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2025年9月26日金曜日

Y. Kodama, Shuji Funo, S. Hokoi, N. Yamamoto, T. Uno, T. Takemasa: Surabaya EcoーHouse An Experiment in Passive Design in a Tropical Climate.Part2 Evaluation and Simulation of the Effects on Thermal Performance, Sustaining the Future EnergyーEcologyーArchitecture, Proceedings of the PLEA'99 Conference Brisbane (ed. Steven S Szokolay), September 22ー24 , 1999

Surabaya Eco-house

Experiment on Passive Design in Tropical Climate Part2

Evaluation and Simulation of the Effects of Heat Performance

 

 

1.  The Mode of Monitoring

After the completion of a building, a preparatory monitoring was conducted from July 27 to August 7,1998. On the basis of the results, positions and time of observation were changed, and observation modes were determined.*1

In order to verify the effects of the installed passive cooling system and influence of living styles, operation of a water circulation system was combined with that of openings to determine five modes.  The observation modes and their periods were shown in Table 1 and Fig. 1.

 

 

Table 1 Observation mode

Fig. 1 Observation Period Depending on Modes during Experiment

 

Under the observation mode I, openings remained open all day long with the water circulation system operation.  Under the mode II, openings remained closed with the water circulation system operation.  Under the mode IIIA, openings were open in the daytime with the water circulation system operation.  Under mode the IIIB, openings was open with the water circulation system suspended (similar condition to a general lifestyle in Indonesia).  Under the mode IV, ventilation was on at night with ventilation and a water circulation system operation in the daytime.  This is the mode under which the passive cooling system was expected to operate most efficiently when the experimental building was designed.  Pomp for water circulation was powered by solar cell in the daytime as long as solar radiation was available.

 

2. Effects of passive cooling

The latest experiment was conducted from December 7, 1998 to February 13, 1999, later than the initial schedule due partly to a lag in preparation of materials.  Following are the results of the observation.

1) Thermal insulation of roof a Shown below is the temperature of roof surface subject to solar radiation and temperatures of respective parts of a roof.  The temperature of the roof tile surface rose to 53 degrees Celsius in the daytime, whereas the temperature inside did not go up greatly, displaying significant effects of the ventilation layer and heat insulation materials. The thermal resistance value of coconut fibers is estimated at 0.06 Kcal/mh, testifying to high heat insulation performance (Fig. 2).

 

 

Fig.2 Effects of Heat Insulation(Observation on December 7 and 8 under more II)

 

Fig. 3 shows the temperature of insulation simulated depending on conductance as a variable in comparison with the actual data measured from 0.00am 4th Aug0.00am 6th Aug 1998.  We can also estimate the heat conductance of coconut fiber as 0.06kcal/hC and the heat capacity is estimated at 20kcal/m3 . These are competitive to those of Glass wool that is usually used

 

 

Fig. 3 Temperature of Insulation Simulated Depending on Conductance as a Variable

 

b. The Velocity of the Air

     We can also estimate the velocity of the air within the double roofing. It is estimated at 0.3m/s (4th Aug) and 0.25m/s (5th Aug). Fig.4 shows the data calculate in case of 0.35m/s for 4th Aug and 0.22m/s for 5th Aug.

 

 

2)         Effects of water circulation system (by measurement)

Effects of a water circulation system under the mode I are studied on the basis of the results of the observation on January 15 and 16, 1999.  As shown in Fig. 4, room temperature charts the course almost similar to that of ambient temperature because an opening remains open.  The temperature of floor surface displays milder changes, compared with room temperature, helping cool room temperature.  This attests to cooling effects resulting from heat capacity of concrete slab.  Such effects are expected to become greater if combined with the water circulation system and nighttime ventilation.

 

 

Fig. 4 Temperature Fluctuation of 3rd-Floor Room Facing Northeast

Observation on January 15 and 16 under mode I

 

3)         Cooling effects of nighttime ventilation (by simulation)

Shown in Fig. 5 are the results of a simulation study on effects of cooling concrete floor by massive ventilation at night when the temperature falls.  Used for simulation were typical climatic conditions in Surabaya (8°south latitude, 112°of east longitude) in December.  The Figure shows changes in room and floor surface temperatures when ventilation is carried out three times in the daytime (6:00 to 19:00) and 30 times at night.  For comparison, changes are also displayed when ventilation is conducted three times a day (with no nighttime ventilation).  Room temperature in the day under the former case is two degrees lower than the latter case.  Cooling effects from floor surface are also expected.

 

 

 

Fig. 5 Cooling Effects from Nighttime Ventilation (by simulation)

 

4)         Cooling effects from water circulation (study by simulation)

Fig. 6 shows the results of a simulation study on the cases where the temperatures of water to be circulated are 28 and 26 degrees.  Pumps are operated when solar radiation is available.  The lower water temperature, the greater cooling effects.  Nevertheless, it is confirmed that 28-degree water produces sufficient cooling effects. 

5)         Effects of combined use of water circulation system and nighttime ventilation (by simulation)

Fig. 7 shows the results of a simulation study on combined use of nighttime ventilation and a water circulation system.  Under the same climatic conditions as the case 3), water of 26 degrees is circulated.  Floor surface temperature is even lower than the cases

3) and 4), where nighttime ventilation and a water circulation system is used respectively.  Room temperature changes in the lowest range thanks to effects from lower floor surface temperature.

 

 

 

Fig. 6 Effects of Water Circulation System (by simulation)

 

 

 

 

 

Fig. 7 Effects of Combined Use of Water Circulation System and Nighttime Ventilation (by simulation)

 

 

3. Effect of Ventilation in Common Space

     We use 'Stream' as a simulation software. The hypothetical condition: East wind 1.5m/s

a.      In case of All the windows (openings) open

Fig. 8 shows the section in the center.  Fig. 9 shows the plan 0.4m above the level of 2nd floor. The velocity of the wind in the 2nd floor is estimated at 0.5m/s. The velocity of the wind in the 3rd floor is estimated at 1.8m/s

 

 

 

  b. In case of East windows closed

     Fig. 10 shows the section in the center

     Fig. 11 shows the plan 0.4m above the level of 2nd floor

   The wind flows toward the north and south balcony at the 2nd floor.  The wind flows toward the high-side roof and 2nd floor vertically through the void of the floor at the 3rd floor. The velocity is estimated at1.2m/s.

 

 

4. The Heat Transfer in case of heat generation from the human body

     We use also 'Stream' as a simulation soft The Heat Generation 50kcal/hpersonx4person on the 2nd floor

  a. In case of No Wind (Fig. 12)

The vertical flow of the air is generated at the velocity 0.7m/s The air flows outside through the void of the floor and high-side. The room temperature is estimated at 28C

  b. In case of East wind 0.3m/s (Fig. 13),

     Almost all the heat is let out through west window. A few of it flows to 3rd floor through the void of floor.  The heat is discharged vertically in case of no wind through the void. The heat is discharged in case of east wind through the windows.

 

 

Footnote

*1 Major change is that we decided to measure temperature of the circulating water that was not collected during preparatory monitoring.








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