Outcomes are reported from two New Zealand community-based housing interventions designed to improve the energy efficiency of older housing and thereby the occupants’ health. The Housing, Insulation and Health Study showed that insulating 1,350 houses, built before insulation was required, improved the occupants’ health and wellbeing as well as household energy efficiency. The Housing, Heating and Health Study investigated the impact of installing more effective heating in insulated houses for 409 households, where there was a child with doctor-diagnosed asthma. The intervention increased indoor temperatures and halved NO2 levels. Children reported less poor health, lower levels of asthma symptoms and sleep disturbances by wheeze and dry cough. Children also had fewer days off school.