FH Salzburg study finds night ventilation can halve cooling demand

A study by Salzburg University of Applied Sciences, reported by ORF, has found that night-time ventilation can reduce the cooling demand of residential buildings by half, although some days above 26 degrees Celsius will remain unavoidable even with effective ventilation and shading.

Daniel Heidenthaler of the university’s Department of Green Engineering studied how buildings without air conditioning could be cooled. The research comes as the number of days above 30 degrees in Salzburg has more than doubled this summer compared with around the turn of the millennium.

The study identifies measures to reduce solar radiation as the first priority. These include roof overhangs, carefully planned window orientations and limiting the size of window areas. External blinds and other passive measures are considered efficient and necessary, but not sufficient on their own.

The researchers also examined active cooling using the ground or groundwater. Heidenthaler said a conventional split air-conditioning unit was less suitable in terms of efficiency and operating costs than systems such as heat pumps with ground heat exchangers or groundwater-based cooling. In those systems, the ground and cool groundwater provide the cooling with very low operating costs, he said.