Zoning in newbuild heating systems

Zoning is an essential aspect of heating system design in newbuild properties across the UK. Fausto Grilo, Technical Director at ESi controls Ltd, and Neil Stone, Managing Director of REDD, explain what zoning is, the regulations that apply and how zoning works with different heating systems. 

Zoning refers to the division of a home’s heating system into independently controlled areas or zones. Each zone is equipped with separate temperature and scheduling controls, enabling different parts of the house to be heated at different times and temperatures. For example, living areas may require heating during the day, whereas bedrooms might only need heat in the evening and early morning.  

A well-designed zoning system helps to improve the energy efficiency of the home by only heating the required areas. Heating bills could be reduced because unoccupied spaces and areas, such as bedrooms, are only heated when needed, so the homeowner’s comfort is increased by allowing the temperature to be controlled to suit their needs. Zoning is easy to use, as it works effectively with smart controls for automation and remote management. 

Zoning in England and Wales is regulated under Part L of the Building Regulations, which covers the conservation of fuel and power. It states: ‘For wet heating systems in new dwellings with a floor area of 150m² or greater, a minimum of two independently controlled heating circuits should be provided’. Typically, these will be the downstairs living area and the upstairs sleeping area. If radiators are the chosen heat emitters, thermostatic radiator valves (TRVs) should be fitted in all rooms without a room thermostat to allow room-by-room temperature control.  

Each zone is controlled by zone valves, which are typically motorised and controlled by electric actuators, to open and close the valve based on the input from the room thermostat. The thermostats regulate the zone valves to maintain the desired temperature in each zone. When the valve is open, it allows hot water to flow through the heating system into the designated zone. And when the valve is closed, it stops the flow, shutting off heating to that area. 

Previously, Building Regulations Part L stated there should be a minimum of two zones in all properties, but that didn’t benefit smaller two and three bed homes, because the room stats were too close together and conflicted with each other. With good insulation, the whole house would heat up at the same rate, so the regulations have gone back to one zone for smaller properties (ie, the whole house is controlled with one room thermostat and timer and TRVs on each radiator) and at least two zones for larger properties (over 150m²). 

For newbuilds in other parts of the UK, the Scottish Building Standards and Building Regulations (Northern Ireland) apply. While the regulations vary slightly between regions, the common theme is a strong emphasis on energy efficiency and effective heating control through zoning, TRVs, and programmable thermostats. Both the Scottish and Northern Ireland Standards currently follow the same guidance as England & Wales (under Building Regulations Part L) as stated above. 

Newbuilds with gas boiler systems heat up very quickly. The room thermostats can be set to come on before the household wakes up, so the upstairs will be nice and warm, and the living area will be cosy during the evening, or if they are at home during the day. TRVs allow individual control of each room, so they can be turned up or down to suit. This is particularly important with today’s highly insulated, airtight properties, which keep in the warmth for longer. 

Smart controls really come into their own in this situation, because they will ensure the boiler, and consequently the different zones, run as efficiently as possible. So, whatever flow temperature the end user sets, a multi-zone control with OpenTherm will run the boiler at its optimum efficiency, smoothly and without the on/off cycling that can cause wear and tear on system components. 

www.esicontrols.co.uk