Heat pump for an 80 m² house: what capacity do you need?
Preliminary capacity by energy class
| Energy class | Assumed W/m² | Space heating | Hot water (3 people) | Total (preliminary) |
|---|---|---|---|---|
| A++ | 15–25 W/m² | 1.2–2.0 kW | 0.6–0.9 kW | 1.8–2.9 kW |
| A | 25–40 W/m² | 2.0–3.2 kW | 0.6–0.9 kW | 2.6–4.1 kW |
| B | 35–50 W/m² | 2.8–4.0 kW | 0.6–0.9 kW | 3.4–4.9 kW |
| C | 45–65 W/m² | 3.6–5.2 kW | 0.6–0.9 kW | 4.2–6.1 kW |
| D | 60–85 W/m² | 4.8–6.8 kW | 0.6–0.9 kW | 5.4–7.7 kW |
Preliminary estimate. Calculated with the formula of our heat pump sizing tool: Q = area × W/m² for the energy class × corrections (2.7 m ceilings, 2 storeys, double glazing) × (20 − Tdesign)/43, with a design outdoor temperature of −23 °C. For hot water we add 0.2 to 0.3 kW per occupant (3 people). The W/m² bands are assumptions typical of Lithuanian buildings in that class.
A small house is a different challenge
An 80 m² home is usually a single-storey house, a summer house converted for year-round living, or a renovated older farmstead. The main risk here is not too little but too much capacity. If the heat pump's minimum output exceeds what the house needs in spring and autumn, the compressor cycles on and off frequently, which hurts efficiency. For a small house, how far the output can modulate down matters as much as the maximum.
A single-storey house has a larger roof and floor area relative to its living space, so our tool applies a 1.05 factor for one storey. Hot water is a large share of total demand here – 0.6–0.9 kW for three occupants – so cylinder size and reheat time must be matched with the capacity.
What to choose
- A well insulated house with underfloor heating is often well served by a compact ECODAN air-to-water system.
- If the house is used seasonally, we also discuss an air-to-air heat pump as primary or supplementary heating.
- For a renovated farmstead we first check whether the radiators are large enough for a lower water temperature.
Location matters too: for a class B 80 m² house the tool shows a preliminary 3.4–4.9 kW in Vilnius (−23 °C), 3.3–4.8 kW in Kaunas (−22 °C) and 3.2–4.6 kW in Klaipėda (−20 °C). The engineer takes the exact design temperature for your address from STR 2.01.02.
Next step
Enter your home's details in our heat pump sizing calculator – it shows a preliminary range with all assumptions and matching Mitsubishi Electric units from the catalogue. Then send a request: an EKO2ŠILUMA specialist will assess the house and propose a specific system.
All figures on this page are a preliminary estimate, not an engineering design. The final heat pump capacity, emitters and cylinder are confirmed by an EKO2ŠILUMA specialist after assessing your home's heat loss.
FAQ
Is an air-to-air heat pump enough for an 80 m² house?
In a well insulated open-plan house an air-to-air system can cover much of the heating, but it does not produce hot water and heat spreads unevenly into closed rooms. We decide after reviewing the floor plan.
Why not simply choose a bigger unit "to be safe"?
An oversized unit in a small house runs in short cycles, which lowers efficiency and wears the compressor faster. We size to the heat loss and provide backup heating for the coldest hours.
Does the same calculation apply to a summer house?
Only if the house is insulated and heated all winter. For an uninsulated summer house the result can exceed even the class D range, so we first recommend assessing the envelope.
Suitable equipment
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