The Building Conservation Directory 2022

102 T H E B U I L D I N G CO N S E R VAT I O N D I R E C TO R Y 2 0 2 2 C AT H E D R A L COMMU N I C AT I ON S in the edge of the door are common, and brush strips fastened onto the outside door frame are an easy to fit measure. Self-adhesive strips of foam are readily available and are mounted onto the frame. Where the gaps are large, and the door substantial, as with a church door, off the shelf products are sometimes not enough; bespoke solutions may be needed such as a wad of leather or hessian fixed onto the masonry check. The door is then closed onto this cushion. Letter boxes should have a sprung hinged flap to prevent draughts. DESIGNED VENTILATION While many areas of older buildings have some accidental air ingress or movement, some areas were deliberately designed to admit air in a controlled way. External vents are a common detail in many traditional buildings. They normally consist of a rectangular opening through the wall covered by a grille often made of cast iron. Generally, they are set at ground level, allowing air from the outside to pass under the floors. These vents perform an important function in keeping the solum area dry. They should always be kept open and clear of debris and plant growth, and generally they should be above ground, but in many buildings ground levels have risen. Some vents in public buildings had internal louvres at shoulder height with adjustable baffles to allow control of the incoming air according to the outside conditions and internal activities. Another way of managing internal conditions using passive techniques is the use of high-level vents in cupolas and on roof ridges. In some cases, these have been replaced by mechanical systems as seen in figure 5. However, in most domestic buildings good indoor air quality can be achieved passively. For more on indoor air quality and refurbishment see the HES Technical Papers in the Recommended Reading section. And more topically, the current situation regarding Covid-19 obliges higher rates of ventilation in all buildings and traditional approaches to ventilation will be of relevance in developing solutions to these circumstances. CHIMNEY FLUES AND HEARTHS Fireplaces, flues and chimneys are important ways of providing ventilation and allowing the dispersal of water vapour in traditional buildings. If a fireplace is no longer used, the flue can be closed off temporarily to reduce draughts in the winter. Some fireplaces may have built- in dampers as part of the cast iron hood; when the hood is pushed back flush, the flue is closed off. Where there are no such features, a chimney balloon is a good way to close of a flue (see figure 6) as it can be removed easily when ventilation is required in the summer. As overheating is becoming a problem in many cities, especially in upper floors, this may be a useful option. Generally, it is important that some form of air movement is retained within a flue and removing a chimneypiece and blocking the opening is not recommended. ENERGY PERFORMANCE CERTIFICATES For most homeowners and occupants of older buildings, the EPC is the primary assessment option for domestic buildings in the UK. The EPC methodology does not have an airtightness measure, but the measures above should be considered as otherwise insulation work alone will not yield the desired energy savings. Recommended Reading HES Guide to Energy Retrofit of Traditional Buildings, http://bc-url.com/hes-retrofit HES Technical Paper 6, Indoor Air Quality and Energy Efficiency in Traditional Buildings, http://bc-url.com/hes-air- quality HES Technical Paper 12, Indoor Air Quality in Refurbishment, http://bc-url.com/ hes-tp12 HES Technical Paper 14, Keeping Warm in a Cooler House, http://bc-url.com/ hes-tp14 HES Inform Guide: Ventilation in Traditional Houses, http://bc-url.com/ hes-ventilation HES Inform Guide: Domestic Chimneys and Flues, http://bc-url.com/hes- chimneys HES Inform Friday recording on ventilation: https://www.youtube.com/ watch?v=kcx8fN6Ln18 LILA ANGELAKA is a Senior Technical Officer in Historic Environment Scotland’s Technical Research Team. Her background is in architecture and conservation. She currently provides technical advice, produces technical publications, as well as delivering events about maintaining and retrofitting older buildings. ROGER CURTIS is a Chartered Building Surveyor who manages the HES Technical Research Unit, its programme, and its published outputs on themes of energy efficiency, sustainability, and the role of the traditional environment in the circular economy. Figure 5. Traditional passive ventilation cowl on a stairwell cupola, seen next to a more modern installation in Edinburgh. Figure 6. The use of a chimney balloon to temporarily close off a chimney flue