By Chris Cowley and Ciarán McAliskey at Keystone Lintels
It has been described as the ‘fifth fuel’ and the cheapest of all, but energy efficiency is the most important measure to save energy and reduce carbon emissions. The built environment has some of the most untapped energy efficiency potential, which is why a fabric first approach to building design will maximise the performance of the building envelope and make our homes more sustainable. The use of building materials and components that make up the building envelope can make an important step in the journey to ensure homes meet new building regulations, as well as being futureproofed for our climate change challenges.
Regardless of the type of development, whether it is a residential property or large scale social housing, a critical element of the fabric first approach will be addressing the issue of thermal bridging, which can be responsible for up to 30% of a home’s heat loss. Eliminating thermal bridging through good design and correct product specification will be essential if we are to ensure we meet ambitious new building regulations, which will require all new homes to cut carbon emissions by 31% as an interim uplift, and by a further 75-80% in 2025.
Whilst there are some design, measurement and calculation issues, the other concern in terms of thermal bridging is that we are not building consistently what we design, or we are not detailing the right products in the right places. There are also issues with site skills and workmanship; when you fail to build correctly it undermines the good work carried out in the first place. This can lead to a performance gap between as- designed and as-built building performance. It’s why these weak spots can have a significant impact on a building’s heat loss and have a detrimental affect on the overall fabric effiency of the external wall.
High performance lintel
It might be overlooked when it comes to thermal efficiency due to a focus on insulation, window and doors, but traditional steel lintels can create a significant thermal bridge in homes due to the high thermal conductivity of steel and because they span over long lengths in a typical build. However, there are solutions to address this.
For instance, Hi-therm+ has set a new standard for thermal efficiency in steel lintels. It incorporates a thermal break and is up to five times more thermally efficient than a standard lintel. Hi-Therm+ is a very cost-effective solution, particularly if we look beyond the unit price, as getting the fabric right will save energy throughout the entire life span of the house.
The Hi-therm+ Lintel has made a significant impact on the thermal efficiency of homes and is specified on many housebuilder projects around the UK due to its low cost and improved performance in lowering carbon emissions within the Standard Assessment Procedure (SAP).
The importance of lintels should not be understated. The Hi-therm+ Lintel has a positive impact on the SAP calculation due to its impressively low thermal conductivity performance, which contributes towards its Psi value of between 0.03 & 0.06 W/m.K. This makes it the ideal low cost and sustainable solution for specifiers aiming to achieve building regulations with the fabric first approach. When you consider the BRE has found that thermal bridging can account for up to 30% of heat loss from buildings, then paying close attention to the details and structural elements such as lintels can have a huge impact on the overall thermal performance of a building.
Soaring inflation and spiralling energy costs has meant that boosting energy efficiency will go some way to making homes more affordable to heat and achieve our climate change targets. There will be challenges for housebuilders, but fabric first will be a key priority in locking in energy savings throughout the lifecycle of a building.