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![windows-and-doors.jpg]({"1201":"/medias/sys_master/root/h1d/h54/11541564031006/windows-and-doors/windows-and-doors.jpg"} "windows-and-doors.jpg")
Energy Efficiency h1
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Housing and Buildings under 300m2
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Windows and Doors
Buildings under 300m2 - Walls
New construction R-values & how to achieve them
Insulation is a barrier. It helps keep the heat in during the winter and can help keep the heat out during summer. This means that insulation is beneficial even in the warmest part of the country.
To be effective, the barrier has to be continuous in the building. That’s why the changes to Building Code clause H1 Energy Efficiency look at insulating all parts of a building – including ceilings, walls, floors, windows, doors and skylights. Below is an overview of the changes to construction R-value requirements in different parts of a building, and how they can be achieved.
Minimum R-values for Windows & Doors for housing in H1/AS1 and H1/VM1
| Options | Climate Zone | |||||
| 1 | 2 | 3 | 4 | 5 | 6 | |
| Windows & Doors | ||||||
| Previous minimum requirements | R0.26 | |||||
| Current minimum requirements | R0.46 | R0.46 | R0.50 | |||
New construction R-values for Windows
The first phase of implementation – from 3 November 2022 – saw windows and doors in houses in all areas of the country require a rating of R0.37.
This means minimum compliance can be achieved through a change in glazing, and specifically through the use of high-performance, double glazed Low E Insulated Glass Units (IGUs) in aluminium frames.
Low E glazing achieves a lower rate of heat loss due to thin layers of silver or other low emissivity material on one side of the glass, which is enclosed in double or triple glazing to protect the coating. To achieve further insulation, inert gas like argon is used between layer of glazing.
However, once requirements are lifted to R0.46 or R0.50, aluminium framing will not suffice. Thermally broken aluminium, uPVC or timber framing with double-glazed Low E IGUs will be required to meet or exceed the standard.
For Zones 3, 4, 5 and 6, those higher R-values need to be met starting 1 May 2023. For Zones 1 and 2, requirements will be lifted to R0.46 on 2 November 2023.
New construction R-values for Doors
The thermal performance of doors has a significant impact on a building’s energy efficiency. The new H1 changes outlined here – for housing and buildings other than housing that are less than 300m² – now treats door thermal performance the same as windows
The minimum R-value of doors and windows is currently R0.37 in Climate Zones 1 and 2; this will increase to R0.46 from 2 November 2023. It is already set at R0.46 in Climate Zones 3 and 4, and in Climate Zones 5 and 6, it is R0.50.
A wide range of materials are used in door construction, some of which deliver better thermal performance than others. A common first step to meet the required R-value is to specify a thermally broken aluminium or composite door. Timber, uPVC, or fiberglass insulated doors can also significantly increase the R-value. If the door includes glazed sections, or is fully glazed, then low-emissivity, argon-filled double-glazing provides the highest R-value performance.
There are three methods available in the new H1 compliance documents for showing that door thermal performance is compliant; these are schedule, calculation, and modelling.
Glazed, partially glazed and opaque doors
The new H1 requirements apply to glazed, partially glazed and opaque doors. ‘Opaque’ refers to timber, metal and other non-transparent material.
Glazed doors count as part of the window area for H1/AS1 and, as such, they must have an R-rating that is the same as specified for the window joinery.
A door that is partially glazed must assess compliance of the opaque area separately from the areas with glazing.
Acceptable methods for determining the construction R-values of opaque doors or door panels are contained in NZS 4214.
For partially glazed and opaque doors, the H1/AS1 schedule method may only be used if the opaque door area is no more than 6m2 or 6% (whichever is larger) of the total wall area.
Calculating R-ratings
There are several permitted methods for calculating the R-rating for doors, depending on the method being used to show compliance. The intent is that the thermal performance of doors (both opaque and glazed and including the frame) would be calculated according to ISO10077-1 and ISO10077-2.
Any house can demonstrate compliance using H1/AS or H1/VM1. Note there are extra requirements if the building has embedded heating systems.
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