Glossary · Controls, energy efficiency and insulation
What are heating zones?
A heating zone is an area of a home with its own temperature control, so it can be heated separately from the rest. Zone control is the system of controls that does this. In the building regulations a heating zone is an area on one floor with the same thermal characteristics and control needs throughout.
Key points
- Approved Document L defines a heating zone as an area on one floor with the same thermal characteristics and temperature control requirements.
- New wet heating systems in dwellings of 150m2 or more should have at least two independently controlled heating circuits.
- A zone can replace room-by-room control in a single-storey open-plan home where the living area is over 70% of the floor area.
- Two adjacent rooms with similar use and heating needs, such as a kitchen and utility room, can be treated as one zone.
- Domestic hot water should have time control that is separate from space heating where it comes from a hot water store.
How heating zones work
Without zoning, one thermostat and one timer decide the heating for the whole house. With zoning, the home is divided into areas. Each can have its own temperature setting, and in many designs its own timing. A typical split is bedrooms and living areas, or one floor against another.
Approved Document L, the energy efficiency guidance under the building regulations in England, defines a heating zone as a conditioned area of a building on one floor, with the same thermal characteristics and temperature control requirements throughout.[1]Ministry of Housing, Communities and Local Government, Approved Document L, Conservation of fuel and power, Volume 1: Dwellings, 2021 edition incorporating 2023 amendments
What the rules ask for
The guidance sets out several points that relate to zones.
| Situation | What Approved Document L says |
|---|---|
| New wet system, dwelling of 150m2 or more | A minimum of two independently controlled heating circuits |
| New dwelling, or boiler replaced in an existing one | Each room should have thermostatic control, or each heating zone where justified |
| Single-storey open-plan home, living area over 70% of floor area | The whole dwelling can be treated as one heating zone |
| Two adjacent rooms with similar function and heating needs | They can be treated as one zone, for example kitchen and utility room |
| Hot water from a store | Time control independent of space heating, plus electronic temperature control |
The guidance says these room or zone standards can be met in several ways. One is a thermostat in a room the circuit serves plus a thermostatic radiator valve on each emitter outside that room. Another is an individual room or zone thermostat for each room or heating zone. A third is a networked control on each emitter.[1]Ministry of Housing, Communities and Local Government, Approved Document L, Conservation of fuel and power, Volume 1: Dwellings, 2021 edition incorporating 2023 amendments The same standards apply to underfloor heating.[1]Ministry of Housing, Communities and Local Government, Approved Document L, Conservation of fuel and power, Volume 1: Dwellings, 2021 edition incorporating 2023 amendments
Example
Ayesha has a large new-build in Wetherby with a floor area of 150m2 or more. Her wet heating system needs at least two independently controlled circuits, so the installer splits it into ground floor and upstairs, each with its own thermostat. Her hot water has its own timer, separate from the heating.
Zone valves, wiring and anything on the boiler side are work for a qualified engineer, and gas work for a Gas Safe registered one.
What people get wrong
People assume more zones always save money. The guidance only asks for zoning in set situations, and it allows a single zone in some homes, such as an open-plan bungalow. The right number depends on the layout and how you live.
Another point is confusing a zone with a timer. A central heating programmer controls when heating runs. A zone controls where it runs. A zoned system can have both.
The bottom line
Zone control lets different parts of a home be heated to suit how they are used. For new wet systems in larger homes in England, at least two controlled circuits are expected, while smaller or open-plan homes may use fewer. A heating engineer can tell you whether your layout would gain from splitting into zones.
Common questions
What is zone control in central heating?
It is a set of controls that lets different areas of a home be heated to different temperatures or at different times, for example upstairs and downstairs, instead of heating everywhere together.
Do I need zones in a larger house?
For a new wet heating system in a dwelling with a floor area of 150m2 or more, Approved Document L says a minimum of two independently controlled heating circuits should be provided.
Can thermostatic radiator valves act as zoning?
Approved Document L treats a room thermostat plus a thermostatic radiator valve on each emitter outside that room as one way to meet its room-by-room control standard, so valves give room-level control.
Are heating zones the same for hot water?
No. Where hot water comes from a store, Approved Document L says it should have its own time control independent of space heating, and an electronic temperature control.
Sources
We cite the original source for every figure: government, regulators, standards bodies and manufacturers' own documents. Each one shows the date we last checked it.
- Ministry of Housing, Communities and Local Government. Approved Document L, Conservation of fuel and power, Volume 1: Dwellings, 2021 edition incorporating 2023 amendments. Checked 11 November 2026. ↩