Warmer Kiwi homes improves lives - research

Ōtautahi - New Zealand’s warmer Kiwi homes project has completed more than 110,000 insulation and heating retrofits, and a new Energy Efficient and Conservation Study (EECA) has found the programme is effective, and good value for money.

The almost two-year long research looked at people’s health and wellbeing in their homes; the homes’ indoor environment (including temperature and humidity); and the outdoor environment from nearby weather stations electricity consumption.

So far, warmer Kiwi homes (WKH) has completed over 110,000 insulation and heating retrofits, and the study shows the programme is effective, and good value for money.

Warmer Kiwi Homes is a government programme offering insulation and heater grants to low-income home owners.

In the winter of 2021 the research found households that had a heat pump installed 77 percent reported an increase in warmth in the living area; 87 percent reported an improvement in comfort and  89 percent reported a reduction in condensation on living room windows.

Furthermore other findings were:

• 47 percent reported a reduction in damp in the living area

• 81 percent reported being more satisfied with their home

• 65 to 71 percent reported a reduction in having to restrict their heating due to cost

• A net 15 percent reported an improvement in their overall satisfaction with life, keeping in mind this measure will also have been affected by the 2021 lockdowns and other factors.

Last winter improvements were sustained. Higher temperatures were amplified including: prolonged increases in warmth due to the heat pump and indoor temperature gains were highest when outdoor temperatures were low with an estimated indoor temperature gain of 1.9C when the external temperature was 0C

Other improvements were:

• Indoor temperature gains, relative to outdoor temperatures, were greatest at breakfast time and at dinner time

• Draughty houses experience lower gains in indoor temperature with the average gain in a draughty house being 0.9oC compared with 2.1oC for a non-draughty house

 • Installation of a heat pump significantly reduced living area indoor relative humidity and CO2

• Houses that used the heat pump as an air conditioner over summer recorded lower indoor temperatures, with the temperature reduction peaking at 6 to 7pm.

• Electricity use through winter falls in a house fitted with a heat pump by an estimated 16 percent relative to a house without a heat pump installed.

• Electricity savings are negligible at night and increase through the day, peaking at 5-9pm

• Peak electricity reductions occurred when there are also indoor temperature gains reflecting replacement of previous energy inefficient heaters by more efficient heat pumps.

• The EECA commissioned analysis estimates no significant increase in electricity consumption over summer for houses that use the heat pump as an air conditioner

The findings of this evaluation indicate that installation of a heat pump through the WKH programme results in households that are more comfortable in their homes, with living areas that are materially warmer and drier in winter.