When scientist Mohd Peter Davis moved to Malaysia over 20 years ago there was one thing he found hard to take – the sweltering tropical heat. But first he solved the problem for sheep at his university. His faculty had imported Australian sheep and they were doing badly (small one below).
Peter guessed that they were suffering from heat stress and so he looked at their sheds and re-designed them to be naturally cooler.
Taking an experimental approach, he studied and recorded the temperature profiles in the old and new sheds and compared the mortality and growth rates of the sheep. His diagnosis was correct.
He then went on to study the temperature in single storey houses near the university and made astonishing discovery – that the animals in his new shed were more thermally comfortable than the humans in their homes! He plotted out the temperature profile in the typical home and compared with outdoor temperature under shade and this was what he found:
The outdoor temperature (even on the hottest days) is cool at dawn, warms up in the morning, peaks at about 33 degrees, starts to come down in the afternoon, then further cools down in the evening. But the poor occupants of the ‘modern’ house suffer from high temperature all day and all night. Peter’s finding suggests that the vast majority of Malaysians living in brick houses suffer from heat stress and that they would be more thermally comfortable if they all moved outdoors and live under trees!
This absurd situation shows that it is not the country’s climate which is at fault, but rather that the design of its ‘modern’ houses which are defective. Other than installing air-cons, can something be done to improve the Malaysian home? Peter looked at potential solutions:
- Air cons – they work but for the high electricity bills
- Kampong house – these are ambient buildings that track external temperature; they worked well in the cool countryside but not in towns that suffer from the heat-island effect
- Queensland type raised houses with verandas all round – he built one for himself, but the verandas were costly
- Lightweight, highly insulated homes – he built a few experimental homes on campus: they worked to an extent but still needed the air-con for the hottest days of the year.
The main problem with the conventional brick house is in the roof: the space gets heated up from the sun’s radiation, stores the heat then gives it off at night. It’s best to cut this out by placing thick insulation just under the roof tiles to prevent the attic from heating up.
Windows allowing direct sunlight into homes have to be shaded. The walls too have to be shaded: just like the roof space, they get hot from direct sunlight and store that heat too. Using a computer simulation program, Mohd Peter was able to optimize the amount of insulation and shading. It also pointed to an additional improvement: this was to use mechanically ventilation at night. Bringing cool outdoor night air into a house would not only cool down the internal space, but also the brick walls and concrete floors which can store the coolness. During the day, the walls absorb heat and help to keep the rooms cool.
So this is his solution to thermal comfort without air-con:
The conventional Malaysian house is like a hot water bottle, heated up during the day to keep its occupants warm night. Now, this analogy gets turned upside down - the house gets cooled down at night to keep its residents cool all day.
You can download a free copy of his Ebook "Thermal Comfort Housing" if you subscribe to this web site. You can contact Peter at mohd_peter@hotmail.com
