Looking to keep your building cool without blowing your energy budget on air conditioning? There are many systems and simple techniques which can help…

Passive cooling

This is a non-mechanical way of cooling homes by controlling the heat entering and leaving the building, reducing the reliance on electrically powered fans and air conditioning. There are two main methods: preventative and modulation.

Preventative techniques can protect the building against heat, by taking into account the local environment and exposure to sun and wind. Shade windows from the sun by planting trees outside, fitting reflective film on windows or installing awnings. Consider the building’s orientation and manage the interior to reduce overheating, while promoting ventilation and airflow through multi-storey buildings.

Other considerations include using energy-efficient lighting and electronic equipment which emit less heat.

Modulation, or heat dissipation, allows a building to store heat and then release it into the environment using natural ventilation. Night ventilation involves keeping the building closed during daylight hours before being opened at night when the air is cooler.

Other techniques include cooling air by using an internal water feature such as a pool or fountain. Some buildings even pump up ground water to be used in climate-control systems, this is a hybrid cooling system as it does involve mechanical pumps.

Earth coupling involves using the soil to absorb heat from the building through conduction. This can be by direct contact via a wall buffer or by buried tubes which carry the heat from the building to the soil.

Here are some passive cooling techniques to use at home…

Create a breeze

If there’s a slight breeze outside, open a window on the side facing the wind and then another on the opposite side of your home. For the best results, use a smaller window facing the breeze as this will increase the airspeed through the house. You can then open and close doors to force air through rooms which you want to cool. If there isn’t much wind, you can place an electric fan under the open window to help push a breeze through your home. This method works best on single-storey buildings.

Thermal chimney

To cool a building with multiple floors, open the lowest windows on the coolest side of the house. Then open the highest windows in the house on the opposite side. In theory, the hot air will rise and exit the building from the top windows, creating a vacuum pulling cool air from downstairs. The cooler air should absorb warmth as it flows through the building, thus continuing the thermal cycle.

Close curtains

Research has shown that up to 30 percent of unwanted heat comes from your windows, so closing your curtains can save you up to 7 percent on heating bills and lower indoor temperatures. This stops your home from becoming a greenhouse, especially if you have south-facing windows.

For better results, heavy curtains with white plastic backings to reflect the heat can reduce a home’s heat gain by up to 33 percent.

Change your bulbs

Traditional incandescent bulbs waste around 90 percent of their energy in heat, so using energy-efficient CFL bulbs will cool your home while lowering your electricity bill.

The main advantage of employing passive cooling methods is lower energy usage and costs. Every year, air conditioning across the globe accounts for more than double the total energy consumption of the African continent. Therefore, air conditioning is a major contributor to global warming, both through fossil fuels and the greenhouse gases emitted from refrigerants. Passive cooling is the sustainable solution…


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