01 / Climate Zone & Building Geometry
Wall Areas — m²
Window & Door Areas — m²
Typical window Uw values:
• Single glazing: 3.5–5.0 W/m²K
• Double clear: 2.8–3.0 W/m²K
• Double Low-E + argon: 1.0–1.3 W/m²K
• Triple Low-E + krypton: 0.5–0.8 W/m²K
Get values from manufacturer WEERS data for H1 compliance.
• Single glazing: 3.5–5.0 W/m²K
• Double clear: 2.8–3.0 W/m²K
• Double Low-E + argon: 1.0–1.3 W/m²K
• Triple Low-E + krypton: 0.5–0.8 W/m²K
Get values from manufacturer WEERS data for H1 compliance.
02 / Result — H1 Trade-Off Check
Trade-off summary — proposed vs. reference building
| Assembly | Proposed U | Ref. U (H1 Limit) | Proposed HL | Ref. HL | Status |
|---|
H1/AS1 glazing trade-off — limitations. This tool provides an indicative check using the simplified heat loss method from BRANZ H1 Calculator methodology. The official compliance tool is the BRANZ H1 Calculator (currently v10, December 2025), available free from the MBIE website. Actual H1 compliance requires: verified thermal properties from manufacturer documentation (WEERS data), correct R-values for all insulation products, thermal bridge factors (ψ values) for junctions, and correct climate zone classification. The trade-off is only valid when the proposed building's total heat loss does not exceed the reference building's total heat loss. Minimize glazing area in Zones 4 and 5 where possible. All H1 building consent applications must use the BRANZ H1 Calculator or have equivalent thermal modeling by a qualified practitioner.