

difference between the inside and outside. For

the case of a dynamic outside temperature

variation, thermal resistance values are not a

sufficient characterization and the heat

capacity of building elements must be considered. The thermal time constant is a dynamic

parameter defined as the time in which the

internal air temperature reaches 63 percent of

its steady-state value when an external step

6.6. Nighttime Setback Tests

Tests 3 and 5 were special purpose tests to determine the reduction in energy usage due to lowered inside temperture at night. To provide

meaningful results it was necessary that the test house be exposed to identical diurnal outside air temperature cycles and operation during each

test. Outside air temperatures for the periods of the tests are shown on figures 59 and 60 which are

the simulated weather cycles for Kalamazoo,

Mich, and Macon, Ga., respectively. Also on

these plots are shown the temperatures at the

thermostat and in the crawl space below the

house. The cycles as shown in these plots are from

10 p.m. (2200) to 10 p.m. the next day.

The first cycle is with no "setback" of the

thermostat and the indoor air temperature is maintained at about 75 °F continuously. At the

start of the second cycle the thermostat was

lowered 10 °F from 75 to 65 °F and the indoor air temperature dropped as shown until the

thermostat called for heat. After an 8-h period,

the thermostat was raised to 75 °F calling for continuous heating in the house until the indoor

air temperature reached 75 °F. The third cycle

is a repeat of the second cycle. Before each of the

34
THERMOSTAT SETBACK

70

UJ 50

(E< —

UJ£ 40 1—

INDOOR AIR

CYCLE I CYCLE 2 CYCLE 3

CRAWL SPACE

OUTDOOR // AIR

10 -

\

\

J I I L J L

22 2 6 10 14 TIME OF DAY, HOUR

Figure 59. Cyclic variations for outside thermostat and

space air temperature for test 3.

THERMOSTAT SETBACK

6 10 14 TIME OF DAY, HOUR

Figure 60. Cyclic variations for outside therm.ostat and crawl space air temperature for test 5.

two night setback tests, the chamber was

maintained at 35 °F and the indoor temperature

at 75 °F for 2 days, and then one complete diurnal

cycle of outdoor temperature preceded the three

cycles. The purpose was to eliminate transient

heat flows and insure steady periodic conditions.

Table 11 is a summary of the results for the night

setback tests. For each cycle, measurements

were recorded of the electrical energy usage. The

percent energy reduction is taken as the differ- ence between the energy usage without setback

and with setback divided by the energy usage

without setback multiplied by 100. The furnace on-time in minutes for each hour was determined from recordings of an event

meter. Results for the two tests are shown in figures 61 and 62. An approximate method for calculating energy reduction is to substitute total furnace on-time for energy usage. Because these tests were performed under

steady-periodic conditions, the total amount of heat for any diurnal cycle may be calculated

using eq (5) and the average temperature differ- ences given in table 11. Results of the calculations

are given in table 11. Note that at the smaller

inside to outside temperature differences (Macon

cycles) the calculated reduction in energy usage

does not compare as favorably with the

measured reductions and the heat on-time reductions. The reason for this is believed to be the

sensitivity of the air infiltration term in eq (5) at the smaller inside to outside temperature

difference.

The calculated values of KWH are within 2 percent of the measured values and it appears

reasonable that corrections can be made to the

measured values due to the change in the average

crawl space temperature from cycle to cycle.

Adjustments can be made by using the differences

between the last term of eq (5) for the various

cycles. The adjusted values for percent energy

savings are also given in table 11. Using cycle number 1 as the control condition,

the average outside air temperature for the other

two cycles did not vary by more than 1 °F. This is not true for the average crawl space temperature

which decreased from cycle to cycle. The reason

for this is that the earth below the crawl space

takes a long time to come into equilibrium with

the outside air temperature cycle and is, therefore, able to maintain the crawl space at

35
Table 11. Results of nighttime setback tests

Test No. 3 Kalamazoo Cycles

Test No. 5 Macon Cycles

1 1

Duration of setback, hours per day

Cycle measured energy usage, KWH

Reduction in energy usage %

Heat on-time, min. daily cycle

Approx. reduction in energy usage %

Calculated energy usage, eq (5), KWH

Calculated reduction in energy

usage %

Temperature at thermostat °F Average during cycle

Average before setback Average setback (heat on)

Effective setback

0 8 8 0 8 8

156.5 142.4 144.9 102.5 90.7 92.3

9.0 7.4 - 11.5 10.0

846 765.5 781.2

9.5 7.7

562 496 503

11.7 10.5

158.5 144.6 146.4 100.5 92.0 91.7

7.53

8.8 7.6

71.4 71.8

74.7 74.3 65.9 65.9

8.8 8.4

76.1

8.5 8.8

73.1 72.7

76.0 75.5 66.9 66.1

9.1 9.4

Outside air temperature

Average during cycle

Average during setback

Average crawl space temperature

10.1 10.8

2.9

10.7

2.5

47.6 45.6 43.5

34.0 33.4 33.8

20.6 20.9

53.7 52.2 51.4

Temperature difference

Inside to outside

Inside to crawl space

Adjusted reduction of energy

usage for cycle to cycle change

in crawl space temperature

°F

65.2 60.6 61.1 27.7 25.8 28.3

9.3 7.9

42.1 39.7 38.9

22.4 20.9 22.9

11.8 10.4

temperatures above the mean temperature of the

outside air for fairly long periods of time. The

effect of the decreasing crawl space temperature

during the test period was to increase the heat loss from the test house. Therefore, the measured

energy savings would have been larger, if the

crawl space temperature variation had been

maintained the same for each 24-h period.

6.7. Steady-State Winter Test

For the steady-state winter test (test 7), the

outside air temperature was maintained at approximately 27.9 °F for a 4-day period. The

average crawl space temperature for the last day was 54.2 °F. The rate of heat input to the electric heaters was adjusted so that a continuous

operation of the system maintained an average

of 74.6 °F inside the house. The simulated party

wall was maintained at 75 °F over its surface.

The first 3 days of this test were provided in order

to eliminate transient heat flows and insure near

steady-state conditions for the fourth day. The

constant rate of heat input to the house was 15,300

Btu.h'.

From the values given in table 7 for the

thermal transmittances and areas of the various

surfaces, temperature differences and air infil- tration rates given in appendix A, it is possible to determine a calculated heat loss for the house.

Neglecting the heat loss due to air infiltration,

the calculated value involving conduction heat

flow is 10,606 Btu h-^ If the remaining heat loss,

4724 Btu h~^ is considered to be due to air

36
infiltration, the air change rate is calculated to be .61 air changes per hour. Air infiltration tests show that for a temperature difference, 74.6 -

27.9 = 46.7 °F, the rate is about 0.63 air changes

per hour, which gives a heat loss of 4893 Btu h"'. The unaccounted loss is 169 Btu h"i or 1.1 percent

of the total heat loss. Using the thermal transmittance values given

in table 7, heat fluxes were calculated and

compared to heat flux rates measured by heat

flow meters. Values are given in the following

table.

