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- KĀINGA ORA HOUSE RENOVATION, ONE TREE HILL TRADE ACADEMY
EnergyTight™ Retrofit delivers 88% of the energy benefit of a traditional renovation, at a fraction of the time and cost.
88% of the energy savings. None of the disruption.
Energy modelling on a Kāinga Ora house renovation, using NZGBC ECCHO
software shows that an EnergyTight™ Retrofit achieves 88% of the energy reduction of a full deep renovation, while costing significantly less, taking days not weeks, and leaving the property completely undisturbed internally.
The key difference is that the EnergyTight™ Retrofit achieves this by improving airtightness and ventilation rather than retrofitting wall insulation — avoiding the cost and disruption of removing internal linings. All scenarios include ceiling and underfloor insulation, which is non-intrusive and straightforward to add.
Cost comparison
Traditional deep renovation
$150,000
Remove linings, add wall insulation and double glazing. 12 ACH50
$36,000
$12,000
“For the cost of one traditional renovation, you could upgrade 12 homes with an EnergyTight™ light retrofit — or 4 with a deep retrofit. The difference in energy performance between the approaches is surprisingly small.”
Energy performance comparison
Beyond energy — the full case for EnergyTight™ Retrofit
Days, not weeks
An EnergyTight™ Retrofit is typically completed in one to two days. No linings removed, no trade sequencing. Tenants return immediately. A traditional deep renovation takes weeks and leaves units uninhabitable throughout.
Ideal between tenancies
The vacancy period is the perfect window. Work is complete before the next tenancy begins — no disruption to tenants and no loss of rental income during extended renovations.
Health and indoor air quality
Controlled mechanical ventilation delivers fresh filtered air continuously —
reducing condensation, mould and indoor pollutants. Airtightness and ventilation provide health outcomes that
insulation alone cannot deliver.
Moisture management and durability
Airtightness prevents warm moist air entering wall and ceiling cavities — eliminating hidden condensation that leads to mould, timber rot and long-term building damage. Protects the asset, not just the occupant.
Measured and certified
Every AeroBarrier install has an airsealing certificate. The result is measured, not estimated.
Portfolio scale
At the low cost of An EnergyTight™ Retrofit, a community housing provider
can upgrade an entire portfolio for the
cost of a handful of traditional renovations — with comparable energy
outcomes and far less disruption.
“We’ve taken a 1970s Kāinga Ora home from 19 air changes down to just 1.7 ACH50—a level of performance well beyond most new homes. Absolutely amazing.”
Charlotte McKeon, Project Leader, One Tree Hill, Trade Academy