Insulation for a heat pump: what do you need?

With heat pump insulation the same rule applies as with a boiler: your home must hold heat. A boiler sends water at roughly 70 to 80 degrees to your radiators. That can heat a draughty 1930s home too. A heat pump delivers heat at a lower temperature, usually between 30 and 55 degrees. That is efficient, but only if your home keeps that heat inside.

In a poorly insulated home you lose heat faster than the delivery system can replace it. The pump has to run harder, stay on longer and use more power. Insulation lays the foundation: less heat loss means the unit can heat at a lower temperature and still stay comfortable.

Low-temperature heating (LTV) is ordinary heating with radiators, convectors or underfloor heating, but at a lower water temperature than your boiler uses. Because the water is less hot, the delivery system needs more surface area to give off enough heat. Underfloor and wall heating are built for that; many existing radiators can work too or be adapted.

Radiators with two or three panels and fins between them often already deliver enough capacity. If there is little capacity left, radiator fans, a larger radiator in the same spot or underfloor heating during a floor renovation can help. Whether you choose a hybrid or all-electric heat pump depends on how good your insulation and delivery system already are.

For a fully electric heat pump you generally need at least reasonable insulation: think of roughly 8 to 12 centimetres of roof and floor insulation (Rc around 2.5 or higher), a filled cavity wall where possible and HR++ glazing in heated rooms. That is the floor Milieu Centraal sets for all-electric. Whether your home meets it depends on what was insulated after construction, not build year alone.

If insulation is moderate, a hybrid heat pump is often a wiser first step. The pump does most of the year; the boiler steps in on cold days and supplies hot water. That way you already save gas while you insulate at your own pace. Only when insulation and delivery are in order is all-electric usually comfortable and efficient.

Want to know if your home is ready for low temperature? Run the heating test in the heating season. Set your boiler flow temperature to about 50 degrees. Set the thermostat at night no more than 1 or 2 degrees lower than during the day. See whether it warms up fast enough in the morning, even after a cold night. More on low-temperature heating is on Milieu Centraal.

Does it stay comfortable, even when it freezes hard outside? Then your home is probably ready for a heat pump, perhaps with small radiator tweaks. Is it chilly or does warm-up take very long? Then insulation or a better delivery system pays off first, or a hybrid setup until you are further along. In doubt, ask us during a heat pump survey.

Start with the biggest heat losses. Roof, facade and cavity wall, floor and glazing together decide how fast your home cools. Good glazing, extra roof or cavity insulation, floor insulation and sealing gaps often make the biggest difference. Which measure helps you most depends on build year and what has already been done.

Besides insulating, the delivery system counts. Radiator fans, larger radiators in the same place or underfloor heating with a new floor help the unit run efficiently at low temperature. If you replace the floor, consider hydronic underfloor heating, not electric floor heating: that is usually a poor match for heat pumps.

Not everyone can tackle everything at the same time. A sensible order is: fix the biggest leaks first (roof, cavity, glazing), then check delivery with the heating test, then choose hybrid or all-electric. A hybrid setup is a fine intermediate step: you already save a lot on gas while you keep insulating.

Later you can often still move to all-electric, provided insulation and radiators or underfloor heating keep pace. Subsidies for insulation and heat pumps can reinforce each other if you take both within a set period; check current conditions on RVO (ISDE) before you plan.

During a heat pump survey we look not only at your boiler, but also at cavity wall insulation, roof insulation, glazing and the type of radiators or underfloor heating. A 1930s home in the Randstad often needs different measures than a recently built terraced house.

Based on that we advise hybrid or all-electric and which insulation steps give the most before or after installation. That way you avoid the pump having to work harder than necessary. Read more on our heat pump page. Request a quote and we walk through the survey with you.