Where to find each number
Power input (kW)
This is what the unit draws, not what it puts out. The older Energy Rating Label showed it as 'Power Input kW', and the specification sheet lists it too. Don't use the heating capacity: that's heat out, not power in.
Hours a day
Be honest about winter mornings and evenings. Consumer NZ's product test team says a heat pump should only run when you're home, because in most houses heat left running all day just leaks out.
Your power rate
Find the cents per kWh on your power bill. If your plan has different rates by time of day, use the one for the hours you'll run it. Leave it blank and you'll still get the kWh.
Why the answer is only a guide
Power input is a full-load figure, and a heat pump often runs below full load, so its real use usually differs from the answer. BRANZ adds that lab efficiency figures run high: a unit rated at a COP of 2.0 to 4.5 may manage only about 1.5 to 3.0 overall in practice.
Your settings matter too. Mitsubishi Electric NZ recommends 18 to 22 degrees in heat mode, and says turning it up to 28 won't warm the room any faster.
EECA's way: the yearly kWh on the label
Newer heat pumps carry the Zoned Energy Rating Label, which gives yearly heating and cooling kWh for each climate zone. All of New Zealand is in the Cold zone. EECA's method is to add the heating and cooling kWh for that zone and multiply by your own rate.
EECA says those yearly figures are only an indication, because every household uses its unit differently, and lower is better. It also says they're more useful to buyers than the old label's full-load power figure. Our running costs guide walks through both methods.