NBSIR 83-2728

Automated Control of Lighting

and Fenestration

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Building Technology

Washington, DC 20234

July 1983

Prepared for: Naval Facilities Engineering Command

U.S. Navy

Washington, DC 20390

Directorate of Civil Engineering

U.S. Air Force

Washington, DC 20330 and

Office of Chief of Engineers

U.S. Army

Washington, DC 20314

rational bureau

of STANDARDS

NBSIR 83-2728

AUTOMATED CONTROL OF LIGHTING

AND FENESTRATION

S. J. Treado

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Building Technology

Washington, DC 20234

July 1983

Prepared for: Naval Facilities Engineering Command

U S. Navy

Washington, DC 20390

Directorate of Civil Engineering

U.S. Air Force

Washington, DC 20330 and

Office of Chief of Engineers

U.S. Army

Washington, DC 20314

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

ABSTRACT

This paper describes a methodology for an automatic system for controlling the

lighting and window shading in a commercial building. The system utilizes a microcomputer to monitor solar radiation and illumination levels and interior

and exterior air temperatures, processing the input parameters to determine

the optimum lighting level, window area, and solar film position to minimize

building heating and cooling loads due to windows and lighting. The control

methodology and logical flow are presented. The response of the system to

various combinations of weather conditions is examined.

Keywords: automatic control; daylighting; lighting control; microprocessor;

window management

iii
TABLE OF CONTENTS

Page

1. INTRODUCTION 1

2. LIGHTING AND FENESTRATION CONTROL SYSTEM 2

3. CONTROLLER OPERATION 6

4. CONTROL PROGRAM AND SIMULATION 8

5. CONCLUSION 9

REFERENCES 10

LIST OF FIGURES

Page

Figure 1. Schematic of typical control system 11

Figure 2. Heat gain Ql as a function of glass area Aq 12

Figure 3. Sample Output from controller simulation program 13

iv
NOMENCLATURE

A = area

DF = daylighting factor

I = illuminance

LP = lighting power

SF = shading factor

SR = solar radiation

T = temperature

AT = temperature difference

U = thermal transmittance

Subscripts

d = diffuse

F = film

G = glass or unshuttered window

I = point of inflection

R = reference point

S = shutter or shuttered window

T = total horizontal

V = vertical

xa, xb = x-intercept

out = exterior

in = interior

max = maximum

min = minimum

O(zero) = zero value

v

1 INTRODUCTION

Building energy consumption is primarily due to heating, cooling and lighting

demands. In many commercial buildings, the largest annual energy cost is for

cooling, especially since core areas experience a temperature rise due to

internal heat gains. Electric lighting impacts building energy requirements

in two ways. First, the energy must be purchased to provide light. Second,

the heat dissipated from the light fixtures will be a heat gain to the interior building space. This may be a benefit in winter if heating is needed,

while under summer conditions cooling load will increase. However, even in

winter it is possible that excessive heat gain due to solar radiation or lighting could result in overheating, unless some of the heat can be distributed to

other parts of the building.

Large window areas will result in high daylight levels , thereby reducing

electric lighting requirements. However, large windows also allow more con- ductive heat transfer, as well as increased solar heat gain due to transmitted

solar radiation. Window heat transfer due to conduction will depend upon the

interior and exterior air temperatures, and heat flow can occur in either

direction. Thus, a trade-off must be made, between reducing lighting load

through the use of large windows, and increasing window heat transfer. In

most cases, window area is fixed, so any adjustment of the heat transfer characteristics of the window is accomplished through the use of shades and blinds,

which are adjustable, or films and screens, which are usually fixed. These

would be examples of a strategy called window management, whereby the thermal

and/or visual characteristics of a window system can be selectively altered as desired, either manually or automatically.

