BUILDING FABRIC 57


A VIABLE SUSTAINABLE ALTERNATIVE


There are multiple considerations when comparing polymer and aluminium windows, especially when it comes to sustainability, performance, and design fl exibility. Here, Steve Tonkiss of REHAU addresses the debate head-on.


s we approach government decarbonisation targets for 2030 and 2050, and with the recent introduction of the Future Home Standard, pressure to comply with new regulations for thermal performance and sustainability is mounting. Consequently, more energyeffi cient windows consisting of recycled materials are becoming more attractive to homebuilders and developers. Additionally, raising awareness around the need for sustainable products means consumers’ expectations have changed and they now expect greener options. Scrutiny has therefore increased around window materials.


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POLYMER VS ALUMINIUM The sleek, modernlooking fi nish of aluminium windows may suit certain home styles, but not others. By contrast, polymer is more adaptable for both modern and traditional-looking properties, with indistinguishable wood ‘facsimiles’ and foils in multiple colours available, alongside traditional white. Additionally, PVCu tends to be more costeffective  aluminium fl ush fi t casement windows can be up to three times more expensive – and offers greater thermal effi ciency, whereas metal’s thermal conductivity leaves windows susceptible to condensation. Though this can be resolved by installing polymer


thermal breaks, further issues can arise from incorrect installation.


HOW SUSTAINABLE ARE THE MATERIALS? Aluminium has been recyclable for decades – around 75% of the material ever produced remains in circulation today – and its recycling process uses 5% of the energy that it takes to produce new aluminium, making it sustainable. As it needs to be re-smelted at temperatures above 600°C, aluminium recycling is energy-intensive however, with an


average equivalent of 0.5 tonnes of CO2 emitted per tonne of material recycled gate-to-gate. Extraction of raw materials like bauxites – including mining and


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