NEOBIOME

OT_029: Rewiring Aotearoa / EECA (2024) — Electric Homes Technical Report

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topicsenergy_generation, energy_storage_grid, building_habitat, mobility_transport, community_finance, nz_specific

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OT_029: Rewiring Aotearoa / EECA (2024) — Electric Homes Technical Report

Source

https://www.rewiring.nz/electric-homes-report — original source (opens in a new tab; the file is not redistributed)

Rewiring Aotearoa / EECA (2024) — Electric Homes Technical Report

Advocacy-charity report — peer-reviewed, EECA-co-modelled, transparent parameters

Authored by Rewiring Aotearoa (a charity advocating electrification); dataset commissioned and co-modelled by EECA (Dr Gareth Gretton); peer-reviewed by Prof. Shaun Hendy; released March 2024. Directional conclusions favour electrification, but every price/efficiency/finance parameter is disclosed in the methodology appendix, so individual figures are usable with the assumption set attached. All figures are average-home values (2.8 people, 1.8 vehicles), 2023-price, 15-yr lifetime, 5.5%/1% finance — re-derive for community-scale aggregates. Primary source behind the heat-pump COP 3.5 (CR_014) and the regional space-heat index (CR_015).

Summary

The Electric Homes Technical Report (Rewiring Aotearoa, dataset commissioned and co-modelled by EECA, peer-reviewed by Prof. Shaun Hendy, March 2024) is a national NZ techno-economic model of fully electrifying the “average” New Zealand home — 2.8 people, 1.8 vehicles, ~11,000 km per vehicle per year — across space heating, water heating, cooktops, vehicles, rooftop solar, and home batteries. Its headline finding is that NZ is “one of the first countries where the electrification of homes and vehicles can deliver both cost-of-living savings and emissions reduction simultaneously”: an average gas/LPG-plus-petrol home spending ~19,137/year (annualised, incl. capital at 5.5% finance) can save ~1,485/year by electrifying on the grid, or ~$4,699/year with solar + battery at 1% green-loan finance. The report frames household energy as a decarbonisation decision point — ~31% of NZ’s domestic-use emissions trace to household energy decisions — and argues that today’s commercially available, scaled technologies are sufficient.

The technical core is a per-appliance lifecycle comparison. Heat pumps are the lowest-cost and lowest-emission space-heating option (COP ~350% in NZ vs gas ~75–85%, resistive ~100%, wood ~55–75%); heat-pump-with-solar water heating is the cheapest hot water; induction cooktops are ~2–3× more efficient than gas/LPG; and electric vehicles convert 87–91% of input energy to motion vs 16–25% for petrol (≈4× efficiency). On the supply side, rooftop solar is presented as the lowest-cost delivered energy available to NZ homes at ~6 c/kWh (0% finance) or ~12 c/kWh financed, versus ~34 c/kWh average grid delivered cost (~24 c/kWh excluding fixed costs). Home batteries are at a NZ tipping point at 700–1,300/kWh installed (~17–28 c/kWh per stored cycle). The full-household model (7 kW solar + 7 kWh battery) cuts average daily energy use from 87 kWh to 27 kWh and 15-year operational emissions from ~105 t CO₂e to ~4.5 t CO₂e.

