Learning from History: Traditional Low-Energy Approaches to Comfort
Research with Historic England, due to be published soon
The construction sector is under pressure to reduce its carbon footprint; the current focus, therefore, is to ‘upgrade’ existing buildings to make them more energy efficient. Such technology- driven processes aim to improve the building’s fabric and services. For listed buildings, the need to preserve their character often conflicts with retrofit solutions, while meeting increased comfort demands results in high energy use.
Our research challenges contemporary practices in achieving energy efficiency for traditional buildings. It does so by adopting a retrospective lens: we carried out a wide-ranging survey of how people made their buildings work before we began to rely almost entirely on mechanical systems to alter the temperature of the indoor air. There is still much to be learnt from these people-centred pre-Industrial approaches to building usability, which responded to occupant’s physical and emotional sensations of discomfort.
There are many forgotten past practices such as tapestries, external awnings and blinds. Just as people change clothes to adapt to changing seasons, these additional layers helped buildings adapt to the weather, with no additional energy expenditure.
Fabric linings are a recurrent theme to deal with winter; varied fashions range from medieval and renaissance tapestries to Georgian and Victorian fabric linings. In fact, Interiors in the past were as heavily layered as its occupants in winter. Cheaper versions of tapestries were abundant, ranging from carpets, rugs as wall hangings, woven cloths, painted cloths (canvas or linen), block printed cloths and embroideries that have been used in stately homes as well as much more humble houses.
Floors were also heavily layered with rugs, carpets, canvas, block printed fabrics etc. and underlays, and windows with many layers of curtains. The spring clean was a change over time, with heavier fabric, curtains etc. taken down and replaced with lighter versions for summer, if needed.
Another common strategy to deal with cold was to compartmentalize the room, and the part of the room more in use. This would be done using curtains or screens and sometimes spaces would be nested within a room on the same principle, such as via an Inglenook. Entrance halls were often compartmentalised with ‘draught lobbies’ which leads dealing with draughts, another common reason for feeling cold.
External shutters have been used in vernacular buildings since before glass was used in windows, as protection against weather as well as intruders. Internal shutters, combined with heavy curtains, can achieve a U-Value close to that of double glazing.
It is becoming increasing clear that it is not just heating demands, but meeting increased cooling demands will be the new challenge. There is serious potential to use the building as a resource instead of resorting to air-conditioning. This involves stopping heat gain by using external shading devices, using the thermal mass via night flushing, increasing cross-ventilation/ stack effect ventilation in every room via chimney stacks and using fans. Awnings were a popular feature to shade windows and begin to appear in Georgian times as the windows become larger; and by the Victorian era they were prolific.
The chimneys have been a recognised source of ventilation. In the summer, it is possible that the chimneys could become a stack-effect ventilation source, creating cross-ventilation within each room.
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 report detailing the full research is due out soon. A discussion of the research and its finding was done for the Historic England webinar ‘Energy Efficiency: Retrofit in Traditional Buildings Policy and Research Update’. The recording of the webinar is now available here.