The Energy Glossary

What is an Agreed Supply Capacity (ASC)?

What is an Agreed Supply Capacity (ASC)? – Also known as the Available Capacity or Maximum Import Capacity (MIC), it is the maximum electrical load your site is permitted to draw from the local network. Set with your Distribution Network Operator, it ensures the network can safely support your demand and determines the capacity charges you pay as part of your electricity costs.

Can I change my ASC? – Yes. You can request an increase or decrease through your electricity supplier or directly with the DNO. Changes usually require notice, and some DNOs apply administration or amendment fees.

What is the impact if I reduce or increase my ASC?

• Reducing your ASC may lower your capacity charges, but if you later need to increase it, the DNO may charge significant costs (potentially including network reinforcement) to restore any relinquished capacity.
• Increasing your ASC will raise your capacity charges, and you may also incur assessment or upgrade fees. However, this will ensure you have sufficient headroom for growth, changing operations, or new equipment.
• Your ASC also affects TCR charge bandings, which influence the fixed network charges you pay.

What are AMR Meters?

What are AMR Meters? – AMR meters automatically send consumption readings to suppliers using one-way communication. They are commonly used by commercial sites to reduce manual meter readings and improve billing accuracy, particularly ahead of smart meter rollout.

How do they work? – AMR meters use one-way communication, typically via GSM, radio, or cellular networks, to transmit readings. They improve billing accuracy but cannot receive updates or configuration commands from the supplier.

How frequently is the data available? – Data frequency varies by device but is typically available daily, sometimes more frequently depending on the system. Some AMR solutions can provide half-hourly data, though this is not guaranteed across all meters.

Do I need to change my AMR meter if I change supplier? – Some AMR meters may lose their automated functionality when switching supplier, depending on who installed them and the communication method used. The meter itself may not need replacing, but data automation is not always maintained after a switch.

What is BSUoS?

What is BSUoS? – BSUoS (Balancing Use of System) is a charge raised on UK electricity consumers.  It covers the cost of the National Grid Electricity System Operator (ESO) to operate the electricity transmission system, and to balance supply and demand in real-time. BSUoS is essential for ensuring the stability and reliability of the UK’s electricity system

How does it work? – In addition to the ESO’s operational costs, BSUoS covers the costs associated with managing the difference between forecasted and actual electricity generation and consumption. If there is an imbalance between supply and demand, the ESO may need to take actions such as calling on flexible generation or demand-side response services to balance the grid. 

Does it impact me? – Every electricity customer contributes to the cost of BSUoS.

Historically the cost was shared by customers and generators.  However, from April 2023 generators were no longer required to pay for BSUoS, meaning that all the costs are now levied directly onto consumers.

What affects the cost of BSUoS? – The rate of BSUoS need to be competitive and in line with wholesale electricity prices, to ensure the ESO can secure the necessary power from generators which will allow them to effectively balance the network.

In addition to fluctuating wholesale prices, volatility in network demand can also impact the rate of BSUoS. The increase of renewable generation means that network demand may vary to a greater degree, introducing more uncertainty in the future costs of BSUoS.

What is the Capacity Market?

What is the Capacity Market? – The Capacity Market (CM) was introduced by the UK Government to help protect consumers from the potential of future blackouts. Payments are made to generators (to encourage investment in new capacity, or for existing capacity to remain open) as well as demand-side providers (those who are able to turn down consumption and provide relief for the grid during times of high demand).

How does it work? – Capacity Market Auctions take place twice a year, in which the amount of capacity the network requires is declared. Generators then bid at what level of price and demand they are willing to commit. If successful, the generator will be awarded an agreement which confirm their obligations, and the payments they are entitled to receive (provided they can demonstrate their capacity is available if called upon).

Does it impact me? – The cost of CM payments is recovered by suppliers through their customers’ invoices. The rates each customer will pay under CM shall depend on their forecast consumption during certain peak times – those with higher consumption will pay more, on the basis that this reflects the higher amount of demand they place on the grid during those peak times. The forecast cost will be included into fixed price contracts, and if you are billed on a “pass through” basis, you should see this as a line item on your invoice. 