Control of window heat exchange and lighting loads can be accomplished through

window management and daylight utilization. Window management devices include

solar films and screens, shutters, drapes, and louvers. Many types of lighting

controls are available to enable continuous dimming of lighting in response to

daylighting levels [1,2,3]. The beneficial aspects of controllable window

management and daylight utilization are well recorded [4,5].

This paper will focus on the net effect of window management and lighting level

on building heating and cooling requirements, and how to reduce these requirements through the use of a microprocessor-based control system. An additional

benefit of this type of control system is that peak heating and cooling loads can be reduced, thereby enabling use of smaller heating and cooling systems.

Such systems are beginning to be used in buildings for various control purposes

[6]. An automatic control system consisting of a microcomputer, a group of sensors, and output actuators, determines the optimum window area and decides

whether a reflective film should be lowered. Window area can be adjusted

through the use of motorized insulating shutters, and the reflective film is

tracked at the window frame. Thus, the reflective film can be raised or lowered, and the position of the shutters controlled in response to the decision of the controller. The purpose of the reflective film is to reduce solar

heat gain (through reflection) and to reduce radiative heat transfer between

the room and the interior window surface (due to lower surface emittance). The

shutter would be used to reduce window conductive heat transfer when daylighting

1
is not needed, or when the benefit of daylighting is outweighed by undesirable

window heat transfer.

The basic operation of the system is as follows. The interior air temperature

is compared to a reference value. If these two agree within a specified bandwidth, the controller will attempt to maintain that temperature by configuring

the windows and lighting for zero heat gain. If the interior air temperature

should rise above the acceptable band, the controller will minimize heat

gain. Conversely, if the temperature falls below the band, heat gain would be

maximized. This measurement and decision process would be repeated at cyclic

intervals. The illumination reference level is the level which must be maintained, through a combination of daylighting (natural light) and electric

lighting. The reference level could be set to zero for non-working hours and

weekends. Manual override lighting switches would enable lights to be turned

on in different areas as needed for maintenance crews and after-hours building

occupants

.

Daily, weekly or annual control schedules could easily be superposed on the

system, enabling night setback, weekend shutdown or any other operating procedures to be implemented. The system could also control the HVAC equipment,

calling for heating and cooling as needed, in response to building air temperature. This report deals only with the portion of the control system which is

controlling the lighting and window management.

2. LIGHTING AND FENESTRATION CONTROL SYSTEM

A schematic of a typical system is shown in figure 1. Three window options

are available: first, a double-pane clear window; second, the same window

with a reflective film which can be automatically raised or lowered; third,

an insulating shutter. The shutter can be opened and closed any amount, so glass area can be varied continuously from 0 to 100 percent of total window

area. Any combination of glass, film and shutter can be used, except, for

simplicity, the film must be completely up or down.

Performing a heat balance between the exterior and a typical office module,

and including only those terms which are related to window heat exchange or lighting, the following equation is obtained:

Heat Gain = Q L= LP + TRANS + COND + CONV + RAD (1)

where LP = lighting power

TRANS = transmitted solar radiation

COND = conductive heat transfer

CONV = convective heat transfer

RAD = radiative heat transfer

If eq. (1) is negative, a heat loss is indicated. If eq. (1) is positive, a heat gain results. At some point, Ql may be zero, indicating that the combined

effect of window and lighting on room heat gain is zero.

2
The transmitted solar radiation terra of eq. (1) can be evaluated as

TRANS = SF(SRv

)Ag (2)

where SF = shading factor

SRy = vertical solar radiation

Aq = glass area

The shading factor is a dimensionless parameter which is the ratio of solar

heat gain to incident vertical solar radiation, for each window option. Solar

heat gain associated with a window consists of two components, namely directly

transmitted solar radiation, and absorbed solar radiation which is transmitted

to the building space by convection and radiation. The transmittance of a window is dependent upon the angle of incidence of the incident solar radiation,

however, the angular distribution of the incident solar radiation is very difficult to measure, and typically not known. Thus, a simplifying assumption is

made to treat the shading factor as being a constant. The value of SF for the

reflective film option would be less than that for the clear glass, while SF

for the shutter is equal to zero.