Building surface

Heat flow (Btu h-'ff^)

Calculated Measured

Ceiling Insulation 2.08 2.39

joist 5.15 4.13

Walls Insulation 2.96 2.97 stud 6.44 4.47

Carpet Insulation .65 1.24 Floor joist 1.69 1.26

The agreement between measured and

calculated values is good for heat flow through the

glass fiber insulation in walls and ceiling. The

measured values are consistently lower for heat

flow across wood through members. This may be

due in part to thermal resistance of the heat flow

meter being placed in series with the relatively

high conductive wood through members. In

addition, the heat flow pattern spreads upon

entering and leaving a through member. This

two dimensional effect causes the heat flow meter

to see only a portion of total heat flow through the

through member, and thus indicates a lower heat

flow rate. For heat flow through the carpeted floor with insulation, the calculated value was about

one-half the value measured by the heat flow meter. This is believed to be due to the

uncertainty of measurement using heat flow meters at relatively low heat flux rates. Multiplying the calculated values by their respective areas (table 7) and summing gives a value of 6994 Btu h"^ and the corresponding measured

summation is 6868 Btu for the opaque areas of

the house. Thus, the use of heat flow meters on all opaque areas of the house when taken together as

a whole yielded a reasonably good comparison.

THERMOSTAT SETBACK T -1 1 TV 1 1 \ 1 1 1 r

I r.

— CYCLE I — CYCLE 2 CYCLE 3

6 10 14 TIME OF DAY, HOUR22

Figure 61. Furnace system on time for test 3.

THERMOSTAT SETBACK n—[~

J I I I L J L

22 2 6 10 14 18 22 TIME OF DAY, HOUR

Figure 62. Furnace system on time for test 5.

The average temperature drop across the

inside and outside surfaces of the double pane

windows was 15.6 °F. The conductance of the

double pane window calculated from eq (3) gives

1.42 Btu h-i ft-2 F-i and a heat flux of 22.15

Btu h"^ ft~^. Based on this value, the thermal

transmittance for windows, U — 22.15/46.7 =

0.47 Btu h"^ ft"^ F"^^ The value used in previous

calculations was t/ = 0.46 Btu il'^ F^^.

37
6.8. Temperature Distribution During

Winter Tests

to maintain small temperature gradients as shown in figure 64.

Density differences cause warm air to rise in a room so that in the absence of other driving forces

there wiU be a temperature gradient from floor

to ceiling in a room. In the test house studied in

this report the warm air outlets were located in the

walls near the ceiling level, except in upstairs

bedroom 4 where the outlet was located in a wall close to the floor level. During operation of the system for winter

heating, warm air was introduced into aU but one room at the ceiling level. The warm air due to its decreased density tended to remain at the ceiling

level giving fairly large temperature differ- ences from floor to ceiling. This is shown in figure

63 where temperatures at various distances

above the floor level are given as a function of time for the downstairs rooms during test 1. For

this test the floor to ceiling temperature

difference averaged 18 to 20 °F where the

nighttime temperature in the kitchen was as low

as 55 °F at the 3-in level. The vertical temperature

difference in the occupied region from the 3-in

to the 72-in level averaged 12 to 15 °F. Similar

temperature gradients were found for all winter

tests. For test 1, the upstairs bedrooms were able

DISTANCE ABOVE FLOOR Q 3 INCHES 0 30 INCHES A 60 INCHES + 72 INCHES X 84 INCHES

93 INCHES

Tine - HOURS

Figure 63b. (Family room).

DISTANCE ABOVE FLOOR Q 3 mCHES 0 30 INCHES A 6C INCHES

72 INCHES X 84 INCHES « 93 INCHES

T 1 1 1 1 1 1 1 0 3 6 9 12 15 18 21 24 Tine - HOURS

Figure 63a. Downstairs temperatures at various levels for test 1 (living room).

3SDISTANCE ABOVE FLOOR Q 3 INCHES

30- 0 30 INCHES ^ 60 INCHES + 72 INCHES X 84 INCHES

85> « 93 INCHES

AO-

'S70-

65-

60-

t

0 3 6 9 12 IS 10 21 2* TIME - HOURS

Figure 63c. (Kitchen).

38
DISTANCE ABOVE FLOOR Q 3 INCHES 0 30 INCHES

ij 60 INCHES + 72 INCHES X 84 INCHES $ 93 INCHES

TIME - HOURS

Figure 63d. (Bedroom 1 ).

DISTANCE ABOVE FLOOR Q 3 INCHES 0 30 INCHES A 60 INCHES

72 INCHES X 84 INCHES « 93 INCHES

TIME - HOURS

Figure 63f. (Bathroom. 1 ).

DISTANCE ABOVE FLOOR Q 3 INCHES Q 30 INCHES A 60 INCHES ^ 72 INCHES X 84 INCHES « 93 INCHES

TIME - HOURS

Figure 63e. (Bedroom 2).

DISTANCE ABOVE FLOOR Q 3 INCHES Q 30 INCHES £ 60 INCHES • 72 INCHES X 84 INCHES « 93 INCHES

TIME - HOURS

Figure 64a. Upstairs temperatures at various levels (Bedroom3).

39
DISTANCE ABOVE FUXIR P 3 INCmS 0 30 INCHES

90- A 60 INCHES + 72 INCHES X 84 INCHES « 93 INCHES

BS60-

S5-I ; 1

1 ; 1 1 1 0 3 6 9 12 IS 18 21 24 TinE - HOURS

Figure 64b. (Bedroom 4).

During test 2 a temperature scan was made

during an operation of the furnace system to determine the effect of heating operation on the

vertical temperature difference. Figure 65 shows

temperature profiles at the center of the kitchen

for times corresponding to the start of system

operation, 2 min after start-up, and 4 min after

start-up. Four minutes of operation increased the

floor-to-ceiling temperature difference from 15

1/2 to 22 1/2 °F.

The mean temperature difference across the

upstairs and downstairs occupied zones of the

test house for test 2 (gas heat) are compared with

the corresponding values of test 1 (electric heat).

The occupied zone is defined as the indoor space 3

to 72 in above the floor and 2 ft from the exterior

walls. The mean temperature difference across

the upstairs occupied zone was calculated by

taking the arithmetic average of the temperature differences between the 72- and 3-in levels at the center of the two upstairs bedrooms. The mean temperature difference across the

downstairs occupied zone was similarly calculated.

The outside air temperature cycles for these

tests were practically identical, although there was a tendency of the outside air temperatures

for test 2 (gas heat) to be approximately 2 °F

higher than for test 1 (electric heat).

