Source
https://www.branz.co.nz/pubs/bulletins/bu677/ — original source (opens in a new tab; the file is not redistributed)
Summary
BRANZ Bulletin 677 (2022) is the roof-specific guidance to the H1 5th edition amendment 1 of the New Zealand Building Code’s Energy Efficiency clause, which from 3 November 2022 raised roof thermal-envelope requirements for new housing and buildings other than housing up to 300 m². Its headline: under the schedule method, the minimum construction R-value for roofs is now R6.6 in every one of the new six climate zones — a single national roof requirement (the calculation and modelling methods can trade this off against better performance elsewhere). The bulletin then sets out the practical detail behind that number — the sloping-roof perimeter allowance (R3.3 over the outer 500 mm), how to lift a perimeter-derated roof back to an overall R6.6 (Table 1), the three compliance methods and their glazing limits, the updated skylight R-values, the impact on skillion roofs, and the condensation-risk and installation caveats that come with a higher-performance roof. For Neobiome Intelligence it is the roof-leg authority behind the ④c standard building_standard baseline — the roof-specific companion to OT_043 (element schedule), OT_044 (calculation method) and OT_057 (House Insulation Guide 6th ed).
Key claims
- claim: "From 3 November 2022, the 5th edition amendment 1 of Acceptable Solution H1/AS1 and Verification Method H1/VM1 replaced the old 4th edition for Building Code clause H1 (Energy efficiency), for all housing and for buildings other than housing up to 300 m² (non-residential buildings over 300 m² fall under a new H1/AS2 and H1/VM2). The 5th edition has six climate zones, replacing the previous three. The new minimum construction R-value for roofs using the schedule method is R6.6 in all climate zones. Building consent applications for housing submitted before 1 May 2023 could still use roof, wall and floor construction R-values equivalent to the 4th edition."
source_location: "§1.0.1–1.0.5, §2.0.1–2.0.2, §3.1.1 (pp.1–4)"
- claim: "In roof spaces where insulation is installed over a horizontal ceiling and under a sloping roof, the R-value of the roof may be reduced to R3.3 for up to 500 mm from the outer edge of the ceiling perimeter where there is not enough space for the thicker insulation required to achieve R6.6. With the schedule method the R6.6 does not need to be corrected for this provided the reduced R-value is at least R3.3 in a perimeter width of no more than 500 mm; with the calculation method the R-value of any ceiling part, including edges, cannot be reduced below R3.3 (H1/AS1 §2.1.3.8); the modelling method has no such limit."
source_location: "§2.0.3–2.0.6 (pp.1–3)"
- claim: "A roof with R6.6 in the central portion and R3.3 for 500 mm around the perimeter gives an overall construction R-value below R6.6; a higher central-portion R-value can be specified to lift the whole-roof R-value back to R6.6. Table 1, by ceiling area-to-perimeter (A/P) ratio, gives [effective overall R with R6.6 central + R3.3 perimeter / central-portion R needed for a whole-roof R6.6]: A/P 1.6 → 5.1 / 11.1; 1.8 → 5.2 / 10.1; 2.0 → 5.3 / 9.5; 2.2 → 5.4 / 9.1; 2.4 → 5.5 / 8.8; 2.6 → 5.6 / 8.5; 2.8 → 5.6 / 8.3; 3.0 → 5.7 / 8.1. This procedure is not a requirement in H1/AS1."
source_location: "§2.0.7 + Table 1 (p.3)"
- claim: "Three compliance methods are retained: the schedule method (each element meets or exceeds its construction R-value), the calculation method (H1/AS1 §2.1.3 — the proposed building overall performs at least as well as a reference building insulated to the schedule values), and the modelling method (H1/VM1 Appendix D — the sum of the proposed building's annual space heating and cooling loads does not exceed those of a reference building of the same geometry, orientation and climate zone). The schedule method can be used only where: glazing area is ≤30% of total wall area; combined glazing on east, south and west-facing walls is ≤30% of the wall area of those walls; skylight area is no more than 1.5 m² or 1.5% of total roof area (whichever is greater); and opaque door area is no more than 6 m² or 6% of total wall area (whichever is greater)."
