OT_146: Earthsong Eco-Neighbourhood — Home Energy Rating (HERS) Assessment, one dwelling, unit number redacted…

OT_146: Earthsong Eco-Neighbourhood — Home Energy Rating (HERS) Assessment, one dwelling, unit number redacted…

Source

https://www.earthsong.org.nz/resources/documents — original source (opens in a new tab; the file is not redistributed)

Earthsong Eco-Neighbourhood — Home Energy Rating (HERS) Assessment, one dwelling (unit number redacted)

The as-built energy-rating outturn of a NZ rammed-earth passive-solar eco-build — grounds the D04 thermal-envelope lever + the Earthsong case in an actual rating

A Home Energy Rating (HERS) assessment of one Earthsong dwelling (457 Swanson Road, Ranui; unit number redacted). AccuRate NZ (CSIRO software) gives an 8-star (of 10) building rating with a modelled heating demand of 44 MJ/m²/yr (1 cooling, 45 total) — a strong passive-solar result achieved despite single-glazed windows (U 5.232), uninsulated rammed-earth walls, an uninsulated concrete slab and an uninsulated profiled-metal roof: the 350–400 mm rammed-earth thermal mass (OT_093) plus passive-solar orientation carry the performance. Water heating is solar-thermal with electric boost (flat-plate thermosiphon, 150 L low-pressure), rated 5½ stars, ~$225/yr. ⚠ This is an INTERIM report stamped “Draft”: the room-heating rating is not currently available, the figures are modelled (not metered), and the doc states ratings “may change slightly in the final report” → data_quality: high (provisional primary), not verified.

Summary

An EECA EnergyWise Home Energy Rating (HERS) report for one Earthsong dwelling (unit number redacted), 457 Swanson Road, Ranui, Waitakere City — assessed by ABSA-accredited assessor Ben Bell (Low Impact Limited) using AccuRate NZ v1.0 (the CSIRO-developed rating engine) in the Auckland climate zone. The unit scores an 8-star (of 10) building rating on a modelled heating requirement of 44 MJ/m²/yr (cooling 1, total 45), a strong passive-solar outcome given the fabric it captures: single clear glazing in timber/PVC frames (U value 5.232, SHGC 0.727), rammed-earth external and internal walls with no insulation (plus an R2.4 weatherboard element), an uninsulated concrete slab, an uninsulated profiled-metal roof over an R3.5 plasterboard ceiling, and eaves shading (0.6 m). The rammed-earth thermal mass (documented in the OT_093 materials schedule) plus north-facing passive-solar orientation are doing the work. Water heating is a solar water heater, flat-plate, thermosiphon, electric-boost, 150 L low-pressure unit rated 5½ stars at an indicative $225/yr — the per-unit confirmation of Earthsong’s solar-thermal HW account (INT_006 / OT_093, which record 180/330 L Beasley cylinders on other units). The report’s modelled improvement levers are double-glazing (to WERS 29 → 74% heating-load reduction, 8→9 stars) and managing north-side tree shading (~23% of heating load). It is an interim/draft report: the room-heating rating is not yet available and ratings may change in the final. For Neobiome Intelligence it is a rare as-built energy-rating outturn for the earth-wall/thermal-mass envelope the D04 model otherwise treats qualitatively, and for the thesis it adds the first building-energy datapoint to the earthsong_ranui case.

