Frequently Asked Questions

Your new billing provider

From 1 March 2021, your heat billing service will be managed by Vital Energi. You will no longer receive any bills or communications from ISTA from 1 March 2021.

Vital Energi is an energy provider with over 30 years experience in delivering a variety of energy solutions to support our clients in meeting their net zero carbon targets.Our services include complete metering and billing solutions to provide our customers, housing providers and energy providers with absolute confidence in the accuracy and reliability of their systems

We currently manage over 36,000 meters throughout the country and provide both Credit Billing and Pay As You Go solutions. We have worked with the University of Cambridge for many years and currently provide a number of services on the North West Cambridge Development

Our in-house Customer Service Centre is based at our Head Office in Blackburn and supports our customers and clients throughout the country. We are on hand 8am-6pm Monday to Friday (excluding public holidays) to help you to make the switch to becoming a Vital Energi customer

To learn more about Vital Energi, our services for you and transitioning to us as your new billing provider, Click here

Why is my bill being produced by a new company?

The re-procurement of services is standard practice to ensure both the client and their customers continue to receive the best value and highest standards of service possible.

Following a rigorous procurement process, Vital Energi have been awarded the billing services contract. This will see Vital Energi take over the day to day management of the billing contracts from ISTA, the previous billing provider

Vital Energi will provide the billing services from 1 March 2021. All customers will receive further information about Vital Energi via letter, along with an explanation of the next steps to complete the switch to your new billing provider.

For further information on Vital Energi and the services we will be providing, please click here

What do you need to do as a result of the move of billing to Vital

During February 2021, you will receive a Welcome Letter through the post which will outline what you need to do as a result of Vital Energi becoming the new billing provider.

The Welcome Letter will include registration / switching instructions. Alternatively, this can be done online via our registration page here

The Welcome Letter will also provide your Authorisation Code and Customer Code, which will allow you to register onto our online Glass metering and billing platform.

New Direct Debits will need to be set up with Vital Energi to enable you to pay your bill.

Please ensure that you provide us with the most up to date and correct contact details at the time of registration.

More information about Glass can be found here

What is my Core tariff?

There are different tariffs depending on the type of resident you are. Please click on the below tariff document appropriate for your situation.

Download Tariff Document for University tenants on new rental model

Download Tariff Document for Private Apartments

Download Tariff Document for Private Houses

Please note retail units are dealt with on a case-by-case basis. Please contact us for more information.

All unit rates and charges include VAT at 5%

I’m a landlord and want my tenants to pay their bills – How do I do this?

If you are a landlord it is your responsibility to provide the Heat Supply Agreement and Registration Form to your tenants to sign and return to Core via email. The account for the property will then be created in the tenant’s name and all bills will be sent to that tenant. This process must be repeated for each change of tenancy.

Download Heat Supply Agreement for Private Houses

Download Heat Supply Agreement for Private Apartments

Download Heat Registration Form

Incorrect Heat Supply Agreements will not be accepeted as a binding contract and it is imperative to ensure the correct contract is filled in and completed infull.


To help you manage any arrears payments to Core, we are able to create a payment plan based on your circumstances which will allow you to continue receiving heat while reducing the amount of your heat debt.

If you wish to arrange a payment plan, please contact our customer service team.

We don’t ever want to disconnect your heat supply and we will always explore every alternative. However if no solution can be found we will install a 'pay as you go' meter, which means unless regular payments are made your heating and hot water supply will be cut off. Before we install a 'pay as you go' meter we will provide written notice of at least two weeks in advance.

If you are having any payment difficulties, please contact us to discuss your circumstances. We will never knowingly disconnect the energy supply if you are a registered vulnerable customer.

What happens if i move house?

If you are a homeowner and are leaving your Eddington property, please make sure to let us know so you are no longer responsible for the property’s Core bills. Please email us on to tell us of any change in circumstances.

Why do we have a district heating network?

As part of the planning requirements to build Eddington the development was required to include a District Heating Network. As well as this the North West Cambridge Development is committed to creating a sustainable community. Innovative and unique sustainability initiatives are built into every aspect of our community, to minimise the environmental impact of the development and offer a high quality of life.

How does the Energy Centre and District Heating Network work?

At Eddington, there is a centralised heating system, which combines an Energy Centre and a District Heating Network. Together this delivers hot water directly to each property from the central shared supply. The heat distribution network provides all of the heating and hot water requirements, without the need for individual gas boilers within the homes. The primary elements of the system are as follows:

Energy Centre

The Energy Centre is the central location where heat and hot water is generated.

Heat Interface Unit (HIU)

This is the heat unit within each home, which delivers heating and hot water. The HIU enables individual temperature control within the home, and allows for each home to be individually metered for its own heat and hot water use.

Heat Metering and Billing

Each HIU has a heat meter which enables heat used to be billed to each dwelling on a periodic basis.

Distribution Network

The distribution network is the system of pipes distributed across the development to deliver hot water to each home.

How is CORE Greener?

The central plant reduces emissions by heating the water used for all buildings, instead of hundreds of gas boilers all working to heat small amounts of water that may not be used. This means Core only produces heat that is used, with far less waste and excess emissions.

Does CORE Use Renewable Energy?

The Core central plant is gas fuelled. However, the way in which heat is generated and transferred results in a more efficient system than a traditional individual boiler.

Core did look into using alternative sources of fuel but they would have been unreliable, less available and inappropriate for a residential development. Please be assured that we have left room in the energy centre to switch to other methods of energy production with future-proof technology.

We would also like to reassure residents that Eddington uses a large number of photovoltaic panels which are on the roof of most buildings on the development which contributes to our renewable energy strategy. There is also an extensive water recycling system on the development to reduce water wastage and all buildings on the development are at Level 5 against the industry-recognised Code for Sustainable Homes or BREEAM Excellent for non-residential buildings.

How is this different from a traditional gas bill?

The misleading issue with comparing Core to other utility companies is that we charge you for the amount of heat and hot water that your home uses. Other companies charge you for the gas provided to your home. Gas and heat, while they are both measured in kWh, cannot be compared readily on a like-for-like basis as it does not take energy losses and efficiencies associated with conventional gas systems into account.

But my Energy Performance Certificate says I should be paying less?

The Energy Performance Certificate is a very general estimate of how much energy a home uses. This is a Government-designed document that is a “one size fits all” estimate.

This can create much confusion for customers across the energy industry, but all utility companies are required to produce the certificate, even if it is inaccurate.

How can I reduce my bill?

As your usage costs are based on how much heat your home actually uses, your bill will go down if you cut usage. Here are some tips on how to save:

Turn Your Thermostat Down

Understand Your Heating System And Its Controls

Keep Furniture Away From Radiators

Manage The Temperature Of Your Home

Avoid Drying Clothes On The Radiators

Any other questions?

If you have any questions or concerns about your Core bill please email or call 01254 296 000.