source_location: "§1.0.4, §3.1.1, §3.2.1, §3.3.1 (pp.1–5)"
- claim: "Limits on the calculation method: it can only be used where glazing is 40% or less of the total wall area (a change from the H1/AS1 4th edition 50% limit); the construction R-value for roofs, walls and floors in the proposed building must be at least 50% of the corresponding reference-building element R-value (including any reduced-R ceiling edges); it cannot reduce the performance of elements with embedded heating systems; and it cannot provide values lower than the minimum R-values that Acceptable Solution E3/AS1 specifies for walls, roofs and ceilings."
source_location: "§3.2.2 (p.4)"
- claim: "All skylights in housing must achieve a minimum R0.37 from 3 November 2022; from 1 May 2023 the minimum rises to R0.46 in climate zones 1 and 2, R0.54 in zones 3 and 4, and R0.62 in zones 5 and 6 (the R0.46/0.54/0.62 values apply to buildings up to 300 m² other than housing from 3 November 2022). Skylight R-value calculation was updated (H1/AS1 & H1/VM1 Appendix E) to reflect inclined-IGU performance — the Table E.1.1.1 vertical-window values are not representative for skylights. Over a full year skylights very often lose more energy than they gain, and in summer can contribute to overheating."
source_location: "§9.0.1–9.0.5 (p.6)"
- claim: "The new H1 requirements have a particular impact on skillion roofs — many skillion structures that complied with the 4th edition of H1/AS1 or H1/VM1 will not comply with 5th edition amendment 1. New approaches may include deeper rafters, higher-density insulation, or a secondary insulation layer (on the interior, or on the exterior as a hybrid warm roof if the primary framing is also insulated); a secondary layer fixed at right angles to the rafters also reduces thermal bridging."
source_location: "§4.0.1–4.0.2 (p.5)"
- claim: "Installation and durability caveats: a minimum 25 mm clearance is required between insulation and roofing or flexible roof underlay to prevent moisture wicking (NZS 4246:2016 §6.2.10); installing insulation in two layers typically produces a total R-value that is less than double a single layer because of compression; H1/AS1 and H1/VM1 do not include the use of foil insulation. Raising thermal performance (as the 5th edition does) is likely to raise the risk of condensation in the roof space, because less heatflow leads to colder roof decks and reduced drying capacity — so ceiling air-barrier quality is critical, and a warm roof (insulation attached to the roofing, roof space near interior temperature) is one mitigation. BRANZ recommends assessing insulation embodied carbon on a whole-of-life basis (BRANZ CO2NSTRUCT tool). Roof R-values are determined using NZS 4214:2006; the BRANZ House Insulation Guide 6th edition presents FEM-determined roof R-values."
source_location: "§2.1.1–2.1.2, §5.0.4–5.0.7, §6.0.2, §7.0.1–7.0.5 (pp.3, 5–6)"Neobiome Intelligence relevance
This is the roof-leg authority behind the model’s ④c building_standards baseline (context: ni, feeds D04). Its calibration value is four-fold.
- ④c
building_standards— the roof leg is R6.6 nationwide, zone-invariant. The schedule-method roof minimum is R6.6 in all six climate zones OT_133 — so unlike the floor and window legs (which vary by zone: floor R2.5–R3.0, window R0.46+, per OT_043 / OT_057), the roof leg of thestandardbuilding_standard baseline (heat_demand_multiplier 1.00) is national and zone-invariant. That directly suits the all-NZ national scope: no per-region roof value is needed, and the earlier pilot-zone uncertainty flagged on OT_043 never applied to roofs. - Effective whole-roof R sits slightly below the nominal R6.6. The sloping-roof perimeter allowance lets the roof R drop to R3.3 over the outer 500 mm of the ceiling perimeter, so a nominal-R6.6 roof’s effective whole-roof R is below R6.6 — Table 1 gives ~R5.1 (A/P 1.6) to R5.7 (A/P 3.0) effective if the central portion stays at R6.6 OT_133. A small as-built roof-leg derate, paralleling the wall-framing derate BRANZ notes on D04 (real walls ~34% framing, OT_057 / ER53) — design nuance, not a change to the model’s roof baseline number.
