We believe further transparency is important in the sector. To help provide customers with information on the costs associated with heat networks, we have developed a Heat Cost Calculator.

The Heat Cost Calculator provides a general indication of what you could expect to pay for heating and hot water in a similar sized property that used an individual gas boiler. It has been created for information purposes only and does not provide a bespoke assessment.
There are few information sources available to help customers get a sense of the cost of heat networks compared to an alternative. The Heat Cost Calculator has been developed to provide customers access to better information on the cost of their heating and hot water needs against a common alternative.

It is a starting point. The Heat Cost Calculator is a tool which we intend to improve over time. Feedback from users will help inform future developments and improvements to the information the Heat Cost Calculator can provide customers.
The Heat Cost Calculator is operated by Heat Customer Protection Ltd, which manages Heat Trust.
The Heat Cost Calculator compares against gas central heating as it is the most common type of heating in the UK.

However, for a number of properties, particularly high-rise flats or off-gas grid properties, the correct alternative heating system to compare against would be electric heating.

We do intend to update the Heat Cost Calculator so that it can also compare against electric heating.
HIU stands for Heat Interface Unit, or sometimes a Hydraulic Interface Unit, which is a more technical term for the same thing. It is the bridge between the main heat network and the individual heating pipes in each individual property. On modern heat network schemes, in place of a gas boiler, each property has an HIU. There are four main types of HIUs: Direct HIU, Indirect HIU, Heat only HIU and a HIU with a cylinder for hot water.
The Heat Cost Calculator is not looking to assess the efficiency of the heat network. It aims to provide a general indication of what you could expect to pay for heating and hot water in a similar sized property that used an individual gas boiler. It has been created for information purposes only and does not provide a bespoke assessment.

It does not, therefore, factor in the performance of the heat network or the HIU.

The Building Engineering Services Association (BESA) has published a UK test standard for HIUs recently. BESA is now conducting tests on different HIUs and will publish results on its website here: https://www.thebesa.com/heating-interface-units 

The Calculator takes the amount of heat you use (or an estimate if you are unsure) and factors in boiler efficiency, repair and maintenance costs, and the cost to replace a boiler for the size of your property.
Anyone can use the Heat Cost Calculator, but if you live in a rented property or you do not have an individual heat meter, the Heat Cost Calculator is less reliable.

Council / Housing Association properties: Where the landlord is a council or a housing association, customers can be charged in different ways. Some customers pay their heat charge with their rent. Others receive their heat charge as two bills, for example, a customer may pay some of their heat charge as part of their rent and other costs such as repairs, as part of their service charge.

Some council and housing association homes do not have separate meters to record how much heat each customer is using, so bills may be a share of heat and hot water used by the whole building.

Private rented sector: For customers that rent from a private landlord, there are some costs that would be borne by the landlord as the owner of the property, such as the cost of installing a replacement boiler or boiler repair and maintenance. These costs may be passed on to the customer in rent.

Due to the variation in billing methods, the Heat Cost Calculator assumes that a single heat bill is provided. Therefore, the Heat Cost Calculator will be most relevant to owner-occupiers that receive a single heat bill from their heat supplier.
The Heat Cost Calculator is a guide, not a bespoke assessment. It is for information purposes only and is not intended to show whether or not your heat price is fair. If you have any concerns about your heat charge, you should contact your supplier directly.
Yes, you can still use the Calculator, but the result will not be accurate as the Calculator will still calculate the annual cost for heating and hot-water for a home using a gas boiler.
Yes. If you do not know how much heat you have used, the Calculator will use an estimate based on the size of your property.
Please choose the one that is the closest match.
For a property with an individual gas boiler, gas is received from the national gas network, which is then used within the property to provide heating and hot water. The costs of servicing the boiler, repairs, insurance and replacement of a boiler are separate additional costs, on top of the gas bill.

For a property on a heat network, all the costs associated with heating a home are typically within a single heat bill. This includes the cost of the fuel (e.g. gas, biomass), repair, servicing and maintenance costs, and metering and billing costs.

In order to provide a more like-for-like comparison, we take into account boiler replacement, repair and maintenance costs.

All of the quotes used are within two standard deviations away from the mean. This principle is used to remove substantial outliners. The average of the quotes is used by the Calculator.
To make the Calculator as transparent as possible, we have only used publically available data. This allows customers using the Calculator to understand exactly how the calculation is made. Other analysis has used unpublished data which Heat Trust is not able to verify and customers cannot access.
The information you provide and the results that the Calculator produces will be held by Heat Trust. We may, as part of a wider project, share results from the Calculator with the Department for Energy Security and Net Zero.

All data is collected and held in line with the Data Protection Act as set out in our data protection policy.

No personal data is collected by Heat Trust.
Yes. We would welcome feedback on the Heat Cost Calculator via our feedback survey which you can access here.
If you have a problem with the tool, try refreshing the webpage. If this does not work, please send an email to This email address is being protected from spambots. You need JavaScript enabled to view it.