Key claims

- claim: "INTERIM HOME ENERGY RATING REPORT. BUILDING RATING: 8 (of 10). Client: [occupant name and unit number redacted — privacy], 457 Swanson Road, Ranui; Council: Waitakere City Council. ROOM HEATING RATING: NOT CURRENTLY AVAILABLE. WATER HEATING RATING: 5½ — indicative running costs $225 per year. Key recommendation for improvement: 'Double glaze all windows to WERS 29 or equivelent.' The report states: 'This report is an interim report pending ratification of rating band settings and availability of the room heating rating. A final report will be issued to you automatically and free of charge once these elements are finalised. Please note that your ratings may change slightly in the final report.' Ratings are valid 7 years from the date of assessment. Assessor: Ben Bell, Assr #90004; assessor-verification stamp reads 'Draft'."
  source_location: "p.1 — Building Rating page (client details, building/water-heating ratings, key recommendation, interim-report note, expiry, assessor verification stamp). ⚠ Occupant/client personal name redacted from this claim at ingest (privacy)."
- claim: "ASSESSOR DETAILS: Ben Bell, Low Impact Limited (ABSA Assessor #90004) — personal contact details (business address, phone, email) redacted at ingest (privacy). ASSESSMENT DETAILS: Software type & version = AccuRate NZ v1.0; Climate Zone = AK-Auckland; File Name = (blank); Plan ID = Na; Plans Prepared By = Na; Date Plans Issued = Na. ASSESSMENT TYPE (three options printed): 'Design stage (assessments based on plans identified above; no site inspection undertaken)' / 'Existing home (site inspection undertaken)' / 'For New Zealand Building Code H1 compliance' — the selected tick-box is not machine-readable from the PDF text. The report notes the modelling uses CSIRO-developed software (AccuRate) and standard occupancy/temperature/climate/energy-cost assumptions, so actual use may differ."
  source_location: "p.2 — Assessor Details / Assessment Details / About This Report / Disclaimer"
- claim: "CURRENT BUILDING RATING: 8. TECHNICAL INFORMATION — Current calculated energy requirements (MJ per m² per year): Heating 44; Cooling 1; Total 45. Conditioned floor area printed as '0 m²' (template placeholder — no floor area entered in the report). HOW TO IMPROVE YOUR BUILDING RATING: (1) 'Trees to North add 23% to heating load.' — reduction in heating/cooling load 23%, typical savings $20–80 per year, potential building rating 8; (2) 'Double glaze all windows to WERS 29 or equivelent.' — reduction in heating/cooling load 74%, typical savings $40–240 per year, potential building rating 9. Note: 'These energy requirements do not include the efficiency of the room heating and cooling systems installed. They should not be used to infer actual energy consumption or running costs.'"
  source_location: "p.3 — About Your Building Rating + How To Improve Your Building Rating (recommendations table)"
- claim: "CURRENT ROOM HEATING RATING: N/A (NOT CURRENTLY AVAILABLE). CURRENT WATER HEATING RATING: 5½. WATER HEATING — Appliance Specifications: 'SWH FP T EB 150L LP 8Lpm' (solar water heater, flat-plate, thermosiphon, electric-boost, 150 L, low-pressure, 8 L/min). ROOM HEATING — Appliance Specifications: (blank). WINDOWS (Product ID 'Wers 04'): Glass = Single clear; Frame = Timber or PVC; U value = 5.232; SHGC = .727. SKYLIGHTS: none listed."
  source_location: "p.4 — Room Heating / Water Heating Rating; p.6 — Specifications (Water Heating, Room Heating, Windows, Skylights)"
- claim: "SPECIFICATIONS FOR THIS HOME. EXTERNAL WALLS: Rammed Earth (Insulation: None) and Weatherboard (Insulation: R2.4 Bulk Insulation). INTERNAL WALLS: Rammed Earth (None) and Plasterboard (R2.4). FLOORS: Concrete (Insulation None; Covering None) and Timber (None). CEILINGS: Plasterboard (R3.5). ROOF: Profiled Metal above attic (Insulation None). FIXED SHADING — Eaves (width inc. gutters / height above windows): 0.6 / 0.3. ORIENTATION, EXPOSURE, VENTILATION & INFILTRATION: Building Description 'Post 1960, Simple design, >120m2 airtight windows'; Orientation of nominal north elevation 10 degrees; Site Exposure Medium Sheltered; Roof Space Openness Standard; open fireplaces 0, metal flues 0, passive window vents 0."
  source_location: "p.6 — Specifications For This Home (External/Internal Walls, Floors, Ceilings, Roof, Fixed Shading, Orientation/Exposure/Ventilation/Infiltration)"

Neobiome Intelligence relevance

context: both — the calibration value is the as-built thermal-performance outturn of a real NZ rammed-earth eco-build; the case value is the first building-energy datapoint for Earthsong.

• A rare as-built energy-rating anchor for the D04 thermal-mass / earth-wall envelope. The unit reaches an 8-star (of 10) building rating on a modelled heating demand of just 44 MJ/m²/yr (≈12.2 kWh/m²/yr) despite single-glazed windows (U 5.232), uninsulated rammed-earth walls, an uninsulated concrete slab and an uninsulated profiled-metal roof. This is the passive-solar / high-thermal-mass envelope D04 otherwise treats qualitatively, here with an actual AccuRate rating outcome — and it corroborates the OT_093 as-built materials schedule (350–400 mm rammed earth) with a performance figure. Use it as an order-of-magnitude passive-solar reference, not a hard model input (interim/draft, modelled, no floor area stated).
• Solar-thermal DHW datapoint. Water heating is a solar water heater with electric boost (flat-plate thermosiphon, 150 L low-pressure) rated 5½ stars, ~$225/yr indicative — the per-unit confirmation of Earthsong’s solar-thermal HW (INT_006 / OT_093, which record 180/330 L cylinders on other units; this unit runs a smaller 150 L LP tank). A concrete NZ solar-DHW cylinder-size + running-cost point.
• Fabric-upgrade levers, quantified. The report models double-glazing (to WERS 29) at a 74% heating-load reduction and an 8→9 star jump, and managing north-side tree shading at ~23% of heating load — order-of-magnitude glazing/shading levers for the retrofit / above-baseline path (the current single glazing at U 5.232 is the largest fabric weakness).
• Thesis / case (earthsong_ranui). First building-energy-rating evidence for the earthsong_ranui case, alongside the water (OT_092), waste (OT_094), water-cost (OT_078) and whole-project-cost (OT_098) primaries. Partly addresses the case’s open “energy performance vs Beacon prediction” question with a concrete 8-star building rating.
• Scope caveats (why this is high, not verified). (a) Interim/DRAFT report — the room-heating rating is not currently available and the doc says ratings may change in the final; (b) modelled, not metered (AccuRate standard assumptions); (c) conditioned floor area printed as “0 m²” (template placeholder), so the 44/1/45 MJ/m²/yr are per-m² intensities without a stated floor area in the document; (d) a single unit, not the whole neighbourhood. Strong qualitative/indicative anchor, not a calibrated model number.

