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Last night’s Passivhaus Trust/AECB event hosted by CEREB of South Bank University saw a packed theatre despite the blizzard conditions hours earlier.

The format supported a lively debate: 4 speakers all with slightly different opinions on how useful the Passivhaus standard for retrofit – EnerPHit – is at addressing the challenge of effectively reducing energy use in the UK. Each spoke for 15minutes followed by questions.

Naturally I was interested in specifically retrofit of the historic environment and the breadth of discussion helped place this in the context of the UK’s existing built environment. Much of the focus was on housing – single dwellings – however this rightly highlighted the emotive subject of financial economics which spans the entire construction industry.

Despite their various stances on Passivhaus as an aspirational standard I found all were convincing. Helen Brown of Encraft kicked off the event with a heavy pro-Passivhaus delivery. Helen acknowledged that it does cost more money, but why not do fewer buildngs to a better standard? You get what you pay for.

Bob Prewett, of Prewett Bizley Architects, presented ‘deep’ retrofit work most closely aligned with heritage. His work intricately examines the existing construction and requires careful workmanship to execute the refined details. When the audience queried the seemingly extra cost of such projects Bob offered a rule of thumb: 1/3 architectural work (extensions etc), 1/3 remediation of the building fabric which would be necessary, 1/3 energy retrofit.


Andy Simmonds, of AECB and Simmonds.Mills, presented findings of thorough research on different levels of retrofit – light touch to deep for three typical housing types. This addresses the possible concerns of occupier as investor in terms of the financial pay-back period. An acceptable benchmark for time was taken as a mortgage term – 25-30 years. The results were tangible and will aid the industry’s influence on the government with an eye on 2050 to financially assist homeowners more effectively than currently experienced.


Russell Smith of Parity Projects brought up the rear with an engaging presentation. For me the most hard-hitting factor he showed was the value in the construction industry of ‘major works’ compared to ‘minor works’.


Major works – such as development, extensions and insurance work forms the ‘minor’ portion of the industry’s turnover.


In fact the ‘minor works’ of repairs, redecoration, replacement and aesthetic changes is worth 5 times that of the major works.

Russell offered that tapping into the minor works is key to making reduced carbon footsteps in the right direction to minimise energy use. A solution on finances was out of the box: concurrent working to reduce labour. He illustrated this as he trained his electrician to install his internal wall insulation – and saved £3000 by encouraging a more efficient working method.

This summary is only a short taster of the rich discussions that were covered in such a short space of time.

The message was clear: retrofit is not just the big statement – easily quantifiable solar panels – it’s the invisible details, the quality of execution, the aspiration of the idea of reduced energy. Russell quite rightly threw left-of-field ideas into the arena: as an industry we have to use our creative talents to rethink how things are done and tap into what is important to our clients. He emphasised the understanding of what motivates people, and what affects their ‘ability to proceed’ – often money and finding an effective delivery team – and if that saves CO2 then all the better.

As for heritage it was encouraging that time and attention to detail is being paid to retrofit. Perhaps the key to unlock clients’ investment lies in remediation works highlighted by Bob. Whilst taking the building ‘back to its bones’ as Bob described, there is opportunity to make the client’s money work harder incorporating Russell’s ideas. This offers opportunity to build longevity into the construction by improving its inherent structure, and to enhance its fabric performance for today’s living standards.