WattRumo estimates the cost of providing the same amount of useful heat through three technologies. It is a simplified educational model, not a building energy assessment.
Useful heat demand
Reference heat power (kW) = heated floor area (m²) × the selected W/m² assumption ÷ 1000. Average useful heat power = reference power × selected load factor. Daily useful heat (kWh) = average heat power × operating hours. Multiply by days and heating months for monthly and seasonal energy.
Cost per useful kWh
Direct electric heat: electricity price per kWh. Heat pump: electricity price divided by the average effective COP. Pellets: price of a 15 kg bag divided by 15 × pellet energy content (kWh/kg) × useful stove efficiency.
Important limitations
Default reference powers, utilisation, prices and efficiencies are examples rather than measured values. The calculator does not determine whether a particular appliance can heat every room, and excludes equipment purchase, distribution, servicing and fixed energy charges. Check US DOE heat-pump principles for equipment context, not for local price data.