ALUMINIUM
‘ Future Homes Sustainable Cities ’ by Wojciech Brozyna - MD of Aluprof UK
» AROUND A THIRD OF ALL OUR energy use in the UK is used in our homes . With the majority of this energy used in heating , this equates to about forty MTOE ( million tonnes of oil equivalent ) used every year . The UK Government have some ambitious plans to cut energy usage by 2050 in many sectors . Glasgow will be hosting the 26th UN Climate Change Conference of the Parties ( COP26 ), from 31 October to 12 November 2021 and the UK is striving to take a global lead to drastically cut carbon emissions .
The last change to our legislative window U-values for new homes was implemented in Approved Document , Part L in 2013 . Little has changed since then , but , that is all set to change following the Government ’ s recent Future Homes Standard Consultation . The updated Part L will likely be finalised and released at the end of 2021 to be introduced into legislation early in 2022 . This will likely mean the introduction of window systems having to meet a lower U-value of 1.2 W / m 2 K ( in England ) for the ‘ notional ’ building and the possible introduction of triple glazing . Following this change , it is likely that Part L will be further revised in 2025 , possibly taking window U-values down to 0.8 W / m 2 K . The changes are the result of the Government mission to achieving net-zero carbon by 2050 and ensuring that new homes are built to be “ zero-carbon ready ” as the National Electricity Grid decarbonises .
With the introduction of revised air tightness requirement , down from the limiting value of 10 m ³/ h . m ² at 50Pa to 8 m ³/ h . m ² at 50Pa ( with 5.0 m3 / h . m2 at 50Pa for the notional building ) using the ‘ blower door ’ test method or a new ‘ Pulse ’ test method , our building structures are likely to become even more airtight . It is suggested that a house achieving an airtightness of 5 m ³/ h . m ² will use 40 % less energy on space heating than a house built to 2013 standards of 10 m ³/ h . m ². With stricter airtightness , this calls into question how we can retain heat in our buildings in winter whilst maintaining healthy indoor air quality for well-being with controllable natural ventilation .
Will the change in thermal requirements in Part L and the revised guidance in Approved Document L Volume 1 change the material of choice for specifiers ? Probably not , as both of the predominant materials chosen for new construction , aluminium and PVC , can achieve the U-values required , albeit they will be thicker , more thermally efficient and may carry triple or quadruple glazing , consequently products will become more expensive . Balancing this increased cost will be increased product quality which is likely to offer products an increased in-use life , possibly up to twice the current life expectancy .
There are three areas of carbon emissions we have to remember ; the production and installation of a product , what the product can save ( or use ) during its useful life and what value it has at its end of life , or how it can be reused or recycled . Reducing the rate of replacement will significantly reduce carbon . In the future , we may be required to prove a carbon payback if a lesser performing product is to be replaced with a newer carbon saving product . Aluminium has proven its almost 100 % recycling ability with no loss of structural strength , however , with long life comes the shortage of end of life recycling and currently , we can only supply up to 50 % of the global demand for the material . Product recycling and sustainability are crucial if we are to ensure cyclical ‘ cradle to cradle ’ material resources in the future . Specifying aluminium will ensure its continued use for generations to come . 75 % of all aluminium ever produced since 1880 , when it became commercially viable , is still in use today . There will likely be a move to adopting differing designs of windows and doors in the future to make the most of high insulation glazing , such as reducing sightlines to a minimum . This may mean a move to sliding systems for large glazed opening doors and the adoption of tilt turn window systems . Will this herald a move away from the UK ’ s love of the outward opening ‘ casement ’ window ?
What does seem to be missing in this rapid move towards increasing thermal efficiency and airtightness in our future builds is the need for air ventilation , particularly in our homes . This is crucial for our well-being and continued health . We know that sealing up a small dwelling will eventually lead to condensation appearing on the coolest elements in the room , sometimes a wall or an abutment with a ceiling , where dampness can turn quickly into unhealthy mould
growth . This is particularly relevant in social housing where occupants may be reluctant to ventilate due to the cost incurred in reheating . It , therefore , seems logical for future legislation to include mechanical ventilation with efficient heat recovery , or indeed cooling of incoming fresh air depending on the time of year .
Another issue that we do need to attend to as an industry is the robust detailing of interfaces between windows and doors and the building structure . Cold bridges often decrease the claimed efficiencies within a building construction that can reduce the effectiveness in use of a designed build by up to 50 % of its claimed thermal efficiency . As an industry , should we be doing more to incorporate or encourage the specification of interface designs that reduce cold bridging to an absolute minimum ?
aluprof . co . uk
32 » OCT 2021 » CLEARVIEW-UK . COM