Key claims

  • The average NZ home is modelled as 2.8 people and 1.8 vehicles, driving ~11,000 km per vehicle per year. OT_029 (Fig 1 source note p.3; p.48)
  • Annualised whole-home cost (15-yr lifetime, capital incl., 5.5% finance): LPG appliances + petrol vehicles 19,137/yr; gas + petrol 18,445/yr; electrified on grid 17,355/yr; electrified with 7 kW solar + 7 kWh battery 17,306/yr → savings of 1,485/yr at 5.5% finance** and **4,699/yr at 1% finance (average). OT_029 (Fig 1, p.3; Fig 41–42, p.45)
  • ~31% of NZ’s domestic-use emissions (38.2 Mt of 80.8 Mt total 2021) are household energy decisions. Household emissions = 18.2 Mt, of which household vehicles 8.7 Mt, household combustion (e.g. gas) 2.7 Mt, household electricity use 1.2 Mt. OT_029 (Fig 2–4, pp.6–8)
  • Heat-pump space heating COP ~350% (3.5) on average in NZ, dropping to ~200% in very cold conditions and exceeding 400% in warm; gas/LPG ~75–85%, resistive electric ~100%, wood fire ~55–75%. OT_029 (pp.12, 14; methodology p.54)
  • Space-heating energy per day (average home): gas/LPG 11.6 kWh, wood fire 14.3 kWh, resistive electric 9.3 kWh, heat pump 2.7 kWh. OT_029 (Fig 8, p.14)
  • Space-heating 15-yr total cost (upfront + operating): LPG 26,396, gas 20,608, wood 13,848, resistive electric 15,318, heat pump 11,805, heat pump + solar/grid 10,815. OT_029 (Fig 7/10, pp.13, 16)
  • Space-heating 15-yr operating emissions: LPG 13,907 kg, gas 13,843 kg, wood 1,963 kg, resistive 5,002 kg, heat pump 1,429 kg, heat pump + solar/grid 1,000 kg CO₂e (gas/LPG ≈10× heat pump). OT_029 (Fig 11, p.17)
  • Water-heating energy per day: gas/LPG instant 6.88 kWh, resistive tank 7.26 kWh, heat pump 2.07 kWh; heat-pump water-heating efficiency ~350% (315% in-model incl. 10% tank losses). Annual operating cost LPG 709 → heat pump+solar 67. OT_029 (Fig 14–15, pp.19–20; methodology p.54)
  • Cooktop efficiency: gas/LPG ~30%, electric resistance 70–80%, induction 80–90%; energy/day 2.08 / 0.89 / 0.81 kWh; switching gas→electric saves ~2,000 kg CO₂e over 15 yr. OT_029 (p.24; Fig 20–23, pp.24–27)
  • Vehicle efficiency: EVs convert 87–91% of input energy to motion vs 16–25% for petrol (≈4×); model uses ICE 27.4 MPG, EV 116.8 MPG-equivalent. Annual driving cost petrol 4,336, EV grid 2,230, EV solar $1,703. OT_029 (pp.12, 28; Fig 25/27/29; methodology p.55)
  • Per-vehicle 15-yr operating emissions: petrol 42,488 kg; EV (fast or grid) 4,313 kg; EV solar-charged 0 kg CO₂e. OT_029 (Fig 30, p.33)
  • Rooftop solar is the lowest-cost delivered energy for NZ homes: ~0.06/kWh (0% finance) or ~0.12/kWh (5.5% finance), vs grid average 0.34/kWh (Gen 0.15 + Dist 0.09 + Retail 0.06 + Trans 0.02 + Metering 0.02) or 0.24/kWh excluding fixed costs; assumes solar 2,000/kW, 30-yr term, 15% capacity factor. OT_029 (Fig 31–32, pp.34–35)
  • Home batteries are at a NZ tipping point: installed 700–1,300/kWh → ~17–28 c/kWh per stored cycle (15-yr/one-cycle-per-day life incl. degradation), vs ~33 c/kWh grid (24 c excl. fixed); 5,475-cycle life, 95% round-trip efficiency. OT_029 (p.38; methodology p.56)
  • Full-household electrification cuts average energy use from 87 kWh/day to 27 kWh/day; whole-home 15-yr operational emissions LPG+petrol 105,266 kg → electrified+solar+battery 4,461 kg CO₂e; embodied emissions of solar + battery pay off in ~2 years. OT_029 (Fig 37/43, pp.42, 46; pp.58–59)
  • NZ delivered-energy unit costs (methodology): **electricity volume 24.2 c/kWh; ripple-control off-peak 18.0 c; gas 11.0 c; LPG 18.9 c; petrol 27.4 c/kWh (2.59/L); diesel 20.6 c/kWh; wood 11.3 c/kWh**; electricity fixed cost 689/yr. Appliance install benchmarks: heat pump 3,800 + 1,050; heat-pump water heater 4,700 + 2,320; induction cooktop 1,400 + 1,300. OT_029 (methodology pp.55–57)
  • Regional space-heating-energy and solar-CF variables: Auckland 74% / CF 15.5%; Wellington 173% / 14.9%; Christchurch 124% / 14.3%; Dunedin 198% / 12.5%; average 100% / 15% (Table 1, p.47) — the regional space-heat index used as the method anchor in CR_015. OT_029

