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Our Partner Sarah Khan writes in the September RIBA Journal about her research into sustainability. The article focuses on some traditional methods, which can be re-introduced to improve comfort in traditional builidngs in a zero-carbon way. The article can be accessed from the RIBA Journal website.

The article is also reproduced below:

RIBA Intelligence/ Engery Use/ History Lessons:

‘Traditional, low-tech methods can improve comfort in old buildings’

draping walls with tapestries is a simple way of improving the comfort in old buildings as here in the Crimson Bedroom, Montacute House, Somerset. Credit: Edwin Smith, RIBA Collections

The changing climate and its impact put increasing pressure on buildings in an era where energy reduction is necessary to meet global climate mitigation targets and practically to reduce energy bills. Heating and lighting have so far been the main sources of energy use, though with the rise in summer temperatures it is predicted that air-conditioning will soon surpass this. This general concern took a very practical shape during my study of the Georgian Grade I listed Architectural Association (AA) School in Bedford Square, London, which like many traditional buildings had a low SAP rating and an issue with occupant comfort. Summer overheating in this case was a particular concern, and occupants often asked about installing air-conditioning. My study took an experimental approach, and showed that using traditional passive methods, energy could be saved lowering carbon footprint while improving occupant comfort.

The current focus is on retrofitting existing buildings to make them more energy efficient, or add additional services to meet the increasing heating or cooling demands. For traditional buildings, especially listed ones, the need to preserve their character often conflicts with retrofit solutions, and the need to maintain breathability requires careful thought, so often meeting increased comfort demands results in high energy use. Installing air-conditioning throws up all sorts of issues that would seriously compromise building and may still fail to provide satisfactory occupant comfort; one modern air-conditioned extension at the AA achieved exactly the same level of occupant satisfaction as the rest of the traditional buildings while using a lot more energy to do so.

Sustainable architecture is too focused at the moment on technology-driven processes. We must remember that it is people, not buildings, who use energy, and people have historically used traditional buildings more efficiently. My research therefore adopted a retrospective lens: old buildings, after all, have existed for centuries and have been through many cycles of extreme weather. Just as people change clothes to adapt to changing seasons, they also used additional layers such as tapestries, external awnings and blinds etc. as to adapt their buildings to the weather, with no additional energy expenditure.

The research mainly employed the experimental method to understand existing conditions and test out proposals. Various suitable traditional controls based on historical archival evidence were selected and their efficacy for winter and summer tested out in two near identical rooms at the AA. one was designated as the experiment room (which received treatments), and the other one as a control room (which remained unchanged). The winter experiment was carried out in March towards the end of winter, and summer experiment July/August. Each experiment ran for at least three weeks, with week 1 monitoring existing conditions, week 2 monitoring conditions after intervention, and week 3 monitoring post-experiment conditions. After this it was left to the occupants to choose whether they wanted to continue with any of the installations.

The winter experiment interventions were tapestries/wall hangings, local radiant heat sources such as foot and seat warmers and small personal radiators, task lighting coupled with natural daylight instead of ceiling lights, translucent curtains for glare control and warmer upholstery. The radiators were turned off during the experiment week.

The internal room temperature in the experiment room’ was only slightly below that of the control room in the experiment week, and both rooms retained an internal temperature of well above 21oC, indicating that the building’s thermal mass was effective. The experiment room occupants reported that they were comfortable although there were individual differences. Local radiant sources were used only for an hour or two in the day, except for one occupant who benefitted from the seat warmer. The occupant who benefitted from wall hangings felt comfortable throughout, and did not use her radiator at all, even though she had reported feeling the coldest before the experiment. She initially found it difficult to believe the wall hangings could be a reason for this, until presented with the experiment results later on.

The task lighting meant that ceiling lights stayed off until the blinds were drawn to reduce glare. The occupants initially disliked the translucent curtain for aesthetic reasons, and reported it as a failure. However, time-lapse photography showed that all three blinds were drawn only on the days when direct sunlight was streaming through the windows. On other partly cloudy days, the middle blind with the translucent curtain was the only one that stayed up. The curtains were useful in blocking glare, but the effect was not immediately noticeable to the occupants.

The heating had stayed off for the entire week post experiment as well.

Interest in using the treatments was initially low, but after their benefits were explained, most people were willing to try it. Even after their use initially participants were convinced it must be due to better weather rather than the interventions. As experiment results were shown to them, they quickly became enthusiastic participants, and the summer experiment benefitted from this experience.