Figure 66 is a plot of the mean temperature

differences across the upstairs occupied zone

(lower set of curves) and the downstairs

occupied zone (upper set of curves) for these tests. The outside air temperature cycle for test 2 (gas

heat) is also included on this graph. The dips in the mean temperature difference curves for the

downstairs occupied zone should be attributed to a reduction in furnace operation and air infil- tration during warmer periods of the day. The

GAS HEAT

1 1 1 1 1 TIMES IN MINUTES AFTER START OF FURNACE OPERATION /"^

0 2 4

START OF FURNACE / // END OF HEATING OPERATION // / CYCLE

1

I 1 1

I- 6

70 80 TEMPERATURE,

KALAMAZOO-WINTER

1 1 1AVERAGE

7I.3F- __^mF. — ELECTRIC HEAT \pOWNSTAIRS/

GAS HEAT

. UPSTAIRS y^^^^-^ _ 67.7_F

73.9F

\OUTSIDE

1 1 1 1

10 s

! 12 16 TIME OF DAY, HOUR

Figure 65. Vertical temperature distribution at center of Figure 66. Mean temperature difference of occupied zones for

kitchen during furnace operation for test 2. tests 1 (electric) and 2 (gas).

40
percentage of furnace operation for these tests is plotted versus time in figure 67. Comparing the

upstairs temperature difference curves, the

temperature difference curve for test 1 (electric

heat) is consistently higher than the corre- sponding curve for test 2 (gas heat). For the

electric heat test the rate of heat output of the

system was intentionally made lower, so that during periods of cold outside temperature, the

heating system would operate a greater per- centage of the time. The greater amount of operating time for test 1 (electric heat) causes the

temperature difference across the downstairs

occupied zone to be consistently larger. The

temperature difference across the upstairs

occupied zone for both gas and electric heat was

very nearly a constant value of 4 °F. The dips in these curves during periods of warm outside

temperature was much less pronounced than the

corresponding curves for the downstairs. For

these tests the upstairs supply register dampers

were closed in order to achieve a balanced

temperature distribution throughout the test house.

KALAMAZOO-WINTER

ELECTRIC HEAT GAS HEAT

q: .8 —

O

,1 I I I I I I 0 4 8 12 16 20 24 TIME OF DAY, HOUR

Figure 67. Heating system on-time for test 1 (electric) and test 2

(gas).

6.9. Mean Radiant Temperature

One of the factors affecting human comfort is the radiation exchange between a person and his surroundings. The radiation environment is

usually expressed in terms of its mean radiant

temperature (MRT) which is defined as the

temperature of a uniform black enclosure in which a solid body or occupant would exchange

the same amount of radiant energy as in the

existing nonuniform environment. At thermal

equilibrium the heat gained or lost by radiation

to a Vernon globe thermometer must equal the heat lost or gained by convection. In terms of heat

transfer relationships:

r, = + 0.103 X io» VH^(r^-ra) (7)

where

= mean radiant temperature, °F abs

(black body equivalent)

Jg = globe temperature, °F abs

W = air velocity, fpm

^, ~ globe, ambient air temperature, °F abs

Under the dynamic test conditions of this study

and the intermittent operation of the furnace

and air conditioning system, the recorded

instantaneous ambient air temperatures

possessed random fluctuations. The air temperature which should be used in the above

equation is the average temperature for a time

period. This may be achieved by applying a harmonic analysis to the data for the air temperature adjacent to a globe thermometer and using

only the first four harmonics of the resulting

series. Air velocities in the vicinity of the globe

thermometers were measured and found to be in the range of 7 to 10 fpm. An air velocity of 8 fpm

was used in the mean radiant temperature

analysis.

The daily variation of the MRT in the living room, family room, and the kitchen for winter

heating test 2 is plotted in -figure 68. The peak

MRT values occurring at 2000 h in the living room

and family room are due to the delayed effect of the maximum outdoor temperature being

propagated through the wall and roof surfaces.

The peaks at 0930 and 2000 h in the kitchen are

attributed to cooking activities. The operation of the oven and burners increases room surface

temperatures through radiation exchange with

these surface temperatures and through an

increase in the room air temperature which

41
eel 1 1 I 1 i i 0 4 8 12 16 20 24

TIME, HOURS

Figure 68. Calculated MRT in the living room, family room and kitchen for test 2.

transfer heat by convection to these surfaces. The

daily variation in the MRT in the four bedrooms is plotted in figure 69. The difference between the MRT and the

ambient air temperatures is plotted in figure 70. The ambient air temperature used was the

temperature measured at the 30-in level, since

this is the level at which the globe thermometers

were placed. Notice that there was a tendency for the MRT to be higher than the ambient temperature in the downstairs rooms, whereas a reversed

behavior was observed in the upstairs rooms.

74

66

1 1 BR #3

BR 4*4 \

1 1 1

BR « 1 —

1

1

BR tt2

1 1 1

TIME, HOURS

Figure 69. Calculated MRT in bedrooms for test 2.

Referring to the temperature distribution curves

given in figures 63 and 64, inside air temperatures as high as 87 were measured at the 84-in

level. This high-temperature air warmed the

ceiling surfaces and caused the MRT for the

downstairs rooms to be higher than the observed

ambient temperatures.

6.10. Humidity Analysis

For the winter conditions the indoor rela- tive humidity was maintained at very nearly a constant value by the humidifier attached to the

furnace system. The humidifier had a limit control

which monitored the relative humidity of the air

Figure 70. Difference between MRT and adjacent air temperatures for test 2.

42
in the return of the furnace system. When the

relative humidity was below some prescribed set

point, this limit control caused the humidifier to add moisture to the house during the operation

of the furnace system. The relative humidities in the living room, kitchen, master bedroom, and

downstairs bathroom for the Kalamazoo winter

test with electric heat (test 1) are plotted versus

time in figure 71. The two sharp peaks at 2100 and

2200 h in the bathroom are due to a bath and

shower, respectively. Notice that the relative humidity is slightly higher in the upstairs master

bedroom compared to the downstairs rooms. There is a tendency for warm air to rise in the

house, causing air exfiltration from the window

cracks and vent opening of the second floor. This

upward warm air movement transports water

vapor, causing the relative humidity to be higher

in the upstairs rooms of the house.

The rate of air infiltration and the rate of water consumption by the humidifier is plotted versus time in figure 72. The rate of air infiltration was calculated from the linear relationship

between the rate of air infiltration and the

difference in temperature between indoor and

outdoor air (see app. A). Notice that there is a tendency for the rate of water consumption by

the humidifier to decline during periods of low

infiltration. The exfiltration of indoor air transports water

vapor from the house. The daily mass, M, of water

lost through exfiltration may be calculated by

the relation:

1 50

< 20

LIVING ROOM

• KITCHEN A BED ROOM No 4 BATH No. I

^^^^^^^^^^^^

J L

8 12 16 TIME OF DAY, HOUR

24

Figure 71. Measured daily variations of relative humidity

for test 1.

