© Jesus Rodriguez

A research report on the energy efficiency of New Zealand homes has revealed that current minimum requirements for insulation under New Zealand’s building code are not the most cost-effective.

The research shows millions of dollars are set to be saved through higher standards of insulation.

Across all New Zealand cities, insulation levels higher than the current minimum required could save residents $70 million over 30 years; the benefits far outweighing the upfront cost.

On average, ceilings required a 50 percent increase in insulation and walls up to 35 percent. Inadequate insulation for both heating and cooling will cost individual households anywhere up to $5,500 over time.

The research was carried out by Pitt & Sherry for Knauf Insulation and is endorsed by the Association of Wall and Ceiling Industries, Australia and New Zealand (AWCI), and the Australian Alliance for Energy Productivity (A2EP).

It analysed the current ‘deemed to satisfy’ levels against ‘cost-optimal’ levels in different climates and house-types.

Knauf Insulation managing director Stuart Dunbar says that when it comes to insulation, the majority of new buildings will only adhere to the minimum code requirements.

“This research highlights that in most cities and house-types this is not the most cost-effective. Across the board, New Zealand homes would benefit from insulation levels above the current standard.

“In addition, the study found that retrofitting is also very cost-effective and pays for itself through savings on energy bills in less than eight years in almost every case. This is solid evidence of just how cost-effective insulation is for New Zealand homes.

“The benefits of insulation should last the life of the building with minimal maintenance, unlike heaters and air conditioners which need to be serviced and eventually replaced.”

AWCI executive director Ian Swann believes the analysis highlights an important issue, given heating and cooling makes up an average of one third of home energy bills.

“This is significant because recent data has highlighted that nearly 60 percent of New Zealand homes still have inadequate insulation. Yet 35 percent of the energy used in the average New Zealand household is used for heating.

“Cost is compelling, but it’s also important to consider the health and sustainability benefits of better-insulated housing. Uncomfortably low indoor temperatures in winter have an adverse impact on health and heating is expensive.”

Topping up ceiling insulation in existing homes was shown to be the number one priority. An uninsulated home loses and gains more heat through the ceiling and roof than any other part of the house.

About 25 percent of heat from the average uninsulated house is lost through the walls and up to 35 percent of heat is typically lost through the ceiling.

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