Energy & Sustainability
Home Energy Calculators & Guides
Find → measure → cost → prioritise. Start from your bills, not an average household.
Collect electricity and heating bills, then measure the loads you can identify. Use the audit calculator to estimate appliance energy and running cost; compare these estimates with the bill before ranking changes. For the measurement sequence, start with the DIY audit guide.
What do you want to work out?
Where should I begin an audit?
Inputs to gather
Bills or meter records, appliance labels, measured energy or wattage, and operating hours.
Find the baseline, measure loads, calculate their cost and prioritise changes. A rating label is an input to an estimate, not proof of actual annual consumption.
Which measured appliances cost the most to run?
Inputs to gather
Appliance power, operating hours, electricity price and total bill consumption.
Compare annual kWh and cost, then check the gap between listed appliances and your bill. This is not a professional building heat-loss assessment.
Find, measure and prioritise home energy useWhat do my always-on loads cost?
Inputs to gather
Measured standby watts, hours powered and electricity tariff.
Rank devices by annual cost using measured power. Decide whether a proposed change is safe and practical before treating all standby demand as avoidable.
How do I compare gas meter readings with energy bills?
Inputs to gather
Gas volume or energy units, billing calorific value and any correction factor.
A volume-to-energy conversion needs billing assumptions. Compare like-for-like energy quantities, not cubic metres directly with electricity kWh.
Guides behind the calculations
Convert inputs when needed
Before choosing a calculation
Which appliance should I investigate first?
Start with the largest measured annual cost or an unexplained portion of your bill. Watts alone do not rank annual use: operating hours matter too. Use measurements rather than a universal household percentage.
Why does my appliance list not add up to my bill?
Check missing loads, cycling equipment, operating hours and the period covered. Treat the difference as something to investigate, not an automatic estimate of waste.
Should I insulate or install generation first?
Measure your baseline and compare each proposal’s cost, expected energy change and practical constraints. The audit helps prioritise; it does not establish that one investment is always best.
Your next decision
Use the heating demand you established to compare replacement running cost and payback.
Use your consumption and tariff records as inputs to the generation and savings decision.