Can it be mitigated? – Customers with flexible or pass through agreements (in which CM charges are reconciled) could reduce their costs by reducing the amount of power they consume during the peak times.

Businesses who qualify for Energy Intensive Industries (EII) relief can also receive significant exemptions from the cost of CM.

What is the Climate Change Levy?

What is the Climate Change Levy? – The Climate Change Levy (CCL) is a tax charged against the energy consumed by UK businesses and public sector organisations. It was designed to improve energy efficiency and reduce emissions, on the basis that the less energy these users consume, the less CCL they will have to pay.

Does it impact me? – CCL is levied against every kWh of gas and electricity that an organisation consumes from the network. Therefore, CCL will typically make up a proportion of your total energy cost each month.

Whether you have a fixed or flexible contract, you should see CCL charged as a separate line item on your energy invoice (similar to VAT).

What if I use renewable/green energy – do I still pay CCL? – If you received that gas or electricity via the network, yes. The CCL scheme incentivises consumers to reduce not just their emissions, but their overall energy demand – in particular their reliance on the national grid. If the renewable energy is generated and consumed “off grid” e.g. through on-site solar panels, it will be exempt from CCL.

Are there any other exemptions? – An organisation may be exempt from CCL (or qualify for a reduced rate) if:

• Your consumption is below certain thresholds
• You have charitable status
• You have a registered Climate Change Agreement (CCA)
• Your industry or specific operations are classed as exempt.

What are Contracts-for-Difference?

What are Contracts-for-Difference? – The Contracts-for-Difference (CfD) scheme was designed to encourage investment in new low-carbon generation assets. Generators wishing to participate in the CfD enter a competitive auction process, and successful bidders receive a “strike price” – a guaranteed rate for the power they produce. If the prevailing market rate is lower than the strike price, the shortfall is recovered through a levy applied to customers electricity invoices.

How does it work? – The CfD comprises two elements – an Operational Levy and a Supply Levy.  The first covers the administrative costs of the scheme, whilst the second covers the subsidy payments generators receive. The cost of the latter is largely determined by the prevailing wholesale market price. Low energy prices result in high CfD costs, whilst high energy prices can lead to negligible, or in extreme cases, even negative costs.

Does it impact me? – Where required, the CfD is levied against every kWh of electricity consumed from the network.  Where you have a fixed price contract, the cost will be wrapped up in your unit rate. If you are billed on a “pass through” basis, you should see this as a line item on your invoice. 

Can it be mitigated? – As CfD is charged against kWh of electricity consumed from the grid, customers can reduce what they pay by consuming less, or by consuming electricity which is not sourced from the grid i.e. on-site generation or through private wire arrangements.

Businesses who qualify for Energy Intensive Industries (EII) relief can also receive significant exemptions from the cost of CfD.

What is meant by Daily Metered?

What is meant by Daily Metered? – A Daily Metered (DM) gas supply is equipped with automated equipment that records and sends consumption data to the network every day. It’s used for large gas users whose demand can significantly impact the gas system.

What determines whether a supply should be Daily Metered? – A site becomes Daily Metered when its annual consumption exceeds the industry-set threshold (currently 58,600,000 kWh/year). Gas transporters monitor usage and mandate DM status when this threshold is met.

How do I know if my supply is Daily Metered? – Your gas bill or contract should reference ‘DM’ or ‘Class 1’. You may also have automated telemetry equipment fitted, and your supplier or shipper will confirm if your site is settled daily.

What are Data Collectors and Data Aggregators?

What are Data Collectors and Data Aggregators? – Data Collectors (DCs) are responsible for retrieving and validating your metered electricity data, while Data Aggregators (DAs) group this data for use in industry settlement. Together, they ensure your consumption is accurately recorded, checked, and submitted so suppliers can bill correctly and the market can balance energy usage across the system.

Do I need to have one? – Yes. Every electricity supply in the UK must have a registered Data Collector and Data Aggregator. These roles are essential for accurate billing, settlement, and compliance with industry rules.