M = Jl' IpV{oj,-wJdt (8)

12 16 TIME OF DAY, HOUR

where

= rate of air infiltration,

air changes per h = density of air, Ibm ft"^ - inside volume of house, ft^ - indoor humidity ratio, Ibm water

vapor per Ibm of dry air = outdoor humidity ratio, Ibm water

vapor per Ibm of dry air = time, h

During Kalamazoo winter test with electric heat (test 4), the outdoor humidity ratio was

P

V

(X);

Figure 72. Daily variation in the rate of air infiltration and the

rate of humidifier water consumption for test 1

maintained at approximately a constant value of 0.0006. This value corresponds to a dew point of -

5 °F. The indoor relative humidity was maintained

at an average value of 20.5 percent at an indoor

temperature of 73 °F. This corresponds to an

indoor humidity ratio of 0.0035. Substituting the

indoor and outdoor humidity ratios, the volume of the house {V = 9240 ft^), the density of air at room

temperature (p = 0.074 Ibm/ft'), and the rate of air infiltration / as a function of time, the above

expression may be integrated over a 24-h period

to give the daily mass of water lost from the house

43
due to air exfiltration. This integration was

performed giving a daily loss of water of 29.2 Ibm.

The net water supplied by the humidifier over

this time period was 17.3 Ibm. The difference

between the water loss by air exfiltration and

the water supplied by the humidifier, 11.9 Ibm,

must be equal to the water given off by occupantrelated activities relating to water usage such as

baths, showers, dishwasher operation, etc. Since

the net daily hot water supply was 901 Ibm, water

given off by occupant-related activities was slightly

greater than one percent of the net daily hot water

consumption.

For the Kalamazoo winter test with gas heat

(test 2) the outdoor humidity ratio was maintained at an average value of 0.0008. The indoor

humidity ratio was maintained at a constant

value of 0.0042 corresponding to a relative humidity of 22.7 percent at an indoor temperature of 74 °F. The water lost by exfiltration calculated by eq (8) was 34.2 Ibm. The water

supplied by the humidifier during a 24-h period was 17.7 Ibm. The difference in these values (16.5

Ibm) is equal to the water introduced by

occupancy-related activities relating to hot water

usage. This value, 16.5, seems somewhat high, but

studies [6] have shown that the average daily

production of water vapor for a family of four may

be as much as 25 Ibm excluding such appliances

as humidifiers, and automatic washers and

dryers.

The above moisture balances do not take into account window condensation. The effect of including window condensation in the analysis

would be to increase the estimated moisture

release from occupancy-related activities. For the Kalamazoo winter tests, visual

observations were made of the visible condensation, frost and ice formation on windows and

frames. Ice formations were found on the lower

surfaces of aluminum frames for all windows of the first floor except in the kitchen. In some cases

the ice extended a short distance up the frame

becoming condensation on the frame halfway up

the window. There was no condensation or ice

formation on the upper half of the frames.

Depending upon the outside temperature there was frost or condensation on the glass of the

window. These formations occurred in patches,

usually in corners, and predominately in the

lower half of the window.

7. Conclusions

On a full-scale four-bedroom townhouse a comparison was made between measured values

of energy consumption and values predicted

using the NBS Load Determination Computer

Program. The test house was placed in an

environmental chamber and exposed to various

dynamic temperature cycles to simulate winter,

fall, and summer conditions. During the tests the activities and occupancy of a six-member

family were simulated. The rates of heating and

cooling input energy were measured, and these

values were compared to corresponding

predicted values of the NBSLD computer program.

For the computer validation tests, NBSLD

predicted maximum heating and coohng

consumption rates within a difference of 9.2

percent from the measured values. The average

difference for predicting maximum energy input

rates was 2.9 percent. In predicting daily energy

requirements, the maximum difference was 8.2

percent, whereas the average difference was 4.5

percent. Thus, the NBSLD computer program may

be used with confidence for predicting peak

heating and cooling loads and energy requirements for a domestic dwelhng.

Separate tests were performed to investi- gate the energy savings achieved by night

temperature setback. An 8-h 10 °F night

temperature setback produced an 11 percent

savings in energy for a design day at Macon, Ga.,

and a 9 percent savings for a design day at Kalamazoo, Mich.

Experimental measurements under controlled

laboratory conditions corroborated the earlier finding that the rate of air infiltration for a building is linearly related to the difference in temperature between the inside and outside.

And finally, it was found that the practice of placing the furnace warm air outlets at the ceiling

level caused large temperature gradients to exist

in the living space of a house. Temperature

gradients as high as 25 °F were observed for the

most severe winter condition.

8. Nomenclature and Conversion Factors

A surface area, ft^ c tracer gas concentration, parts per

million

44
C thermal conductance, Btu

Cp specific heat of air, Btu Ibm"' F"^

CR common ratio, dimensionless

Eq rate of cooling energy input, Btu h~'

Eh rate of heating energy input, Btu

I rate of air infiltration, h"' M mass of water lost by exfiltration, Ibm

number of significant terms of series

P number of surfaces, dimensionless

Q rate of heat transfer, Btu h^^

Q total amount of tracer gas in house, Ibm

t time, h

T temperature, F

TI temperature history of inside surface, F

TO temperature history of outside surface, F

U air-to-air thermal transmittance,

Btu h-i F-i ft-2 V volume of house, ft^ V air movement rate, ft^ h"' W air velocity, ft h"^ X response factor at inside surface,

Btu h-' ft-^' F-' V response factor at outside surface,

Btu h-i ft-2 F-'

Greek Symbols

8 standard deviation, dimensionless

Tj furnace efficiency, dimensionless

p density of air, Ibm ft"^

(j) coefficient of performance, dimensionless

CO humidity ratio Subscripts and Superscripts

a air space or air property

b electric lighting

c crawl space air d door

e equipment

g globe thermometer

HWH hot water heater

i inside air or inside surface

j time index of summation

/ latent L total heat loss m surface index of summation

n surface index of summation or current time interval index o outside air or outside surface or occupancy

P number of s :rfaces

r return air or surface index of summation

s supply air w mean radiant property or window

Conversion factors to metric (S.I.) units

Physical

quantity Symbol To convert from To Multiply by

Length X ft^ meter 3.04* X 10"' Area ft'

3 m 9.290 X 10"' Volume ft' m 2.832 X 10"' Temperature Fahrenheit Celsius = (/f - 32)/1.8 Temperature

difference Fahrenheit Kelvin K = (ArF)/1.8 Mass Ibm kg 4.536 X 10"' Density P Ibm ft' kg/m' 1.602 X 10' Thermal conductivity k Btu h ft^ (Fin)

W/mk 1.442 X 10"'

[/-value U Btu h ft^ F W/m'K 5.678 Thermal resis- tance R F Btu h ft') 1.761 X 10-' Heat flow qiA Btu h ft' W/m' 3.155 Heat flow Btu h W 2.931 X 10"' Heat flow ton (of refrigeration) W 3.517 X 10' Flow cfm m'/s 4.719 X 10"^ Velocity fpm m/s 5.08" X 10"' Cooling effi- ciency Btu h kW 2.931 X 10"*

Specific heat Btu Ibm j/kg.K 4.187 X 10'

•Exact value: others are rounded to fourth place. 45
The authors wish to thank D. R. Showalter,

J. D. Allen, and J. W. Grimes for their technical

assistance in the installation of the instrumentation and day-to-day operation of the experi- ments. The very helpful suggestions and

comments made during review of this paper by P. R. Achenbach are gratefully acknowledged.

