Researchers from Brunel University London, UK, and Ho Technical University, Ghana, found that painting a roof with ‘cool paint’ – which is designed to reflect the sun’s rays – can reduce the temperature of a room by almost five degrees Celsius, reducing the requirement for energy-hungry air-conditioning.

It’s hoped the paper, Cool Roofs: High tech, low cost solution for energy efficiency and thermal comfort in low rise, low income houses in high solar radiation countries, Cool Roofs: High tech, low cost solution for energy efficiency and thermal comfort in low rise, low income houses in high solar radiation countries, published in the journal Energy & Buildings, could provide a framework for Ghanaians to reduce their energy demands in the face of high bills.

“Poorly insulated buildings combined with high solar radiation levels and high ambient temperatures can create uncomfortable internal conditions,” said Prof Maria Kolokotroni, theme leader for Resource Efficient Future Cities at Brunel’s Institute of Energy Futures.

“These can impact quality of life – particularly for the young and the old, who have a reduced thermal comfort threshold limit, compared to healthy adults.

“When house owners can afford it, they install add-on air conditioning systems, which results in higher electricity bills and contributes to increased electricity demand and possible power cuts.”

To test how effectively cool roofs reduced internal room temperatures, the researchers coated a single-storey, semi-detached home in Portmore, Jamaica, with highly reflective paint.

Measurements were then taken over a period of months in the living room, kitchen and two bedrooms to determine how effectively the cool roof lowered internal temperatures.

The researchers, who were funded by the EPSRC Global Challenges Research Fund, showed that the internal ceiling temperature was reduced in the living room by up to 18 degrees Celsius, whilst the air temperature was up to 4.5 degrees cooler. Computational studies for Ghana and north Brazil showed similar improvements.

This translates to a significant reduction in energy loads in properties with air conditioning, reducing owners’ electricity bills and carbon footprint.

“Cool roofs reflect solar radiation, resulting in a lower external roof temperature – so there is less heat transferred to the inside of the building,” said Prof Kolokotroni.

“By lowering the temperature of property, you reduce the requirement for artificial cooling. This could help people lower their bills and use less electricity.”