Winter

The winter interventions were tapestries/wall hangings, local radiant heat sources such as foot and seat warmers and small personal radiators, task lighting coupled with natural daylight instead of ceiling lights, translucent curtains for glare control and warmer upholstery. Radiators were turned off during the experiment week.

The internal room temperature in the experiment room was only slightly below that of the control room in the experiment week, and both rooms retained an internal temperature of well above 21°C, indicating that the building’s thermal mass was effective. Experiment room occupants reported that they were comfortable although there were individual differences. Local radiant sources were used only for an hour or two in the day, except for one occupant who benefited from the seat warmer. The occupant who benefited from wall hangings felt comfortable throughout, and did not use her radiator at all, even though she had reported feeling the coldest before the experiment. She initially found it difficult to believe the wall hangings could be a reason for this, until presented with the experiment results.

The task lighting meant that ceiling lights stayed off until the blinds were drawn to reduce glare. The occupants initially disliked the translucent curtain blinds for aesthetic reasons, and reported them as a failure. However, time-lapse photography showed that all three blinds were drawn only on days when direct sunlight was streaming through the windows. On partly cloudy days, the middle blind with the translucent curtain was the only one that stayed up. The curtains were useful in blocking glare, but the effect was not immediately noticeable to the occupants.

The heating had stayed off for the entire week after the experiment as well. Interest in using the treatments was initially low, but after their benefits were explained, most people were willing to try them. Even after their use participants were convinced the effects must be due to better weather rather than the interventions. As experiment results were shown to them, they quickly became enthusiastic participants.

Summer

Pre-experiment monitoring occurred during the hottest week of the summer, and temperatures exceeded 30°C internally. Thermal imaging showed internal blinds absorbing sunlight and giving off heat almost like radiators.

Internal blinds in use, absorbing heat and re-radiating it out as shown in the corresponding thermal image.

The summer controls adopted were external awnings/blinds, opening up a chimney to facilitate stack effect cross ventilation within the experiment room, a ceiling fan (not strictly traditional in the UK but used in many hot countries) as well as night cooling. Task lighting and translucent curtains were tried again to check their efficacy for summer conditions.

Internal blinds thrown out of the windows and tied to balconies to turn them into external awnings. The windows immediately become cooler, as shown in the corresponding thermal image.

Internal blinds thrown out of the windows and tied to balconies to turn them into external awnings. The windows immediately become cooler, as shown in the corresponding thermal image.

Perhaps unsurprisingly night cooling was the most successful option: just one window left slightly open, combined with chimney ventilation, produced a reduction in air temperature of up to  1.5°C. The awnings reduced the solar radiation gain. The chimney introduced a welcome draught, and the ceiling fan was used only on some days as on occasion it made the occupants feel too cold. The translucent curtains were very popular and different occupants tried them for their windows and were happy with the results. A follow-up study a year later saw some of the tested methods in place. The black blinds have now been replaced with light reflective blinds, the chimney was open for ventilation and ceiling fans were in the process of being installed.

Many of the measures proposed can be adapted to current uses and can be used with modern services. They could be equally applicable to modern buildings. External awnings and shades, for example, have been the hallmark of many sustainable modern buildings. Passivhaus designs, for example, include strategies such as external shading, stack ventilation and night flushing.

For the past few decades we have been using our traditional buildings in a way that goes against their grain – by not understanding how they were designed to work, and slowly denuding them of their components. This research shows that our approach to sustainability of traditional buildings needs to be rethought, and a return to a seasonal way of living could be a way forward. It is, perhaps, time for the flow of beneficial inspirations to reverse. We need to learn from the past, so that we may better design the architecture of today and tomorrow.

The proposed measures are low impact solutions, which put control back in the hands of a building’s users. These solutions serve to enhance, rather than compromise, the historic character of listed buildings. They could point the way towards a more sensitive, contextually relevant zero-carbon approach for historic buildings.

Queen Victoria's Diamond Jubilee Garden Party at Buckingham Palace. Showing external awnings on windows.

Queen Victoria’s Diamond Jubilee Garden Party at Buckingham Palace. Showing external awnings on windows.

Some Winter measures
Tapestries and wall hangings
Foot and seat warmers
Mini radiators
Task lighting
Translucent curtains
Warm upholstery

Some Summer measures
Blinds
Task lighting
Translucent curtains
Ceiling fan
Night cooling: chimney plus window ventilation