FOCUS ON NZEB
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Thermal image of house using default Y-value of 0.08
Thermal image of house with default 0.15 Y-value
a once-off investment requiring no maintenance or replacement and will ensure the efficiency and longevity of the heating system and plant. nZEB represents a significant challenge for the construction industry but also a huge opportunity to make a positive change in the way we construct our buildings and mitigate against the adverse effects of Climate Change. We cannot continue to waste energy and damage our environment for future generations - Kingspan is committed to providing solutions to protect that future and is committed to a Net Zero Energy future. HOW TO ACHIEVE NZEB The starting point for nZEB compliance is to maximise the performance of the building fabric elements, which includes floors, walls, roof and windows. A key decision is the construction methodology, which typically starts with the walls. For example, our Kooltherm® Cavity Wall insulation solutions tick all the boxes here, in terms of superior thermal performance, minimising wall thickness, buildability and affordability achieving U-values as low as 0.13 W/m2K.
Then choose the preferred floor, roof and wall constructions to complete the high performance building envelope. Key to nZEB is to minimise the energy demand from the outset. Compliance can be achieved without excessive reliance on ‘bolt on’ mechanical and renewable technologies by using premium, thermally- efficient products, good detailing and attention to detail on site. Investing in the building fabric is a long-term, low-cost strategy requiring no maintenance or replacement for the functional life of the building, while guaranteeing complete thermal comfort. When individual building fabric elements are finalised, it is imperative to consider how these elements come together. With high performance building fabric the impact of these junctions becomes increasingly important. There are four options here: 1 Use Thermal modelled details such as Kingspan Performance Junctions to achieve a Y-value as low as 0.04 or lower. (illustration 1) 2 Use the standard Acceptable Construction Details and use the default Y-value of 0.08. (illustration 2)
3 Use a combination of the modelled details and the standard ACDs to derive a project specific Y-value. 4 Accept the default 0.15 Y-value. (illustration 3) As the above images illustrates the first is the best option. By constructing our buildings to nZEB levels, we in the construction industry can help to achieve the net zero target by 2050.
Sean McGuigan, is National Business Development Manager for Kingspan Insulation Ltd, Bree, Castleblayney, Co Monaghan, Ireland
T: +353 (0)42 979 5000 www.kingpsaninsulation.ie
Buzzwords
Psi-value: This is the additional heat-loss per linear metre at building element junctions and is calculated by numerical modeling of the respective junctions. Y-value: A penalty added to the total element heat-loss and is calculated by dividing the sum of all the thermal bridges by the total exposed surface area.
“nZEB represents a great challenge for the construction industry but also a huge opportunity tomake a positive change in thewaywe construct our buildings and mitigate against the adverse effects of ClimateChange.”
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