PHAM NEWS | APRIL 2025 Radiators & Towel Warmers 27


Radiator low running costs confi rmed by research


The latest fi gures produced by test houses at the University of Salford suggest that it’s cheaper to run homes heated with radiators than it is to combine a radiator system with underfl oor heating. Tim Wells from Stelrad reveals more.


R


esearch on the performance of a large collection of diff erent heating systems present in


the Future Homes test houses at the Energy House 2.0 facility at the University of Salford – where a modern renewable heating system is the source of heating and hot water – has provided clear evidence that new homes heated by radiators have lower running costs than those heated by a combination of underfl oor heating (UFH) and radiators in the same building. Application of heat pumps


in new builds can lead to the default adoption of UFH downstairs with radiators upstairs. However, this latest evidence suggests that the use of radiators throughout a new property off ers signifi cant benefi ts where heat is provided by an air source heat pump rather than a traditional boiler. The houses at the Energy


House 2.0 facility were built by Bellway Homes and a partnership between Saint Gobain and Barratt


Developments. The latest report follows up on a report published in 2023 on the fabric performance of both of these homes.


Tim Wells Engineering manager at Stelrad


The research confirms our


understanding that radiators are the optimal choice when it comes to heating economically and flexibly


Diverse technologies The systems were selected, designed and installed by the housebuilders and their partners. The research team had no input on the design of these systems and were focussed only on the measurement of the performance of these systems, which number 28 in total, and covered a range of technologies including infrared heat panels and air source heat pumps (fl oor mounted and roof mounted). Diff erent heat emitter technologies were also tested including underfl oor heating, skirting board heating and, importantly for Stelrad, radiators. All methods of heating the


home were measured in the same chamber conditions refl ecting typical (5°C) and more extreme (-5°C) winter temperatures found in the UK. This allows for a comparison


between these technologies that up to this moment has not been possible and represents unique research. Interestingly, systems with


radiators throughout – on each fl oor – showed lower running costs than the systems with a combination of UFH and radiators. This was not focused on in the report but can be unambiguously calculated from data published within it. Using the external ASHP


with radiators throughout, the running cost was 11% less than with UFH. Using the loft ASHP with radiators throughout, the running cost was 13% less than with UFH. These outcomes are very revealing and highlight the running cost benefi ts of selecting radiators throughout a new home powered by an air source heat pump of any design.


Most economic Radiators throughout a home were shown to be consistently more cost eff ective than UFH and radiators combined when looking at the most realistic scenario, ie a SAP intermittent heating pattern, at average winter temperatures. Out of all 28 tests carried out and researched, the most economic confi guration was the external ASHP with radiators throughout running the SAP pattern in a 5°C environment. Analysis of other heating


Stelrad’s Vita Compact K3 radiator


regimes tested indicated that if constant 24 hour heat is required then ground fl oor UFH has the lowest running costs. However, this is shown to be 25% to 35% more expensive than the standard SAP heating pattern with radiators throughout the home. In the overwhelming majority of homes, heating is targeted at times when it is required – not


on 24 hours a day. Radiator based systems are clearly better suited to this. They are more responsive than UFH, more fl exible and cost eff ective. The ability to target heat


is very simple with radiators via a locally mounted TRV. Temperature control is intuitive and simple. No external wiring, controls or confi guration are required. A popular function of heating


controls is the one-hour boost. It’s a simple way of countering a cold snap or quickly raising the temperature outside of the normal occupational routine. It is also the ‘go to’ control method for those who fi nd modern controls confusing or who are trying to control costs. Radiator based systems are the best solution in all of these cases. Due to the high thermal


mass and low response times of a UFH system, the user is committed to heating for longer periods, potential expensive repairs and restricted fl oor covering options. It is fundamentally suited to constant heating but in real world situations it lacks fl exibility and it is therefore less economical for the majority of households.


Fit for the future This research confi rms our understanding that radiators are the optimal choice when it comes to heating economically and fl exibly. It’s particularly reassuring that these results were achieved in an environment optimised for UFH. We can therefore be confi dent that radiators are just as fi t for the future as they have always been, whether the heat is provided by traditional means or renewable technology. ◼ phamnews.co.uk/425/39


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