The heat gain due to conduction, convection and radiation can be evaluated as

COND + CONV + RAD = UgAgAT + U^AT (3)

where U = overall transmittance

AT = temperature difference (Tqux “ T;qj)

A = surface area Subscript S = shutter, G = glass

The required lighting power can be determined by consideration of the required

illumination level (Ir). As the level of daylight increases, lighting power

can be reduced. If the actual interior illumination (Ij) meets or exceeds the

reference level, Ir, no lighting is needed. That is:

(IR - I

T

) —^

LPmx - LP (4)

where LP max = maximum lighting power

It is possible to calculate the level of daylight with each window option,

based on the exterior vertical illumination, which can be easily and accurately measured. The daylight factor method uses a factor (DF) which is to be

multiplied by the exterior vertical illuminance (Iy) to determine the interior

illuminance Ij [7]. The daylight factor can be measured or calculated, and

typically is less than 10 percent. This factor is scaled proportionally with

window area by the area ratio Aq/A^. Thus:

IX = Iy(DF) (5)

Arji

where Ap = total fenestration area.

3
When direct beam solar radiation (and illumination) is incident upon a window,

the transmitted direct beam may be excessive, from the standpoints of glare

and local overheating near the window. In addition, direct beam illuminance

may not be as effective in providing work-plane daylight, because the direct

beam frequently strikes the floor and must undergo multiple reflections before

reaching the task surface. The control system could be programmed to account

for these effects. Glare and local overheating could be minimized by setting a maximum limit on transmitted solar radiation, so that the reflective film would

be used whenever a high level of direct beam solar radiation was incident upon

the window. A typical value for the maximum limit would be 500 w/m^, since

diffuse radiation rarely exceeds this value [8] . This limit could be set and

adjusted by the building occupants as required. The effect of direct beam daylight possibly being less effective than diffuse daylight at providing workplane illuminance could be handled by derating. Levels of incident diffuse

illuminance rarely exceed 60,000 lux [8]; if the incident illuminance exceeded

that amount, the calculation of interior daylight could be made using a lower

value for the incident illuminance. The adjusted value could be chosen conser- vatively to be 60,000 lux, or perhaps chosen to be 60,000 lux plus a percentage

of the illuminance over 60,000 lux.

Both of these direct beam effects occur only for windows facing the sun when

skies are clear. Thus, the potential for problems exists for only a small percentage of the hours of the year, so neglecting direct beam effects would probably have a small impact on building energy or occupant comfort. Glare or overheating problems could also be overcome when necessary by manual over-ride

of the window management system by the building occupants. Since the potential

for problems associated with direct beam solar radiation is highly dependent

upon individual building designs and locations, the remainder of the analysis assumes that no special control strategies are implemented for direct beam solar

radiation.

If the shutters are in a partially closed position, some heat exchange will be

occurring through both the glass portion of the total fenestration area and the

portion covered with the shutter. Considering this and eqs. (2-5), net heat

gain due to windows and lighting is:

QL = UgAgAT + Us (At-Ag)AT +

I R-Iy(DF)(Ap

LP,max

+ (sf)(sr

v

)(a

g

) ( 6 )

This equation can be rearranged to yield:

+ LP + (u

s )(at

)(at) (7) max

4
AclKi + K2 - K3 ] + K4 + K5 ( 8 )

Room heat gain is seen to be a function of window area A^ plus two constant

terms. The control program determines the optimum window area, which is the

portion of the window not covered by an insulating shutter, for each window

option, and then compares each option to determine the most desirable one.

For each window configuration at any particular instant in time, all the

variables on the right side of eq. (7) are known, either as constants or measured values, except for the glass area, A^. Aq is determined based upon

whether the building is in a heating mode, cooling mode, or within the acceptable temperature band. For example, if it is desired that the indoor air temperature be maintained within a 5°F band, then the modes would be determined

according to table 1.

