Summary of the Workshop for Eco Project--Mini Research Meeting

Date: 28 October 2004 (Thursday) 18:00-
Place: Meeting Room C, 25th F, Boissonade Tower, Ichigaya Campus, Hosei University, Tokyo

（1）Tropical Environment of Waterside Residences in Thailand (architectural survey)　　　　　　　　　　　　　　　　　　　　　　　　
1. Introduction
Although there are many raised houses in Southeast Asia, the effectiveness of the environmental technology of raised pillar houses for the area's hot and humid weather has not been clarified. The goal of this research is to clarify the relationship between houses built on the riverbank or on the water and the comfort level provided by the wind from the river and temperature changes in the houses on the water, and also the influence of the temperature, humidity, wind, and distance from the river. We also measured and compared air temperature and atmospheric environment of houses along the river, on the water, and those built above land. In addition, we also took environmental measures from various points along and at a distance from the river.

2. Outline of Survey
We conducted our survey in Lopburi, Bangkok, and Nonthaburi from 31 July to 7 August 2004. This is the time of the rainy season in Thailand. Lopburi is a city located on a flat land to the north of Bangkok. In Lopburi, we measured the temperature, humidity, and wind velocity from several points along the river. In Bangkok, we surveyed houses both above the water and on land, and in Nothaburi (to the northeast of Bangkok) we surveyed only houses built above the water. The house above the water in Bangkok is well built with a terrace facing the river, with regular gaps in the floorboards to allow for airflow. and has the gaps on the floor board (Fig. 1). In Nonthaburi, the houses above the water have the special characteristic of terraces sticking out into the river (Fig. 2). From there, the wind was very comfortable.

3. Survey Results
(1) Distance from river and its relation to temperature and humidity
Measurements of temperature and humidity were taken at various distances from the river in Lopburi at 13:00 on 31 July 2004 and at 1:00 on 1 August 2004. At 13:00 at a point level with the river, the humidity measured 68% and the temperature was about 31 degrees Celsius, and at other points the humidity was around 58% and the temperature was between 33 and 34 degrees Celsius. Thus, for the area within about 10 meters from the river, the temperature along the river was two to three degrees lower than more distant points but also had about 10% higher humidity.
(2) Comparison between houses on the water and the ground
By using the SET (Standard New Effective Temperature) index, we compared the comfortableness between the houses on the water and the ground. Table 1 gives the SET values used for comparative calculation, and Figure 3 provides the calculated results. The results listed in Table 1 were measured on 2 August 2004 and 3 August 2004. From this comparison, it is clear that the houses on the water showed a maximum lower SET value of 4.5 degrees Celsius, which were more comfortable than those house built over land. While this survey shows little actual difference in temperature between the houses above water and those built over land, it does show that the velocity of the wind blowing over the river accounted for the difference in comfort levels.
(3) Distribution of wind direction and velocity on the water houses
Figure 4 shows the wind direction and velocity both inside of the water house and its terrace at Nonthaburi at 13:00 on 7 August 2004. The basic method for measuring wind velocity is at a point four meters from the floor with other measures taken at one meter above floor level. While wind velocity is overall quite strong on the terrace, the standard velocity of 1.7 m/s on terraces that stick out into the river was 0.8 m/s for those terraces of only half the standard length.
3. Summary and Further Topic of Research
The affected area of the river temperature and humidity extended to about ten meters on either side of the river with temperatures becoming lower and humidity higher nearer to the river. The houses built above the water cool down from below the floor to make the overall room temperature lower. In case of the tin-roofed houses, the temperature of their rooftops was higher. The wind velocity over terraces along the river became higher and contributed to the feeling of coolness. From the Thai Meteorological Department, we also obtained weather data for Bangkok and other locations. We will continue to examine the particularities of this data in the future.

（2）The Cooling Effect of Rooftop Water Spraying (experiment summary)

1. Research Goal
The factors involved and the way evaporated water sprayed on a roof causes cooling remains unclear. In this research, it is our goal to clarify the relationship between the three factors thought to strongly correlate to the effectiveness of evaporation and cooling; that is, the amount of water sprayed, the roof-top materials, and weather conditions (Figure 1).

2. Research Methods
In this research, we used two comparative models as shown as in picture 1. On one model we sprayed water on the roof (spray model) , and on the other we did not spray water (non-spray model). By comparing the two models, we clarified the effect of spraying the roof top. Table 1 shows the conditions for this experiment. Five patterns of water volume were used (e.g. two, six, ten, twenty and forty kilograms of water per hour). The roof top materials selected were sheet metal and slate. For all the experimental conditions, we tested each set of conditions twice on different days to determine the relationship between weather and the effectiveness of evaporation on cooling. The experiments were conducted between July and September 2004 atop the roof of the research building at Koganei Campus, Hosei University.

3. Experiment Results
* Relationship between the amount of spraying and evaporation
Table 2 shows the relationship between the amount of spraying and evaporation. On the sheet metal rooftop, water evaporated at a greater rate at a volume of 2 kg/hr than at volumes of 6 kg/hr or 10 kg/hr. And, for the slate rooftop, the least evaporation occurred with the spraying of 10 kg/hr.
* Relationship between the rooftop materials and the volume of evaporation
Table 3 shows the rooftop materials and the volume of evaporation. At a volume of 40 kg/hr of sprayed water, more water evaporated from the sheet metal roof than the slate one. On the other hand, when the volume of sprayed water was set at 6 kg/hr, the slate roof top resulted in more evaporation than for the sheet metal rooftop. There was little difference in the amount of evaporation between the sheet metal and slate rooftops for spray volumes of 2, 10, and 20 kg/hr.
* Relationship between weather conditions and cooling efficiency
Table 4 shows the relational factors between the lowest level of heat inflow and weather. The lowest level of heat inflow and the amount of sunlight and outside temperature showed a correlation, but there was no correlation between the lowest level of heat inflow and outside humidity and wind velocity.

（3）Wind Towers in Dry Regions and Humidity Cooling (computer simulation)

1. Research Goal
The purpose of this research is to clarify and verify with a computer simulation the various wind and temperature related environmental techniques used in the traditional architecture of desert regions.

2. Research Areas and Buildings
The area selected is for this research is that broadly defined as arid or desert (a subcategory of the dry climate) within the K_ppen Climate Classification system (Figure 1). The special characteristic of this climate is the large fluctuation in daily air temperature and strong winds. Therefore, the traditional architecture in these regions exhibit any number of adaptations to the climate. This research focuses on the so-called "wind towers," which catch wind and channel down into the a building, by verifying the effects of the following three points:
* Verify the methods used catch wind with wind towers (Pictures 2 and 3)
* Confirm role of wall thickness and changes in temperature both inside and outside of buildings and the cooling of outside air as it enters the building
* Investigate the customary use of water in pools and fountains and effectiveness of cooling with humidification (Figure 4)

3. Research Methods
Because few traditional buildings continue to exist, we used a dissected three-dimensional system to measure a modeled building, the flow of outside air, and the ambient temperature. We also calculated for change over time for a two day period (48 hours) by using meteorological data for the amount of sunlight and outside temperature.

4. Research Results
By conducting a survey of the literature on wind towers, we verified that wind towers are roughly divided into two types according to the prevailing winds. We also confirmed how outside winds are channeled indoors (Pictures 5 and 6). In addition, we verified a small amplification in the indoor temperature when compared to the outdoor temperature (Figure-7).