This community based study utilised a randomised cluster design to determine whether insulating existing houses increased indoor temperatures and improved occupants’ health and wellbeing. The 1,350 households comprising 4,407 participants were based in seven low income communities in New Zealand. Whilst the energy consumption of insulated houses was 81% that of uninsulated homes, the relative humidity was lower (–2.3%) in those with insulation. Bedroom temperatures were warmer in insulated houses (0.5°C), with 1.7 fewer hours of temperatures below 10°C each day. There were also reduced odds of the following self reported measures in insulated homes: fair or poor health (OR 0.50; 95% CI 0.38-0.68); wheezing in the past three months (OR 0.57; 0.47-0.70); children absent from school (OR 0.49; 0.31-0.80); adults absent from work (OR 0.62; 0.46- 0.83). The occupants of insulated houses also reported less frequent GP visits (OR 0.73; 0.62-0.87) and fewer hospital admissions for respiratory conditions (OR 0.53; 0.22 to 1.29), although the latter was not statistically significant (p = 0.16).
