Source
https://www.branz.co.nz/pubs/research-reports/sr385/ — original source (opens in a new tab; the file is not redistributed)
BRANZ SR385 (2024) — Industry Perspectives on Exceeding the Minimum
MacGregor C & White V. 2024. Industry Perspectives on Exceeding the Minimum. BRANZ Study Report SR385, BRANZ Ltd, Judgeford. ISSN 1179-6197. Funded by the Building Research Levy. Part of the BRANZ Exceeding the Minimum programme.
Secondary for the cost figures
SR385’s Homestar capex numbers are reported from two 2018 primaries — e-Cubed Building Workshop (2018) CBA and Ade (2018, pp.34–35). SR385 is an authoritative BRANZ report that reproduces them (Table 1), but the deepest cost origin is Ade 2018 (→ RT_283) — now ingested at origin as OT_156 (BRANZ SR391; RT_283 resolved). Figures are 2018 NZD unless noted.
Summary
A nationwide industry survey (n=496) plus a literature/CBA review of what it costs
and benefits to build above the NZ Building Code minimum. For the NI model the
load-bearing content is §2.5–2.6 (construction costs + cost-benefit of Homestar)
and Table 1 — the Homestar star-rating capex premiums that underpin the ④c
building_standards high-performance cell (via CR_017).
The survey half (barriers, willingness-to-pay, advocates) is qualitative
market-behaviour evidence: cost is the greatest barrier, but the main driver to
exceed the minimum is health, and architects/designers are the main influencers.
Key claims
- claim: "e-Cubed Building Workshop (2018) CBA (Homestar v4, code-minimum → 6/7/8-Homestar, Auckland/Wellington/Christchurch): 6-Homestar capital cost $1,142/$2,510/$2,370, ~$465–471/yr hard savings, 2–5 yr payback; 7-Homestar $14,955/$22,305/$19,290, savings $2,115/$2,325/$1,613, 7–12 yr payback; 8-Homestar $21,055/$33,835/$34,810, savings $2,094/$2,475/$1,768, 10–22 yr payback."
source_location: "§2.6 (p16–17)"
- claim: "Ade (2018) Table 1 — median additional cost above a Building Code standard (10 Hobsonville Point dwellings, 2018 NZD): Homestar v3 — 6★ $18,813 / 7★ $39,625 / 8★ $65,901 / 9★ $93,639 / 10★ $110,279; Homestar v4 — 6★ $11,677–$14,618 / 7★ $13,896–$37,726 / 8★ $47,372 / 9★ $67,365 / 10★ $85,446. Certification costs alone varied $380–$3,800/dwelling."
source_location: "Table 1 (p17); Ade 2018 pp.34–35"
- claim: "Ade (2018) percentage premiums: 6-Homestar median +3–5%; 7-Homestar +12% under Homestar versions 2 and 3 but only +4% under version 4 — i.e. the newer Homestar v4 is materially cheaper to reach a given star rating than v2/v3."
source_location: "§2.6 (p17)"
- claim: "The industry survey (n=496) found cost is the single greatest barrier to exceeding the minimum, with a mismatch between real and perceived costs/benefits; the main driver to exceed was health (not energy savings); architects and designers are the main influencers in getting projects beyond Code."
source_location: "Abstract; Executive summary; §4 (p1, p22–27)"
- claim: "Threshold for consumer notice (McCabe 2011, cited): a ~10% energy saving is too little to motivate uptake; at ~20% savings investors take notice — and even then the durability of savings must be demonstrated."
source_location: "§2.7 (p18)"Neobiome Intelligence relevance
Primary behind the ④c building_standards high-performance capex premium (D17).
Firms CR_017’s high_performance premium
(~$35,000/dwelling), which CR_017 derived from “SR385 Homestar cost data (2018),
inflation-adjusted ~30%.”
- **High-performance tier (
35k) — well-supported.** Bracketed by e-Cubed's 8-Homestar capital cost (21k–34k, 2018 → ~28–44k inflated) and Ade’s Homestar-v4 8★ ($47,372). The model central sits squarely inside. - **Passive House tier (
60k) — NOT in SR385.** SR385 only brackets it indirectly via Homestar 9–10 (Ade v4:67k–$85k). Thepassive_housepremium stays on its PHINZ/Basham/Jason Quinn basis; SR385 is a Homestar-9 sanity bracket, not its source. - Wide spread is real. Costs vary strongly by region, Homestar version (v4 ≪ v3 for the same star) and compliance pathway — the model premium is a central point in a genuinely broad band, which the ±-band audit should reflect.
- Upstream primaries: Ade (2018) and e-Cubed (2018) → now ingested as OT_156 (BRANZ SR391, Ade 2018 — the deepest cost primary at origin; RT_283 resolved).
Research targets
Documents to retrieve
- RESOLVED → OT_156 — RT_283 (resolved) — Ade (2018) [the deepest cost primary behind SR385 Table 1; 10 Hobsonville Point case-study dwellings, Homestar v2–v4 additional-cost analysis, pp.34–35] — to cite the Homestar capex table at origin rather than via SR385. Low priority (SR385 reproduces it with full attribution).
Research gaps
- None new — SR385 resolves RT_205 (the high-performance capex primary). The Passive-House premium remains on its PHINZ basis (not a new gap; pre-existing).
Connections
Links to
Referenced by