The Sensitive Retrofit of Traditional Buildings in the Commercial Sector
Claire Truman recently attended our Responsible Retrofit of Traditional Buildings conference, and we were delighted when she agreed to write a guest news piece for us. Claire is an Associate at EPR Architects, a BREEAM Accredited Professional and RIBA Conservation Registrant. Having worked at specialist practices – for ‘green’ architecture, and separately conservation – she now looks to bring these successfully together.
As a project architect I work predominantly on large commercial heritage conversions. Most discussion to date on the sensitive retrofit of traditional buildings, however, has been centred on the domestic sector. The application of this knowledge to the commercial sector is often valid, although problems can be compounded.
Research into the actual performance of traditional construction continues apace – and is providing evidence their physical attributes are often superior to that assumed by regulations. Empirical evidence of actual U-values, air tightness and influences of location-specific weather is desperately needed not only to improve the sensitive and appropriate thermal upgrade of our heritage, but to underpin a cultural shift in the execution of commercial schemes.
Challenges – Scaled-Up
Challenges faced by large commercial heritage projects are many and complex: factors include a large number and range of stakeholders involved, the securing of financial investment, availability of suitably skilled contractors, and the management of a large workforce on-site. Common problems reported at the domestic scale are just as relevant to commercial schemes, but their impact potentially greater.
Redevelopment of Grade II listed Gainsborough Hotel and Spa, Bath © EPR Architects
Education – In the domestic sector it is acknowledged improved householder knowledge will make for better decision-making. Education of all stakeholders is important – from putting together a suitable client team, to skills demanded on-site. The recent recession has possibly seen a generation of traditionally skilled people evaporate. As the talent pool reduces so costs increase, demand decreases, knowledge is lost.
Poor workmanship – observation of failed installation details on domestic sites has highlighted the importance of close monitoring of workmanship. The physical nature of large heritage buildings – with numerous rooms and labyrinthine layouts – can leave pockets of workers unobserved for lengthy periods. Capturing all poor detailing can be close to impossible.
Programme – this can be relatively flexible on domestic schemes where works can be quickly mobilised and contractors have a high degree of control over programming – often to the frustration of homeowners! On commercial projects the programme is an animal to be wrestled with and ultimately penalties for overrunning can be financially crippling.
The drive to meet the programme can run rough-shod over selection of construction methods and materials. Often cited is the conundrum of lime plaster: requiring skilled labour drawn from a smaller pool, the application itself is lengthy and can affect progress of other works, therefore commonly targeted for ‘substitute’ materials.
Refurbishment scheme to Grade II* listed 2 Waterhouse Square, Holborn Bars © EPR Architects
Leadership and Management – it is imperative to keep morale high to retain an effective workforce. Projects can often be on-site for many years, and if delays creep in this can erode enthusiasm and leave personnel vulnerable to being picked off by recruitment agencies. Time and again it has been proven historic knowledge of a project is critical in both the execution of details on-site and the management of paperwork. Losing people can have serious implications on construction detailing and affect both programme and quality.
Impact of Forthcoming Research
Up-coming research on thicknesses of internal wall insulation by the Sustainable Traditional Building Alliance (STBA) could have a large impact on commercial projects. It is anticipated optimal insulation thickness will be proven to be within a range of 40-80mm, subject to thermal treatment of reveals. The financial savings of large volumes of insulation could be huge.
The STBA working with NDM Heath Ltd, Prewett Bizley Architects and Fourwalls, in conjunction with Bristol City Council are due to publish documentation in the Summer on good practice construction details. The knowledge gap of thermal bridging and associated moisture migration routes should start to close.
An Improved Future
Rather than leading by volume it can feel like the commercial sector is falling behind current thinking, relying on a push from research on smaller projects where information can be more quickly turned around. It will take a sea-change in knowledge and culture, but at the Responsible Retrofit Conference in Bristol it distinctly seemed momentum is building.
Head over to Claire’s blog, progressiveheritage.wordpress.com, for posts on the sensitive and intelligent re-use of heritage buildings. You can also check out our 2015 Responsible Retrofit of Traditional Buildings conference in pictures here.