The NZ Energy Stack

In what order should a Kiwi homeowner upgrade their home? Spend in this order and every dollar after the first works harder than the one before it.

1

Insulate & seal first

Ceiling, underfloor and draught-stopping. The cheapest kWh is one you never have to buy.

Cuts heating bills by up to 30% (EECA)
Typical cost $2k–$4k
90% co-funded for pre-2008 owner-occupiers (Warmer Kiwi Homes)
Why first? Sizing a heat pump or solar system for a leaky house is like buying a bigger jug because the lid's off. Fix the envelope first and everything that comes after gets smaller, cheaper and more effective.
2

Switch every bulb to LED

Smallest job on the list, fastest payback. Often done in one Saturday afternoon.

Uses ~80% less power than halogen
Payback 6–18 months
Total cost typically under $400
Why next? Almost-free quick win that lowers your baseline load before you size HVAC and solar. No paperwork, no installer, just a screwdriver.
3

Hot water + space heating (heat pumps)

The two biggest power users in most NZ homes. Modern heat pumps deliver 3–4 kWh of heat per 1 kWh of power.

Hot water = ~30% of the average bill
Heating = ~25–35% of the average bill
WKH covers up to $3,450 on a heat pump
Why now? With a tight envelope and a lower lighting load, a smaller, cheaper heat pump system will keep you just as warm — and the running cost is roughly a third of resistance heating.
4

EV & smart charging

If a battery-electric or plug-in hybrid is on your horizon, get the wiring sorted now — it shapes how solar pays back.

EV running cost ~$0.04/km off-peak vs $0.18/km petrol
Wall charger $1,500–$2,500
Pairs with night rates & solar self-consumption
Why before solar? An EV is a giant daytime battery if you charge from your roof. Knowing whether you'll have one (and a 7kW charger) changes the optimum solar & battery size by a meaningful amount.
5

Solar PV & battery (last, not first)

Now you know your real load profile, you can size solar to match it instead of guessing.

Sized to your roof, retailer & usage
Typical 6kW system $12k–$16k
Eligible for 1% Green Home Loan
Why last? Solar payback is ruled by self-consumption — i.e. how much of what you generate you use yourself. Doing the cheaper steps first shrinks the system you need, often by 30–40%, and shortens the payback by years.

One principle to remember

Reduce, then replace, then generate. Cut the load before you size the gear. It's the difference between a $35k retrofit and a $20k one with the same outcome.

Want this tailored to your home?

Our free home audit applies the stack in order, factoring in your climate zone, year of build, retailer rates and any Warmer Kiwi Homes grant you may qualify for.

Start My Free Audit