Table 1

Condition Mode Response

|Tr - TinI <2.5 I Ql

- 0 Stable

t r

" t in > 2 * 5 II Ql max Heating

tr

" T IN < ~2 ’ 5 III Ql •* min Cooling

(9)

where TR

= reference temperature (setpoint), °F.

To illustrate the use of the control methodology, an example is presented in

the following section.

Shading factors, daylight factors and U-values for the different window options

used in the example are listed in Table 2. These are typical values for the

parameters for this system configuration. Other types of window treatments

could easily be accommodated by insertion of different values.

Table 2

Option U SF DF

Double Pane 0.58 0.87 0.10

w/film 0.38 0.17 0.03

w/ shutters 0.10 0 0

5
3. CONTROLLER OPERATION

When the control system is in operation, the values from Table 2 are substituted into eq. (7), and the values of the K constants are determined for

the case of clear glass and of glass with film. The optimum value of Aq will

depend upon the mode (i.e. heating, cooling, stable) and on the values of the

K's. and K5 function as a constant offset, and the y-intercept, (K^ + K5 ), can be negative or positive. Since K4 equals LPmax , it is always positive.

Ki and K5 can be either negative or positive, depending upon the indoor-outdoor

temperature difference. K2 must always be positive, since solar radiation

level is never negative.

From eq. ( 8 ), when A(j = 0

QL = K4 + K5 ( 10 )

As window area A^ increases, can increase or decrease. If (K^ + K2 - K3

) is

negative, the slope of Ql will decrease with increasing Aq; if (Kj + K2 - K3 ) is positive, Ql will increase.

Eq. (7) does not hold when the daylight level exceeds the illumination set

point. When this occurs, eq. (7) would have a negative lighting power term.

Since this is impossible, eq. (7) must be modified so that lighting power never

becomes negative. A point of inflection in the plot of will occur when the

required lighting power reaches zero. Under some conditions this point will

not be reached unless window area exceeds the maximum possible (total window

area A-j.). At other times, this may occur at an intermediate window area.

The window area at the inflection point is

Al

IR

I v DF

where Ai = glass area at inflection

(ID

If Aj is greater than zero and less than or equal to the total window area,

a change in slope of Ql will occur at some intermediate window area. For this

value of Aj and these conditions, Ir will equal Ij, so no lighting will be

needed. At this point K3 and K4 cancel each other. For any greater values

of Ac, the heat gain is given by eq. ( 12 ), since no more decrease in lighting

power can occur.

Ql

= AcOCi + K2 ) + K5 (12)

The signs of the conduction terms, Kj , and K5 , are dependent upon whether

interior temperature is warmer or colder than exterior. Since K3 is positive,

K l + K2 > K x + K2 - K3 ( 13)

Considering eqs. ( 8 , 12, 13) it is apparent that the slope of Ql must always

increase following an inflection. Several possibilities for the Ql vs. Aq plot

6
are summarized in figure 2. In 2a, the initial slope is positive, increasing

after inflection. However, the slope of b changes sign at the inflection.

Plot c has an x-intercept (zero Q^) and d starts out negative and continues

decreasing. Other variations are possible, but all would be treated the same way in the analysis. The optimum value for Aq is dependent upon the mode; that

is, whether the aim is to maximize, minimize or set to zero the heat gain Ql.

In all cases, the proper value of Aq is one of the following:

Aq = zero glass area

Ap = area at inflection

Ax = area at x-intercept

Ap = maximum window area.

This is due to the nature of the relationship between Ql and Aq. As shown in

figure 2, Ql is given by two linear functions, one before the inflection point

and another after. The values of Ql that are of interest are those within the

range of admissible window areas which are maximums (Qmax)» minimums (

Q

mj n ) , or closest to zero (Qo) depending on the mode. By inspection, the max and min

points must always occur at Aq, Ap or Ap. When Ql equals zero for an admissible window area, an exact solution is found. If no acceptable x-intercept is

found, the value of Ql closest to zero will again occur either at Aq, Ap or Ap.