Can I choose my Data Collector and Data Aggregator? – Your supplier normally appoints a default DC-DA to ensure every supply has compliant and reliable data services. However, for many commercial sites – especially Half-Hourly supplies – you can appoint your own DC-DA contract. Contracting directly for these services often allows for better data access, improved reporting, and potential cost savings. Your supplier will then register your chosen agents in industry systems.

What is a DNO?

What is a DNO? – The UK electricity network is split up into 14 geographic regions, each one managed by a DNO (Distribution Network Operator).  The DNO is responsible for operating, maintaining, and upgrading their regional electricity network, which delivers power from the national transmission system to homes and businesses. 

They manage connections, outages, and infrastructure investment on the local network, as well as set Distribution Use of System (DUoS) tariffs, recovering those costs from suppliers, who pass those through to their customers.

What is DUoS?

What is DUoS? – DUoS (Distribution Use of System) charges cover the cost of delivering electricity through local distribution networks, as well as the funding of network maintenance and upgrades.

How is it charged? – DUoS is charged via your electricity supplier and either included within your unit rates or as separate pass-through costs, depending on your contract structure. The types of charge can vary – in addition to fixed charges, different unit rates may be applied based on your metered consumption during specific time bands (red, amber, green).

What influences the amount of DUoS I pay? – several factors affect DUoS costs.  These include: Your region (each DNO sets its own tariffs); Your supply’s voltage level; Your contract structure; Your demand profile, such as how much you use during peak ‘red’ periods.

What is the EII Support Levy?

What is the EII Support Levy? – The EII Support Levy is a tax which supports the funding of the Energy-Intensive Industries (EII) Support Scheme. That scheme provides financial relief to UK businesses operating in key sectors, in an effort to make them more competitive with their international counterparts.

Does it impact me? – Unless your business qualifies for EII support, yes. The cost of the EII Support Scheme is charged to suppliers based on their market share. Suppliers then recover those costs via the EII Support Levy in their customers’ invoices.  

Where you have a fixed price contract, the cost will be included up in your unit rate. If you are billed on a “pass through” basis, you should see this as a line item on your invoice.

What is the Feed-in-Tariff?

What is the Feed-in-Tariff? – the Feed-in-Tariff (FIT) scheme was designed by the UK government, and aimed to increase the uptake of renewable and low-carbon technologies. Participants are paid for the energy the generate and export to the grid via their installations, and the money they received is collected via the Feed-in-Tariff levy.

Could I receive the FIT for my installation, and how much could I be paid? – The FIT scheme was closed to new participants in April 2019, but generators who are already registered can receive support for up to 25 years. The rates a participant receives can vary depending on what type of installation they have, its capacity, and when it was registered.

Does it impact me? – The cost of Feed-in-Tariff is recovered by a levy applied to every kWh of electricity consumed from the network. Where you have a fixed price contract, the cost will be wrapped up in your unit rate. If you are billed on a “pass through” basis, you should see this as a line item on your invoice.
The rate at which FIT is charged can vary, depending on factors such as the tariffs of each participant, and the volume they generate.

Can it be mitigated? – As FIT is charged against kWh of electricity consumed from the grid, customers can reduce what they pay by consuming less, or by consuming electricity which is not sourced from the grid i.e. on-site generation or through private wire arrangements.
Businesses who qualify for Energy Intensive Industries (EII) relief can also receive significant exemptions from the cost of FIT.

What is a Half-Hourly Meter?

What is a Half-Hourly Meter? – A Half-Hourly meter automatically records and sends electricity consumption data every 30 minutes. It’s typically used for larger commercial sites or supplies with higher demand, providing highly accurate billing and detailed usage insight.

How do I know if my supply is Half-Hourly? – Your electricity bill or contract will show a profile class of ‘00’ at the beginning of the MPAN, which indicates a Half-Hourly supply. You may also have a dedicated HH data collector appointed to your account.

Can I get access to my consumption data? – Yes. Half-Hourly data is available through your supplier or data collector, often via online portals. Businesses can use this data to analyse consumption, identify inefficiencies, and improve energy management.

What is a Kilowatt-hour?