9. References

[1] Kusuda, T., National Bureau of Standards

Heating and Cooling Load Determination

Program, Building Science Series in progress.

[2] Peavy, B. A., Powell, F. J., and Burch, D. M.,

Dynamic thermal performance of an experimental masonry building, Nat. Bur. Stand.

(U.S.), Bldg. Sci. Ser. 45, 103 pages (July

1973).

[3] Kusuda, T., Thermal response factors for multilayer structures of various heat conduction

systems, ASHRAE Transactions, pp. 250-

269, Part I, 1969.

[4] Bahnfleth, D. R., Moseley, T. T., and Harris,

W. S., Measurement of Infiltration in Two

Residences, Part I: Technique and

Measured Infiltration, Part II: Comparison of Variables Affecting Infiltration, ASHRAE

Transactions, Vol. 63, pp. 439-452, 1957.

[5] Procedures for Determining Heating and

Cooling Loads for Computerized Energy

Calculations, The Task Group on Energy

Requirements for Heating and Cooling,

ASHRAE, 345 East 47th Street, New York,

1971.

[6] Hite, S. C. and Dray, Research in Home

Humidity Control, Purdue University

Engineering Experiment Station Research

Series No. 106, November 1948.

46
Appendix A

Air Infiltration Measurements on the Four- Bedroom Townhouse

1. Introduction

Air leakage is one of the important paths by

which a house gains or loses heat. To determine

the rate of exchange between the house and its surroundings the rate of disappearance of a

tracer gas was measured. This is a common

method of measuring infiltration rates, and a number of gases have been used for the purpose.

These include helium [1, 2],' and ethane [3] as well

as other gases. More recently sulfur hexafluoride

[4] has been used for the purpose, and this gas was used in the present measurements because

it is relatively nontoxic, nonflammable, and may

be conveniently measured in concentrations of the order of 5 to 20 ppb.

2. Theory

The principle of the tracer method for measuring air exchange may be outlined briefly

by considering the average rate, v„, at which air leaks into a house, and which must equal the

average rate at which air leaks out unless there is some steady buildup or decrease in pressure. The

rate of change in the total amount of tracer in the

house may be expressed by the relationship,

f

= (C. - C) v., at (A-1)

where Q is the total amount of tracer in the house

at time C„, and are concentrations of tracer

in the outside and inside air respectively, v, is the

volume rate at which air enters and leaves the

' Figures in brackets indicate the literature references given

at the end of this appendix.

house. If V is the total volume of the house,

equation (A-1) becomes

\ dQ ^ V dt dt (Co - Q) V (A-2)

where vo/V is the infiltration rate expressed in air changes per unit time. If the outside concentration of tracer is small enough to be neglected,

eq (A-2) reduces to

dt = - C' V (A-3)

which in integrated form becomes

10 e V

or

log. = 2.303 logio

V

(A-4)

where Cj, is the concentration of tracer at time / =

0. Thus if log Ci/Ci, is plotted against time the

idealized relationship calls for a straight line of slope - v,/2.303V. Since the air exchange rate, /,

is usually expressed in air changes per hour while

flow rate, v„, is measured in cfm,

2.303 X 60 X slope. (A-5)

One of the tacit assumptions of this derivation is that air leaving the house has the same average

tracer concentration as the air in the house.

Also, it is assumed that sampling is representative. Both of these assumptions are approximations.

47
3. Measurement Techniques

Sulfur hexafluoride (SF^) concentrations were measured with a Panatek Model 2000 leak detector

operated in the chromatographic mode. In this mode, oxygen, which is also an electron capturing gas, is separated from SF^ and the tracer is measured separately by means of the detector.

If is the standing current with pure carrier gas

and / the current when a small amount of SF^ is present, the response is treated as logarithmic.

That is,

log -L =- kC (A-6)

0

where C is the concentration of tracer, and k is an

arbitrary constant. In the chromatographic

mode, /o is a more or less steady standing cur- rent while / is the trough of a deflection. To ac- commodate for drift in the response of the detector

with time and to minimize ballistic errors the

instrument was usually calibrated three or four

times during the course of each air exchange

measurement with air containing 13.8 ppb SF^.

Tracer concentrations in the house were usually

in the range of 13.8 ± 5 ppb.

Air samples were taken at recorded times

and analyzed for SF^. Three different methods of sampHng were compared. In method 1, samples were collected manually with a hand pump and

a balloon, going from room to room in a timed

sequence. The upstairs and downstairs were

analyzed separately. In method 2, samples were

collected through a sampling network consisting

of 16 polyethylene tubes (6 mm i.d.) of identical

length. One or more tubes extended to each of the rooms and hallways and all converged in a small

pump with a capacity of 12 liters per min. In method 3, samples were drawn directly from the

return air to the blower of the air distribution

system. When infiltration measurements are made in occupied houses it is usually not possible

to use methods 1 and 2, and method 3 is commonly used [3]. Data was analyzed separately

for each method and also pooled for the three

methods.

^ Certain commercial materials and instruments are identified

in this report in order to specify the experimental procedure

adequately. Such identification does not imply recommendation

or endorsement by the National Bureau of Standards, nor does

it imply that the equipment is necessarily the best for the purpose.

4. Results and Discussion

A number of measurements were made

under conditions of electric heat with an indoor

temperature maintained at about 75 °F, and

outside temperature maintained at different

selected values. The results, showing infiltration as a function of the difference between inside and

outside temperature are given in table A-1 for three methods of sampling.

Table A-1. Air exchange rate as a function of temperature difference between inside and outside

Temperature

difference Air changes per h between

inside and Method 1 Method 2 Method 3 outside (Hand (Network (Return air °F sampling) sampling) sampling)

52.3 0.61 0.59 0.61

52.1 .74 .74 .82 51.1 .68 .70 .70 49.3 .64 .72 .66 49.1 .55 .57 39.5 .46 .51 .60 36.8 .43 .55 .52 23.6 .45 .50 .50 23.6 .48 .28 .42 14.5 .17 .16

14.3 .29 .24 .33 9.6 .17 .22

The results show that when wind velocity is eliminated as a variable a strong correlation is obtained between infiltration rate and temperature difference, AT. The temperature effect has

also been observed by others [1,3,5]. The data in table A-1 also shows considerable scatter. A best

fit straight line was obtained to correlate the

data for each of the sampling methods. The

equations and corresponding root mean square

deviations for the three methods of sampling are given below:

hand: = 0.113 + 0.0104Ar, 8 = 0.070

network: = 0.117 + O.OIOSAJ, S = 0.072

return: = 0.124 + 0.0114AJ, 8 = 0.071

where 8 is the root mean square deviation. While

there is considerable scatter in individual points.

