RE: https://flipboard.com/@euronews/europe-news-vn516gnfz/-/a-HbO0G_D4QQGdBKeek2r9mg%3Aa%3A89340020-%2F0

"Waste heat is the excess warmth given off by everyday processes, such as a supermarket running its refrigerators. Instead of letting this escape into the air, which risks contributing to the urban heat island effect, it can be captured.

This is usually done using heat pumps that “upgrade” the temperature and then pipe the heat into the same building or a nearby district heating network that provides spaces with heating and hot water."