Too many air conditioners could further heat Vienna, expert warns

Installing large numbers of air conditioners would further heat Vienna, Jan-Philipp Richter, a building physics and building ecology expert at TU Vienna, told ORF.

The Austrian government plans to make it easier to install air conditioning to help people cope with hot homes. But Vienna’s buildings are poorly equipped for current heat peaks of up to 40 degrees Celsius, Richter said in an interview with ORF’s “Wien heute”. Existing building standards are based on historical climate data and passive heat protection. Future guidelines should make greater use of climate forecasts so buildings are designed for expected developments, he said.

Air conditioners cool rooms but release the extracted heat, along with additional waste heat, outdoors. If very large numbers were used across an entire city, they would make the city warmer, Richter said. This is already happening in the Global South. Climate researchers have calculated that Paris could become one to two degrees warmer if very large numbers of air conditioners were installed throughout the city.

Richter recommended prioritising external sun protection, such as blinds or shutters, because it keeps heat from entering buildings in the first place while also saving money and electricity.

Thick walls in older buildings can buffer heat only to a limited extent, he said. Existing buildings can nevertheless be cooled sustainably. Richter advised starting with protection on the outside of the facade, followed by cooling powered by renewable sources, heat pumps or highly efficient air-conditioning units.

There are many possible approaches, but each building would need a specific solution, Richter said. In an ideal case, building components could be combined with a type of geothermal system that could provide both heating and cooling.