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Ecological comparison of facade systems


The results of an ecological comparison of facade renovation systems are revealed by Ian Anderson, managing director at rainscreen cladding manufacturer Steni UK


building are not affected by interstitial condensation. The environmental performance of different cladding


systems and fixing methods in renovation projects was the subject of a study by the Tampere University of Technology (Department of Civil Engineering, Institute of Construction Economics and Management) in Finland. This focused on the impact of manufacture and use and maintenance. The Ecological Comparison of Facade Renovation report helps


specifiers better understand the environmental credentials of the various rainscreen systems and make better-informed design and specification decisions. It concluded that glass fibre reinforced polyester composite


T


he growing popularity in the UK of dry-trade con- struction methods has led to a plethora of rainscreen cladding systems, ranging from thin-film aluminium


or steel cassettes to fibre cement and glass fibre reinforced polyester composite panels. Along with the actual panels themselves, the fixing systems


also differ, with specifiers and designers able to choose between wood, aluminium or steel stud in different thicknesses as well as glue. So where on earth do they start when choosing which cladding system to use? Given their capability not only of transforming a building’s


visual appeal but also its performance, particularly in terms of thermal insulation, rainscreen cladding systems have become something of a modern-day wonder product although they in fact date back decades. Not only are they capable of breathing new life into ugly,


tired and poorly-performing commercial, education, healthcare, leisure and residential buildings, including high-rise tower blocks, they are also a highly efficient way of branding build- ings, with a wide range of colours and finishes enabling them to adopt corporate colours. The principles of ventilated rainscreen cladding allow for


thermal movement and moisture dispersion through panel joints and a ventilated cavity. Basically the cladding is fixed back to the main support structure with one of the aforementioned methods, to form a weather, impact and rot-resistant, colourful and relatively lightweight jacket. The benefit of the rainscreen system is that any moisture,


either ingress or humidity, is ventilated out of the cavity at the rear of the panels, ensuring the insulation and inner leaf of the


rainscreen panels ecologically outperform competitors in numerous tests, ranging from Global Warming Potential (GWP) to Photochemical Ozone Creation Potential (POCP). The study states: “The comparison shows that of those


facade coating products examined, glass fibre reinforced poly- ester composite has the least impacts on environment, measured by the LCA factors.” The study was conducted using mainly Life Cycle Analysis


developed by the Society of Toxicology and Chemistry (SETAC) – transportation and the effects of the energy required for renovation work were not taken into account. The investigation considered seven different system materi-


als – glass fibre reinforced polyester, fibre cement, brickwork, concrete panel, plastering, thin film steel cassette and thin film aluminium cassette. Insulations studied were glass wool and expanded polystyrene. Framing systems were aluminium, steel, wood studs and punctual fastenings. The Global Warming Potential, Acidification Potential


(AP), Nutrification Potential (NP), Photochemical Ozone Creation Potential (POCP) and Critical Air Volume (CAV) were compared and in each category glass fibre reinforced poly- ester panels recorded the lowest – and therefore most advanta- geous – readings. Indeed, in most cases, its results were less than half of its closest rival. Take for example the GWP results. Glass fibre reinforced polyester rainscreen cladding panels 8mm thick returned a


reading of 2,400g of CO2 per sq m of wall surface. The next closest was 8mm-thick fibre cement boards at 5,800g CO2/m². An 85mm brick facade was rated a massive 28,000g and a


130mm brick facade even greater at 39,000g CO2/m². As mentioned previously, these results were mirrored in all


Continued overleaf... respond online at www.architectsdatafile.co.uk


‘The benefit of the rainscreen system is that any moisture, either ingress or humidity, is ventilated out of the cavity at the rear of the panels’


Ian Anderson, managing director at Steni UK


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