34 Y E A R B O O K 2 0 1 3 distinction between ‘historic’ and ‘traditional’ buildings here. Although not explicitly stated in o!cial documents, this separation is e"ectively established by the current Approved Documents 1%2 and 1#2, which cover conservation of fuel and power for existing buildings. Historic buildings may be defined as those which are designated because of their cultural significance, while traditional buildings are those constructed of ‘permeable fabric that both absorbs and readily allows the evaporation of moisture’. Most historic buildings are, of course, traditional, but it is the latter, technical category which is of principal concern in the legislation and there are large numbers of traditional buildings throughout the UK, many of which are not considered historic. Where a particular building is designated as historic, the methodology needed is clear (even if the wording of the legislation sometimes isn’t). All such buildings must be upgraded when works are carried out up to the point at which their cultural significance would begin to be unacceptably damaged. As long as the cultural significance is properly established at the outset, the degree of appropriate upgrading can be determined. The technical issues, however, are not so straightforward. The vast majority of buildings constructed before %&%&, and many later buildings too, were designed using rule-ofthumb methods which evolved over centuries alongside changing patterns of use. These do not translate well into modern positivist models of scientific assessment. Most sustainable building experts now regard these traditional methods of design as essentially inferior, although they were sometimes highly e"ective. A short unpublished study carried out some years ago by English Heritage suggested that traditional buildings may often use on average only half the energy indicated by assessment under the government’s standard methodology for energy certification. Moreover, since the actual energy used in the buildings was measured, the study indicated that the calculation methodology itself may be seriously deficient. Unfortunately, even if we could establish that the findings are representative, perhaps by measuring a larger sample of buildings, we do not fully know the reasons for this di"erence. There are, however, some suggestions. In the case of a typical stone wall, for example, the movement of moisture may be more complicated than moisture vapour simply di"using through the wall from the inside to the exterior. Moisture can move through a permeable wall, but it will do so in varied and dynamic ways, changing from vapour to liquid and back again, as well as being transported via a range of di"erent mechanisms including vapour and liquid di"usion, capillarity, adsorption and desorption. To this must be added the fundamental and inseparable link between moisture vapour levels and air temperature, normally expressed as relative humidity. This means that changing the temperature within the wall (for example by adding insulation) will alter moisture levels, and vice versa. The dynamic processes involved, which are also a"ected by time of day, weather patterns and season, mean that the actual consequences of intervening in such structures can be extremely damaging and very di!cult to predict. (These issues are thoroughly explored in the #$%# report Responsible Retrofit of Traditional Buildings, see Recommended Reading.) CURRENT MODELS ‘TOO SIMPLISTIC’ It is now clear that the historic and traditional buildings sector must engage far more fully with the scientific tools and techniques necessary to allow accurate modelling of older buildings and to predict their behaviour. Furthermore, the sustainable building professions need to accept that their current models are too simplistic for traditional construction and often badly misrepresent the performance of such buildings. Until these two cultures can progress, hopefully through open cooperation, we cannot be certain how best to treat individual buildings. The wrong actions, however wellmeant, can be hugely detrimental to the health of a building and the thermal e!ciency they seek to improve. Under these circumstances, one can usually assume that the more certain people are of the rightness of their actions in this field, the more likely they are to have misunderstood or overlooked something significant. Students are participants Students are an audience Emphasis on research content Emphasis on research processes Research-tutored Engaging in research discussions Research-based Undertaking research and inquiry Research-led Learning about current research in the field Research-oriented Developing research skills and techniques The research-teaching nexus (after Gri"ths, 2004 and Healey, 2005)
RkJQdWJsaXNoZXIy MjgyMjA=