- Compliance-method flexibility + glazing caps (the above-baseline route). The three methods and their limits — schedule glazing ≤30% of wall area (≤1.5 m²/1.5% skylights), calculation ≤40% (element R ≥50% of reference), modelling on annual heating+cooling load — document how a Neobiome high-performance build trades a bigger passive-solar glazing area against a higher-R roof/walls OT_133, complementing the calculation-method mechanism in OT_044.
- Design-and-cost signals (skillion roofs, skylights, condensation). Certain roof forms carry a materials/cost premium under the new code — many 4th-edition-compliant skillion roofs now need deeper rafters, higher-density or secondary insulation (a cost signal feeding the high-performance-capex context, not a specific NZD number) OT_133. Skylights must reach R0.37 (rising to R0.46/0.54/0.62 by zone) and typically net-lose energy over a year, so daylighting via skylights is a thermal trade-off, not a free gain. And raising envelope performance raises roof-space condensation risk — reinforcing the D04 finding that warmth must be paired with ventilation / air-barrier quality (OT_048, OT_042).
Scope note: a guidance bulletin restating the H1/AS1 5th-edition-amendment-1 roof requirements — the authoritative per-zone schedule and the reference-building heat-loss equations live in the H1/AS1 document itself and in OT_057. No new NZD cost data — its value is baseline detail (the R6.6 roof leg + effective-R nuance) and the compliance framework, not a new cost/energy number.
Research targets
Documents to retrieve
- RT_373 (low priority) — ER70 PHINZ High-performance construction details handbook (2022) — referenced here (§1.0.8, §4.0.2) for secondary insulation layers, thermal-bridging control and high-performance detailing. Not yet its own source page (mentioned only in CR_017 and OT_085); would firm the detailing basis behind the model’s
high_performancebuilding_standard. → D04.
Research gaps
- RT_374 (low priority) — the effective whole-roof R-value for a code-minimum roof (R6.6 central + R3.3 over the 500 mm perimeter) at typical NZ house A/P ratios: Table 1 gives the central-R needed for a whole-roof R6.6 but not the as-built effective R of an unadjusted code-minimum roof, so the small roof-leg as-built derate on the ④c baseline is not quantified. → D04.
Notes
Authoritative BRANZ Bulletin 677 (Oct 2022, ISSN 2537-7310, © BRANZ 2022, 7 pp), downloaded PDF (not AI-prepared), read verbatim via pdftotext -layout — every figure traces to a numbered paragraph / Table 1 → data_quality: verified. No retrieval-provenance block required (not AI-prepared).
⚠ data_quality classification: the two older direct H1 siblings OT_043 and OT_044 carry data_quality: high, while this page is set verified (an authoritative PDF read verbatim with every figure traced). The corpus is not yet consistent across the three.
⚠ Roof R6.6 is not a NEW number to the corpus — the R6.6 roof value is already recorded on OT_043 (Table 1), OT_057 and the D04 page. This source adds the roof-specific detail (all-zone invariance, the R3.3/500 mm perimeter allowance + Table 1 effective-R, skylight schedule, skillion impact, condensation caveats), not a new baseline figure. It is additive/confirmatory to the roof leg, so the D04 evidence bullet is framed as roof-detail, not a new baseline.
Connections
Links to
Referenced by
EDT domains (1): D04: Sustainable Habitat & Building Technology
Sources (1): OT_134