Originally more widespread elsewhere in Europe, underfloor heating has now become a more mainstream technology in the UK. Graham Richardson of Rehau reports
In the past ten years, underfloor heating has become mainstream and is the first choice in applications such as schools, sports centres, hospitals and luxury housing developments.

When Rehau entered the underfloor heating market in the UK in the 1980s, it was seen as a pioneer of a niche product. Although proven in Germany, where Rehau is based, and across mainland Europe, underfloor heating was then still viewed with a degree of scepticism in the UK.

Things are different today. And, alongside other manufacturers, Rehau has worked hard to turn around negative perceptions surrounding what was viewed as unproven technology. It targeted architects, specifiers and clients to persuade them of the benefits of the concept and in turn encouraged best practice among installers so that underfloor heating gradually built a deserved reputation for performance and reliability.

Sales and marketing have only been half the reason for its success though of course. The compatibility of underfloor heating with condensing boilers underpinned all of its efforts. And, as the market has switched towards high-efficiency boilers, so underfloor heating's share of the market has increased rapidly alongside.

It is the low-return flow temperatures of underfloor heating systems (typically around or below 45ºC) which allow condensing boilers to operate in efficient condensing mode for most of the time. This makes them perfect partners, and the market has responded to that.

And now, it is these same low-return flow temperatures which are opening up an opportunity for underfloor heating manufacturers and installers in the ground source energy market where its compatibility with the new technologies is starting to have a significant impact.

Companies such as Rehau, which helped to create the market in the UK for underfloor heating systems 25 years ago, are now turning their attention to a new opportunity. They are demonstrating the natural benefits of using underfloor heating as part of a ground source energy solution.

Ground source technology - whether in the form of probes, piles or ground source collection systems - relies on the fact that at 1.5m below the surface the ground is 8-12ºC across the seasons and at 15m deep it is a constant 10ºC all year round.

Typically, the return temperature of a ground source loop is 5ºC and a heat pump is required to raise this up to the temperature required for the heating system. The higher this heating temperature, the harder the heat pump has to work and therefore the more energy is used.

Because underfloor heating systems can be designed to run with a flow temperature as low as 35ºC, the amount of energy used by the heat pump can be minimised and the coefficient of performance maximised to somewhere in the order of five.

A recent project in Kent, which featured on Channel 4's Grand Designs programme in April, demonstrated just what can be achieved.

Paul Tarling, an ex-employee of Rehau, project managed the build of a contemporary new bungalow for his parents-in-law. On the project, he used much of his knowledge of the potential of the two technologies and how they can be used to work together to fill the property with interesting and potentially ground-breaking innovations.

Strikingly, the bungalow is built on 46 10m-deep concrete piles, inside each of which is a steel cage containing a loop of 20mm pipework.

Each loop feeds into a ground source heat pump inside the house, which provides the heat required for the underfloor heating system. And the curved roof of the property also features a large solar panel managing both the solar gain and heat dissipation.

Built off site in 23 sections, the roof comprises steel and reinforced concrete sandwiched around a layer of insulation. Fitted inside the top layer of concrete is the same pipework that has been used for the underfloor heating and energy collection piles which is collecting, storing and radiating heat via the roof.

Maximising the potential of the ground source energy on a compact site by using structural piles as a ground source is not an entirely new concept.

As underfloor heating moves into the mainstream, there is a danger it will be viewed almost as a commodity product and that manufacturers and contractors will find margins squeezed and their point of difference increasingly difficult to define.

However, with the potential which exists in the ground source energy market and the willingness of manufacturers, architects and developers to break new ground, all those in the underfloor heating sector have an exciting opportunity ahead.