What is a Kilowatt-hour? – A kilowatt-hour (kWh) is a unit of energy representing the use of one kilowatt of power over one hour. It is the standard measure for electricity consumption in the UK, used for billing, monitoring usage, and comparing the energy demand of different appliances or sites.

Is kWh also used for measuring gas consumption? – Yes. Gas usage is often converted from therms or cubic metres into kWh to standardise energy measurement and allow comparison with electricity consumption.

What are Limpet Meters?

What are Limpet Meters? – A limpet meter is a small, clamp-on water meter that attaches externally to a pipe, allowing flow measurement without cutting or altering the pipework. Often used for sub-metering, temporary monitoring, or sites where intrusive installation is impractical, it provides a cost-effective, low-disruption solution for tracking water consumption.

Why might they be preferred over an AMR? – Limpet meters are non-intrusive, easy to install, and ideal for temporary or hard-to-access sites. Unlike traditional AMR meters, they avoid pipe modifications, and can cost less to install and operate.

What are Losses?

What are Losses? – Losses refer to the electricity that dissipates as heat when power flows through the transmission and distribution networks. These losses are unavoidable and vary depending on distance, voltage, and network conditions. Suppliers pay for losses on behalf of customers, who ultimately see these costs reflected within their electricity charges.

What determines the level of Losses that apply? – There are a number of factors can impact losses, including your geographic location, the voltage level of your supply, and the overall efficiency of the network at different times.

Is there any way to improve the Losses associated with my supply? – Loss factors themselves cannot be changed by an individual customer. However, businesses can limit the impact by improving their energy efficiency and reducing overall consumption, or by exploring on-site generation, which reduces the volume of electricity drawn from the wider network.

What is a Meter Operator?

What is a Meter Operator? – A Meter Asset Manager (MAM) is a company responsible for a gas or electricity meter, including installation, maintenance, safety checks, and asset tracking. They ensure meters comply with industry standards and are correctly recorded in national databases, supporting accurate billing, regulatory compliance, and reliable operation.

Do I need to have one? – Every metered gas or electricity supply requires a registered MAM to ensure the meter is safely installed, compliant, and correctly maintained.

Can I choose my Meter Operator? – Usually, your energy supplier appoints a default MAM for your site, but business customers can often contract directly with an alternative accredited MAM – potentially securing better commercial terms or service levels.

What is a Meter Operator?

What is a Meter Operator? – A Meter Operator (MOP) is a specialist provider responsible for installing, maintaining, and managing electricity meters at commercial sites. They ensure metering equipment is accurate, compliant, and capable of sending reliable data to industry systems. MOPs also provide fault support, communications equipment, and other services essential for Half-Hourly metering and accurate billing.

Do I need to have one? – If you have a Half-Hourly electricity supply, you must have a contracted Meter Operator. For Non-Half Hourly sites, a dedicated MOP isn’t mandatory but may still be beneficial in certain cases.

Can I choose my Meter Operator? – Yes. Whilst your electricity supplier will appoint a default MOP to ensure that every Half-Hourly supply is legally compliant, you are free to appoint your own MOP directly. Contracting directly with a MOP can offer improved service levels and often more competitive pricing. Your supplier must then register your chosen MOP in industry systems.

What is an MPAN?

What is an MPAN? – An MPAN (Meter Point Administration Number) is a unique 21-digit reference number that identifies the electricity supply point for a property or site in the UK. It’s sometimes called an “Electricity Supply Number”.

What is it used for? – Suppliers use the MPAN to locate your electricity meter, confirm supply details, quote for new contracts, and manage changes such as upgrades, meter exchanges, or site works.

How can I find out my MPAN? – Your MPAN appears on your electricity bill, usually in the “Supply Number” or “S Number” box. If you can’t locate it, your current supplier or distribution network operator (DNO) can provide it.

What is an MPRN?

What is an MPRN? – An MPRN (Meter Point Reference Number) is a unique number that identifies your gas supply point. They are typically 6–10 digits long, and are specific to gas connections.

What is it used for? – Suppliers use your MPRN to match your business to the correct gas meter, arrange new contracts, validate consumption, and manage site changes or upgrades.

