New Zealand’s rules for building warm, energy-efficient homes are about to change – and the shift could do more than tidy up compliance paperwork.
Done well, it will help designers and developers build homes that are more comfortable to live in, cheaper to run and more affordable to buy.
From November 27, the familiar “schedule method” for demonstrating compliance with H1 – the Building Code* clause covering energy efficiency – will no longer be applicable
Instead of simply specifying a prescribed level of insulation for each part of a home, designers will need to use a calculation or modelling approach that considers how the whole house performs.
That sounds like more red tape. But James Gallagher, general manager of EnergySmart, sees it as an opportunity to make better decisions earlier – when designers can still improve both comfort and project economics.
“The Government deemed that the schedule method was a wasteful and expensive way of demonstrating compliance,” explains Gallagher.
“We’re moving to a calculation method and yes, there’s a bit of time and energy that goes into the calculation, but the benefits of it far outweigh the costs.”
From checklist to whole-home thinking
Under the old schedule method, designers would choose an insulation product with a specified thermal rating for a wall, roof or floor, and tick the box.
That’s straightforward, but is also a blunt approach. A designer may over-specify one part of a home because it is the most obvious way to meet the rule, even if the same overall performance could be achieved more sensibly by improving another element.
The new calculation method, in contrast, looks at the entire thermal envelope – the complete barrier between indoor and outdoor conditions.
That includes walls, roofs, windows, floors, insulation, timber framing, cladding and the many small design choices that affect how quickly heat moves in or out of a house.
“It looks at the overall performance of the house,” says Gallagher.
“Rather than having a very expensive concrete slab which may be required to meet the old schedule method, we can now say, ‘We can take some cost out of that concrete slab because overall this house is compliant.’”
That does not mean building lower-performing homes, though.
Gallagher argues the opposite: the H1 standard is already much higher than New Zealand’s previous settings, and calculation-based design provides a more precise way to meet it.
Better choices before consent
The practical challenge is timing.
H1 calculations are often completed when a building design is almost finalised and the consent application is looming. At that point, a question such as whether a slab detail can change, or whether spending more on windows would permit savings elsewhere, can mean sending plans away to an external specialist and waiting for an answer.
That delay is exactly what EnergySmart wants to address with HONE, a new online tool developed by its in-house team.
The name is a play on H1, but it also reflects the goal: helping users hone a design towards a chosen outcome, whether that is lower build cost, better thermal performance or both.
“The tool allows you to test alternate models very, very efficiently,” Gallagher says. “The best time to do your thermal design is pre-consent, because that’s when you can change anything you like, so long as it’s compliant.”
A designer can enter the dimensions and construction details of a project, test alternative specifications and generate an H1 report.
For those who do not want to do the calculations themselves, EnergySmart also offers a Done For You service, where its specialists assess uploaded plans and complete the work.
HONE lets designers test combinations of materials without repeating the same information. Should the budget go into higher-performing glazing, a better floor specification, wall insulation or the roof? The tool will provide the answers.
“If there’s an extra $30,000 in the budget, you can look at where you’re losing the most energy,” says Gallagher.
“You might put more money into windows. But you’re not going to put another layer of insulation in the roof if the roof is already performing pretty well.”
The team’s design brief for HONE was to deliver fewer clicks, logical menus and the same natural sequence in which a designer thinks about a building.
Gallagher’s test was simple: “It needs to have the flow and simplicity of buying an airline ticket.”
Comfort – and affordability
Better thermal decisions should result in homes that are easier to heat, and less prone to uncomfortable temperature swings.
There is also a direct affordability case. EnergySmart says its approach has helped identify savings of $15,000 on a show home, $50,000 across a builder’s annual portfolio and $500,000 across a 150-home development, by finding more efficient ways to balance a building’s thermal envelope.
“Pulling $15,000 out of a house creates a material difference to the level of affordability for people to buy housing,” Gallagher says.
HONE is free for approved designers, builders and other genuine users. EnergySmart has also made the platform product-inclusive rather than limiting users to its own insulation products.
That’s a pragmatic move to help the industry navigate a more complex rulebook, and earn business through competitive pricing, quality and service. More importantly, it could help shift H1 from an end-of-project compliance exercise into an early design decision – where warmer, healthier and more affordable homes are actually made.
Hone your plans. Simplify H1. Try the free HONE calculator for your next project at honecalculator.co.nz