48
overall agreement between the three methods of sampling is fairly close. For pooled data for all three sampling methods the equation is

/ = 0.117 + O.OlOSAr, 8 = 0.074.

The pooled data and the corresponding least squares line are presented in figure A-1. The effect of sealing doors and ducts was also measured, and the results are given in table A-2. The effect of sealing exhaust fan openings and

doors was insufficient to outweigh the effect of inside/outside temperature difference. However,

at a temperature difference near 50 °F data

obtained with sealed openings averaged about 0.1

of an air change per hour less than that obtained

with normal operation. It was noted by Elkins and

Table A-2. Effect of sealing doors and vents in air infiltration rates

Temperature

difference Air changes per hour between

inside and Method 1 Method 2 Method 3 outside (Hand (Network (Return air Conditions sampling) sampling) sampling)

Kitchen, bathroom and

clothes dryer fan ducts sealed 52.4 .68 .48 .55 Kitchen, bathroom and

clothes dryer fan ducts sealed 50.9 .58 .60 .58 Kitchen, bathroom, and

clothes dryer fan ducts sealed. Doors

also sealed. 49.5 .67 .48 .75

Table A-3. The effect of operating exhaust fans

Temperature

difference Air changes per hour between

inside and Method 1 Method 2 Method 3 outside (Hand (Network (Return air T sampling) sampling) sampling)

Kitchen fan on 52.6 0.77 0.88 0.88 Kitchen fan on 51.2 .98 1.16 l.IO Upstairs bathroom fan on 51.2 .85 .92 .89 Upstairs bathroom fan on 48.0 .88 .90 .87 Operate clothes dryer 51.6 .92 1.05 1.12

O HAND SAMPLING A NETWORK SAMPLING

o RETURN SAMPLING

LEAST SQUARES LINE

° 10 20 30 40 50 60

TEMP. DIFF. INSIDE TO OUTSIDE, °F

Figure A-1. Air exchange rate as a function of difference in temperature between inside and outside of townhouse.

49
Wensman [3] that opening doors under conditions

of very low wind velocity had little effect on air exchange rate. The results in tables A-1 and A-2

would tend to confirm this observation.

The infiltration rate during operating of the

kitchen or bathroom exhaust fans or the clothes

dryer are given in table A-3. They result in an

increase in infiltration rate as might be

expected. Data showing the effect of operating the

main circulating fan is not shown. This fan was

an integral part of the heating and cooling system

and could not be turned off without turning off the

furnace or air conditioner. When this was done

and the house temperature allowed to drift, infiltration rates lower than those shown in table A-1 or figure A-1 were obtained. However, if the

heating or cooling system were on, it made little difference whether the fan operated continuously or intermittently.

5. References

[1] Bahnfleth, D. R., Moseley, T. T., and Harris,

W. S., Measurement of infiltration in two

residences. Part I: Technique and measured Infiltration, Part H: Comparison of variables affecting infiltration, Amer. Soc. Heating and Air Conditioning Eng. 63, 439-

452 (1957).

[2] Coblentz, Carl W. and Achenbach, P. R.,

Design and performance of a portable

infiltration meter, Amer. Soc. of Heating and

Air Conditioning Eng. 63, 477-482 (1957).

[3] Elkins, R. H. and Wensman, C. E., Natural

Ventilation of Modern Tightly Constructed

Homes, paper presented at the American Gas

Association of Gas Technology Conference on

Natural Gas Research and Technology,

Chicago, 111., February 28-March 3, 1971.

[4] Drivas, P. J., Simonds, P. G., and Shair, F. H., Experimental characterization of ventilation systems in buildings, Env. Sci. and

Tech. 6 (7), 609-614 (1972).

[5] Coblentz, C. W. and Achenbach, P. R., Field

measurements of air infiltration in ten

electrically-heated houses, Amer. Soc. Heating, Refrigerating and Air-Conditioning

Eng. 69, 358-365 (1963).

50
Appendix B

Interior Noise Levels in the Four- Bedroom Townhouse

Donald S. Blomquist*

1. Objective

The objective of these tests was to obtain

information regarding interior noise levels due to the heating and air conditioning unit and two

garbage disposal units.

2. Test Procedure

All tests were performed in accordance with

the procedures outlined in American National

Standard Methods for Measurement of Sound

Pressure Levels, SI. -13-1971. Measurements of the noise levels due to mechanical equipment were carried out for comparison with the "noise criteria (NC) curves"

given by Beranek (p. 564 in "Noise and Vibration Control", McGraw-Hill, 1971). The following

locations and equipment were measured.

1. Living room: heater on.

2. Front bedroom, second floor: heater on.

3. Back bedroom, second floor: heater on.

4. Front bedroom, first floor: heater on.

4. Kitchen: heater on.

6. Kitchen: air conditioner on.

7. Kitchen: exhaust fan on.

8. Kitchen: two different garbage

disposers on. A total of six microphones, in a modified

spherical array was used for all tests except the

Garbage Disposal tests where one microphone was

positioned over the sink at a height of 5 ft above

the floor. Temporal averages of sound pressure levels were obtained using a real time analyzer set to an

integration time of 20 s. The digital output of the

real time analyzer was connected to a minicomputer which switched the microphones,

*Applied Acoustics Section, Mechanics Division, Institute

for Basic Standards, National Bureau of Standards. Washington,

D.C. 20234.

averaged the signals from the different microphones, and combined the 1/3-octave band data

into 1/1-octave bands for comparison with the NCcurves. Using this procedure, the statistical error due to temporal averaging is less than 1.2 dB (at a confidence level of 95%).

The uncertainty in measured sound pressure

level, due to random and systematic uncertainties associated with the overall data acquisition system, is estimated (95% confidence level)

to be less than ± 1 dB.

For all measurements the background noise

(measured with the equipment off) was at least 10 dB below the operating noise with the

equipment. Thus, the effect of any background

noise on the measurement is less than 0.5 db.

For testing of garbage disposers unpopped

popcorn was used as a load. Extensive measurements were made on this housing system as part of Operation

BREAKTHROUGH testing; these measurements

include noise reduction and impact isolation of the interior walls and floors. The results of these

tests are reported in NBSIR 73-191, "Acoustical

Evaluation of a Single Family Attached WoodFrame Modular Housing System Constructed on

an Operation BREAKTHROUGH Prototype Site,"

1973.

