(1) themorningstudio – iStock, (2) Marc Beckmann – co2online, (3) michal-rojek – iStock, (4) Marc Beckmann – co2online, (5) Illya_Vinogradov – iStock, (6) Roman Tyshchenko – iStock, (7) artist-unlimited – iStock, (8) Familie Küfner, (9) INIMAGES – Westend61, (10) co2online, (11) Energieagentur Schaumburg