the cooling water load on the aar river is reduced by the district heating system refuna, that provides eleven surrounding municipalities with up to 150 gw·h/y. beside döttingen, the connected municipalities are bad zurzach, klingnau, unterendingen, endingen, böttstein, tegerfelden, and in the bordering baden district, würenlingen and untersiggenthal, and in the other bordering brugg district, rüfenach and villigen. the heat extraction, at a supply temperature from 125 °c in winter down to 80 °c in summer, induces a loss of electric power, but less than 18 gw·h/year at 2 mw average electric power loss. the energy content of the average 142 gw·h/y provided heat, is about the same as of 14,200,000 m of natural gas, averaging more than 5,800 m of natural gas consumption yearly saved for each of the 2,432 connected homes and customers.