3. Results

Results of the measurements are shown in figures B-1 through B-8. Figure B-1 shows the 1/1 octave band noise levels in the living room with

the heating system operating. Figures B-2 through

B-4 show the noise levels in the bedroom due to the heating system. Figures B-5 and B-6 are the

results in the kitchen for the heating and air conditioning system, respectively. Figure B-7

shows the noise level due to the kitchen exhaust

fan (without the HVAC system on). Figure B-8

shows the noise level (at a single position) for

51
two models of garbage disposers produced by the same manufacturer, one being the most

expensive and the second the least expensive.

These results are summarized in table B-1. In "A

Guide to Airborne, Impact and Structure Borne

Noise-Control in Multifamily Dwelling," U.S.

Department of Housing and Urban Development,

Washington, D.C., 1963, the following

recommendations were made for interior noise:

1. for residential urban and suburban areas considered to have the average noise

environment, interior noise environments

should not exceed NC 25-30 characteristics.

2. for residential urban and suburban areas considered to be "noisy locations" interior noise environments should not exceed NC35 characteristics.

Table B-1. The measured noise criteria characteristics of the housing system

Equipment

Room

measured NC

Heater on living room <55

Heater on front bedroom <40

Heater on back bedroom <45

Heater on front bedroom <40

(first floor) Heater on kitchen <55

Air conditioning on kitchen <55

Exhaust fan on kitchen <60

Inexpensive garbage disposal kitchen <65

Expensive garbage disposal kitchen <70

1 1 1 1 1 1 1 1

^\ — ~

^°

' 40

1 1 1 1 ^ 30

1 1 1 1 250 500 IK Frequency, Hz

Figure B-1. The symbols show the octave band sound pressure

levels in the living room with the heating sysitm operating.

The numbered curves are "noise criteria curves."

250 500 IK

Frequency, Hz

Figure B-2. The symbols show the octave band sound pressure

levels in the front bedroom {second floor) with the heating

system operating.

The numbered curves are "noise criteria curves."

52
250 500 IK Frequency, Hz

250 500 IK

Frequency, Hz

Figure B—3. The symbols show the octave band sound pressure

levels in the back bedroom (second floor) with the heating

system operating.

The numbered curves are "noise criteria curves."

Figure B-5. The symbols show the octave band sound pressure

levels in the kitchen with the heating system operating.

The numbered curves are "noise criteria curves."

Frequency, Hz Figure B-4. The symbols show the octave band sound pressure

levels in the front bedroom (first floor) with the heating system Figure B-6. The symbols show the octave band sound pressure

operating. levels in the kitchen with the air conditioning system operating.

The numbered curves are "noise criteria curves." The numbered curves are "noise criteria curves."

53
250 500 IK

Frequency, Hz

Figure B— 7. The symbols show the octave band sound pressure

levels in the kitchen with the exhaust fan operating.

The numbered curves are "noise criteria curves."

250 500 IK

Frequency, Hz

Figure B-8. The symbols show the octave band sound presstire

levels in the kitchen with two different garbage disposers

operating.

The numbered curves are "noise criteria curves."

54
Appendix C

Mathematical Simulation for the Test House

The mathematic model used in the computer

a building treats the building as a one-room

enclosure. The various external wall, floor, and

ceiling surfaces are treated as separate heat flow

paths. The internal wall and ceiling partitions,

the internal furnishings, and equipment are

treated as plane slabs. Other assumptions made in the thermal analysis are:

1. The conduction heat transfer through

components of the test house is one- dimensional. Heat conduction through thermal

bridges such as wall stud is treated as a separate heat flow path with no lateral heat

flow between adjacent components.

2. The heat-transfer coefficient for the inside

and outside surfaces of the building is constant.

3. All building materials are homogeneous,

having constant thermal and physical

properties.

4. Heat and mass transfer of water in vapor or

liquid form or the latent heats of condensation, freezing and evaporation is neglected,

since the dew point temperature of the outside

air was maintained below that for any

temperature in a daily cycle.

5. The temperature distribution inside the

house is uniform.

Using the above assumptions for simulating

the thermal behavior of the test house may be

derived. The Response Factor Method predicts the

rate of heat conduction, at the current time

interval, n into the surface of a solid as the sum of the response caused by a series of individual

temperature pulses occurring at the bounding

surface for preceding time intervals, or

N

qjA - 1 {X; r/„_, - Y; TO^.;) + A) CR.

>0 (C-1)

The values of the Response Factors, X^ and

Y-, and the number of significant series terms, N

depend upon the type of structure and are precalculated in a separate routine in the

computer program. The last term in the above

equation represents the effect of the preceding

rate of heat flow on the present value. The

methodology dealing with the calculation of the

Response Factors is discussed by Kusuda [3]. For a surface having negligible heat capacity

such as windows and most doors of a building, the

rate of heat conduction, g„ is given by the relation

qjA = U (Ti^ - TOJ (C-2)

The heat loss due to air infiltration is given by

g„ = p VI (TI, - TOJ. (C-3)

The time dependent heat loss from a building

is then equal to the sum of the rates of heat

conduction through the surfaces having signifi- cant heat capacity, plus the sum of the heat flows

through the windows and doors, plus the heat loss due to air infiltration. The net heat loss may be

expressed by the relation

P N

qc= S Ad^ (XfTI,^, - Y) T0„_.,) + q\,, Ci?M

+ UMTh-TOJ+U^A^iTI,,-TOJ

+ pC,VIiTI,-TOJ. (C4)

Notice that the heat flows through windows

and doors have been lumped into separate terms

in the above equation. If a building had different

types of windows and/or doors, then each type

would have to be handled by a separate term in

this equation. In addition, when the first term

applies to a floor surface over a crawl space, then

the temperature TO would be the temperature of the crawl space air.

55
The indoor activities of a family such as hot

water consumption, the operation of household

appliances, etc., release a significant amount of heat and wiU contribute to the heating and cooHng

loads of a domestic dwelling. In particular, the

heat release by occupant-related activities, over some time interval is given by

= Qb + Qo + + <?HWH (C-5)

where

(Jb = energy for electric lighting = heat given off by household appliances

g„ = sensible heat released by the

occupants

<7hwh ~ heat release due to hot water

consumption

The input energies supplied to the appliances

with the exception of the hot water heater are considered to be instantaneous heat releases

to the house. The heat release for the hot water

heater is taken to be equal to the jacket skin loss without hot water consumption. When hot water

is used, the additional heat release from activities such as baths, showers, etc., is taken into account

by multiplying the jacket skin loss by a factor

1.833.For the present study the activities of a six- member family were simulated, so that internal

heat generation from occupant-related activities would be realistic. The sensible body heat given

off by the occupants were simulated with light bulbs. For the computer simulation it was possible to input to the computer program exact

values for the energies for lighting, q^,, occupant

body heat, q^, and equipment, q^. If this building

simulation program were run on a house for which the schedule of indoor activities was not

available, then it would be necessary to make

reasonable estimates for these energies based on

engineering judgment.

