How much electricity does a heat pump use, and what drives it?

A heat pump’s electricity consumption is determined by three things: the house’s heat demand, the heat pump’s efficiency and the weather. The rule of thumb is that a heat pump delivers typically three to four times as much heat as it uses in electricity — that is the whole point of the technology. The exact consumption depends on your house: size, insulation, desired temperature and whether the heat pump also produces hot water. There is no single number that fits everyone — but you can read your own pattern, and you can make the consumption work for you.

What determines a heat pump’s electricity consumption?

• The house’s heat demand. A large, older house with modest insulation needs far more heat — and thus electricity — than a new, tight one. Heat demand is the single biggest factor.
• Efficiency (COP/SCOP). Efficiency states how much heat the pump delivers per kilowatt-hour of electricity used. It drops the colder it is outside and the hotter the water the system must deliver — underfloor heating with low flow temperature is therefore cheaper to run than old radiators with high.
• The weather. Consumption follows the cold: the most expensive weeks are the coldest. That is also why annual consumption varies from year to year.
• Hot water. If the heat pump also produces domestic hot water, that adds a steady consumption all year round.

If you want your own number, read the heat pump’s electricity meter (or the house’s) over a period of typical weather — that beats any table.

When is electricity for the heat pump cheapest?

With an hourly-priced contract, the price swings across the day — typically cheapest at night and most expensive at the late-afternoon peak. The grid tariff also varies across the day and pulls in the same direction. On the electricity prices page you can enter your postcode and see your total price hour by hour.

Heat pump consumption is hard to shift manually, though — the house needs to be warm when you are home. This is where control makes the difference: the house and the hot water tank act as storage, so heat can be produced slightly offset from when it is used.

From cost to income: let the heat pump work for the grid

The heat pump’s flexibility is worth more than just shifting consumption after the price. The grid must be kept at 50 Hz at all times, and Energinet buys reserves such as FCR-D in daily auctions — and a heat pump can take part through a virtual power plant. Activations are short pauses of seconds to minutes, drawing on the heat already in the house and the hot water tank — too brief to be felt on the temperature. Activations come in bursts: some days 5–6 of them, then perhaps ten days without — on average a few per week.

NM1 can connect heat pumps to the virtual power plant: larger installations from 10 kW through Balance, and if you have a smaller heat pump, contact us and we will assess whether it can be connected. Revenue is shared with you, with quarterly payout as an ordinary bank transfer — see what your heat pump can earn under calculate your earnings. FCR-D prices vary from auction to auction — past earnings are no guarantee of future earnings. In the web app you can follow your devices, activations over a chosen period and your payouts.

Where to go next

If you are unsure whether the heat pump, the water heater or a battery is best suited to deliver flexibility, read the comparison of the three devices. To understand the market behind the income, the article on grid balancing for households is the right place to start — and you can sign up your heat pump on the get started page.