Calculate annual kWh savings, dollar savings and payback period for upgrading ceiling, wall or floor insulation.
A typical NZ home with no ceiling insulation (R0) upgraded to R6.6 over 80 m² in Wellington can save 1,500–2,500 kWh per year — approximately $480–$800 per year at 32c/kWh. Payback on a $2,000–$3,000 installation is typically 3–5 years.
Yes. Insulation works both ways — it reduces heat flow into the house in summer and out of the house in winter. A well-insulated ceiling can reduce summer indoor temperatures by 2–4°C and significantly reduce air conditioning costs.
NZ HDD (base 18°C) varies significantly by location: Auckland ~800, Wellington ~1,800, Christchurch ~2,100, Dunedin ~2,400, Queenstown ~2,800. NIWA provides precise data. Higher HDD means more heating required and greater insulation savings.