The heating load is equal to the difference

between the calculated heat loss, q^^ and the heat

released by occupant-related activities, q^,. The

energy required by a heating plant to overcome

this heating load is equal to the heating load

divided by the efficiency, rj of the heating plant, or

Eh = i<li - q,)ly). (C-6)

In air conditioning applications the sensible

cooling load, (7, is equal to the sum of the

calculated heat gain (negative of the calculated

heat loss, heat generated by occupantrelated activities, q^. The energy required by the

cooling equipment to overcome this cooling load

is equal to the sum of sensible cooling load, q^ and

the latent cooling load, divided by the coeffi- cient of performance, (^^ of the cooling equipment, or

56
NBS-114A (REV. 7-73)

U .6. DEPT. -OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. I-'UHI.K ATION OK KI-I'OICI' NO. NBS -BSS - 57

2. (u)v't Ac

No.

3. Kc( i(>i<'nl *s Ac-c c's.sion No.

4. TITLE AND SUBTITLl- Comparison of Measured and Computer-Predicted Thermal

Performance of a Four Bedroom Wood-Frame Townhouse

5. I'ubl ic ation l)at April 1975

6. Performing Organization ( <><ii

7. AUTHOR(S)

B. ,A. Peavy, D. M. Burch, C. M. Hunt, and F. J. Powell

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Proieci/Ta.sk/Work Unit No.

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Same as 9. and Department of Housing and Urban Development

451 7th Street, S. W. Washington, D. C. 20410

13. Type of Report &: Pcrioci Covered

Final FY 74-75

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Number: 74-20830

16. ABSTRACT (A 200-word or less factual summary of most si^ilicant information. If document includes a significant bibliography or literature survey, mention it here.) Measurements of the dynamic heat transfer in a four bedroom townhouse were made und^r

controlled conditions in a large environmental chamber to explore the validity of a com- puter program developed at NBS, labelled NBSLD, for predicting heating and cooling loads

and inside air temperatures. This study was supported jointly by the Department of

Housing and Urban Development and the National Bureau of Standards, and is a part of a broader research program supported by both agencies to Improve performance test procedures and criteria for housing.

The test house was a factory-produced four bedroom townhouse of modular design and

of lightweight (wood) construction. Tests were performed with simulated outside summer,

winter and fall diurnal temperature cycles. The inside temperature was maintained at about 75 °F. Also during the tests, the activities of a six-member family were slmulatec

The time-varying energy requirements were measured, and these values were compared

with computer predicted values. For example, the disparity between predicted and measure daily heating energy requirements averaged 3.1% with a maximum departure of 4.9% for five

tests. The computer program NBSLD was experimentally validated for predicting the peak

heating and cooling loads and the energy requirements for the test house.

The air leakage of the house was measured by a tracer gas technique over a range of

outdoor conditions, and algorithms were developed to account for its effect on heating

Ofids and energy requirements. (Continued)

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons) air leakage measurement; building heat transfer; computer

programs; dynamic thermal performance; heat flow analysis; heating and cooling loads;

temperature predictions; thermal analysis; thermostat setback; transient heat flows

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Separate tests were also performed to investigate the energysavings achieved by night temperature setback. An 8-h 9 "F setback

from 75 °F produced an 11 percent diurnal savings in energy for an

average nighttime temperature of 20 'F and a 9 percent savings in

energy was achieved for the same setback when the average nighttime temperature was 2 °F.

U.S. GOVERNMENT PRINTING OFFICE : 1975 O-565-603
Announcement of New Publications in

Building Science Series

Superintendent of Documents,

U.S. Government Printing Office,

Washington, D.C. 20402

Dear Sir:

Please add my name to the announcement list of new publications to be

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NBS TECHNICAL PUBLICATIONS

PERIODICALS JOURNAL OF RESEARCH reports National Bureau

of Standards research and development in physics,

mathematics, and chemistry. It is published in two sections, available separately:

• Physics and Chemistry (Section A)

Papers of interest primarily to scientists working in these fields. This section covers a broad range of physical and chemical research, with major emphasis on

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year. Annual subscription: Domestic, $17.00; Foreign,

$21.25. • Mathematical Sciences (Section B)

Studies and compilations designed mainly for the mathematician and theoretical physicist. Topics in mathematical statistics, theory of experiment design, numerical analysis, theoretical physics and chemistry, logical design and programming of computers and computer

systems. Short numerical tables. Issued quarterly. Annual subscription: Domestic, $9.00; Foreign, $11.25. DIMENSIONS/NBS (formerly Technical News Bulletin) —This monthly magazine is published to inform

scientists, engineers, businessmen, industry, teachers,

students, and consumers of the latest advances in science and technology, with primary emphasis on the work at NBS. The magazine highlights and reviews such

issues as energy research, fire protection, building tech- nology, metric conversion, pollution abatement, health and safety, and consumer product performance. In addition, it reports the results of Bureau programs in measurement standards and techniques, properties of matter and materials, engineering standards and services, instrumentation, and automatic data processing. Annual subscription: Domestic, $9.45; Foreign, $11.85.

NONPERIODICALS

Monographs—Major contributions to the technical liter- ature on various subjects related to the Bureau's scientific and technical activities. Handbooks—Recommended codes of engineering and

industrial practice (including safety codes) developed

in cooperation with interested industries, professional

organizations, and regulatory bodies.

Special Publications—Include proceedings of confer- ences sponsored by NBS, NBS annual reports, and other

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Applied Mathematics Series—Mathematical tables, manuals, and studies of special interest to physicists, engineers, chemists, biologists, mathematicians, computer programmers, and others engaged in scientific and technical work.

National Standard Reference Data Series—Provides

quantitative data on the physical and chemical properties of materials, compiled from the world's literature and critically evaluated. Developed under a world-wide

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administers this program as a supplement to the activities of the private sector standardizing organizations. Federal Information Processing Standards Publications (FIPS PUBS)—Publications in this series collectively constitute the Federal Information Processing Standards Register. Register serves as the official source of information in the Federal Government regarding stand- ards issued by NBS pursuant to the Federal Property and Administrative Services Act of 1949 as amended,

Public Law 89-306 (79 Stat. 1127), and as implemented

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D.C. 20402. BIBLIOGRAPHIC SUBSCRIPTION SERVICES

The following current-awareness and literature-survey

bibliographies are issued periodically by the Bureau:

Cryogenic Data Center Current Awareness Service A literature survey issued biweekly. Annual subscription: Domestic, $20.00; foreign, $25.00.

Liquefied Natural Gas. A literature survey issued quarterly. Annual subscription: $20.00. Superconducting Devices and Materials. A literature

survey issued quarterly. Annual subscription: $20.00. Send subscription orders and remittances for the pre- ceding bibliographic services to National Technical Information Service, Springfield, Va. 22161.

Electromagnetic Metrology Current Awareness Service Issued monthly. Annual subscription: $100.00 (Special rates for multi-subscriptions). Send subscription order and remittance to Electromagnetics Division, National Bureau of Standards, Boulder, Colo. 80302.
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