Rex Ingram of Timoleon highlights the scientific evidence behind the change in the way we heat the commercial buildings of Britain.
Underfloor heating is now taking care of business. The technology has developed from being the choice of the discerning for quality homes, into a standard solution for the commercial and public-sector buildings of Britain.

The advantages of integrating underfloor heating into large commercial and even industrial buildings are easy to see.

Easy access to all areas, maximum use of space, virtually no maintenance requirement over the long life of the system; it's an impressive list.

But one benefit overshadows all the others - energy saving. With the UK set on course for a low-carbon economy, designers must now utilise minimum-energy solutions if we are to reduce the carbon emissions from building services, which account for nearly one-third of the national total.

And this is a must because encouragement to take the low-energy path has become compulsion. Now, when any new large commercial or industrial premises are being planned, the amount of energy that will be used to heat them is a key factor.

We are already seeing obligatory planning stipulations, specifying the minimum quantity of renewable energy that a building must use, as in the Merton Rule. And, with energy never likely to be as cheap in the future as it is now, a building's energy cost will inevitably become an ever more significant factor in assessing its value.

Driving all building codes

The European Energy Performance of Buildings Directive (EEPBD), which became effective in January 2006, is the central piece of legislation that is driving all building codes throughout Europe.

It is also the driving force behind the classification of building energy efficiency into an A-G band and this form of classification will, in due course, be used to force owners to improve the efficiency of all their buildings - old and new alike.

The result is a revolution in the way we approach the heating of big buildings. In the past, large spaces such as atria, museums, warehouses and factories have mostly been dependent on radiators or warm-air heater/blowers, using gas as the primary fuel.

Occasionally, overhead gas-fired radiant heaters have been used to keep factory or warehouse staff warm by supplying localised heating. Warm workers, possibly - but the best use of precious energy?

No. The problem with all these forms of heating is that, the moment you heat the air in a space, it becomes buoyant and rises to ceiling level. How many factories and arehouses have energy-consuming de-stratification fans at high level, to blow the accumulated warm air back to the ground? How many offices have radiators directly below windows, enabling heat to escape through external walls or through the windows?






Energy-saving legislation is a key factor, but there are others. The government's latest target, to reduce total UK carbon emissions by 2050 to 20% of 1990 levels, has major implications for all building owners. It's possible that the permitted 20% could be entirely used up by carbon emissions from aircraft, lorries and industrial processes.

There may be no allowance at all left for use in heating our buildings.

Although 2050 seems a long way off, almost all current projects and a large number of existing buildings will still be in use when the 21st century reaches the halfway mark. The implications are clear. At some point, the heating systems in these buildings will have to be switched over from reliance on gas or oil to an alternative fuel.

The most likely alternative is electricity, which will by then be generated by nuclear plant and/or renewable sources such as hydro, wave, wind or solar.

Heat pumps

If we must use electricity, then the most efficient way we can use that is through a heat pump - either air-source or ground-source - because a properly designed heat pump system is typically able to convert one unit of electricity into four units of thermal energy. Many future buildings may generate the electricity needed to power the heat pump at source making them self-sufficient in energy terms.

So, energy efficiency is the order of the day. Underfloor heating has always been claimed to be more energy-efficient than radiators, and now there's scientific evidence to support those claims.

The EEPBD required that a methodology should be developed for comparing the energy performance of different buildings, and this has recently been completed in the form of a series of internationally agreed EN standards in both new and modified form.

A study undertaken by the Danish Technical University in Copenhagen and the University of Padua in Italy, has now applied these new standards to a comparison of energy used in three standard buildings.

These were a single-family house, a block of offices and a 10m-high industrial building - constructed in either Venice or Brussels or Stockholm, in order to provide a range of external climate conditions.

The buildings modelled are fitted with either underfloor heating or low-temperature radiators. Heat source is either a high-efficiency condensing gas boiler, or an air-water, or ground-source heat pump.

In all cases, the study revealed that a building fitted with underfloor heating used the least energy and was responsible for the lowest carbon roduction.

By comparison with low-temperature radiators, underfloor heating showed savings of 5% with condensing gas boiler, 20% with an air-water heat pump, and 30% with a ground-source heat pump. The results were achieved despite an allowance for variations in the way electricity is currently generated in the countries chosen for the study.

We've seen that the future will bring change. Employing underfloor heating now can help to make the heating system future proof. A high proportion of commercial and industrial buildings have solid concrete, or screeded floors. It's a simple process to incorporate underfloor heating into the structure of such floors, just before the concrete (or the screed) is poured.

Once the pipe has been installed, the heating system can use a gas or oil boiler for a few more years yet, after which it can be easily replaced by a heat pump. If that pipe is not fitted from the outset, the cost of installing it at a later date will be much, much higher.

In practice

So much for theory; does it all work in practice? Yes, it does, and Timoleon's own building in Exeter is proof of the energy-saving potential of underfloor heating at work.The building is 1,700m2 overall, with 400m2 of offices, and is 7m to the eaves. It is heated by an underfloor system, which is currently served by a gas boiler.

The main factory area requires a flow temperature water of just 32 degrees Celsius in order to maintain the specified 17 degrees Celsius internal air temperature when external temperature is -3O degrees Celsius. Although the carbon creation is already very low, the gas boiler can be replaced with a heat pump at any time in the future, driving the CO2 emissions down even further.

The gas supplier, by the way, has always been puzzled that the building uses only one-fifth of the gas that would be expected for one of its size. The system works today and it is ready for anything tomorrow may bring.