As you may have already heard, the World Green Building Council is committed to supporting market transformation towards 100 per cent net zero carbon buildings come the year 2050, buildings that need to be energy efficient and make use of renewable sources for their energy needs in order to reach the Paris Agreement levels of global emission reductions.
By 2030, all new buildings being constructed must operate at net zero carbon – but what about the existing building stock in the UK and beyond?
Tackling the carbon footprint of the built environment that already exists will prove to be rather more challenging, according to the Royal Institute of British Architecture (RIBA), citing a report from the Institution of Engineering and Technology and Nottingham Trent University revealing that more than 26 million deep retrofits will be needed by 2050 to hit the UK’s zero carbon targets.
And given that our housing stock is made up of lots of energy-inefficient Edwardian and Victorian houses, it could prove even more of a challenge than you might at first think. But engineer Kit Knowles has already had some success in this regard, having already achieved a deep petrochemical-free Passivhaus refit on two Victorian properties in Manchester.
Almost all original bricks used in the initial construction of the townhouses were retained, as well as the joists and rafters from the 100-year-old roof – and the projects also exceed the Passivhaus retrofit standard by reaching Enerphit Plus levels. This means that buildings generate at least 60kWh of renewable energy annually per square metre of floor area.
Technologies used included an aerogel external wall insulation, solar-powered rainwater harvesting, hybrid solar PV-thermal panels and hybrid heat recovery with passive stack ventilation.
Mr Knowles also used Organowood, a Swedish wood product, for external cladding on the buildings, a material preserved by dissolving inert silica into the wood fibres to replicate the process of fossilisation – which eliminates the need for petrochemical products.
Passivhaus buildings themselves aim to provide a high level of comfort for the occupants while using as little energy as possible for heating and cooling, built according to principles developed by the Passivhaus Institute in Germany.
These buildings achieve a 75 per cent reduction in space heating requirements compared to standard practice for new builds in the UK. This standard will, therefore, prove particularly useful in helping the industry achieve the 80 per cent carbon reductions set out as a target for the UK government.
Practically, this means very high levels of insulation, accurate design modelling using the Passive House Planning Package, airtight building fabric, extremely high performance windows with insulated frames, thermal bridge-free construction and a mechanical ventilation system with very efficient heat recovery.
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