Cooling tricks could cut AC bills in UAE villas by 40%

Researchers found a significant reduction in electricity consumption when they tried out changes

Villas built with large window panes will require more cooling and be less energy efficient. Pawan Singh / The National

Incorporating shading, improving ventilation and taking other actions to reduce the warming effect of the UAE’s hot climate can cut air conditioning demand in buildings by 40 per cent or more, a new study has found.

The research highlights the importance of passive cooling measures, which can keep temperatures down without using electricity.

Air conditioning accounts for as much as 70 per cent of the UAE’s electricity consumption, so reductions in usage could have a significant effect on the country’s power demand and carbon emissions.

The new study looked at the energy consumption of a two-storey villa with three bedrooms, plus living areas, with space for eight people.

Cooling designs

“By adding some passive design strategies like thermal insulation material (including green roofing), shading devices, and ventilation, we could minimise the demand for energy load cooling,” researchers from the University of Sharjah wrote in the study.

“[The UAE] should always consider passive cooling design in all residential, commercial and industrial buildings as a developing country.”

A green roof is one covered with vegetation to reduce heat in urban areas.

The General Services Administration, a US government agency, says green roofing can cut the amount of heat transferred to a building from the roof by up to 72 per cent.

Shading devices, meanwhile, refer to physical shades - either horizontal or vertical - that are attached to a building or put near to it to block out the sun.

The new study, Applying Passive Cooling Strategies to Improve Energy Consumption of Governmental Housing in the UAE, was presented at a conference in Iraq and published online by the American Institute of Physics Publishing last month.

In a separate study released in Cleaner Energy Systems last year, scientists in Qatar and Canada wrote that the growth in energy demand in buildings because of “excessive use of air conditioning” was an “alarming concern in hot and humid climates”.

Analysts have previously said that the low price of electricity in the UAE means that relying on air conditioning is often the default approach when buildings are designed.

The villa at the centre of the new study was chosen as an example of the type of housing provided by the UAE government, although the outcomes apply equally to private sector properties.

Without passive cooling features, the building’s energy demand was estimated to be about 8,000 kilowatt hours in January and 11,000 kilowatt hours in August, when energy demand increased due to higher temperatures.

Using computer modelling techniques that have been shown to give similar results to real-world studies, the researchers looked at what effect adding insulation to the walls, windows and roof could have.

They found a marked reduction in the electricity demand, with a fall to 4,200 kilowatt hours in January and 8,300 kilowatt hours in August. This represents a reduction in electricity consumption of 47.5 per cent in January and about 25 per cent in August.

Simple solutions

While its effects were smaller, shading also resulted in a fall in electricity consumption, to 7,000 kilowatt hours in January and 11,000 kilowatt hours in August.

A traditional way to achieve passive cooling in the UAE has been to incorporate a wind tower into a building, as this promotes airflow. Researchers found that adding one to their villa cut electricity use to 6,000 kilowatt hours and 8,000 kilowatt hours in January and August.

Ensuring that the building and its openings, such as windows, were orientated also helped to reduce heating cut demand.

If all measures were used together, consumption was 4,000 kilowatt hours in January – about half what it was with no passive cooling features – and 7,000 kilowatt hours in August, a reduction of about 42 per cent compared to the original villa.

“Overall, there is a possibility of reducing the cooling load by more than 40 per cent after applying these passive cooling strategies and saving up to 10 metric tonnes [of carbon dioxide] per year, which helps reduce global warming,” the researchers wrote.

Prof Emad Mushtaha, who chairs the Architectural Engineering Department at the University of Sharjah, said all the measures outlined in the study could be incorporated into buildings in the UAE, either at the design stage or after construction.

“All the proposed strategies are doable and can be implemented in the new design and retrofitted,” he said.

He said that while passive cooling measures could reduce the demand for air conditioning, they do not eliminate the need for it.

“The issue here is that in the UAE, passive design can only reduce a certain amount of energy consumption, but cannot achieve thermal comfort alone due to extreme temperatures. So the active system is important to achieve thermal comfort,” he said.

Globally, the number of air conditioning units is expected to triple by 2050, according to World Bank figures, as countries develop and demand increases amid rising average temperatures.

Over time, air conditioning units are likely to become more efficient, so the expected tripling in the number of installations is expected to result in a doubling of electricity consumption for air conditioning by the middle of the century.

The UAE is heavily involved in efforts to reduce electricity consumption by air conditioning units. In 2022, Strata, the aerospace unit of Mubadala, Abu Dhabi’s sovereign investor, signed a partnership with an AI company and an industrial 3D printing firm to develop an air conditioner 10 times as efficient as current models.