Dwellow, described as a renewable heating company, launched an interactive heat pump running cost calculator on 22 September 20261. The company said the tool lets users change the variables behind the calculation and immediately see the effect on predicted running costs1.
Users can adjust annual heating demand, heat pump efficiency, electricity tariff, existing heating system and energy prices, and can model the potential impact of solar PV and battery storage1. The tool then recalculates the figures in real time, allowing different scenarios to be compared rather than presenting households with a single headline estimate1. Dwellow said the calculator is free to use and does not require users to submit an email address or contact details1.
Dwellow said the calculator was designed to address a wider problem with discussions around heat pump economics: estimates can appear definitive when they are actually highly dependent on the assumptions behind them1. The company stated that a change in seasonal coefficient of performance (SCOP), for example, can materially alter projected electricity consumption, and that moving onto a different electricity tariff can change the economics without anything about the heat pump itself changing1. It said the calculator allows those assumptions to be adjusted individually1.
"The problem is that there isn’t one meaningful answer. Two households with apparently similar properties can have very different running costs depending on heat demand, system efficiency, electricity tariff and how the heat pump has been designed and operated."
Adam Raw, co-founder of Dwellow, said a calculator is only as useful as the assumptions behind it, and that if somebody is shown a heat pump will save them a particular amount every year, they should be able to understand where that figure came from1. He said the tool is designed to help people understand the maths rather than simply trust the output1.
Neither source reported a price for the calculator beyond it being free to use, nor any figures for typical running costs, savings or payback periods1. No launch date beyond 22 September 2026, and no availability details beyond the calculator being live, were reported1.
Why it matters for households
Running costs are the part of a heat pump decision that depends least on the appliance and most on the home and the tariff it sits on. A household comparing a heat pump with a gas boiler is comparing two sets of assumptions as much as two technologies, and the heat pump vs gas boiler running costs comparison turns on electricity and gas unit prices, efficiency and how much heat the property actually needs. A tool that exposes those inputs, including solar PV and battery storage, lets a household see how much of a projected figure comes from the tariff rather than the equipment. That matters for energy independence in the practical sense: a home with solar and a battery can shift when it buys electricity, and the calculator is built to model that alongside heating demand and efficiency. The wider heat pump running costs picture, and the heat pumps themselves, remain the two halves of the same question.
What happens next
No next steps, updates or further product plans were reported by either source1.