Making homes healthier

In the only national study of its kind for 20 years, nine out of 10 Kiwis consider their home to be a “healthy” place to live, although many still experience cold, damp, condensation, and mould, and wish their home was warmer.

The BRANZ study is collecting data from over 750 households across New Zealand. This includes a survey of 425 households, with 287 of these being monitored for energy usage and indoor conditions.

Data from the household survey and early data from a smaller group of 125 homes monitored over winter 2023 show that homes – especially bedrooms – are warmer than when BRANZ last conducted this study 20 years ago. However, almost half (48%) of survey respondents said they had mould in their home (11% said it was larger than a sheet of A4 paper) and 33% said their home was damp at least some of the time. Around one in five said they could see their breath inside and a similar amount said their home was cold enough that they shivered at least some of the time in winter.

Homes warmer
While average daytime and evening living room temperatures in the homes studied exceeded the recommended healthy minimum of 18°C, average night-time bedroom temperatures remain too cold, with some significantly below the ideal.

According to BRANZ General Manager Research Dr Chris Litten: “The overall results suggest that home temperatures during winter are better than they were 20 years ago, but issues of damp, cold and mould persist.”

Evening living room temperatures have risen from an average of 17.8°C to just under 20°C, and average night-time bedroom temperatures have increased from 13.6°C to 16.1°C, which could reflect an increase in the number of bedrooms that are heated as well as increased levels of insulation.

Unhealthy night-time bedroom temperatures are more common among lower-income households in the study. Bedrooms for young children were more likely to be heated than for others, however, around one in three reported never heating these bedrooms.

“It’s good to see an increase in bedroom heating and temperatures,” says Dr Litten. “This suggests that improvements in insulation and thermal performance are having the desired effect, but building better needs to remain a focus,” he adds.

BRANZ is extending the scope of its original research to explore how energy can be used more efficiently, making living costs more affordable and reducing carbon emissions.

• Additional insights from the study are expected to be released in early 2025. The full research report is available at: branz.co.nz/pubs/research-reports/sr495/