Neobiome Intelligence relevance

This is the most directly NI-load-bearing national NZ source for household-scale electrification economics, and the primary behind two earlier synthesis ingests: its heat-pump COP 3.5 is the figure CR_014 cited via EECA, and its Table 1 regional space-heat index (Auckland 74% … Dunedin 198%) is the method anchor CR_015 used. It supplies, in one peer-reviewed and EECA-co-modelled package, the per-appliance efficiency factors, NZ unit energy prices, install-cost benchmarks, and solar/battery assumptions the NI energy and habitat skills need.

  • D01 (Renewable Energy & Storage) — the rooftop-solar delivered-cost stack (6 c/kWh unfinanced, 12 c/kWh financed, vs 34 c/kWh grid) and the battery tipping-point band (700–1,300/kWh → 17–28 c/kWh per cycle) are national anchors corroborating the community-scale benchmarks in CR_008 and the yield in CR_010 (the report’s 15% CF is conservative vs Lower Moutere’s 15.4–15.8%).
  • D04 (Sustainable Habitat & Building) — heat-pump COP 3.5, the heating-option lifecycle cost/emissions ladder, induction/resistive cooktop efficiencies, and appliance install costs feed the demand-reduction side of any community-scale building model — the appliance-level numbers behind the BRANZ HEEP end-use shares referenced via CR_009.
  • D05 (Smart Mobility) — the EV-vs-petrol TCO and ≈4× efficiency figures, plus the solar-charged-EV zero-operating-emissions result, give the household-economics layer beneath the fleet/charger inventory in RD_010 and RD_011.
  • SSI (I01/I07/I06) — the whole-home savings (1,485/yr grid, 4,699/yr solar+battery) and the resilience framing (Cyclone Gabrielle, Christchurch earthquake) are evidence for financial sufficiency, basic-needs, and shock resistance (relevant in prose; not fed as entity updates).

Caveats for NI use: Rewiring Aotearoa is an advocacy charity; directional conclusions favour electrification, but all parameters are transparently disclosed and EECA-co-modelled. Figures are average-home (2.8 people, 1.8 vehicles), 2023-price, 15-yr/5.5%/1%-finance — re-derive for community aggregates. The 12 c/kWh feed-in tariff and ripple/off-peak rates are 2023 values now superseded by the 1 July 2026 time-varying buy-back reform tracked in CR_011.

Research targets

Documents to retrieve

  • Australia & New Zealand Residential Baseline Study 2021 (energyrating.gov.au, publ. Nov 2022) — the primary behind every average-home energy-use figure here (space/water heating, cooktop, appliance shares); would let NI cite per-appliance NZ energy use directly. Cross-ref.
  • Frontier Energy Residential Cooktop Performance and Energy Comparison Study (2019) and MfE Warm Homes Technical Report (2005) — primaries behind the cooktop and space-heating efficiency factors. Cross-refs.
  • MBIE Energy Prices + QSDEP 2023 — the NZ unit-price series behind all operating-cost figures (later vintages when published). Cross-ref.

Research gaps

  • The “national per-region household energy-use + solar-CF table” OT_029 lacks (only 4 regional scenarios) is already met by the national solar yield (RD_013, 16 regions) and regional demand (RD_016) now in the wiki — no new target.
  • Battery cost-per-cycle recalibration — reconcile OT_029’s 17–28 c/kWh-per-cycle band against the Powerwall-3 89% full-cycle RTE and commercial-scale $300–550/kWh in CR_008 (relates to existing RT_111/RT_150).
  • The flat 12 c/kWh feed-in tariff is superseded by the post-1-July-2026 time-varying regime (CR_011) — apply current export economics in any whole-home savings figure.

Connections

Links to

Sources (10): CR_008 · CR_009 · CR_010 · CR_011 · CR_014 · CR_015 · RD_010 · RD_011 · RD_013 · RD_016

Referenced by

Sources (3): OT_067 · OT_070 · OT_162

EDT domains (3): D01: Renewable Energy & Storage Systems · D04: Sustainable Habitat & Building Technology · D05: Smart Mobility & Electrified Transport

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