How can I find out my MPRN? – Your MPRN is shown on your gas bill. If unavailable, you can obtain it from your current supplier or the Meter Point Administration Service (MPAS).

What are MW and kW?

What are MW and kW? – Megawatts (MW) and Kilowatts (kW) are units of power representing the rate of energy use or generation. They are widely used in the UK electricity market to describe generation capacity, demand, and baseload supply in wholesale trading and settlement terms. 1 MW = 1,000 kW.

How are MW and kW used in wholesale trading? – In wholesale markets, generators and suppliers trade electricity based on MW. Baseload contracts represent continuous MW supply over a period, while Peak contracts will reflect higher MW demand during specific hours.

How do MW and kW differ from kWh? – MW and kW measure the rate of energy use or generation, whereas kWh measures total energy consumed over time.

What is a Non-Half Hourly Meter?

What is a Non-Half Hourly Meter? – A Non-Half Hourly meter records electricity usage through manual or periodic reads, rather than every 30 minutes. It’s common for smaller commercial sites where detailed data isn’t currently required for settlement.

How do I know if my supply is Non-Half Hourly? – Your electricity bill or contract will show a profile class between 01 and 08 at the beginning of the MPAN, which identifies a Non-Half Hourly supply. These meters may also show actual, estimated, or customer-submitted reads.

Will I be able to get access to my consumption data in the future? – Yes. Under the Market-wide Half-Hourly Settlement (MHHS) programme, all NHH supplies will move to half-hourly data collection in the coming years. This will give businesses access to more detailed consumption information and more accurate billing once the transition is complete.

What is meant by Non-Daily Metered?

What is meant by Non-Daily Metered? – A Non-Daily Metered (NDM) supply is a gas meter that does not send daily consumption data to the network. Instead, usage is estimated based on annual forecasts and periodic meter readings.

How do I know if my supply is Non-Daily Metered? – Your supply will be listed as NDM or a settlement class between Class 2–4 on bills or supplier documentation. Manual or periodic reads are also a sign of NDM status.

My supply is Non-Daily Metered – How can I get access to my consumption data? – NDM sites can install a data logger (also called AMR or pulse loggers), which records and stores detailed interval data for analysis. This provides near-real-time insights even though the site is not settled daily.

What is the Nuclear RAB?

What is the Nuclear RAB? – The Nuclear RAB is a levy that functions in much the same way as Contracts-for-Difference, with the money collected from end users going towards the funding of low-carbon generation – in this case, nuclear generation assets.

Does it impact me? – Nuclear RAB is levied against every kWh of electricity consumed from the network.  Where you have a fixed price contract, the cost will be included in your unit rate. If you are billed on a “pass through” basis, you should see this as a line item on your invoice.  The relevant rates will be determined by Ofgem, and suppliers may seek to reconcile charges if final rates outturn materially different to forecasts.

Are there any exemptions? – Businesses who qualify for Energy Intensive Industries (EII) relief can receive significant exemptions from the cost of Nuclear RAB.

What is Reactive Power?

What is Reactive Power? – Reactive power is the component of electricity that supports voltage and maintains the magnetic fields needed for equipment such as motors, transformers, and fluorescent lighting. It doesn’t perform useful work but is essential for system stability. Excessive reactive power demand reduces network efficiency, and UK businesses may face additional charges if their power factor is poor.

Is there any way to improve the Reactive Power associated with my supply? – Yes. Businesses can reduce reactive power charges by improving their power factor. Common solutions include installing power factor correction (PFC) equipment, optimising motor loads, maintaining electrical systems, and upgrading inefficient machinery. These measures help reduce unnecessary reactive demand and can lower network-related charges.

What are REGOs?

What are REGOs? – REGOs are certificates that confirm a unit of electricity was generated from renewable sources. They provide transparency so businesses and suppliers an demonstrate the renewable content of their electricity.

How do they work? – Generators receive one REGO for each megawatt-hour of renewable electricity produced. Suppliers then purchase and retire these certificates to evidence the renewable percentage of the energy they supply to customers.

