Air-con is for those who can afford it. For the rest, February has been a bake fest.
Homes are hot. This is the common refrain from the public.
But it is an unusual heat because sometimes it can be cooler outside.
This is an effect of our sixth La Nina-impacted summer in a row, and even though this is a weak variation, the Atlantic high-pressure cell has moved south of East London bringing days of extreme heat.
So what is this lingering, heavy mugginess in our homes which causes lethargy, moodiness, and brings in blood-sucking, whining Culex Pipiens or the southern house mosquito to wake and irritate people?
This invisible enemy is humidity — the amount of moisture in the air — which was sitting at 95% on Sunday, despite a cooler, stormier southwesterly wind.
Bertie le Roux, an Eskom-trained green electrical engineer who lectured on thermodynamics, said: “Humidity doesn’t let you cool off at the rate which your body requires.
“You are unable to sweat at the required rate.”
Roofs are the normal culprit during a heat wave.
John Carter, of Carter’s Roofing Services, said temperatures of 70°C were being measured in East London roofs making it unbearably hot to work in, especially roofs painted with dark colours such as black, charcoal or green.
Homes without proper insulation under the roof tiles during the February heat would make roof space very hot and the heat would penetrate through the ceilings.
“Decent, thick ceilings can also block out the heat.”
Carter, who’s famous slogan is “It will rain again”, said he was earnestly praying for rain which had been sparse this summer.
“We had a couple of sprinkles. Many of us are praying for rain, the poor cows and animals.
“We have not had our normal December and January rain.”
He urged people to paint their roofs with light colours which kept roofs cooler.
However, he said painting flat roofs with silver meant good heat reflection “but it can be quite blinding on the eye”.
Ironically, while many home owners attack foliage which touches their homes, he said leaves or roof gardens kept a roof cool.
Ironically, while so much time was spent on using industrial steel and cement in roofing, thatch, grown locally, was the coolest, most sustainable roof.
But it did catch fire quickly.
He said the coolest Eastern Cape homes were made from mud and thatch.
This traditional style is being replaced by zinc sheeting and bricks.
Could the heat be getting in through brick walls?
Gerald Berlyn, the owner of Air Conditioning Services for many years, said: “Bricks work on the principle of thermal energy where heat seeks out cold.
“Depending on the angle and intensity of the heat source — the sun or the hot ground, it can take up to four hours or more for sustained heat to penetrate and for that energy to be released inside as heat.
“This is why a closed up house in the Karoo retains its cool, but once the heat is inside, keeping doors and windows closed will keep that heat in, as a reverse process.
“One would have to open doors and windows to release that heat energy.”
Builder, surfer and ocean swimmer Greg Harris said: “If there is moisture in walls or in the floors and it gets hot that moisture becomes humidity and without ventilation the house feels like it’s hotter, so ventilation is important.
“You need air bricks and the right amount of windows to circulate the air.
“If a home floor is incorrectly built with a sub-standard water-proofing membrane, water could travel through the fill and create that humidity feeling.”
It all started with solid roofing and windows built to handle solar radiation.
“However, in these conditions we have to today if you don’t have ventilation, the humidity sits in the home making it uncomfortably hot.”
Estate agent and environmentalist Kevin Harris said local homes were heavily affected in February by excessive “solar insolation” — the amount of solar radiation or energy from the sun which strikes the home.
He said the angle at which sunlight struck homes was crucial.
North-facing homes in the southern hemisphere received lower-angled summer sun which spread the rays over a larger area reducing intensity.
Direct sun on homes concentrated energy on small areas.
Homes with high insolation or direct sunlight suffered from intense solar radiation with roofs absorbing massive heat, up to 80°C for a dark roof.
West facing walls were hot in the afternoons.
*Walls* (especially west-facing) heat up in the afternoon.
Other heating processes at work during high humidity days were conduction — heat flows through hot materials into the interior, radiation — hot surfaces re-radiate infrared heat indoors, and convection* — hot air rises and circulates.
Some suggestions, he said were long eaves, north facing glazing, plenty of cross ventilation and shadings.
Off Track’s survival suggestions are: ice packs on your head or neck, wear a wet shirt and cap, take a cold shower, lie on cool tiles, let fans blow over wet towels, wet small carpets and place them on patios burning in direct sun. Many of these hacks were used when this report was written.
Even the hottest breeze will cause a cooling, air-conditioning effect when the moisture on your wet shirt evaporates. — Daily Dispatch
