Heating with coal, oil and natural gas accounts for around a quarter of global greenhouse gas emissions. But that's something we can change, says Wolfgang Feist, founder of the Passive House Institute in the western German city of Darmstadt.
"Buildings can be powered in a climate-neutral way, and that's possible worldwide with renewable energies," he told DW, adding that a crucial factor is to make buildings more efficient so no energy is wasted.
"With good insulation and ventilation systems, it's possible to achieve energy savings — compared to conventional buildings — of 80-90% in new buildings and 75-80% through energy-efficient renovation in old buildings."
The remaining demand could then be met with a mix of renewable energies. And this combination can vary, depending on the region, says Feist, who is a professor of physics and a pioneer of efficient construction methods.
"I see district heating with renewable energies, and heating with ambient heat and heat pumps as important sources here," he says.
The use of wood or wooden pellets is another way of meeting the heating needs of individual buildings, Feist says, adding however that this is "not a sensible option" for entire cities or industries because it's not sustainable and would create excessive demand for biomass.