65 HPM 0413

HPM April 2013

Got a story? Ring us on 01732 748041 or e-mail twood@unity-media.com UNDERFLOORHEATING Dry floors for screeding and heating Advances in dry screed flooring have made it easier to install plumbed underfloor heating which is now both more comfortable and cheaper to run than traditional central heating systems, according to Mark Crowsley, business development manager (flooring) at Knauf... The popularity of underfloor heating (UFH) in the self-build and upmarket residential sectors is longstanding. But, even here, it has tended to be found only on the ground floor while traditional wall-hung radiators continue to dominate on the upper storeys. But that is beginning to change as UFH systems and flooring systems have evolved to become far lighter and far simpler to install. Instead, UFH is being specified for all building types and on all floors, including separating acoustic floors. The drivers for change are the three “C’s”: Cost; Comfort; Convenience. We all know that energy bills are heading inexorably upward so few forward thinking developers will miss the opportunity to build in a 15% saving on heating bills as a marketing aid – and that’s the sort of saving UFH typically offers. The latest figures from British Gas state: “A UFH system that provides precise temperature controls will allow you to save approximately 15% in your heating costs”. When the Energy Efficiency Partnership for Homes compared domestic heating systems in a typical semi-detached home it also found savings in the order of 15%. TRADITIONAL CENTRAL HEATING These savings are the result of UFH being far more direct than traditional central heating. Radiator-based heating uses the principle of convection: the heating warms the air in the room, which then heats the room and its occupants. The result is hot ceilings and floor draughts. UFH simply heats the room and its occupants directly: Radiant heat transfer interacts directly with the room and occupants. It’s the same principle in operation when the sun warms us. In any circumstance a large radiant surface emitter (floor or ceiling) is the most efficient way of heating or cooling a building. UFH running costs are reduced because the flow temperatures in UFH systems do not need to be as high as those in traditional radiator systems to achieve the same comfort levels. The result is that less energy and fuel used and so heating bills are lowered. In general the flow temperatures can be as much as 2ºC less than in radiator-based central heating systems. This has important implications for sustainability both in terms of meeting increasingly stringent regulations and in working with renewable energy sources. UFH can effectively future-proof any WWW.HPMMAG.COM construction because its greater efficiency makes it so much easier to meet the tightening regulations governing energy use. The UK government has sent a target of an 80% reduction in carbon emissions by 2050 (536 million tonnes) while Part L of Building Regulations was revised in 2010 and demands a reduction in energy use by a further 25%. Renewable energy sources such as ground and air sourced heat pumps work better with UFH systems because they work more efficiently with large radiant surface emitters than with radiators. They also work at the lower temperatures found in UFH systems. The increasing popularity of UFH is made possible by a concerted effort by both UFH and flooring manufacturers to develop products that both simplify installation and are suitable for refurbishment and new-build. The flooring manufacturers have produced light dry floor screeds that simplify installation and improve the performance of UFH. In the past underfloor systems have mostly been laid on top of the concrete slabs, and then sealed into a heavy wet screed, often 60mm thick. Dry floor screeds are not only lighter but also far slimmer in profile. Depending on their type, these boards weigh as little as 22–30kg/m2 and have an installation thickness of just 23mm, which allows for the installation of an UFH 64 APRIL 2013 HEATING & PLUMBING MONTHLY system for a total loss in room height of just 50mm. But, most importantly for multi-storey applications, the potential weight saving is about one ton for every 11.5m2, making UFH practical alternative to traditional central heating. Similarly, this type of gypsum fibre board works well with UFH systems because it is thermally transparent. Temperature changes are achieved almost immediately – so there’s no need to heat up a mass of concrete before the environment starts to feel warm. Proprietary dry flooring screeds have typical thermal transmission coefficients of around 0.05-0.08 m2K/W. Acoustic insulation can also be easily incorporated into dry floor screeds without complicating the installation. Some types have an additional layer of ten mm laminated wood fibre that provides high mechanical load resistance and effective footfall sound insulation and so there is no need for acoustic battens. NO SPECIAL TRADES REQUIRED Swift and simple to install, dry floor screeds require no specialist trades because the boards are manufactured with precision, so they fit together smoothly and quickly. Panel joints are simply glued together and fastened with screws, producing a solid, level floor that is ready for a wide variety of finishes – and traffic – within hours. All the hassle associated with wet screed and moisture is avoided: there are no drying times, no additional moisture and none of the trip hazards associated with bulky batten and chipboard systems. UFH manufacturers have also developed systems that are extremely slim – one UFH system is no more than 15mm, less than the diameter of a five pence piece. This means you can install it on top of existing floors without significantly affecting the floor-to-ceiling height. Increasingly sophisticated controls have also extended the appeal of UFH. Whereas once UFH systems could only be installed with hard wired thermostats there are now wireless controls available that both cut out the cost of wiring and eliminate unsightly cables, trunking and chasing. These wireless thermostats make it simple to retrofit existing buildings and are also easy to re-site if the room or zone layout changes. These advances mean that UFH is on its way to becoming the accepted norm and radiators will be seen as old-fashioned, wasteful and downright uncomfortable. enquiry number 148 Knauf Brio Dry Floor Screed is a superb substrate for perfect floors in new build and refurbishment projects


HPM April 2013
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