Performance analysis of a schoolroom model for solar applications

SET2009 - 8th International Conference on Sustainable Energy Technologies, .Aachen, Germany.

August 31st to 3rd September 2009

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Performance analysis of a schoolroom model

for solar applications

Iskandar Makhmudov

1, Hyunjoo Han

2, Young Il Jeon

2,

Sang Hoon Lim3, Wongee Chun

1

1Department of Nuclear & Energy Engineering Department, Jeju National

University, Jeju, 690-756, Korea

2Division of Architecture, Dongguk University, Seoul, 100-715, Korea

3New & Renewable Energy Research Division, Korea Institute of Energy

Research, Taejeon, 305-343, Korea

ABSTRACT: The thermal and indoor daylighting behaviour of a schoolroom was

investigated by using a numerical model whose reliability was experimentally

examined. The schoolroom model, constructed using the modern simulation tool,

has a number of south-oriented windows under which black iron plates are installed

to induce thermosyphoning with arrays of upper and lower vents. A hallway is

considered to cause 0.35 air changes per hour for zones by natural ventilation. For

thermal analysis, simulations were carried out using the standard weather

conditions and physical properties of real materials. Perfect thermal insulation was

assumed for the ceiling, floor and walls between adjoining schoolrooms. Results

showed that the simulation model of the present work, although simple, is accurate

enough to predict the building’s thermal performance. Especially, in the early

stages of designing, the results could be effectively applied to assess various

aspects of design parameters in real cases without undue difficulties.

Keywords: Thermal analysis, Simulation, Daylighting, Schoolroom

1. INTRODUCTION

Passive solar heating technologies can

offer a wide range of benefits for buildings

and our deteriorating environment by

reducing energy consumption and carbon

emissions. Considering the geographical

location of Korea, passive solar schemes

could be efficiently (and economically)

applied to public and residential buildings

for space heating and daylighting.

This paper reports the design, simulation

and in-site measurement results of a

prototype schoolroom with some passive

solar features other than large south-facing

windows. The configuration of schoolroom

design, which contains certain distinctive

characteristics in trapping and utilization of

solar energy, was proposed by the Ministry

of Education in Korea (once considered as

the standard passive solar schoolroom). The

configuration adopts the two-zone system

with black iron plates for quick absorption

and release of solar energy. The thermal

performance of the schoolroom during

winter time will be presented in this study.

SET2009 - 8th International Conference on Sustainable Energy Technologies. Aachen, Germany

31st August to 3rd September 2009

of 4

2. MODEL SCHOOLROOM

The configuration of the schoolroom

model (Fig.1) consists of two parts (zones):

a schoolroom with 7.5m (length) x 9m

(width) x 3.3m (height) and hallway with

2.7m x 9m x 3.3m. The schoolroom has

large south facing windows whereas the

hallway locates relatively small windows on

the north side of the wall. The walls, ceiling

and floor of the schoolroom are made of

concrete and heavily insulated.

Figure 1: Schematic view of the

schoolroom model.

The south-facing area of the schoolroom

is comprised of two sections (Fig.2). The

upper half consists of two layers of operable

windows for direct gains, while the lower

half is characterized by a non-operable

glazing followed by a black iron plate for

quick absorption and emission of solar

energy. The black iron plate is covered with

3mm single glass layer for protection from

environment impacts. As the sun’s rays pass

through the outer glazing and hit the surface

of black plate, this immediately raises its

temperature and in turn heats the air trapped

within glazing and the iron plate.

Figure 2: Schematic view of the

schoolroom south-facing area.

Thermosyphoning could be induced by

opening the upper and lower vents which

allows continuous flow of hot air into the

schoolroom during heating periods. In

summer, overhang prevents the indoor

temperature from overheating and cross-

ventilation is induced by opening the

windows in the opposite (north) side of the

schoolroom.

Weather conditions were taken from the

weather database [1] of the U.S. Department

of Energy for Seoul, Korea. The interzonal

air flow between the schoolroom and

hallway is assumed to be 0.35 air changes

per hour. This accounts for the occasional

opening of the door during intermissions.

Most of the heat flow between the zones is

through the partition wall that separates the

schoolroom and hallway. Each schoolroom

is occupied with 50 students. Classes are

held from 9 a.m. to 5 p.m.



