Creating sustainable value from undesirable buildings

James Wright Zhang

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With building and construction responsible for 39% of all carbon emissions in the world, it's time for all of us to consider retrofitting as a serious alternative to demolishing ‘undesirable’ buildings. Here James Wright-Zhang from our London studio, reflects on how applying EnerPHit guidelines can re-energise the appeal of previously overlooked sites.

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When the first Passivhaus buildings were constructed in Darmstadt back in 1991, few would have predicted that this kind of exacting passive performance would ever become a viable option for the wider construction industry. Today, however, as we find ourselves in the middle of a global climate crisis, the industry, alongside notable UK organisations like the London Energy Transformation Initiative (LETI) are taking cues from Passivhaus standards as they look to reduce environmental impact. 

Passivhaus and retrofitting via EnerPHit

What does this mean for us as urban architects dealing with problem buildings,’ perhaps with outdated services, poor-quality external fabric and low ceilings, where demolition is often seen as the only viable commercial solution? In the design industry, we are beginning to see how passive building is making its mark on the retrofit market through the PHI’s EnerPHit standard, helping unloved buildings to show their potential. 

EnerPHit, developed by the Passivhaus Institut, provides guidance for achieving strong passive performance while considering the additional technical challenges of dealing with existing buildings. Key criteria are determined through the external fabric’s performance, efficiency of appliances, and the ability to integrate MVHR

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Bringing back unloved buildings through retrofitting

While many ornate period buildings might struggle to integrate airtightness and thick insulation for conservation reasons, often their more mundane counterparts are prime candidates for external modifications. Thick insulation and airtight layers can mask an outdated façade and present a new canvas for modern design touches, with the added benefit of enabling the elimination of most thermal bridges to achieve high-performance passive design. Additionally, conservatively sized window openings can often be adjusted to accommodate Passivhaus triple-glazed windows sized to manage gains. Finally, low-ceilings and service duct provisions rarely prohibit efficient MVHR systems from providing the fresh-air and heating requirements for the retrofit. In some instances, integrating this system allows the reclamation of ceiling height and can make the difference between an unviable space and a strong commercial opportunity. 

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EnerPHit and improved energy performance

In terms of long-term performance, achieving the EnerPHit standard’s space heating and cooling reqirement of 25kWh/​m2/​year can result in a building’s total energy costs diving to just 10 – 15% of their original values. This is before considering reduced maintenance requirements and capital savings from reduced carbon levies. When combined with significant savings due to minimal demolition, EnerPHit quickly starts to make financial sense.

Working with challenging air quality/​noise pollution

Working with EnerPHit guidelines can also add value to sites with particularly challenging environmental contexts. At Benoy, we are in the early stages of a mixed-use project faced with both intense air quality and noise constraints. These issues are being eliminated through the effective integration of highly insulated and airtight units with MVHR for cooling and air filtration. Retrofits using EnerPHit’s principles in these situations do not just become desirable but are also uniquely adapted to transform unhealthy conditions into liveable spaces. 

As designers with a passion for sustainable urban regeneration, we’re excited to see how we can apply this retrofit thinking to previously overlooked sites and buildings both in the UK and beyond. 

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