How can I obtain them? – You can obtain REGOs through your electricity supplier as part of a renewable or green tariff, or by purchasing certificates separately through a consultant, broker or specialist trader.

Is there a cost? – REGOs have a variable market value influenced by supply, demand, and wider policy changes. Costs are typically bundled into green tariffs, but standalone certificate prices can fluctuate throughout the year.

How do I know if they’re included in my contract? – Your supply contract or tariff information should state whether REGO-backed electricity is included. If unclear, your supplier or consultant can confirm the renewable content of your agreement.

What is the Renewables Obligation?

What is the Renewables Obligation? – The Renewables Obligation (RO) scheme was designed to encourage investment in large-scale renewable electricity generation. The cost is recovered via a levy which is applied to customers’ electricity bills. Suppliers then use the revenue collected to invest in and secure renewable electricity.

Does it impact me? – Renewables Obligation is levied against every kWh of electricity consumed from the network. Where you have a fixed price contract, the cost will be wrapped up in your unit rate. If you are billed on a “pass through” basis, you should see this as a line item on your invoice.
The rate at which RO is charged has climbed steadily year-on-year, so customers should anticipate and be prepared for future increases.

Can it be mitigated? – As RO is charged against kWh of electricity consumed from the grid, customers can reduce what they pay by consuming less, or by consuming electricity which is not sourced from the grid i.e. on-site generation or through private wire arrangements.
Businesses who qualify for Energy Intensive Industries (EII) relief can also receive significant exemptions from the cost of RO.

What are RGGOs?

What are RGGOs? – RGGOs are certificates that verify gas has been produced from renewable sources, such as anaerobic digestion. They allow organisations to demonstrate credible, traceable renewable gas consumption.

How do they work? – Producers are issued an RGGO for each kilowatt-hour of renewable gas injected into the grid. Suppliers or organisations purchase and retire these certificates to evidence the renewable proportion of their gas use.

How can I obtain them? – You can purchase RGGOs through your gas supplier as part of a green gas product or buy them independently via certificate traders, consultants, or specialist brokers.

Is there a cost? – RGGO prices vary based on market demand, production levels, and sustainability criteria. Costs are not fixed and can change significantly over time, especially for higher-quality or audited certificates.

How do I know if they’re included in my contract? – Your gas contract should specify whether renewable gas or RGGOs form part of the supply. If not clearly stated, your supplier can confirm the proportion, source and certification attached to your tariff.

What is meant by Smart Metering?

What is meant by Smart Metering? – Smart meters are modern electricity or gas meters that automatically record usage and share it via the national smart metering network. They are used by homes and businesses to support accurate billing, detailed monitoring, and time-of-use tariffs.

How do they work? – Smart meters use two-way communication, allowing suppliers to receive readings and send updates to the meter. This enables remote configuration, improved accuracy, and better visibility of consumption patterns.

How frequently is the data available? – Electricity smart meters typically provide half-hourly data as standard, with gas data updated daily. This high-resolution information is useful for analysing usage and identifying efficiency opportunities.

Do I need to change my Smart Meter if I change supplier? – If you have a SMETS2 Smart Meter, it should remain fully functional when switching suppliers. Older meters (those installed before 2019) may lose certain features with some suppliers, but many have now been migrated to the national network.

What is a SPID?

What is a SPID? – A SPID (Supply Point Identifier is a unique identifier for commercial water and wastewater connections in the UK. Each site may have separate SPIDs for potable water, wastewater, and trade effluent.

What is it used for? – Water retailers and wholesalers use the SPID to manage your account, track consumption, handle billing, and resolve operational or service issues.

How can I find out my MPAN? – Your SPID can be found on your water or wastewater bill. If not listed, your water retailer can confirm it by checking your account details or supply address.

What is Surface Water Drainage?

What is Surface Water Drainage? – Surface Water Drainage charges cover the removal of rainwater from roofs, car parks, and other hard surfaces into public sewers. It ensures safe and efficient drainage, preventing local flooding and environmental issues.

How is the cost determined? – Charges are based on the size and type of impermeable surfaces on your property and the water company’s tariff structure. Larger or more heavily paved sites typically incur higher fees.

