UNDERFLOOR HEATING
The benefits of UFH for non-residential heating retrofits
With the 2050 Net Zero deadline drawing closer and energy remaining a significant cost for businesses and public sector organisations, improving the efficiency of existing buildings has never been more important. Here James Griffiths, marketing manager NW Europe at GF Building Flow Solutions (formally Uponor) looks at the role of underfloor heating systems and how these can be retrofitted in existing buildings
T
he UK government has set the target of achieving a 78% cut in greenhouse gas emissions by 2035 compared to 1990 levels, on the way to reaching Net Zero by 2050. As one of
the largest sources of emissions, the decarbonisation of heating and power for buildings will be necessary if the country is to meet these targets, and this is the driving force behind the recent revisions to Part L. There is rightly a focus on ensuring new buildings are designed and built to low- or even zero-carbon standards. However, 80% of the buildings that will be in use in 2050 have already been built, meaning it is essential to improve the energy efficiency of the buildings we already occupy. In fact, the International Energy Agency (IEA) estimates that improving energy efficiency represents more than 40% of the energy-related emissions reductions required by 2040 to meet global targets. For businesses and public sector organisations,
there is pressure to demonstrate how they are reducing their carbon footprint. There is also the financial impact of energy prices that remain comparatively high despite some easing in recent months.
How underfloor heating solutions can help
For most older buildings, achieving the necessary improvements in energy efficiency will require a significant change to how space heating is approached. An effective option for reducing the energy used is to utilise underfloor heating (UFH). The far larger surface area of UFH systems in comparison with traditional radiators means a lower flow temperature is possible, which in turn minimises the amount of energy required to heat the building. Also, the thermal mass of a screed-based UFH system absorbs, stores and releases heat, minimising the amount of energy required to maintain the target room temperature.
For both domestic and non-domestic
renovation projects, where the wet heating system is being entirely replaced, Part L of the Building Regulations in England and Wales requires a maximum flow temperature of 55ºC. Similarly in Scotland, the compliance guidance states a maximum temperature of 50ºC. In this situation, an underfloor heating system becomes one of the most practical options
for effectively heating the building. However, regardless of the approach selected, a lower temperature system will only be effective if the correct level of floor, wall and roof insulation can be achieved to minimise heat losses. Although the advantages of UFH are widely appreciated for domestic properties, its suitability for commercial buildings is sometimes overlooked, especially for retrofit projects. While electric UFH is inefficient for the large areas typical in non-residential buildings, hydronic (water-based) systems are highly scalable and often easily retrofitted in existing buildings. In fact, UFH may be more suitable for commercial and public buildings than a radiator-based system. This is because, as the heat radiates from the whole floor surface, it eliminates the uneven heating that radiators can produce when used in larger, open plan areas. The added benefit of removing the radiators is that the occupants can use the space more flexibly as the location of heat emitters no longer needs to be considered when placing furniture and equipment.
UFH and low carbon technologies
UFH is also compatible with many of the renewable and low carbon energy sources, such as heat pumps and solar thermal systems,
which are currently the best fit for replacing traditional boilers. The lower flow temperatures possible with UFH also makes it ideally suited for use with a heat network (also known as a community / local heat network or district heating), which uses a single heat source to deliver heating and hot water to multiple buildings on the same site. This includes schools, hospitals and university campuses.
Choosing the right system
There is a wide range of UFH systems available, but choosing the most suitable system will often depend on the characteristics of the building and the level of renovation being undertaken. If the UFH needs to be installed on top of the existing floor substrate or even over the old floor covering, then a low-profile system that produces a minimal floor height increase will often be required. For example, the Uponor Minitec system raises the floor height by just 15mm but, as a screed-based solution, still offers significant thermal mass. In cases where the retrofit must be completed in a tight timeframe, there are dry installation alternatives that offer a similarly small height build-up. In addition, lightweight systems are available that have been specifically designed for floor structures that have a low static weight-bearing capacity. In contrast, where a more significant
renovation is being carried out and the existing floor is being completely removed, a system that is more typically used on new build projects can be utilised. This will often allow greater thicknesses of floor insulation and screed to be laid, maximising the efficiency and effectiveness of the UFH. An example of an effective floor construction is 65mm of screed laid over 65mm of insulation, ideally on a concrete subfloor. However, while all hydronic UFH systems operate in same way, not all products offer the same levels of performance, often due to the design or materials used. Therefore, it is important to look carefully at the product information to ensure the most effective solution is selected. The level of technical support offered by the manufacturer should also be considered as this will help avoid potential issues and simplify the design and installation of the UFH system. For commercial and public sector buildings, underfloor heating provides a highly energy efficient alternative to conventional radiators and allows simpler compliance with the latest standards. The ongoing development of UFH means there are now a variety of retrofit options that allow these systems to be installed in a far wider range of building types.
24 BUILDING SERVICES & ENVIRONMENTAL ENGINEER JULY 2024 Read the latest at:
www.bsee.co.uk
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