Supply chain advice pack: Warm Homes: Heat Networks
Introduction
A heat network in its simplest form consists of a central heat source, which provides heat to buildings (space heating & hot water) via a network of underground and in building pipes.
Networks vary in size and complexity and have different characteristics based on heating technology used. The ultimate goal of a heat network is to provide heat in an efficient and affordable manner to end-users.
Contents
In the UK we use the term ‘heat networks’ as an overarching term to cover a range of network archetypes:
- District Heat Networks – Large campus, neighbourhood or city-wide networks where multiple buildings are connected to the network. These can include a mix of domestic and non-domestic buildings across different tenure types.
- Communal Heat Networks – Typically these networks are single buildings with multiple occupants. These can be mixed use and across different tenures but are predominately made up of domestic connections.
Other forms of network do exist or may be referenced:
- Ambient loop or ambient networks - This type of network is uncommon.
- Campus network - This is typically a reference to a heat network supplying a hospital, University or other campus or building complex.
Benefits of a heat network
- Cost efficiency: Distributing heat from a central source can achieve economies of scale and lower overall installation and maintenance costs.
- Energy efficiency and carbon reduction: Heat networks are more efficient and therefore produce fewer carbon emissions than traditional heating systems. This improves SAP and EPC ratings.
- Regulatory compliance: Upgrading existing networks and creating new networks complies with regulation set out in the Energy Security Bill and the Heat Network meter and billing regulations.
- Energy security: This is achieved by diversifying energy sources and reducing dependence on fossil fuels. Additionally, it can help shield residents from market-dependent oil and gas prices.
- Future proofing: These systems are adaptable and can be upgraded to incorporate new technologies and energy sources, ensuring they remain efficient and sustainable in the long term.
- Local economic growth: The need for installation and maintenance of these systems can create local jobs and stimulate investment in the community.
Warm Homes funding and heat networks
The key aims of the Warm Homes Funds are to:
- Retrofit homes to reach EPC band C.
- Deliver warm, energy efficient homes.
- Reduce carbon emissions.
- Reduce household energy bills and tackle fuel poverty.
- Support green jobs.
- Develop the retrofit sector.
- Improve the comfort, health and wellbeing of social housing tenants; and
- Provide value for money and least regrets approach to retrofit.
Further details on the Warm Homes Fund Scheme Guidance can be found here: WH:SHF Wave 3 Scheme Guidance
Warm Homes: Social Housing Fund - key heat network principles
- Low carbon heat (LCH) measures can include any SAP-eligible LCH measures including Air Source Heat Pumps (ASHP), Ground Source Heat Pumps (GSHP), shared ground loops, solid biomass (in exceptional circumstances only), connections to low carbon heat networks (existing or new) and storage heaters.
- Heat Networks are eligible for the low carbon heat incentive on gas grid (£20,000 grant) and off gas grid (£7500 grant uplift).
- Heat networks and the development of new heat networks are not required to comply with PAS 2035:2023 and installers of heat networks are not required to be MCS registered.
- Communal heat network and district heating schemes must be installed in accordance with the Heat Trust Consumer Protection Scheme.
- Must deliver carbon savings and be optimised for operation with a low flow temperature i.e. below 55°C.
- Heat Network Zoning is to be implemented as a national policy programme in 2025 and connections to these networks will be mandatory within defined zones.
- Warm Homes funding may be used alongside other sources of funding to provide households greater flexibility. However, the following rules must be taken into consideration:
- Funding must not be used simultaneously with other government energy performance schemes (e.g. Energy Company Obligation (ECO) and Boiler Upgrade Scheme (BUS)) to install the same measure. Different measures may be installed at the same property using different schemes.
- It is the responsibility of the local authority (LA) to ensure that the results regarding blended funding from all funding sources are abided by.
- The LA can blend Warm Homes funding with third-party finance or LA budgets.
- LA’s are encourage to use the DESNZ-owned Energy Efficiency Installation Check to ensure that households do not duplicate funding from different schemes for the same resource.
SAP point (EPC) impact of low carbon heat networks
Domestic EPCs are calculated based on the Standard Assessment Procedure (SAP). A dwelling’s energy efficiency is scored from 1-100 which is then converted to an ‘A’ to ‘G’ banding (the EPC rating).
A SAP score of 69 or above represents an EPC of C or above. This score is calculated through a combination of performance criteria dwellings fabric, heating, ventilation and energy use.
In SAP10, carbon intensity factors for different fuels (electricity, gas, biomass) have changed. This means a typical dwelling will have to improve its carbon emissions by up to 35% on the previous versions of SAP.
For heat networks the big change is that the default distribution losses modelling for SAP have been set at 50%.
Therefore, care needs to be taken to properly model network heat losses for entry into the assessment as well as consideration for insulation specification and distribution piping arrangements (i.e., fewer lateral runs with multiple risers can be favourable as smaller bore pipe results in higher network heat losses).
More details of the SAP can be found here: Standard Assessment Procedure - GOV.UK.
Planning for heat networks
When designing your scheme to be compatible for a heat network, you should take the following high level compatibility steps into account:
- Adopt a wet heating system with a centralised heating source and distribution system for each building or across all buildings (communal heat network).
- Install low carbon heating technology and associated distribution systems in accessible locations for future heat network connections.
- Engage with existing heat network operators to ensure the building's heating system is designed for future connection.
- Design systems to enable a transition to the heat network without building shutdowns or heat outages.
Other design considerations for compatibility with heat networks include:
- Design heat emitters and underfloor heating for the temperature of the heat network or lower.
- Ensure appropriate fabric insulation to use heat efficiently and enable low return temperatures.
- Use variable flow pumping systems to help with lower return temperatures.
- Install final customer heat meters where required by regulations.
- Monitor building heat load on a half-hourly basis to determine the required heat network connection size accurately.
Also consider space and planning for future equipment:
- Reserve space for future heat network connection substations, including heat exchangers, filtration, valves, pumps, controls, and heat meters.
- Plan routes for foundation level sleeved pipes into the building and reserved/safeguarded pipes to the interface of the building system.
Account for suitable flow and return temperature design:
- Design heating systems to minimise flow and return temperatures to ensure the efficiency of the wider network.
- Use weather compensation on heating systems to lower average return temperatures.
- Ensure hot water generation equipment is designed to achieve low return temperatures.
And assess options for future connection planning:
- Plan for efficient transitions from existing to new heat providers, avoiding long-term energy or asset contracts without suitable break or variation clauses.
- Design systems to minimise disruption to building users and others in the locality.
Heat networks – other considerations
Heat Networks are currently an unregulated market, however, under the Energy Security Bill (2023) new technical, zoning and pricing regulations will be introduced. Organisations considering connecting to or developing a heat network should consider:
- The impacts of Heat Network Zoning, and whether their building will be mandated to connect.
- The impacts of the Heat Networks Technical Assurance Scheme (HNTAS), and ability of existing networks to meet minimum criteria (CIBSE CP1).
- Impacts of the Heat Metering and Billing Regulations 2014 (HNMBR), and implications on how residents are billed.
- Implications of regulation by OFGEM on customer tariffs and protections.
- Support and advice from industry and associations including the Heat Trust, Citizens Advice, Energy Ombudsman, Association of Decentralised Energy (ADE) and UK District Energy Association (UKDEA).