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Energy & running costs
How to Compare Heating Costs: A UK Homeowner’s Worksheet
Build a heating budget using useful heat demand, fuel prices and performance assumptions. Keep capital, maintenance, standing charges and hot water separate.
A useful heating comparison is a worksheet of assumptions, not a league table with one winner for every home. Different rooms, hours and temperatures change the amount of warmth required before equipment efficiency is considered.
Use the steps below in a notebook or spreadsheet. All figures in the worked example are hypothetical, not current tariffs, a property assessment or an Aircon Elite quotation. Their purpose is to show calculations you can replace with evidence for your own home.
Row one: define the same heating task
Write down the rooms covered, target temperatures and operating hours. Then record an annual useful heat requirement in kWh for that defined task. This should come from an appropriate assessment or clearly labelled estimate, not simply the capacity printed on an appliance.
For the example, assume 3,000 kWh of useful space heat each year. Use that same demand for every option. If one proposal heats fewer rooms, show it as a separate scenario rather than presenting its smaller bill as an efficiency saving.
Row two: enter fuel prices
Record electricity and gas prices in pounds per kWh, including the treatment that applies to your bill. Note the tariff period and whether the rate varies by time of day. Use Ofgem’s unit-rate guidance for context, but your actual contract takes priority.
For this worksheet only, assume electricity costs £0.30/kWh and gas £0.08/kWh. These rounded numbers are not a forecast. If using time-of-use electricity, calculate a credible weighted price rather than applying the cheapest overnight rate to all heating hours.
Row three: state performance assumptions
Enter an assumed average COP of three for an air-to-air heat pump, a boiler efficiency of 0.90 and point-of-use direct electric conversion of approximately one. These are calculation assumptions, not measured values for equipment at your property.
Ask the installer for evidence supporting the proposed heat-pump performance under relevant conditions. A seasonal test figure and an instantaneous COP are not interchangeable. Our electric-heater guide explains the technology difference; include distribution losses consistently when setting the comparison boundary.
Row four: calculate purchased energy and fuel cost
Divide useful heat by the performance factor. The example heat pump uses 3,000 ÷ 3 = 1,000 kWh of electricity, costing £300. Direct electric heating uses approximately 3,000 kWh, costing £900. The boiler uses 3,000 ÷ 0.90 ≈ 3,333 kWh of gas, costing about £267.
These are space-heating fuel totals only. They do not establish whole-house bills or prove a purchase decision. For the detailed gas comparison and a break-even calculation, see air conditioning versus gas heating.
Row five: keep other costs visible
Add separate rows for installation, maintenance, expected repairs and any financing. Record existing standing charges and identify which would genuinely disappear. If gas remains connected for cooking or hot water, do not count the whole gas standing charge as an avoided cost.
Add retained hot-water provision and any additional summer cooling consumption. Keep one-off capital costs distinct from annual expenses. A simple payback figure is meaningful only when the saving is positive, the scope is consistent and the assumptions remain reasonable over the period considered.
Row six: test uncertainty before deciding
Repeat the calculation using lower and higher heat demand, electricity prices and heat-pump performance. Include a scenario where several rooms operate simultaneously if that is realistic. Label every change so you can see what drives the result rather than hiding uncertainty in one total.
Aircon Elite’s custom design service can help assess an air-to-air proposal within its air conditioning range. Compare comfort, coverage and practical constraints alongside the worksheet. The arithmetic is a decision aid, not a guarantee that a predicted saving or payback will occur.