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Title: The effect of air flow inside wall cavities on the thermal performance of cavity walls
Author: McCormick, Duncan
ISNI:       0000 0004 7231 1422
Awarding Body: Glasgow Caledonian University
Current Institution: Glasgow Caledonian University
Date of Award: 2017
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This thesis investigates the resultant effect of air flow inside the masonry external cavity walls of building structures on the heat loss through that part of their fabric. Heat transfer will always occur as materials and their environment seek to achieve equilibrium of temperature. Air flow inside cavities can potentially have an impact on the thermal performance of such walls. A review of the literature identified that the majority of UK housing constructed in the past hundred years or so has been built with external cavity walls. Increased awareness of energy use and efficiency has led to options for improving the thermal performance of such walls being considered. The recent drive to refurbish properties has resulted in the application of external wall insulation becoming increasingly common. However, there is a significant gap in the literature with regard to the effect thermal conditions and air movement within a masonry cavity wall have on heat loss from actual buildings. For this thesis, a methodology was developed that could be used both in the laboratory and on site to collect data that would indicate the effect of air temperature and movement within a cavity on thermal losses through the structure. The development of this methodology was assisted by the use of computer modelling and then applied to examining the thermal performance of external masonry cavity walls. The data collected provided significant findings. First, it found that there is measurable air movement even in an unventilated cavity. Second, that there is variation in heat flow through a wall across its geometric height. Third, that the value of thermal resistance of an air cavity in a wall is up to three times greater than the value given in the literature. The data also indicated that this thermal resistance is variable, not static. Given the foregoing findings, it is recommended that the calculations used to assess thermal performance of cavity walls be revisited. Finally, the effectiveness of externally insulating a cavity wall was assessed and the effectiveness of such insulation was found to be up to 94% lower in practice than by calculation. Thus, it is recommended that external insulation should be applied with caution to any cavity wall structure.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available