Construction R-value

The R-value of a roof, wall or floor from its layers, by NZS 4214 as H1/AS1 modifies it, and then the whole house against the reference building.

  • H1/AS1Sixth Edition27 Nov 2025
  • NZS 4214:2006
  • NZS 4246:2016
  • E3/AS1Second Edition Amendment 75 Nov 2020
  • Building Product SpecificationsFirst Edition Amendment 12 Apr 2026
Tools

Build-up

Each build-up is a starting point, not a specification: change any layer to match your drawings. The insulation's R-value is its declared value (H1/AS1 2.1.3.3). Save the result to use it in section 04.

Pick the element and the build-up to start from, enter the insulation's declared R-value, then save it.

1Element

2Build-upsStart from a preset, or from a build-up you have saved for this element. A roof is picked by its roofing, type and ceiling.

OutsideInside
Construction R-value
–
NZS 4214 Eq. 10
Framing fraction
5.0%

Windows, doors and skylights

Use the supplier's figures, each with the supplier and product it is for, or work them out here: a house's windows and glazed doors from Table D.1.1.1, and skylights, opaque doors and garage doors from the supplier's U-value (Appendix D).

The construction R-values of the windows, doors and skylights: the supplier's figures, or worked out here.

SupplierProductR-value
Windows and glazed doors
Opaque doors
Skylights
Garage doors

The figures

Window R-value
–
H1/AS1 D.1.1.1 b)
Opaque door R-value
–
H1/AS1 D.1.1.2
Skylight R-value
–
H1/AS1 D.2.1.1

  1. Windows and glazed doors, no figure

    No figure for windows and glazed doors. Each one without a figure of its own is taken at R0.15, the default of 2.1.2.13.

    H1/AS1 2.1.2.13

  2. Opaque doors, no figure

    No figure for opaque doors. Each one without a figure of its own is taken at R0.18, the default of 2.1.2.13.

    H1/AS1 2.1.2.13

  3. Skylights, no figure

    No figure for skylights. Each one without a figure of its own is taken at R0.18, the default of 2.1.2.13.

    H1/AS1 2.1.2.13

Construction R-values

A build-up is listed once you save it, or use it as a part in section 04. Take one off with its ×, or add another you have saved.

The build-ups this project uses. Each prints in full, with its working.

Nothing here yet. Save a build-up in section 01, or add one you have saved.

H1/AS1 Calculation Method

Thermal envelope

A part is one roof, wall, floor or slab of the thermal envelope, at overall internal dimensions (2.1.2.10). Give a wall at the gross area of its elevation and a roof at its whole area: the openings in section 05 come out of the wall or roof they are in, leaving the net wall area and net roof area Equation 2.1 sums (Appendix B). Parts with different R-values are summed separately (2.1.2.9).

Add a part for each roof, wall, floor and slab using your saved build-ups to build a calculation report. The opening areas can be deducted in the next step.

Each part is one of your saved build-ups, and none is saved yet.

Each part is one of your saved build-ups, by the name you gave it. Edit opens it in section 01; saved again there, every part using it changes too.

Joinery

The size is the wall opening, frame and opening tolerances included, which is what Appendix B's wall glazing area and opaque door area measure: a glass size or a unit size is smaller. A glazed door counts to the glazing, as Appendix B has it, and a door with glazing and opaque panels is two rows here, its glazed part and its panels.

Add each window, door, garage door and skylight at its size on the drawings, and pick the wall or roof it is in. Its area comes off that part, and it is counted at the R-value from section 02.

No openings yet.

Add aEach row takes the figure for its kind from section 02, or 2.1.2.13's default where none is given there. Where the supplier calculated each unit, tick “The units have figures of their own” and give each row its figure.

Result

Each building's heat loss is the sum of area over construction R-value across its elements (Equation 2.1). The reference building is this building's areas at Table 2.1.2.7's R-values for the climate zone. Passing is not the comparison alone: 2.1.2.11's minimum for every part, 2.1.2.12's for a heated element and E3/AS1's minimum for a roof all apply whatever the comparison says.

The proposed building against the reference building, and what the calculation method makes of the two.

The figures

Proposed heat loss
–
H1/AS1 Equation 2.1
Reference heat loss
–
H1/AS1 Table 2.1.2.7
Verdict
–
H1/AS1 2.1.2.6, 2.1.2.11, 2.1.2.12

  1. Calculation method

    No element has an area above zero.

    H1/AS1 2.1.2.8

The rules behind it

H1/AS1 Energy EfficiencyWhat H1 asks, what the drawings show, and the readings →

This tool reads H1/AS1 Sixth Edition, effective 27 November 2025, E3/AS1 1.1.1, and NZS 4214:2006 as H1/AS1 2.1.3.2 modifies it. It works the construction R-value of a wall, a roof and a suspended floor from the figures entered, reads Appendix E for a slab-on-ground floor and Table D.1.1.1 for a house's windows and glazed doors, and compares the proposed building's heat loss with the reference building's by the calculation method of 2.1.2. It does not run H1/VM1. Every insulation R-value, area, perimeter and choice is the reader's. A construction R-value here is NZS 4214's calculation of the build-up as entered, not a measurement of the one built: where the tool simplifies the method, the result moves by less than R0.1, mostly toward the lower value, and how the insulation is installed is not in it. A roof here is H1/AS1's: a roof/ceiling whose exterior surface is at 60° or less to the horizontal. NZS 4214:2006 Sections 5 and 6 and Appendix E, the figures the method turns on. H1/AS1 Appendix E, Tables E.1.2.1A to E.1.2.1X (Paragraph E.1.2.1), pp.31–54, indexed by Table E.1.2.1, p.30. Table D.1.1.1: Construction R-values (Rwindow) of selected generic vertical windows and doors for housing, p.24 (Paragraph D.1.1.1 a)).

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