By Ash Sunda — Lead Engineer & Co-Founder, Pleasant Plumbers Limited. Gas Safe Registered Engineer No. 946687.
Twenty months. That is how long office landlords with central plant serving multiple tenants have to register with Ofgem — or commit a criminal offence after 26 January 2027.
On 27 January 2026, Ofgem began regulating heat networks across Great Britain. The legal and consultancy press has covered the launch extensively. The operational question for commercial office landlords with central plant serving multiple tenants is less about whether the regulation exists than where its perimeter sits and what the practical compliance position is by January 2027.
The Energy Act 2023 and the Heat Networks (Market Framework) (Great Britain) Regulations 2025 establish two regulated activities: operating a heat network and supplying heat through one. The definition of "heat network" captures both district networks (multi-building) and communal networks (multiple premises within a single building). Houses in multiple occupation and converted residential buildings with shared domestic heating are explicitly exempted. Commercial multi-tenant buildings are not.
A Heat Supply Contract under the new regime is defined to include a lease, a tenancy, or a service-charge arrangement. An office landlord operating central plant that distributes heating to tenants and recovers cost through service charge is, on the face of the regulations, supplying heat under a deemed Heat Supply Contract. Existing operators were deemed authorised from 27 January 2026 and must register with Ofgem by 26 January 2027 via the Heat Networks Digital Service launching this spring. Operating without authorisation after the registration deadline is a criminal offence.
First, the registration question is operational, not aspirational. Where a building serves two or more separate commercial demises from a single heat source, the arrangement is likely to fall within scope. The boundary cases are still being clarified by Ofgem. Where the answer is unclear, the safer position is to scope the registration on the assumption that the network is in scope and seek confirmation rather than the reverse.
Second, subcontracting does not delegate regulatory responsibility. A landlord who has appointed an FM contractor, service provider, or in-house team to operate the heat network remains the operator and supplier under the regulations unless an Energy Services Company (ESCO) has been formally appointed with substantial control over both operation and the consumer contractual relationship. Most landlord-run heat networks fall short of that threshold. The landlord remains the regulated entity.
Third, the technical standards layer is still settling. The Heat Network Technical Assurance Scheme (HNTAS) is planned to launch in 2027 and will phase in mandatory technical requirements through TS1, a standard developed by DESNZ from CIBSE CP1. CP1 was first published in 2015 and updated in 2020. Most office heat networks predate it as the recognised reference, and will need a gap assessment against TS1 ahead of the HNTAS launch. Distribution losses, temperature regimes, metering architecture, and operational performance will become reportable.
For commercial property directors and FM heads with central heating plant serving multiple commercial demises:
Where an FM contractor or service provider is in place, the regulatory responsibility almost certainly remains with the landlord. The question is not whether the contract delegates the work. It is whether the contract delegates regulated supply — and in most cases, it does not.
The deadline for registration is twenty months away. The default position for unregistered operators after January 2027 is unauthorised supply.
Pleasant Plumbers Limited works with London commercial landlords and FM teams on heat network scope assessment, registration support, and TS1 gap analysis. Ash and the engineering team deliver a single written compliance position you can share with legal counsel and Ofgem.
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Ash Sunda is Lead Engineer and Co-Founder of Pleasant Plumbers Limited. Gas Safe registered (No. 946687), Ash leads the commercial engineering function and advises London landlords, managing agents, and FM teams on plant operation, compliance, and statutory readiness across central heating and heat network installations.