Retrofitting low-tech Trombe walls into off-grid homes in semi-arid climates could lead to huge reductions in heating and cooling costs, according to new research out of Sweden’s Lund University.

Architectural researcher Marwa Dabaieh said the vented Trombe wall was an old though still popular passive construction technique that required little energy, making it for suitable for off-grid settlements that don’t always have access to electricity.

Dr Dabaieh, who divides her time between Lund University and the British University in Egypt, has adapted a Trombe wall so it can provide both heating and cooling to a building, and has tested the results in Saint Catherine, Egypt.

In a study published in Solar Energy, the adapted Trombe wall reduced heating load by 94 per cent and reduced the cooling load by 73 per cent compared to a base case, with a payback period of just seven months.

The design features grey paint instead of typical black paint in addition to 15cm reversible natural wool insulation and two 3mm-thick roll-up wool curtains.

“The new design uses renewable wind and solar energy to generate cooling and heating in buildings,” Dr Dabaieh said. “The adjustments have also eliminated the original Trombe wall problem with overheating, which in turn has drastically reduced the total energy consumption and carbon emissions.”

The materials used to build the wall are local stone, wood and wool, as well as locally produced glass.

“Locals have been involved in every step of the process, so that they can easily build the Trombe wall themselves or show others how to construct one. Local construction could also help create new opportunities for young and unemployed people,” Dr Dabaieh said.

She said to overcome future environmental challenges, passive systems that didn’t require fossil fuels were needed.

“The vented Trombe wall has a great potential for meeting the steadily increasing energy demands without increasing carbon emissions.”