What makes a house so hot?
“Boy, it’s hot! It must be 98 degrees outside, and I swear it’s hotter inside than outside.”
Many of us remember visiting our grandparents, or growing up on one of the Out Islands 40 or 50 years ago, sitting at the table and listening to the mid-day news, when we were glad to be on the inside, out of the blistering sun. It was cool and refreshing inside, even without the technology of air conditioning. Conversation would be about family and dreams, rather than about the sweat and discomfort.
Today, many of us dread the coming of summer, sweating as we sit at lunch, or as we try to sleep at night in houses that are unbelievably hot and uncomfortable.
What makes our houses so hot today?
With the many advances in technology and design, changes in the approach to design – especially in the design of the house – have led to changes in the way in which buildings perform. Two hundred, or even 100 years ago, the limitations of technology forced designers to study the forces of nature, to use the cooling breezes and the protective features of the building to create comfort conditions. Whether farmer or fisherman, the builders of traditional Bahamian houses were used to working with the forces of nature, and creating a “cool” house came naturally to them. But those days are gone.
Gone is the ‘natural’ layout of openings to receive a south-east breeze and allow it to flow through the building, to exit at the leeward side, taking with it any build-up of hot, toxic or stale air, while cooling the bodies inside. Floor plans today rely on air-conditioning to cool and refresh the interior, and even when there is no air-conditioning, designers no longer tend to apply “cross-ventilation” principles. In any case, during the design process, their clients are more concerned about style than natural comfort. The breezes are still there, but are no longer invited in.
Gone is the use of those same breezes to cool the floors and ceilings of buildings. Traditional buildings, many with wooden floors, were often raised above the ground, with breezes flowing below, cooling the floor while preventing the build-up of rot-encouraging moisture below. The high-pitched roof of the traditional house was usually ventilated somehow, allowing the breeze to take away the hot air that builds up immediately under the roof. The ceiling below was therefore usually cool. Even open ceilings, vented above head level, were cooler than today’s fancy ‘cathedral’ ceilings, most of which encourage the build-up of heat to hang over the room. Some even use ceiling fans to spread the discomfort.
Gone are the ways of protecting the doors and windows from the hot sun, so that they remain open to receive the breezes. These were the primary uses for the porch and the push-out shutter, two elements of traditional Bahamian architecture seldom seen in so-called modern buildings. Gone with them are the complementary louvers, lattice and trellises that gave character to shading devices.
Gone is the dilly or guinep tree that shaded both the building and the ground nearby, keeping the building cooler and making the family dinner more pleasant.
Gone is the careful selection of materials for the fabric of the house. Advances in technology have made this area more difficult, as material manufacture has become more sophisticated. For example, while it is generally true that a thick wall keeps heat out better than a thin wall, there are thin materials made with special insulation that far out-perform thick materials. There are treatments for glass that stop only the part of the light spectrum that makes sunlight hot. Some materials, like wood, perform differently in different thicknesses. And there are synthetic materials that out-perform their ‘natural’ rivals.
The architect is therefore faced with a three-pronged opportunity to create a cooler and more comfortable house.
First, after the site has been chosen, he must familiarize himself with the direction from which the breezes flow, and orient the building in such a way as to receive those breezes and provide openings that allow for cross-ventilation.
Secondly, he must provide for adequate shading of the openings and the areas near the house. Porches, shutters and the other elements of traditional architecture should be in his toolbox as he formulates the design. He should speak with confidence as he explains to his economy-minded client that to save money up front on these issues is a false economy, as they would eventually pay more expensive dollars for energy to cool the building, even when the conditions outside are not severe. It will always cost less to keep the sun out of the house than to cool an over-heated house.
Finally, the client must select materials that promote a cool interior. Tiled floors are cooler than carpets. Wood floors are cooler in summer and warmer in winter than almost everything else. Exposed glass should either be treated for UV penetration or double-glazed. Lighter colored asphalt shingles reflect more of the heat-producing sunlight than dark-colored asphalt shingles. Styrofoam blocks make a great insulated wall.This approach to the design of the house may or may not show itself in the “look” of the house – that is a matter for the skill of the architect – but working with the climate to provide cross-ventilation, developing an appropriate shading strategy and selecting materials that help protect the house from the onslaught of the sun produces the kind of house some of us would call a dream – a house we can live in.
- Patrick Rahming & Associates is a full service design firm providing architectural, planning and design services throughout The Bahamas and the northern Caribbean. Visit its website at www.pradesigns.com and like its Facebook page. The firm’s mission is to help its clients turn their design problems into completed projects through a process of guided decision-making, responsible environmental advice and expert project administration.