How underfloor heating systems are taking care of business
COLIN PAVEY highlights the benefits that are making underfloor heating the system of choice for commercial and public-sector buildings.Over the past 10 years the trend towards underfloor heating (UFH) has spread from the domestic sector into the commercial world. So much so, that for many types of project — particularly those involving large open-plan areas with high ceilings — it has become a standard solution. There may be no visible evidence (that is, after all, one of UFH’s principal benefits) but beneath the floors of many of Britain’s airport departure halls, offices, museums, art galleries, supermarkets, sports halls and palaces lies a hidden source of comfort. Comfort is the key. In a modern, well insulated building, UFH emits a high proportion of radiant energy, the form most conducive to a feeling of warmth and wellbeing. Heating the room space from the floor up, rather than the ceiling down, is not only much more efficient, it also ensures that the occupants enjoy the warm-feet and cool-head profile that science identifies as ideal for human comfort. Projects of all kinds Applications of this invisible ‘comfort control’ abound in commercial and public-sector projects of all kinds. For example, it can be difficult to find suitable positions for radiators in entrances, foyers and reception areas. The poor receptionist is often effectively screened behind a desk from convection currents and has to sit there shivering — and no doubt cursing the designer of the heating system! These areas often feature high ceilings, so UFH can offer a double benefit by bringing comfort to the receptionist and overcoming expensive stratification problems. The heated floor of the reception area represents a significant mass, so the system gives fast recovery. When warm air is lost — an inevitable result of regular door opening — the space still maintains full comfort conditions, ensuring a warm welcome for visitors. Noisy air curtains at doors are now only required in exceptional conditions. Sports halls can also benefit from the ‘floor upwards’ method of heating. Integrating the heating system into the floor frees up not just the floor and walls but also means that there’s no obstruction high above where the shuttlecocks and basketballs fly! Perfect partner Atria, the ubiquitous glass-domed towers that feature in almost all new office buildings and shopping malls, are notoriously difficult to heat. This is due to the stratification created by convection systems and the lack of convenient positions to locate overhead equipment. Here UFH comes into its own — radiating comfort at low level direct to the occupants, whether seated or passing though the area. Cold employees do not work well and shivering shoppers tend not to linger, so there are hidden financial benefits to underfloor heating as well as in its fuel-saving efficiency. That fuel saving potential is substantial. In areas with high ceilings — like entrance foyers and atria — up to 30% less energy than a radiator/convector system is not unreasonable to expect. Underfloor heating also makes a perfect partner for modern condensing boilers. The low return temperatures — 39°C in a solid-floor construction of the type used in most commercial projects — keep the boiler in high-efficiency condensing mode for maximum economy. Occupancy levels in public buildings can vary widely according to the time of day, the day of the week and the season. To ensure full comfort and economy in all circumstances the underfloor heating can be linked to a boiler optimisation system with external weather sensors. The system calculates the time required to get up to temperature, based on data acquired during the previous operating cycle. The boiler plant will only be switched for the optimum time required to achieve the desired zone temperatures. Boiler run time is thus kept to the minimum required to bring zones up to temperature when the first occupants arrive. Space in offices, schools, hospitals and retail centres is always at a premium. Concealed beneath the floor, underfloor heating creates extra useable space, making it possible to use the entire floor and wall areas. Up to 15% more space can be freed up in this way. Stockport in Cheshire offers a fine example of these benefits in action. Here the local council is creating ‘The Stockport story’, a museum which will present a collection tracing the history of the town. The project manager from the Historic Areas Regeneration department of Stockport Council has no doubt about the considerable advantages of underfloor heating in a development of this kind. He explains, ‘Room sizes are not large in buildings of this period, and the Robbens underfloor heating systems permits completely unrestricted access, while freeing up all the wall space for displays. Not all commercial projects involve large areas. Hotels, for example have to make the best possible use of every inch of space, particularly in bedrooms. At the Clive Hotel on the outskirts of Ludlow, a Grade 2 listed building has been augmented with 11 additional bedrooms, all with en suite facilities — thanks to the space saving qualities of underfloor heating. Improving safety and access Invisibility also reaps other rewards such as improving levels of safety and access. There are no hot sharp cornered radiators to bump against and nothing to impede wheel chairs in corridors and other areas. Low-surface-temperature radiators (LSTs) are also safe, but require a hefty premium in cost and lost room space. They take up large areas of the walls in places such as nursing homes, care centres and other health-sector buildings where rooms are small and every square centimetre counts. LSTs are increasingly losing out to underfloor systems, which, with maximum floor temperatures around 27 to 28°C, offer a safe environment for the vulnerable, from the very young to the very old. Finally, a word about caring for the system. Maintenance is a considerable element in the running cost of virtually all commercial heating system — except for underfloor heating, which requires no maintenance at all. No painting, no cleaning (actually UFH makes it easier to clean floors right up to the skirting) and no need for replacement even in ‘tough’ locations like schools. If they can’t get to it, they can’t break it! Colin Pavey is with Robbens UFH Systems Ltd, 69 Castleham Road, St Leonards Road, Hastings TN38 9NU.