Analysis of various combinations of the K constants enables the proper value

for Aq to be selected for Qmax , Qmin or Qq» For example, if QL

is less than

zero when window area Aq equals zero, and the initial slope (Kp + K2 - K3 ) is

negative, an x-intercept can only occur if there is a change in slope sign. If

that is the case, Q L will be at a minimum at the point of inflection (change

of slope). If the initial slope (Kp + K2 - K3 ) is positive, Qmin will occur

at Aq since all other areas would result in larger Ql, and Qmax will occur at

Ap. However, if there is no change in slope sign and the initial value of Ql

is negative, Ql will be maximum and closest to zero at Aq, and minimum at Ap.

Conversely, again with no change in slope sign, if the initial value of Ql is

negative and the initial slope is positive, Ql will be minimum at Aq, and maximum at Ap. If an x-intercept occurs, that value of Aq would result in Ql equal

to zero. If no x-intercept is possible, the value of Ql closest to zero would

occur at Ap. In a similar manner, the optimum value for Aq can be determined

for each case.

An x-intercept will occur when Ql =0, so from eqs. ( 8 ) and (12), the window

area for this case would be given by:

K4 + K5 AXa = v — for Ax < Ap (14a)

K

3 - K1 - k2

or

Axb = for Ax > Al (14b)

i\| t ^2

Eq. (14a) is the x-intercept of eq. ( 8 ), while eq. (14b) is the x-intercept of

eq. (12). To determine if an x-intercept occurs for either function while in

7
the proper range of window areas, two comparisons must be made. First, a solution to eq. (14a) must also lie between the minimum window area and the area at the point of inflection. This is because if Axa is greater than A^,

eq. (14b) must be used, since eq. (14a) is only valid up to window areas equal

to Aj. Similarly, from eq. (14b), A^ must lie between Aj and the total window area, A-p. It is possible that no x-intercept will occur for permissible

window areas, or two x-intercepts can occur if a change in slope sign occurs while is slightly negative. If two acceptable x-intercepts are found, the one with the largest window area is used, since larger window areas are usually

considered desirable from an occupant standpoint. This convention could easily

be reversed or modified to meet occupant needs.

In all cases, it is necessary to determine if a change in slope sign occurs for

Ql, since that presents a special case. Comparing eqs. ( 8 ) and (13), it is seen that a change in slope sign will occur if:

K x + K2 > 0 and K3 > Kj + K2 (15)

When this is the case, the inflection point must be a minimum, since the slope

must increase after inflection, and therefore must be positive after sign

change, and negative before the inflection.

The values of Kq through K5 , along with the values of Ax , Ap, Aq, Ap1 , are seen

to enable determination of the optimum window area for the clear glass and film

cases. The heating or cooling loads are compared for each option to determine

the most desirable option as required by the mode. When that alternative is

determined, the proper control signals can be sent to the lighting system, film

controller, and shutter controller. The control signals consist of an up or down command to tracked reflective film, a position command to the shutters to

set window area, and a level signal to the lighting controller.

In an actual operation, adjustments could be made to the reference inputs to

limit the minimum glass area to some percentage during working hours, or to

provide nightly setback. A complete building control system could include

analysis of heat transfer through other portions of the building envelope, to

enable the lighting and fenestration energy effects to be more closely matched

to the needs of the entire building. A rate-of-change procedure could be

included to enable the control system to anticipate future load demands.

Another alternative would be to base the control strategy on minimizing building energy requirements rather than heating and cooling loads. This could be

accomplished in a similar manner.