How do I know if Surface Water Drainage applies to me? – SWD applies to most commercial properties connected to a public sewer. Your water bill will usually show a separate line for surface water drainage, or your water provider can confirm if your property is liable.

What is TCR?

What is TCR? – Targeted Charging Reform (TCR) is a regulatory change designed to make electricity network charges fairer and more predictable. It replaces certain demand-based transmission and distribution charges with fixed charges, meaning customers contribute based on their site’s characteristics rather than when they use electricity. This reduces volatility and prevents avoidance of network costs.

Who is affected by this? –  All electricity customers – domestic, commercial, and industrial – are affected. Non-domestic sites are placed into charging bands based on their voltage level and historic consumption. These bandings dictate the rates which will apply each supply

Is it possible to mitigate the impact? – TCR charges themselves cannot be avoided or reduced through load shifting. However, businesses can mitigate overall costs through improvements in efficiency and by reducing their underlying demand. This may allow them to be captured into lower change bandings in the future.

What are Therms?

What are Therms? – A therm is a unit of energy widely used in the UK to measure gas consumption, particularly with regard to trading and forecasting demand. One therm equals 100,000 British thermal units (BTUs) and can also be used for billing, reporting, and market settlement. It provides a standardised measure across sites, suppliers, and gas qualities.

How do Therms relate to kWh? – One therm is approximately 29 kilowatt-hours (kWh) of energy. Gas suppliers often convert therms to kWh on bills and for reporting purposes, enabling a consistent comparison with electricity consumption.

What is TNUoS?

What is TNUoS? – Transmission Network Use of System (TNUoS) charges cover the cost of using the UK’s high-voltage electricity transmission network, managed by the National Grid ESO. These charges fund maintenance, upgrades, and operation of the transmission system, and are recovered from suppliers and passed through to end consumers. TNUoS varies by region, demand, and supply profile.

How is it charged? – TNUoS can comprise of both fixed and demand-based charges:

• Fixed/Residual charges are applied to all connected sites.
• Demand charges are based on a user’s peak electricity usage and location, reflecting the cost of delivering power across the transmission network.

What influences the amount of TNUoS I pay? – There are a number of factors which can influence your TNUoS costs:

• Your location (different regions of the country have different tariffs)
• Your peak demand (higher peak usage can leads to increased charges)
• Supply type (domestic, commercial, or industrial)
• Voltage level and settlement class

What is Trade Effluent?

What is Trade Effluent? – Trade Effluent refers to any non-domestic wastewater discharged into the public sewer from industrial, commercial, or business activities. It differs from normal wastewater because it can contain chemicals, oils, or other materials requiring treatment.

How is the cost determined? – Charges are calculated based on volume, composition, and strength of the effluent. Heavier, more polluting discharges incur higher fees because treatment is more complex and costly.

How do I know if Trade Effluent charges apply to me? – If your business discharges industrial or commercial wastewater into the sewer, your water bill or contract will list Trade Effluent charges. If uncertain, contact your water company for assessment and confirmation.

What is meant by Unidentified Gas?

What is meant by Unidentified Gas? – Unidentified Gas (UIG) refers to gas volumes lost, unaccounted for, or not attributed to a specific shipper or site in the UK gas network. UIG charges are allocated across suppliers, ensuring the system remains balanced and costs are recovered in a fair manner.

How does UIG occur? – The Unidentified (or “lost”) gas can be caused by a number of factors, such as pipe leaks, theft, and consumption via unregistered meters, all of which leaves the gas unaccounted for.

How can it be tracked? – In 2017 the industry implemented Project Nexus, which aimed to gain a more accurate view on the volume of Unidentified Gas through new processes for reads and settlements. In 2020, the volume of UIG in the UK was calculates at more than 40% higher than previous estimates. 

Does it impact me? – As the shortfall cannot be attributed to a specific source, the cost of UIG is spread across all suppliers, who then pass these charges on to consumers in their gas rates.  Every registered meter point will be charged UIG, regardless of the meter type, industry or location, and the rate which applies to each meter will vary based on a number of factors, including consumption.