Page 26 - HW April 2022

building envelope – pre-cladding & insulation
H1 Energy Efficiency – what’s changing?
As signalled last November, a significant Building Code update to H1 Energy Efficiency comes into effect on 3 November 2022.
The update includes expanding the number of Climate Zones used in the insulation requirements from 3 to 6. This will eventually allow insulation requirements to be better tailored to reflect the different temperatures experienced in each zone.
New R-values for roof, window, wall and underfloor insulation are the result of “a clear mandate for ambitious, achievable change while ensuring the stability of the building and construction sector.”
Higher R-values for colder zones were ruled out because industry feedback highlighted current supply issues and MBIE said they were “not achievable” without major changes in how dwellings were designed and built and involving a much longer implementation period.
Under the new system there are different ways to calculate R-values:
• The H1/AS1 schedule method where the roof, windows, external
walls and floor of a new home or small building each need to meet
or exceed minimum R-values for the relevant climate zone.
• The H1/AS1 calculation method and the H1/VM1 modelling
method which allow lower R-values for some elements, provided that the overall thermal performance of the proposed new home or small building is equal or better. Not the work of a moment.
Roofs – The minimum amount of roof insulation required across the country has doubled to R6.6 which should be able to be accommodated without significant changes to roof framing.
Windows – The biggest change nationwide, raising the bar significantly in outcome and in cost...
Walls – Status quo, the result of “strong feedback” around timber supply issues and not wishing to impose different framing practices or higher performing insulation products.“This would be difficult to achieve for residential buildings across the country at this time.That is why we have left the requirements for walls in residential building mostly unchanged,” says MBIE.
Underfloor insulation – Splits the requirements for different floor options “to allow further time for slab on-ground construction practices to change.”
Overall, MBIE calls these changes an “interim step”: “To achieve significantly higher R-values, the sector would need to significantly change the way building elements are designed and constructed.” Simplifying the transition also “reduces the risk of unintended consequences.”
The next phase of the Building for Climate Change programme will introduce caps on carbon emissions and look at the operational efficiency of buildings.
This will require higher performing construction methods and materials – better insulated concrete floor slabs, triple glazing for colder climates, and better insulated external walls – as well as a building’s thermal performance “being optimised to consider the indoor environmental qualities, the shape of the building, size and orientation of windows, airtightness, mechanical ventilation with heat recovery, reduced thermal bridging, and building services (such as heating, cooling, hot water, and lighting).”
This next phase will also look at policies and ways to improve the thermal performance and energy efficiency of existing buildings.
www.mbie.govt.nz
Rigidi air barriers are on the rise but wraps like Thermakraft Watergate are still the industry’s go-to when it comes to cladding underlay.
24 NZHJ | APRIL 2022
same thermal performance as fibreglass in a roofing context, but with a much thinner profile.
With local manufacturing, despite all the surrounding disruptions, supply isn’t a factor, says Anthony, on top of which he insists: “Most architects and most group home builders are still gravitating towards a traditional synthetic underlay like Thermakraft’s Watergate.”
With the H1 changes also representing “a pretty significant disruptor to the New Zealand construction market” there has been widespread acceptance of the need to up the building industry’s energy efficiency game and Anthony Lehmann is another to confirm that Kingspan Thermakraft too has already been fielding enquiries from specifiers looking to adopt the H1 changes early.
Staying with Kingspan Thermakraft, Todd Lindsay is NZ Sales MORE AT www.hardwarejournal.co.nz