4. CONTROL PROGRAM AND SIMULATION

A FORTRAN computer program was developed to simulate the performance of the

control system. The program reads sample input data, such as U, DF, SF, and

Ir, as well as typical values of solar radiation SRy and vertical illumination, and indoor and outdoor air temperature. The program analyzes the input

parameters and determines the best window/lighting alternative. The optimum

configuration (film up or down) and glass area are printed for each case, along

8
with the input data and mode. The program listing and sample output are contained in figures 3 and 4 respectively.

5. CONCLUSION

A digital microprocessor control system for controlling window shading and

lighting is seen to be of value in reducing building heating and cooling loads.

This type of system and methodology could easily be integrated into an overall

building control system, which would enable other building heat transfer

processes to be included in the determination of window option and area. Other window options could be included, such as adjustable louvers or shades.

The options included in this analysis, namely double-pane glass, glass with

reflective film, and fully adjustable insulating shutters, were chosen merely

as examples of typical window management systems.

While the heat transfer processes included in this analysis were treated as linear functions, more complex relations could easily be accommodated, since

nearly any function can be programmed on a digital computer.

Once the components of an actual control system are chosen, the operating and

control programs can easily be stored and executed with a small integrated

circuit microprocessor. The entire system would consist of several radiation

and illumination sensors, connected to the microprocessor through an analogto-digital converter. Desired operating parameters, such as reference temperature and illumination or maximum and minimum allowable window area, could be

entered using a numeric key pad. Such a system would be inexpensive to construct and operate, and should perform reliably. The microprocessor would

direct the operation of an output controller which would send the control

signals to the lighting, shutters and tracked film.

For a control system configured as the one described in this report, analysis

of the response to changes in the values of the input parameters, and the

determination of the optimum un-shuttered window area, is aided through the use of five constants which are determined based on the window system parameters and the measured levels of solar radiation and illumination. When in

operation, the controller would sample the input sensors and adjust the

shutters and/or film position if needed at a cyclic interval as determined by

the building occupants. The system could sample and adjust continuously, or at

five or ten minute intervals to avoid rapid repeated changes which might prove

annoying to occupants.

9
REFERENCES

[1] Pierpoint, P., Intelligent Lighting Control Principles , Civil Engineering

Laboratory, Tech. Note N-1558, 1979.

[2] Crisp, V. H. C., A Preliminary Study of the Use of Automatic Daylight

Control of Artificial Lighting, Lighting Research and Technology, Vol. 9,

1977.

[3] Smith, M. N. , Automatic Lighting Sensing and Control of Lighting Systems

for Energy Conservation, Civil Engineering Laboratory, Tech. Note N-1486,

1977.

[4] Kusuda, T. and Collins, B., Simplified Analysis of Thermal and Lighting

Characteristics of Windows , NBS BSS 109, 19/8.

[5] Selkowitz, S. E., Thermal Performance of Insulating Window Systems , ASHRAE

Transactions, Vol. J15, Part 2, 1980.

[6] Chang, Y. and Shih, J., Microprocessor Applications and Building Control

Systems to Achieve Energy Conservation , NBSIR 80-2065, July 1980.

[7] Lynes, J. A., Principles of Natural Lighting , Applied Science Publishers

Ltd., London 1968.

[8] Treado, S. and Kusuda, T. , Solar Radiation and Illumination , NBS Technical

Note 1148, November 1981.

10
Solar radiation

Illumination

MICROPROCESSOR CONTROLLER

Control

Film roller motor

Double pane

glass

Shutters

open

closed

Shutter adjustment motor

Elevation

not to scale

Cross section

Figure 1. Schematic of typical control systems
q

l

heat

gain

K4

+

K5

for c

+

Figure 2. Heat gain Ql as a function of glass area Aq

12
Outdoor

Temp. (°F)

Indoor

Temp. ( °F)

Vertical

Ilium, (lux)

Vertical

Irrad. (wm~2)

