Energy Efficiency & Sustainability
Window insulation and airtightness is a major requirement in Passivhaus design needing a minimum of requirement of triple glazing for doors , windows and curtain wall . Aluminium , you may be surprised to know can perform exceptionally well at high insulation levels using wide thermal breaks , inserted insulation and wide window seals . Some aluminium window systems can get down to a Uw of 0.55 W /( m 2 K ) and door systems down to a Uw of 0.65 W /( m 2 K ). Whilst these high performance systems come at a premium , the principles of design are now well known and aluminium plus polyamide thermal breaks are relatively quick to design and cost effective to produce , unlike window systems in alternative materials . With today ’ s advanced powder coatings these systems can perform well over several decades .
Passivhaus principles and low-carbon construction take a ‘ fabric first ’ approach , basically there is no point in using alternative heating systems until the whole building fabric is designed for minimal heat losses . There are five principles that need to be introduced into the building before minimal heat sources can be considered . We must also remember that at certain times of the year , even in the UK , we also need to ensure we can keep the heat out in the extremes of weather .
Air tightness to reduce draughts through building structure interfaces and fenestration helps isolate the living / working space from the exterior . Good quality and effective insulation of walls , ceilings and floors , will also ensure that the interior space remains isolated in extremes of temperature . Often between building interfaces , thermal bridging can occur where insulation areas are interrupted , these areas need very careful design . Designs of window reveals is particularly relevant here , including the window cill and head to ensure that the window frames high thermal perimeter performance is not reduced by poor installation and reveal design . Then to the window systems themselves , high thermal performance systems that are located to take advantage of solar gain but not to extremes .
Once we have the building airtight and thermally efficient , air changes are crucial and these can be achieved by using MVHR ( Mechanical Ventilation with Heat Recovery ) which provides fresh filtered air into a building whilst retaining most of the heating energy that has already been used in the building . These systems currently can be up to 85 % efficient .
So for new build and home improvement , where does that place our current supply chain for homeowners ?
As we rapidly move towards Passivhaus , or very low energy homes , window installers will need to consider window reveal designs to ensure ‘ cold bridging ’ does not occur , whilst also maintaining the thermal performance of the window frame . This will increase costs of installations as changes to the reveals may be necessary . The opportunity for the home improvement supply chain is quite considerable when you consider the opportunities of upgrading the building insulation and installing MVHR systems alongside replacement doors and windows .
The landscape is changing rapidly and there are opportunities for businesses to range build and meet the market demand for the new era ahead . Here at CAB we will be keeping our membership informed of developments and pending changes in legislation . Why not consider joining the Association and be recognised as being involved in and helping to shape the future of our Industry .
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CLEARVIEW-UK . COM MAY 2023
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