PHAI EMBODIED CARBON REPORT
INSIGHT
S IX OF ON E AN ANALYSIS OF THE EMBODIED CARBON FROM SIX WAYS OF BUILDING A HOUSE
The climate emergency demands that we minimise the energy we use to operate buildings, as well as the energy we use to construct new buildings, where new buildings are needed. A Passive House Association of Ireland-commissioned analysis may start to shed some light on the embodied carbon impact that different build methods can have. Words by Jeff Colley
T
he embodied carbon of walls and foundations on new homes can be cut by 50 per cent or more, an analysis commissioned by Passive House Association of Ireland (PHAI) has revealed. The PHAI commissioned the Association for Environment Conscious Building (AECB) to conduct the analysis using PHribbon, a tool which enables embodied carbon to be calculated via the PHPP passive house design software. The AECB calculated the cradle-to-grave embodied carbon emissions of a 76 m2 end of terrace house provided by Cork City Council. The building was modelled in Sketchup by AECB chief executive Andy Simmonds, with the calculations carried out by PHribbon creator Tim Martel, working in collaboration with the author, and fellow PHAI board member John Morehead.
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The house was designed to meet compliance with Ireland’s nearly zero energy building (NZEB) standard, including the following energy performance specifications: U-values W/m2K Walls: 0.145 – 1.64 Roof: 0.105 – 0.134 Floor: 0.101 – 0.137 Windows: 1.15 Doors: 1.1 Y-factor: 0.06 Mechanical extract ventilation Airtightness: 3 m3/hr/m2 at 50 Pa. Heating system: 6 kW air-to-water heat pump
Wain Morehead Architects prepared DEAP calculations to demonstrate that the specification complied with Ireland’s NZEB requirement for dwellings. Building LCA modules: a brief explanation With embodied carbon assessment generally there are certain areas where it’s possible to reach relatively clear conclusions with high degrees of confidence, while other aspects of the calculation may be more speculative. Life cycle assessment is divided into four modules: A, B, C and D. Module A deals with the building construction up to the point of practical completion. This is the area where there is most scope for accurate embodied carbon calculation, for the simple reason that it involves assessing the impact of works that have been done.
