Architectural Designers New Zealand (ADNZ) has released new figures that suggests H1 building regulations cost nowhere near the $50,000 figure estimated by a few North Island builders. Research by ADNZ indicates the actual cost could be as little as an additional $5,500 for an average three-bedroom house.

Keryn Davis, CEO of Architectural Designers New Zealand, stated that the research was conducted by ADNZ technical leaders in opposition to recent calls to roll back H1 changes.

“ADNZ was disappointed to learn of calls to roll back H1 changes and that most of the information cited has been purely anecdotal. To combat this, a team of certified professional members led research and calculated a more likely cost for an average three-bedroom home build across a multitude of climates. Analysis found that on average an additional $5,500 was a more accurate figure to integrate H1 building regulations. Interestingly, the investigation by ADNZ also suggested that the higher cost quoted up north was more than likely associated with poor design and an inadequate method of determining compliance,” said Davis.

It is the view of ADNZ that poor design leads to overheating through incorrect building orientation, oversizing of windows, inadequate glazing specification, lack of shade and the incorporation of dark roof and cladding colours.

“What we know is that insulation is not the culprit for overheating. Insulation works with heat in both directions. Alongside the benefit of retaining heat in a home, insulation also stops heat from entering a building.  Increased insulation helps to reduce overheating by decreasing the amount of solar energy that passes through the roof and walls into the home. This is the basics of an energy efficient home, creating a cool house in the summer and warm home in the winter. There are many considerations in designing a home that performs well in all climates. It is the job of a good designer to understand these potential pitfalls and to work to overcome them with creative and sound solutions,” says Davis.

ADNZ also states that selecting the correct method to demonstrate compliance with H1 is vital for understanding the true cost of H1 changes.

“The most basic method of complying with H1, the Schedule Method, is a blunt tool. It requires every wall, roof, floor, window, and door to have an R-value greater than those found in a schedule of R-values. It is our belief that specification increases can be significantly reduced by using the Calculation Method included in H1/AS1. In the design industry, it is standard practice for the Calculation Method to be utilised. It allows projects to trade-off lower R-values in parts of the envelope in return for higher R-values elsewhere. This enables a designer to reposition the insulation to find the most efficient and cost-effective implementation to suit the specific building. Perhaps if the builders making these claims used the correct method, the outcome might improve,” says Davis.

Upgrades to H1 were introduced in May 2023. The upgrades were the first significant improvement to insulation standards in New Zealand in more than a decade and have resulted in the improved energy-efficiency and thermal performance of Aotearoa’s built environment. The 2023 changes to H1 included increased insulation requirements for roofs, walls, floors, windows, doors, and skylights. All are designed to deliver warmer, drier, and healthier buildings that cost significantly less to maintain a healthy indoor environment.

Professional members of ADNZ include respected and senior members of Aotearoa’s design community, many with significant skills, qualifications, knowledge, and experience designing residential buildings. Architectural Designers New Zealand and its members strongly opposes any talk of an H1 roll back. It believes that this action will initiate a setback in the evolution of New Zealand’s Building Code. ADNZ recommends retaining the recent upgrades to the H1 and for the Building for Climate Change programme to continue at speed.