Programmable Thermostatic Valves / Individual Room Control

Replacing manual thermostat heads with programmable or wirelessly networked smart thermostats for room-by-room, time-dependent setpoints.

How does individual room control with programmable thermostats work?

In a conventional heating system, a manual thermostatic head on the radiator regulates the room temperature to a fixed setting, regardless of time of day or occupancy. Programmable or wirelessly networked thermostats (individual room control) replace this head with an electronic actuator with a time programme. Each room thus gets its own temperature profile: the bedroom is kept at 16 °C, the bathroom is only heated in the morning and evening, meeting rooms only during booked times. Wirelessly networked systems can be managed centrally, coupled with window contacts and occupancy sensors, and controlled via building automation. Most thermostats fit valves with the standard M30x1.5 thread; adapters are available for other connections such as Danfoss RA.

Which buildings benefit from individual room control?

The measure is suitable for all buildings with radiators and thermostatic valves: detached houses and apartment buildings, schools and office buildings. It is particularly effective where rooms are used differently and at clearly defined times – classrooms, meeting rooms, guest rooms or rarely used ancillary rooms. In non-residential buildings, combining with occupancy sensors amplifies the effect because unoccupied rooms are automatically set back. Radiators with RA or M30x1.5 connections are required. Important to know: the saving only materialises if the time programmes are actually used and maintained; a programmable thermostat without a configured profile saves nothing.

What does individual room control actually deliver?

Heating energy demand falls by 5 to 12 %, in non-residential buildings with clear occupancy hours by up to 15 %. A detached house with a space heating demand of 18,000 kWh saves around 1,600 kWh of natural gas and about 320 kg of CO2 per year. The thermostats cost 60 to 120 € each; for a detached house with 7 to 10 rooms, that comes to 500 to 1,200 €. Over a 12-year service life, payback is 4 to 8 years. As a side benefit, networked thermostats provide room temperature data that supports further optimisations such as lowering the heating curve.

Energy carrier

Erdgas, Heizöl, Pellet, Fernwärme, Strom → Erdgas, Heizöl, Pellet, Fernwärme, Strom

Savings potential

5-12 %

Worked example

A detached house with 150 m² of living space has a space heating demand of 18,000 kWh per year, met by a gas boiler with an efficiency of 0.90. All radiators are fitted with manual thermostatic heads permanently set to setting 3 – including in the bedroom, the guest room and during the day when nobody is at home. The heads are replaced with programmable wireless thermostats, with a time profile configured for each room: living rooms 21 °C during occupancy, bedroom 16 °C, bathroom warm only in the morning and evening. A saving factor of 0.08 is applied for a residential building. The final energy saving is 18,000 × 0.08 / 0.90 = 1,600 kWh of natural gas per year. With an emission factor of 0.201 kg CO2/kWh, this corresponds to about 320 kg of CO2 annually. At a cost of 500 to 1,200 € for 7 to 10 thermostats, the measure pays back in 4 to 8 years.

Investment & payback

60-120 € pro Thermostat; EFH 7-10 Räume: 500-1.200 € · Service life: 12 a · Payback: 4-8 a

Applicability

Requirements

Typical buildings

Frequently asked questions

How much do smart radiator thermostats cost?

Smart radiator thermostats cost 60 to 120 € each, depending on wireless standard, display and accessories such as window contacts. For a detached house with 7 to 10 rooms, that comes to 500 to 1,200 €. Wirelessly networked systems additionally require a hub or gateway. With savings of around 1,600 kWh per year in a detached house, the investment pays back in 4 to 8 years, over a service life of about 12 years.

Is individual room control worthwhile with a heat pump?

With heat pumps and underfloor heating, the benefit of individual room control is limited because the system responds slowly and low, steady flow temperatures are more efficient than frequent cycling up and down. With heat pumps and radiators, it can make sense if individual rooms are rarely used. It is important that enough heating surfaces always remain open to guarantee the heat pump's minimum flow rate.

Do smart thermostats fit every radiator?

Most smart thermostats fit directly onto valves with the standard M30x1.5 thread, which is common with Heimeier, Oventrop, Honeywell and many other manufacturers. For Danfoss RA, RAV and RAVL valves and older special valves, adapters are usually included with the devices. With very old valves without a thermostatic function, the valve body must first be replaced. A look at the existing valve clarifies compatibility.

What is the difference between programmable and wirelessly networked thermostats?

Programmable thermostats work autonomously: the time programme is set directly on the device, with no networking. Wirelessly networked thermostats communicate via Zigbee, Z-Wave or EnOcean with a hub, can be controlled via app or building management system, and can be coupled with window contacts and occupancy sensors. For detached houses, programmable devices are often sufficient; in schools and office buildings, the central management of networked systems is a clear advantage.

Which standards apply to thermostatic valves and individual room control?

Thermostatic radiator valves are standardised in EN 215, which specifies requirements for control accuracy, hysteresis and closing time. The EN 50491 series of standards applies to electronic home and building automation systems. In Austria, the method for assessing savings from individual room control is described in the Energy Efficiency Guidelines Regulation 2016, which provides for a saving factor of 5 to 10 % for residential buildings and 8 to 15 % for non-residential buildings.

Related measures

Standards & sources

Metering points in the EDM Toolbox

Funk-Thermostate können via Z-Wave/Zigbee/EnOcean in LineMetrics-Gateway eingebunden werden. Damit Raumtemperatur-Logging möglich → Datengrundlage für weitere Optimierungen.

All measures