Plain-English explanations of the jargon you'll find on energy bills, comparison sites, and in the news.
The estimated total you'd pay over 12 months based on typical household usage (Ofgem's Typical Domestic Consumption Values). Use this to compare providers like-for-like.
A government grant of up to £7,500 towards installing a heat pump or biomass boiler, available to homeowners in England and Wales.
A measure of the energy content in gas. Your meter measures gas volume, which is then converted to kWh using the calorific value for billing.
EU Allowances that companies must buy to emit CO₂. Higher carbon prices make fossil fuel generation more expensive, which can push up electricity prices.
If you move into a property and don't choose a supplier, you're automatically placed on a deemed contract — usually the most expensive tariff available.
Most providers offer lower rates if you pay by monthly direct debit rather than quarterly bills or prepayment meters.
Getting both gas and electricity from the same supplier. Many providers offer a discount (typically £20–£50/year) for bundling both.
Multi-rate tariffs that offer cheaper electricity during off-peak hours (usually overnight). Useful if you have storage heaters or can shift usage to off-peak times.
A rating (A–G) showing how energy-efficient a property is. Required when selling or renting. A higher rating usually means lower energy bills.
A charge for leaving a fixed-term contract before it ends. Typically £25–£60 per fuel. Some providers like Octopus have no exit fees.
Your unit rate and standing charge are locked for the contract length (usually 12–24 months). Protects against price rises but you may miss out if prices fall.
A tariff where the supplier matches some or all of your usage with renewable energy certificates (REGOs). Check if the supplier actually generates renewable energy or just buys certificates.
The standard unit of energy used for billing. One kWh is the energy used by a 1,000-watt appliance running for one hour. A typical Great Britain home uses ~2,500 kWh of electricity and ~9,500 kWh of gas per year (Ofgem TDCV, from 1 July 2026).
A unique 13-digit number identifying your electricity supply point. Found on your bill — needed when switching providers.
A unique number identifying your gas supply point. Found on your gas bill — needed when switching providers.
The UK wholesale gas trading hub. NBP prices directly affect what suppliers pay for gas, which eventually impacts consumer bills.
The Office of Gas and Electricity Markets — the UK's independent energy regulator. Sets the price cap, enforces supplier rules, and protects consumers.
A meter where you pay for energy in advance (top up via key, card, or app). Historically more expensive, but Ofgem now caps prepayment rates at the same level as direct debit.
Ofgem's limit on the maximum unit rate and standing charge that suppliers can charge customers on default/variable tariffs. Updated quarterly. Does NOT cap total bills — only the per-unit price.
Requires licensed suppliers to pay small-scale generators (e.g. solar panel owners) for excess electricity exported to the grid.
A digital meter that sends automatic readings to your supplier. Eliminates estimated bills. First-generation (SMETS1) meters may lose smart functionality when switching; SMETS2 meters work with all suppliers.
A daily fixed fee (in pence/day) you pay regardless of how much energy you use. Covers network maintenance, meter costs, and policy obligations. Typically 25–65p/day per fuel.
The default tariff you're placed on when a fixed deal ends. Usually the most expensive option — always check if you can switch to a better deal.
The main European gas trading hub in the Netherlands. TTF prices are a key benchmark for European and UK wholesale gas costs.
The price per kWh of energy you use. Quoted in pence per kWh. This is the main variable cost on your bill — lower unit rates mean lower bills for the same usage.
Your unit rate can change at any time (with 30 days' notice). Offers flexibility with no exit fees, but no price protection if wholesale costs rise.
A government scheme providing a £150 one-off discount on electricity bills for eligible low-income and vulnerable households. Applied automatically for most people on qualifying benefits.
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Octopus continues to lead the UK market on customer service and complaint handling, backed by genuinely competitive smart tariffs and strong financial backing. The clear front-runner on our intelligence dashboard.
Compare SupplierEDF is a steady, financially robust supplier with mid-table service and fair fixed-tariff renewals. Few surprises in either direction.
Compare SupplierThe UK's largest supplier remains financially rock-solid but service and complaint metrics continue to lag the market, with smart-meter billing delays a recurring theme.
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