Major BRANZ study reveals marked gap between perceived and actual health of Kiwi homes

In the only national study of its kind for 20 years, nine out of ten Kiwis consider their home to be a ‘healthy’ place to live, even though many still experience cold, dampness, condensation and mould, and wish their home was warmer

The landmark study is collecting data from over 750 households across Aotearoa 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, nearly half (48 per cent) of the survey respondents said they had mould in their home (11 per cent said it was larger than a sheet of A4 paper) and 33 per cent 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 than 20 years ago

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 twenty 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.

Homes are getting healthier, but faster progress is needed

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

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, while also making it easier to keep homes warm and dry.

“Underheated homes, ill health, and the financial stress of energy bills are a reality for many Kiwis. BRANZ is investing in this research to gain insights that will support positive change towards quality housing, affordable living, and efficient and effective energy use,” Dr Litten adds.

“Accurate, up-to-date, and accessible data on home energy use and indoor conditions will help inform policies and initiatives to help New Zealanders live in healthier homes while using energy effectively and efficiently.”

These new findings are the first early insights from the new study, focusing on winter heating, comfort, and internal temperatures. Following further data analysis, additional insights from the study are expected to be released in early 2025.