Research targets

Documents to retrieve

• (candidate, low priority — surfaced, not minted) The final (non-interim) HERS report for this unit, once the room-heating rating band settings were ratified and the room-heating rating issued — would replace the provisional building/water ratings with finalised values. Likely superseded/unavailable 15+ years on; marginal to the model. No RT minted by default (batch backlog-closing convention); mint only if the reviewer wants the finalised rating chased.

Research gaps

• Metered (vs modelled) whole-of-Earthsong energy performance is already carried as the earthsong_ranui case’s standing open question (“energy performance vs Beacon prediction still open”) — not re-opened here. This HERS rating is a modelled per-unit datapoint toward it, not the metered answer.

Notes

• Primary HERS assessment (EECA EnergyWise Home Energy Rating scheme; ABSA-accredited assessor Ben Bell #90004; AccuRate NZ v1.0, CSIRO engine; Auckland climate zone), read verbatim via pdftotext -layout — every figure (8-star rating, 44/1/45 MJ/m²/yr, 5½ water rating, $225/yr, U 5.232 / SHGC 0.727, R-values, 74%/23% levers) traces to the raw. But the document is an INTERIM report stamped “Draft”: the room-heating rating is not currently available, and it states ratings “may change slightly in the final report” → data_quality: high (provisional primary), deliberately not verified.
• Wall thickness is not stated in this HERS raw (it records only “Rammed Earth / Insulation None”); the 350–400 mm rammed-earth figure cited above is sourced to the OT_093 materials schedule (“350 mm and 400 mm rammed-earth walls”), corrected from a “300 mm” draft slip at commit (ingest-review-approved edit).
• Conditioned floor area = “0 m²” is a template placeholder (no area entered), so the MJ/m²/yr figures are intensities without a stated floor area in the doc. Do not read “0 m²” as a real value.
• Assessment-type tick not machine-readable. Three options are printed (Design stage / Existing home / For H1 compliance); the selected box cannot be recovered from the PDF text. Plan ID / Plans prepared by / Date plans issued are all “Na”, while the specification captures the as-built fabric (single glazing, rammed earth, solar HW, existing north-side trees) — consistent with an as-built/existing-home assessment, but not asserted.
• PDF metadata: created 7 Apr 2008 (pdftk / iText); 6 pages — consistent with Earthsong’s Stage II completion era (the community completed 2008).
• ⚠ Privacy — redaction applied at commit. The raw HERS PDF names the occupant/client and their unit number and prints the assessor’s personal contact details (business address, phone, email). Per the privacy rule applied at the ingest review gate, the occupant’s personal name and the assessor’s contact details were redacted from the key_claims before the page entered the wiki — the research value is the unit and its performance, not the individuals. Only professional attribution (assessor name + ABSA #90004 + company, already in authors:) and the public Earthsong unit/address are retained. The unredacted personal data survives only in the git-ignored raw PDF in source-files/, not in the committed wiki.
• Cross-references: OT_093 (Earthsong materials schedule — same rammed-earth thermal-mass + solar-HW envelope), earthsong_ranui case, and the sibling Earthsong performance/cost primaries OT_078 / OT_092 / OT_094 / OT_098. This page adds the building-energy-rating outturn those don’t carry.
• feeds: d04_sustainable_habitat_building + earthsong_ranui — the D04 thermal-envelope/thermal-mass lever (per the OT_093 precedent: Earthsong build-spec → d04 + earthsong_ranui) and the Earthsong case (first building-energy datapoint).

Connections

Links to

Sources (1): OT_093

EDT domains (1): D04: Sustainable Habitat & Building Technology

Cases (1): Earthsong Eco-Neighbourhood

Referenced by

Sources (1): OT_240

EDT domains (1): D04: Sustainable Habitat & Building Technology

Cases (1): Earthsong Eco-Neighbourhood