050 RCI 0517

RCI May 2017

INSULATION Underfloor heating (UFH) has actually been a desirable feature for British homes since Roman times. In 2013, an Aviva survey showed that these systems were the most common ‘high-end feature’ listed by estate agents for luxury homes. The compact design of modern UFH systems means they are not only a popular option for new-builds and extensions, but also for retrofits. Fitting UFH in existing properties can be a relatively costly proposition for owners so it is crucial to ensure the systems work as effectively as possible. One way this can be achieved is by installing insulation beneath the UFH to limit heat loss through the floor. However, this can prove challenging in solid floor retrofit applications as fitting both UFH and insulation will raise the existing floor level. Vacuum Insulation Panels (VIPs) can provide a spacesaving solution, allowing the desired U-value to be met with a minimal build-up. Why underfloor heating? Perhaps the most obvious advantage of underfloor heating is the ability to clear walls of radiators. This helps owners to declutter rooms, increases usable wall space and provides more flexibility when laying out furniture as there is no need to worry about sofas or chairs blocking the heat from radiators. UFH is a particularly popular choice for properties or rooms with timber, laminate or tiled floors, such as bathrooms and kitchens, which can remain cold underfoot with conventional wall mounted heating. Kingspan Insulation’s specialist technical support team provide clear layouts for each Kingspan OPTIM-R application, ensuring the thinnest possible build-up 050 MAY 2017 RCIMAG.COM There are two common types of UFH system – electric and water. Traditionally, retrofit work has been carried out with electric systems due to their slim profile and relatively low up-front cost. Over the past few years though, slimmer water-based systems have been introduced onto the market. These systems generally operate with much lower temperature water than conventional radiators. As such, whilst the initial purchase costs are typically higher than those for electric alternatives, they can notably reduce energy usage and costs over time. To maximise this energy saving potential, it is important to ensure an effective insulation layer is fitted below the system. Floor insulation On suspended ground floors, this process is relatively simple. A standard rigid insulation board can be installed between the floor joists followed with a polythene sheet separation layer and the UFH can then be fitted above. Rigid insulation boards, such as phenolic insulation, provide a good solution in these applications as these boards can be cut to size with a fine-toothed saw and secured in place with timber battens, galvanised nails or steel saddle clips. By fitting premium performance rigid insulation, it should be possible to maximise heat retention within these applications. For properties with solid floors, fitting both UFH and insulation can be more challenging. The most obvious solution is to install both systems over the existing floor slab, but installing a sufficient thickness of traditional insulation products can require the existing floor level to be significantly raised. This may not be possible if the floor to ceiling height is already relatively small and will require all fittings such as skirting boards and plugs to be raised. The alternative is to remove the existing floor slab and dig down. This requires a substantial amount of manual labour, extending project timescales and causing high additional costs and disruption for owners. VIPs can offer a slim-line solution. VIPs Vacuum Insulation Panels (VIPs), such as Kingspan OPTIM-R, feature a micro-porous core which is evacuated and sealed in a thin, gas-tight membrane. The membrane is capable of withstanding atmospheric pressure, and of maintaining the vacuum over time. This vacuum technology allows them to achieve an aged thermal conductivity as low as 0.007 W/m.K – up Hidden heat to five times better than that of commonly used insulation materials. As a result, they can deliver the desired U-value with a much thinner construction than would otherwise be possible. VIPs are typically accompanied with rigid insulation panels of the same thickness. These boards can be cut to fill awkward spaces between the VIPs or to allow penetration through the insulation layer. To ensure the slimmest possible construction, some suppliers also provide tailored design services to achieve the best possible ratio of VIPs to infill panels. VIPs are well suited for UFH retrofits on solid floors as their thermal performance minimises the required thickness of the insulation layer. In high ceilinged properties, this can allow the existing floor slab to be retained. In cases where the floor to ceiling height is more limited, it can reduce the amount of digging down required to maintain the existing floor level after the UFH system is installed. In either case, the VIP system (including the rigid insulation infill panels) should be fitted above the floor slab, damp proof membrane and a protection layer. By fitting the insulation above the floor slab, heat is retained within the building envelope, helping the property to respond more rapidly to the UFH once it is turned on. A polyethylene separation layer should then be fitted, followed by the UFH system and screed, taking care to not damage or penetrate the VIPs during the process. Complete envelope Floor insulation is obviously a crucial consideration for any UFH application. However, installers should also be aware of the performance of the complete building envelope. As water UFH systems typically operate at lower temperatures than conventional radiators, it is important to ensure that all elements of the building are properly insulated and sufficiently airtight to keep homeowners warm. Products such as VIPs can help to resolve issues in traditionally ‘hard-toinsulate areas’, maintaining heat and internal space and maximising the efficiency of the UFH system. www.kingspaninsulation.co.uk/optim-r Adrian Pargeter of Kingspan Insulation explains why insulation is key when installing underfloor heating Kingspan OPTIM-R vacuum insulation panels have an aged thermal conductivity of just 0.007 W/m.K. The Kingspan OPTIMR Flooring System is suitable for use with most underfloor heating systems


RCI May 2017
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