Efficacy of Energy Efficiency and Thermal Comfort Related Retrofit for Existing New Zealand Houses

Abstract

Many New Zealand studies have argued that house energy retrofit produces limited benefits, but the issue of how existing house retrofitting can lead to better energy performance and comfort improvement is little explored. The aim of this thesis was to examine the influence of house retrofit on energy efficiency and thermal comfort, using house model simulation and calculation. This study gives a holistic house retrofit approach in thermal comfort improvement and energy conservation. Three house retrofit categories were defined by household energy breakdown: Space Heating Retrofit, Hot Water System Retrofit and Appliances Retrofit. This study started with an investigation of New Zealand existing house stock. A typical house model was defined by the summarized common physical characteristics. This house model was used for retrofit testing. For the building space heating retrofit study, a series of thermal simulations was completed with different retrofit options. Thermal simulation results were compared both in thermal comfort and space heating energy requirement. It was discovered that the optimum level full insulation retrofit significantly reduced space heating energy requirement and also improved thermal comfort. Retrofit solutions for water heating, lighting and appliances were compared by cost and energy saving. Cost effectiveness cross comparison for all of the retrofit solutions was carried out. Retrofitting for space heating system and hot water system can be considered for long term cost effectiveness. Appliances and lighting retrofit have a higher efficacy than other retrofit options in terms of energy saving and cost benefit cycle. These findings are used to provide suggestions for retrofitting of existing houses.