The Building Conservation Directory 2021

146 T H E B U I L D I N G C O N S E R VAT I O N D I R E C T O R Y 2 0 2 1 C AT H E D R A L C O MM U N I C AT I O N S by applying window films, or adding blinds to the interior, but these are not the most effective solutions: they do not prevent the glass heating and radiating that heat into the room, and they obstruct the views and external appearance of transparency that may well have been one of the reasons the architect chose glass in the first place. In The Netherlands, conservation architect Wessel de Jonge was able to recuperate the listed HUF building in Rotterdam (designed by Van den Broek and Bakema in 1953) by adding the awnings that he found had been included in the original concept drawings, but never installed. Overheating had caused the building to quickly fall into disuse, but thanks to the awnings it is now considered not just much more comfortable, but arguably more beautiful. That awnings were a viable answer to the building’s long- standing problem has been proved over the ten-plus years since the renovation, as the building continues to host not just shops and offices, but a residential apartment. Since they are so effective, why did awnings disappear? Was it merely a change in fashion? Perhaps they were so ubiquitous that people simply stopped thinking about why they were there and what benefits they offered; and perhaps nobody really noticed they were disappearing, building by building, until it was too late. But a more pertinent question for us now must be: how do we bring them into popular use again? Traditional designs are still available, and indeed some of the original Victorian manufacturers are still operating. Obtaining permissions may prove a more serious impediment. The British Blind and Shutter Association had to fight hard to overturn a ban on awnings by the Ministry of Housing, Communities and Local Government after the Grenfell Tower fire, although awnings had not been used on the building, and there is no evidence anyway that they are a cause of fire spread on any facade. Meanwhile, external insulation (strongly implicated in the fire) continues to be strongly advocated by the UK government. It is true that, to safeguard significance for listed buildings, conservation officers and statutory inspectors will need to carefully consider the arguments for reinstatement, even when there is good evidence that the building once had awnings. In doing that, however, we need to balance the aesthetic value of a building as it appears today (which reflects, among other things, current fashion) with the benefits of restoring the building’s traditional functional performance, which can deliver long-term gains for the building and its occupants as well as wider public benefit in the form of reduced carbon and energy.5 The arguments supporting awnings on windows subject to solar gain are indeed so strong, especially in the face of climate change, that there would be a case for installing them on some listed buildings (and of course on many unlisted ones) even where there is no positive proof that they originally existed. Reinvigorating the love affair the UK once had with these practical and beautiful building elements would seem to be an obvious contribution to effective retrofit. By making the buildings much more usable, they can tick both conservation and sustainability boxes. A typically low-energy low-risk low- carbon traditional approach to effective building operation, awnings are also a perfect demonstration of the untapped potential of the historic built environment to contribute to sustainability and effective climate action. 1 Bessoudo, M, Tzempelikos, A, Athienitis, AK, and Zmeureanu, R, Indoor thermal environmental conditions near glazed facades with shading devices – Part I: Experiments and building thermal model, Building and Environment, 45 (11), 2506– 2516, 2010 2 De Luca, F, Voll, H, and Thalfeldt, M, Comparison of static and dynamic shading systems for office buildings: Energy consumption and cooling load assessment, Management of Environmental Quality , 29 (5), 978−998, 2018 3 Underhill, LJ, Dols, WS, Lee, SK, Fabian, MP, and Levy, JI, Quantifying the impact of housing interventions on indoor air quality and energy consumption using coupled simulation models, J Exposure Science & Environmental Epidemiology , 30 (3), 436–447, 2020 4 Kohler, C, Shukla, Y, and Rawal, R, ‘Calculating the effect of external shading on the solar heat gain coefficient of windows’, Building Simulation 2017, San Francisco CA , Laurence Berkeley National Laboratory Report No LBNL-2001057 5 Khan, S, Learning from History, research report prepared for Historic England, Historic England, London, 2020 Recommended Reading Historic England, Practical Building Conservation: Glass &Glazing . Routledge, 2012 Kyle Normandin and Robyn Pender, ‘A window of opportunity’, Building Science and the Physics of Building Enclosure Performance, ASTM STP 1617, ASTM, Hanover, PA 67–87 For information about where to source new or replacement awnings, contact the British Blind and Shutter Association https://bbsa.org.uk/. ROBYN PENDER is a buildings physicist and a senior building conservation advisor in Historic England’s Building Conservation Team. She was an author and principal editor of the Building Environment volume in the Practical Building Conservation series. A late-19th century shopfront in Harwich with the once ubiquitous stripey canopy (Photo: Jonathan Taylor) The case for reinstating canopies is clear, not only where the original fittings survive. (Photo: Robyn Pender)