Ciaran McAliskey of Keystone Lintels argues the case for taking a fabric first approach to meeting the Future Homes Standard, in order to set housebuilders on the best path to hitting net zero carbon.
Faced with the UK’s ambitious commitment to bring carbon emissions to net zero by 2050 and the resulting stricter Building Regulations, housebuilders are under increasing pressure to consider the long term energy efficiency of all buildings from the earliest stage of the design process.
From 2025, all new housing will be expected to produce much lower carbon emissions compared to current standards under the Future Homes Standard, and will therefore require low carbon heating technologies.
To meet these targets, taking a fabric first approach within SAP will be essential to comply with the new Part L regulations, and is a critical first step to reaching the performance levels required to future-proof UK homes.
The Government is committed to bringing in the Future Homes Standard (FHS) in 2025, which will see a new build house have 75% lower CO2 emissions than one built to today’s standards. This will be achieved by having very high standards of energy efficiency and low carbon heating (i.e. heat pumps). The Part L updates that came into force on 15 June 2022 are an important stepping stone to the FHS and will mean carbon emissions from new homes will need to be 31% lower than at present. To put things into context, the previous Part L uplift in 2013 was 6%. Therefore, this interim 31% uplift will require some fairly significant changes for housebuilders, as ultimately we need our homes to be zero carbon ready to meet future legislation.
TAKING A FABRIC FIRST APPROACH
What will this mean for new homes and how will architects meet these rigorous standards? One key area will be addressing the thermal performance of a building envelope through a fabric first approach to building design. If we get the fabric right and we build as designed, we will go a long way to meeting our targets. It’s an approach that will enable us to meet and even exceed regulatory performance criteria, whether it is for large scale private or social housing or a much smaller residential property.
While a reduction in CO2 emissions is one consideration when designing thermally-efficient housing, an improvement in thermal comfort can also have a positive impact on occupants – adding to their wellbeing, but also aspects like productivity for work.
STOP THERMAL BRIDGING
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 these ambitious new regulations.
While there are some design, measurement and calculation issues, the other concern in terms of thermal bridging is that we are neither building consistently what we design, nor 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 instance. This can lead to a ‘performance gap’ between as-designed and as-built building performance. It’s why these weak spots can significantly impact a building’s heat loss and have a detrimental effect on the overall fabric efficiency of the external wall.
AN OFT-OVERLOOKED BRIDGE
Often overlooked when it comes to thermal efficiency due to a focus on insulation, window and doors, is that traditional steel lintels can create a significant thermal bridge in homes. This is due to the high thermal conductivity of steel, and because they span over long lengths in a typical build. However, solutions have developed to address this.
For instance, a steel lintel that incorporates a thermal break can be up to five times more thermally efficient than standard alternatives, and such a solution has been specified on many housebuilder projects around the UK. 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.
At a time of spiralling energy costs and the current energy crisis showing no signs of abating, making homes more energy efficient through a fabric first approach will go some way to locking in savings for the lifetime of a building and achieving our climate change targets.
NET ZERO HOUSING
We have produced a webinar that’s useful for anyone seeking to learn about the delivery of net zero housing, titled ‘How are we going to deliver Net Zero Housing?’ It is one of four in a series of free webinars featuring expert industry speakers discussing the challenging topics and issues the industry is currently facing.
With changes on the horizon for the design of our new build houses, it will be incredibly important for housebuilders to specify materials and components which deliver the difference between a sustainable and an inefficient home.
Ciaran McAliskey is national specification manager (Ireland) at Keystone Lintels