Area

Ratio QP'P** Mode*

TO TI IV SRV AR

35.00 70.00 1.00 1.00 0.00 1.00 2.00

35.00 7.00 5000.00 100.00 0.00 2.00 2.00

35.00 70.00 20000.00 500.00 1.00 1.00 2.00

35.00 70.00 50000.00 1000.00 1.00 1.00 2.00

55.00 70.00 5000.00 100.00 0.00 1.00 2.00

55.00 75.00 5000.00 100.00 0.00 1.00 1.00

55.00 75.00 20000.00 500.00 .40 2.00 1.00

55.00 75.00 50000.00 1000.00 0.00 1.00 1.00

75.00 76.00 5000.00 100.00 0.00 1.00 1.00

75.00 76.00 20000.00 500.00 0.4 2.00 1.00

75.00 76.00 30000.00 250.00 0.00 1.00 1.00

95.00 75.00 20000.00 500.00 0.00 1.00 1.00

95.00 80.00 20000.00 500.00 1.00 2.00 3.00

95.00 80.00 50000.00 1000.0 0.00 1 .00 3.00

95.00 80.00 1.00 1.00 1.00 2.00 3.00

75.00 76.00 1.00 1.00 0.00 1.00 1.00

65.00 75.00 20000.00 200.00 0.00 1.00 1.00

65.00 80.00 20000.00 200.00 1.00 2.00 3.00

65.00 75.00 5000.00 100.00 0.00 1.00 1.00

65.00 75.00 50000.00 1000.00 0.00 1.00 1.00

50.00 75.00 20000.00 200.00 1.00 1.00 1.00

50.00 75.00 20000.00 400.00 1.00 2.00 1.00

50.00 75.00 20000.00 600.00 .08 2.00 1.00

50.00 75.00 20000.00 500.00 .40 2.00 1.00

50.00 75.00 30000.00 500.00 .40 2.00 1.00

60.00 75.00 10000.00 120.00 0.00 1.00 1.00

60.00 75.00 20000.00 240.00 0.00 1.00 1.00

60.00 75.00 30000.00 360.00 1.00 1.00 1.00

60.00 75.00 25000.00 300 .00 1.00 1.00 1.00

60.00 75.00 22500.00 270.00 1.00 1.00 1.00

60.00 75.00 21000.00 220.00 0.00 1.00 1.00

* MODE: 1 STABLE

2 HEATING

3 COOLING

** OPTION: 1 CLEAR GLASS

2 SOLAR FILM

Figure 3. Sample output from controller simulation program

13
NBS-114A (REV. 2-80

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 83-2728

2. Performing Organ. Report No. 3. Publication Date

July 1983

4.

TITLE AND SUBTITLE

AUTOMATED CONTROL OF LIGHTING AND FENESTRATION

5.

AUTHOR(S)

S. J. Treado

6.

PERFORMING ORGANIZATION (If joint or other than N BS, see instructions) 7 . Contract/Grant No. national bureau of standards

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

Dept of Defense Tri Services:

Naval Facilities Engrg. Command, U.S. Navy, Washington, DC 20390

Directorate of Civil Engrg., U.S. Air Force, Washington, DC 20330

Office of Chief of Engineers, U.S. Army, Washington, DC 20314

10. SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a si gnificant

bi bl iography or literature survey, mention it here)

This paper describes an automatic system for controlling the lighting and window

shading in a commercial building. The system utilizes a microcomputer to monitor

solar radiation and illumination levels and interior and exterior air temperatures,

processing the input parameters to determine the optimum lighting level, window

area, and solar film position to minimize building heating and cooling loads due

to windows and lighting. The control methodology and logical flow are presented,

along with a sample control program written in FORTRAN. The response of the

system to various combinations of weather conditions is examined.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) automatic control; daylighting; lighting control; microprocessor; window

management

13. AVAILABILITY 14. NO. OF

PRINTED PAGES

Uni imited

| | For Official Distribution. Do Not Release to NTIS

| | Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

18

15. Price

$7.00

[_X] Order From National Technical Information Service (NTIS), Springfield, VA. 22161

U S COMM- DC 6043-P 80