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 Aug〜0.00am 6th Aug 1998. We can also estimate the heat conductance of
coconut fiber as 0.06kcal/h゜C 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 28゜C
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.
