The London Assembly Planning and Regeneration Committee is investigating how overheating is affecting the housing stock and who is most vulnerable to extreme heat is increasing. The 2021 London Plan states that active measures such as AC systems are not recommended due to their significant energy requirements and they expel hot air, contributing to the urban heat island effect. The Centre for British Progress's head of energy, Ed Hezlet, believes that efficient active cooling systems should be encouraged. Developers argue that a modern home with all windows and open doors should stay cooler than the outside temperature.