Cold com­fort


Earth-friendly ways to keep your house cool (and the best air-con if you ab­so­lutely must)

The South African plat­te­land isn’t a place for sissies in sum­mer, con­sid­er­ing that the mer­cury soars close to 50˚C in places like the Kala­hari. Such tem­per­a­tures can pre­vent you from sleep­ing at night and might even make you feel slightly un­hinged – I once clam­bered into a foun­tain in the Oudt­shoorn CBD, fully clothed. No, it wasn’t the spirit of the arts fes­ti­val that made me lose my in­hi­bi­tions, but the tem­per­a­ture that had risen to 46˚C.

Ev­ery re­gion, from sub­trop­i­cal KwaZulu-Natal to the arid in­te­rior, of­fers its own chal­lenges in the hot months. There are, how­ever, univer­sal prin­ci­ples you can ap­ply to make your house live­able, whether you’re build­ing, mak­ing struc­tural al­ter­ations or buy­ing an ex­ist­ing house. Cape Town ar­chi­tect Eti­enne Britz of Boukuns ex­plains that the com­fort of a house in dif­fer­ent sea­sons de­pends on the de­sign process as a whole, in which a num­ber of as­pects play a role. Un­for­tu­nately, the mere fact that a house faces north doesn’t mean you’ll en­joy liv­ing there in sum­mer. Eti­enne ex­plains that a north­ern ori­en­ta­tion is rather about the fact that the largest open­ings in your house should face north.

“In arid ar­eas such as the Ka­roo there should be a bal­ance be­tween the size and the num­ber of win­dows and doors on the one hand and the ther­mal mass – the thick­ness and mass of the walls or roof – of the struc­ture on the other hand.”

The ci­cadas are screech­ing, the dogs are look­ing as wilted as the gar­den, and at night you lie awake with a damp cloth on your fore­head. Thank­fully, you don’t have to rely on air con­di­tion­ing to keep your house cool – there are al­ter­na­tive ways to make it live­able.

In lay­man’s terms, this would mean that, on warm days, the walls and roof ab­sorb heat that then warms the house at night when the tem­per­a­ture cools down – ar­chi­tects call this the “ther­mal fly­wheel ef­fect”. “This is the most ef­fec­tive way to reg­u­late tem­per­a­ture in a green way. Just think of those won­der­fully cool old farm­houses with their thick stone walls and only a few small win­dows.”

And then there is good old crossven­ti­la­tion (our grand­par­tents called it a “draught”), which makes the heat more bear­able in sub­trop­i­cal ar­eas such as KwaZulu-Natal.

“In arid ar­eas one should be care­ful in the morn­ings of ex­chang­ing the cool air of the night for warmer air from out­side,” Eti­enne says. “Not ev­ery room needs a win­dow on each side; rather, it is im­por­tant for the air to flow through

the whole house and find its way from the front door to the back door.”

Hav­ing larger win­dows or a greater num­ber of them is not a so­lu­tion ei­ther. “Glass is an ex­cep­tion­ally good con­duc­tor of heat – another rea­son why the old farm­houses had so few win­dows.” Shade from out­side re­mains your best friend, and if you’re build­ing from scratch, Eti­enne ex­plains you should re­cess win­dows deep into the walls so that the side­walls cast shad­ows on the glass. A so­lu­tion for an ex­ist­ing house is a screen that pre­vents the sun from shin­ing onto the glass. “A per­gola in front of the north­ern win­dows makes a big dif­fer­ence in sum­mer and will let sun­light through in win­ter as long as the per­gola is the cor­rect depth (1,2m for a win­dow that is 2,3m from ground level).”

Cool con­struc­tion choices

Re­mem­ber the fol­low­ing when you buy or build a house, says Eti­enne:


• The roof ma­te­rial it­self is not as im­por­tant as the colour. White is a good choice, as it re­flects light the best. • In­su­la­tion ma­te­rial inside the roof is es­sen­tial, and it is re­quired by na­tional build­ing reg­u­la­tions. There must be space be­tween the roof tiles and the in­su­la­tion ma­te­rial. A fi­bre blan­ket such as Aero­lite works well, whereas metal foil placed di­rectly on the ceil­ing sim­ply gath­ers dust and will lose its ef­fec­tive­ness after a year.


• Your choice of floor­ing does play a role, but it should not be so light that it re­flects sun­light and thus heats other el­e­ments in the house. Stone, con­crete and tiled floors keep a house cooler than wood or car­pet­ing does.


A stoep helps to keep a house cool pro­vided the heat can es­cape via a high open­ing or semi-solid roof such as a trel­lis. The dark-red paint or slate tiles you see on old farm­house stoeps en­sure the floor doesn’t re­flect heat into the house.


• Trop­i­cal cli­mates Tim­ber-frame houses (a sus­tain­able build­ing method) work well be­cause they breathe, in a man­ner of speak­ing. • Arid re­gions Brick or stone are your best choices, be­cause they’re rel­a­tively af­ford­able and have ther­mal mass, es­pe­cially if you build a cav­ity wall (a “dou­ble wall” that con­sists of two lay­ers of brick or stone sep­a­rated by a 50mm cav­ity). • Eco-con­scious op­tions Use a va­ri­ety of build­ing ma­te­ri­als, such as a stone wall with in­su­la­tion and tim­ber cladding on the inside. This will make it far eas­ier to get by with­out air con­di­tion­ing. • Ad­ven­tur­ously eco-aware Build walls from rammed earth. Soil from the area is com­bined with ce­ment and rammed in lay­ers, more or less as you would cast a con­crete wall. The ther­mal mass of th­ese walls is ideal for arid re­gions. Be­cause they’re made from the very earth they’re stand­ing on, it’s as though the build­ing is grow­ing out of the land­scape.

Plant clev­erly

You won’t find a bet­ter “screen” than a tree, says Cape Town land­scaper Petro Ja­cobs, but con­sider all four sea­sons be­fore you start plant­ing. “It’s not only the size, shape and root sys­tem that are im­por­tant. Trees and shrubs should also be planted in such a way that they con­trib­ute to good nat­u­ral ven­ti­la­tion. They’re of­ten grouped too close to­gether and, over the years, can be­come en­tan­gled, af­fect­ing the flow of air.” • Chill the north­ern side “De­cid­u­ous trees are my favourites [see left], as they let you wit­ness the change of the sea­sons and al­low the sun through in win­ter,” Petro says. >

• Cool down a hot wall Some­times it isn’t the sun that heats a room but a wall that re­flects heat to­wards the house. Petro solves this prob­lem by plant­ing a creep­ing fig ( Fi­cus pumila). The false olive ( Bud­dleja saligna) works well when you want to cre­ate an in­dige­nous hedge against a wall. • Per­gola to the res­cue If you choose to follow Eti­enne’s ad­vice and make use of a per­gola on the north­ern side, Petro sug­gests you plant a de­cid­u­ous creeper such as wis­te­ria, which will let sun­light through in win­ter. “Edi­ble creep­ers like a granadilla are popular, but this is an ever­green plant that won’t let much sun­light through. If you’d like a fra­grant plant, I’d sug­gest star ­jas­mine ( Trach­e­losper­mum jas­mi­noides), which flow­ers in sum­mer. Keep in mind, though, that it may cause hayfever.”

Eti­enne Britz Petro Ja­cobs petroland­scap­

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