Half-hourly (HH) data is a record of the electricity a meter measures in every half hour: 48 readings a day, usually in kWh. The terms you will meet most often are kWh (energy, what you are billed for), kW (how fast electricity is being used at a given moment), base load (the demand that never switches off) and kVA (the unit your supply capacity is set in).
- Agreed supply capacity
- The maximum demand, in kVA, an electricity connection is set up for. It appears on larger electricity bills and is also called authorised or available capacity. More.
- Annualised figure
- A yearly figure scaled up from the valid readings available. It is used when the data covers less than a full year or has gaps.
- Balancing Services Use of System (BSUoS)
- A charge that covers the National Energy System Operator's cost of balancing the electricity system. A fixed rate per MWh, set in advance for six-month periods. More.
- Base load
- The level of demand a building rarely drops below: what never switches off. The analyser measures it as the 5th percentile of half-hourly demand. More.
- Capacity Market (CM)
- A scheme that pays providers to keep enough reliable capacity available. Businesses pay for it according to their electricity use between 4pm and 7pm on working days from November to February. More.
- Climate Change Levy (CCL)
- A tax on energy used by businesses, charged per kWh. Holders of a climate change agreement pay a reduced rate. More.
- Closed-hours excess
- Electricity used while a building should be closed, above its base load. The analyser ranks sites by it. More.
- Contracts for Difference (CfD)
- Contracts that give low-carbon generators a fixed price. Suppliers pay a levy that rises when wholesale prices are low and falls, even to zero, when they are high. More.
- Coverage
- The share of expected half-hourly readings that are present and valid.
- Degree days
- A measure of how cold (heating degree days) or warm (cooling degree days) a period was. Used to compare energy use across periods with different weather.
- Distribution Use of System (DUoS)
- Charges for using the local distribution network, set by your network operator. They combine unit rates that vary by time band, capacity charges and fixed daily charges. More.
- DNO
- Distribution network operator. The company that runs the local electricity network and your site's connection to it. The first two digits of your MPAN show which one. More.
- Half-hourly (HH) data
- A record of the electricity used in every half hour: 48 readings a day.
- Heatmap
- A chart of every half hour in a period, with one column per day and one row per half hour, coloured by demand. Also called a carpet plot. More.
- kVA
- Kilovolt-ampere. A measure of apparent power, and the unit supply capacity is set in. kVA = kW ÷ power factor.
- kW
- Kilowatt. A measure of power: the rate electricity is being used at a given moment. Divide a half-hourly reading in kWh by 0.5 to get the average kW for that half hour.
- kWh
- Kilowatt-hour. A measure of energy, and what you are billed for. Using 1 kW for one hour is 1 kWh.
- Load factor
- Average demand divided by peak demand. A low load factor means demand has short, high peaks.
- Market-wide half-hourly settlement (MHHS)
- The move to settle every electricity meter in Great Britain using half-hourly data. More.
- MPAN
- Meter point administration number. The 13-digit number on the bottom line of the supply number on an electricity bill. It identifies the supply point. More.
- Non-energy costs
- Everything in an electricity price apart from the wholesale energy: network charges, policy costs and taxes. More.
- Nuclear RAB levy
- A levy on suppliers that funds the building of new nuclear power stations under the Regulated Asset Base model, starting with Sizewell C. More.
- Peak demand
- The highest half-hourly average demand in a period, usually in kW or kVA.
- Power factor
- The ratio of real power (kW) to apparent power (kVA), between 0 and 1. Equipment such as motors lowers it.
- Profile class
- The first two digits of the top line of the supply number. 00 means the supply is settled half-hourly; 01 to 08 mean use is estimated from standard profiles. More.
- Red, amber and green bands
- The time bands most network operators use for distribution unit rates, with a different price in each. Each operator sets its own times. More.
- Renewables Obligation (RO)
- A scheme requiring suppliers to present certificates for each MWh they supply, or pay a buy-out price. The cost is passed on per unit. More.
- Settlement
- The process that works out how much electricity each supplier's customers used, and when, so suppliers pay the right amount for it.
- Time-of-use tariff
- A tariff with different unit rates at different times of day, such as day and night rates.
- Transmission Network Use of System (TNUoS)
- Charges for using the national high-voltage transmission network. For business sites, mainly a fixed charge per site per day, banded by agreed capacity or consumption. More.
- Wholesale price
- The price suppliers pay for electricity on the wholesale market, often called the commodity cost. More.