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3. RESULTS AND DISCUSSION

Thermal analysis was done by

ECOTECT and its results were compared

with previous simulation results of

SUNCODE (Tab. 1). In general, ECOTECT

values [2, 3, 4] fluctuated from 6.0 C to 9.6

C and SUNCODE values showed a range

of 5.9 - 8.2 C. The highest values were

observed at 1 p.m. in both cases.

Table 1: Temperature comparison between

SUNCODE and ECOTECT(C).

___________________________________

Hour ECOTECT SUNCODE Temp. Diff.

___________________________________

00 6.2 6.3 0.1

01 6.2 6.4 0.2

02 6.2 6.3 0.1

03 6.2 6.2 0.0

04 6.2 6.1 0.1

05 6.2 6.1 0.1

06 6.2 6.0 0.2

07 6.3 5.9 0.4

08 6.4 5.9 0.5

09 9.3 6.4 2.9

10 9.4 6.5 2.9

11 9.4 7.2 2.2

12 9.4 8.0 1.4

13 9.6 8.2 1.4

14 9.4 8.0 1.4

15 9.2 8.0 1.2

16 9.2 8.1 1.1

17 9.0 7.8 1.2

18 6.2 7.5 1.3

19 6.1 7.1 1.0

20 6.1 7.0 0.9

21 6.0 6.8 0.8

22 6.0 6.5 0.5

23 6.0 6.3 0.3

___________________________________

Temperatures varied proportionate to the

intensity of solar radiation, which changes

throughout the day. A maximum

temperature difference of 2.9 C was

observed in two cases which deems

relatively reasonable considering the

complexity of the schoolroom model in the

present analysis.

To measure the effect of solar lighting for

the schoolroom, photometric analysis was

also carried out (Tab. 2). Nine photosensors

were placed on the western wall (where a

chalkboard is situated) horizontally and

vertically at a regular interval of 45cm. The

illuminance values shown in Table 2 are

those recorded at 12:30 p.m. under an

overcast sky condition in Seoul (37.5° N and

126.9° E). Simulations were also carried out

for daylighting using RADIANCE whose

accuracy has long been established by many

previous studies.

Table 2: Illuminance value compared at

different locations between the measured

and simulation (lux).

__________________________________

Sensor Simulation Measured

__________________________________

1 421.6 421

2 470.9 414

3 468.0 434

4 323.5 343

5 350.0 350

6 360.3 359

7 254.6 254

8 274.1 265

9 271.8 271

_________________________________

From this table, we could see two agrees

quite well despite measurement

uncertainties and other unknown factors that

could have influenced otherwise.

5. CONCLUSION

In the present study, the typical passive

schoolroom model was investigated for its

indoor thermal and daylighting performance

using different computational tools. For

thermal analysis, ECOTECT was brought in

whose results were compared with those of

SUNCODE. Meanwhile, its indoor

daylighting performance was examined



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using RADIANCE and then compared with

some measured values. It is felt that the

procedures taken for thermal and lighting

analyses in the present study could be

further extended for other types of solar

buildings (systems) to elicit the most

feasible design in reality for maximum

efficiency in utilizing the sun’s energy.

ACKNOWLEDGEMENT

This work was supported by the grant

(No. 2009-0075776) from the Korea Science

& Engineering Foundation.

REFERENCES

[1]Weather database of the U.S. Department

of Energy: http://apps1.eere.energy.gov/

[2] S.H. Lim, N.H. Lee, and B.K. Lim, 1991.

A performance study on Direct Gain

Passive Solar School Buildings. Journal

of Solar Energy Society of Korea, Vol.

11. No. 3. pp.37-43. Korea.

[3]Norbert Lechner, 2000. Heating, Cooling,

Lighting: Design Methods for Architects

(2nd edition).

[4] H. Han, A comparative study on the

thermal performance of passive solar

schoolroom, MS Thesis, Chungnam Nat’l

University, Korea, 1991.

[5] G. Makaka, E.L.Meyer, M. McPherson,

2008. Thermal behaviour and ventilation

efficiency of a low-cost passive solar

energy efficient house. Renewable

Energy, Vol. 33. Issue 9. pp. 1959-1973.

[6] D.B. Crawley, J.W. Hand, M. Kummert,

B.T. Griffith, 2008. Contrasting the

capabilities of building energy

performance simulation programs.

Building and Environment, Volume 43.

Issue 4. pp. 661-673.

[7] C. Reinhart, A. Fitz, 2006. Findings from

a survey on the current use of daylight

simulations in building design. Energy

and Buildings. Volume 38. Issue 7. pp.

824-835.

Performance analysis of a schoolroom model for solar applications

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