Survey highlights need for better insulation and household heating habits


Results in the latest report on the BRANZ House Condition Survey show around half of New Zealand houses still lack adequate insulation, and that householders under-heat their home in winter.

The survey of 560 dwellings found 47% of houses had ceiling insulation below 120mm, the level recommended by the Energy Efficiency and Conservation Authority. The report also draws attention to householder heating habits.

Results from the survey have found whilst living areas are typically heated at some time in winter, almost half of households did not usually heat bedrooms at all. This included bedrooms occupied by children under 18 years old.

The World Health Organisation (WHO) recommends indoor temperatures of at least 18°C in occupied areas of the house, or higher for vulnerable groups such as young children, the elderly or those living with illness.

Unheated rooms in winter are unlikely to consistently achieve this WHO recommended minimum for a healthy indoor environment.

The roof can be a major source of heat loss from the home, but is also one of the easiest areas of the house to insulate.

The survey found one-third of houses have an effective heating system, but have suboptimal insulation in the roof space, so will be losing a lot of this heat to the outside.

BRANZ researcher Vicki White says insulation and heating are essential for maintaining a warm, dry home and ensuring a healthy environment for household occupants, particularly in the colder months.

“Home owners and landlords should consider improving insulation in the roof space to get the most from their heating. Insulation is cost-effective in the long run. Heating a well-insulated room is far more economical as it will retain the heat,” Ms White says.

“Houses kept warm and dry with good levels of insulation, good ventilation systems such as extractor fans, and regularly opened windows and doors will help reduce the risk of damp and mould.”

The BRANZ House Condition Survey — the first of which was undertaken in 1994 — is the largest survey of its kind in New Zealand.

Monitoring housing conditions through an onsite property assessment, the survey provides a comprehensive picture of the state of houses and the general conditions people are living in.

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