# High-Rise Social Housing in Hot-Humid Climates: Towards an 'Airhouse' Standard for Comfort
## 3 Results
### Physical Model Experiments  
The idea of permeable buildings is common in traditional vernacular Malay houses, which have been used for hundreds of years, achieving thermal comfort in the tropical environment [4]. However, these are mainly individual dwellings made out of timber, with all the building elements exposed to the exterior, which is a very different configuration than in the case of high-rise housing. Inspired by the strategies present in vernacular architecture, a predominantly natural/hybrid ventilation system located in the ceiling compartment was considered, which allows a deeper penetration of air within the flats. The use of dynamic insulation (DI) was identified to have potential in solving the four issues mentioned above, as it allows a constant air stream to be delivered through an insulation matrix above an air-permeable ceiling. DI makes use of a fan to suck the fresh air into the room through the porous insulation, which also filters particles, heat, and moisture [22]. Having hybrid ventilation and a filter membrane in its system, the four indoor comfort issues highlighted could possibly be solved using this strategy. DI also has the additional advantage of providing a large volumetric filter membrane that can filter air pollution [22] and at the same time filter heat and moisture [23; 24]. Two tests, using a physical model, have been carried out to evaluate the new proposed DI system, called the 'dynamic hybrid air-permeable ceiling' (DHAPC) (Figure 12). The ceiling was identified as the most suitable element to integrate the system in the already-built high-rise buildings due to the availability of surface and enough floor to ceiling height to integrate the system. The basic concept of the system is the supply of hot and polluted air into the room through the ceiling compartment of the housing units. The air is sucked into the ceiling compartment by a supply fan, filtered by a membrane, and dispersed equally throughout the depressurized indoor spaces before the air is taken out to the depressurized lightwell using an extraction fan (Figure 12). From the fieldwork, we have found that the naturally ventilated lightwells create a short circuit of airflow,  
Figure 12: Dynamic hybrid air-permeable ceiling (DHAPC) schematic design in a high-rise building (not to scale). which contributes to high moisture at lower levels [21]. The large ceiling surface contributes to a better air distribution and a reduction of clogging problems of the filter membrane. DI has so far been implemented mainly in advanced applications using directional airflow, for example in healthcare and electronic facilities, known as 'cleanrooms' [25]. We have considered its potential application in high-rise social housing buildings in Kuala Lumpur. A reduced-scale model of the actual master bedroom in PPR second generation housing was built on a 1:5 scale. The model had three compartments, reproducing the different environments and elements, namely, the outdoor chamber, the DHAPC, and the indoor space (Figure 13). The outdoor chamber compartment tried to reproduce the average outdoor thermal and air quality in Kuala Lumpur during daytime and night-time in the dry season. The condition ranges used were based on the first and second fieldwork studies done by the authors, as described above. The overall form of the test model was a straight duct, equipped with a high-efficiency particulate air (HEPA) filter in the DHAPC compartment, as recommended by ASHRAE 52.2 and EN779. Instruments to measure indoor comfort were placed in the outdoor compartment and indoor space compartment during the test. Two tests of the DHAPC system were carried out using this model, reproducing different types of ventilation, namely, fully passive ventilation, hybrid ventilation, and fully mechanical ventilation. Using three different synthetic insulation materials, test 1 achieved better reduction rates for all four parameters (air temperature, humidity, PM10, and PM2.5) when passive ventilation was applied.