Its official, a two-year study has proven that underfloor heating is more energy-efficient than radiators. Practical experience has now been borne out by this accredited study.
The Building Research Establishment (BRE) was already aware that the results of the study were imminent and, as a consequence, the revised version of SAP, which will become effective from 1st January 2008 will show that having UFH installed is likely to get better SAP ratings than if radiators were fitted.
Announcing the news, a delighted Rex Ingram, Chair of UHMA and Britain’s representative at the European Association for Surface Heating and Cooling (Eu-ray), which commissioned the report said:
“This could be a pivotal event in the development of the UK underfloor heating market. Now we can officially add reduced energy consumption and reduced carbon emissions to the long list of established benefits of UFH in terms of greater comfort, improved safety and hygiene, and reduced maintenance.
Heating our buildings is one of the biggest contributors to our nation’s carbon footprint. Switching our homes, offices, schools and hospitals to underfloor heating will have significant impact.”
Study Results
UFH saves between 5% and 30% energy compared to radiators
In 2005, Eu-ray commissioned the first major application of the new methodology for measuring the energy efficiency of buildings, which has been developed in response to the European Energy Performance of Buildings.
The objective was to compare the energy efficiency of three “standard buildings” constructed in three different parts of Europe - Venice, Brussels and Stockholm – each modelled with both radiator heating and underfloor heating. The chosen buildings were a single-family residence, a block of offices and a 15m high industrial building. The choice of three widely separated locations provided an opportunity to study the effects of differing external climate conditions.
The study was undertaken on behalf of Eu-ray by the Danish Technical University in Copenhagen and the University of Padua in Italy. These institutions were chosen because of their particular knowledge of building science and their close involvement in the development and scrutiny of CEN Standards.
Results from the study show that in each building type and in each location, UFH is more energy-efficient than radiator heating. They reveal that, if a building is heated using a condensing boiler, it will use 5% less energy if UFH is installed, than if radiators are used. However, if a building uses a heat pump, instead of a boiler, the energy saving capability of UFH become much greater. Used in association with an air source heat pump, underfloor heating cuts energy consumption by 20% says the report. Substitute a ground source heat pump and the savings jump to a massive 30%.
The data relating to heat pumps is of particular significance. This technology will be increasingly applied to the new buildings of Britain because of the big reductions in primary energy consumption and CO2 emissions that result.
Rex Ingram points out that the underlying message of the report is even more favourable to the UK underfloor heating industry.
“The savings measured by the Eu-ray study were achieved despite the subject buildings having elemental U Values that are poorer than those demanded by our Part L and despite the fact that the single family residence considered in the study was a single-storey construction – a bungalow. Such a construction is the worst possible case for UFH because any downward loss to the underside is maximised, particularly when the Floor U Value was assumed to be 0.48 instead of the 0.25, which UK demands.
The study also assumed that the radiators would be over-sized and used with 50/35degC water temperatures, which makes them as energy-efficient as possible. That scenario is hardly ever played out in real life Britain.”
UHMA is currently considering commissioning the study team to produce a set of “UK” comparisons; not only using UK elemental U Values and fuel conversion factors, but also based on the kind of multiple-storey housing, which is most typical of UK new-build development.
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