An Investigation of the Effects of Air Infiltration and Thermal Transmittance on the Design of a Single Low Energy Building for the UK Climate

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Abstract

Reducing energy consumption in the UK is necessary, both in terms of meeting the regulations set by the EPBD and in order to mitigate the effects of climate change. This thesis examines the potential for achieving buildings with net zero energy performance in the UK, which can help to reduce energy consumption. The thesis uses a literature review method to determine: building end use energy and the methods by which thermal energy can be lost, retained and even gained (through passive solar design) in a building; the importance of minimising thermal transmittance and air infiltration, without causing damage to the building fabric; and passive solar design techniques that can be used to assist in achieving net zero energy performance and the importance of balancing the reduction of thermal energy demand with the comfort of the buildings’ occupants. Nine buildings from the USA have been identified as low-, nearly zero- or net zero energy buildings and have been critically analysed to identify and determine the effectiveness of the low energy design and operation techniques that have been used to achieve net zero energy performance. In regards to the buildings that failed to meet net zero energy performance, the reasons for this have been identified. A single, low energy building for the UK climate that has the potential for achieving net zero energy performance is designed using thermal energy simulation software. A base case building energy model is created, followed by a parametric study of low energy design techniques and a study to investigate the optimum modifications for achieving very low thermal energy demand. The findings from the investigations of the thesis are then brought together into a coherent argument. A standard for the design and operation of a single type of commercial building that will be able to function with the same annual thermal energy demand regardless of location in the UK is proposed. It becomes apparent that air infiltration and thermal transmittance of construction elements are the parameters to target to achieve buildings with very low energy consumption. The simulation data suggests that infiltration is responsible for the largest net heat loss and that glazing was responsible for the largest heat gain and heat loss although provided a relatively low net heat loss. It also suggests that roofs provide an overall heat loss that is greater than that from walls, despite a lower thermal transmittance value and a lower overall area. The simulations culminate in a model that predicts thermal energy demand of just 7.4 to 7.7kWh/m2/year is achieved across the 10 locations, which corresponds to an average reduction in thermal energy demand of 85% compared to the base case model.

Keyword(s)

Low Energy, Building, Design, Air Infiltration, Thermal Transmittance, Air, Infiltration, Thermal, Transmittance, UK, Climate, EPBD, Europe

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