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Energy positive housing: an integrated systems approach to modelling, technology and architecture

Coma Bassas, Ester 2018. Energy positive housing: an integrated systems approach to modelling, technology and architecture. PhD Thesis, Cardiff University.
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Abstract

Against the current background of dependence on fossil fuels, climate change, global population increase and finite resources; this thesis investigates a performance-driven design method that combines modelling, low carbon technologies and architecture design to achieve an Energy Positive Housing (EPH) model that could potentially decarbonise the new housing sector and help, with a bottom-up approach, achieving a future low carbon built environment. Literature review identifies the main design guidelines for the EPH method. For modelling, the need of a simple and uncomplicated pre-design tool; for technologies, the need of a systems approach to reduced energy demand, building-integrated renewable supply and on-site energy storage; and for architecture design, the need of a replicable, affordable and sustainable design suitable for the UK’s climate and able to hit the mass market. Initially, the EPH tool is developed as a versatile pre-design modelling tool to size renewable energy supply and storage integrated with the grid, to simulate the system’s behaviour predicting demand, supply and storage profiles, and to evaluate the system’s potential considering autonomy, supply/demand ratio and export/import ratio. Afterwards, the tool outputs are used to design the EPH system, which combines photovoltaic panels and lithium-ion batteries, for electrical energy; and transpired solar collectors and a compact unit with exhaust air heat pump, mechanical ventilation heat recovery and hot water tank, for thermal energy. Finally, the energy system is integrated into the EPH design, which is highly insulated and airtight, and built with innovative materials such as low carbon cement, structural insulated panels, insulated render and low-emissivity double-glazed composite windows. The actual performance of the EPH method is examined to verify the tool’s accuracy, the system’s performance and the design assumptions, to provide future feedback for the EPH design’s application and to establish improvements for future implementation. Therefore, the EPH design is built as a real case study, known as Solcer House, and monitored over different seasons for three years. The extensive set of data from the case study allows to validate and calibrate the EPH tool so it is accurate and reliable; assess the performance of each component of the EPH system comparing real performance against manufacturers’ claims; and evaluate the holistic performance of the EPH design. When studying electrical energy, results indicate that the all-electric EPH design is energy positive achieving 70% autonomy, 1/1.03 supply/demand ratio and 1:1.13 import/export ratio, even though photovoltaic panels efficiency is lower than expected and batteries only use 25% of their full capacity. When examining thermal energy, results show components efficiencies to be 8% for the transpired solar collectors, 78% for the mechanical ventilation with heat recovery and a 3.78 COP for the heat pump; but working as a system all together achieve a 5.15 COP with a contribution of 42% from the transpired solar collectors and mechanical ventilation with heat recovery. Finally, when analysing the online survey to visitors, over 80% are impressed with the EPH replicable and affordable house model. The findings suggest that the integration of energy modelling, technologies performance and architecture design has resulted in a successful and viable EPH method that could decarbonise the new housing sector and help solving, with a bottom-up approach, the energy trilemma of security of supply, affordability and sustainability. The proposed EPH performance-driven design method leaves room for creativity, it is not a quantitatively defined standard, but rather a performance-driven design strategy that pays attention to both the principles of passive solar and the direct and active use of renewable energy, in particular solar radiation, therefore liberating the EPH design from the limitations of purely passive strategies such as the Passivhaus standard.

Item Type: Thesis (PhD)
Date Type: Submission
Status: Unpublished
Schools: Architecture
Uncontrolled Keywords: performance-driven design; modelling; low carbon; Energy Positive Housing (EPH); model; decarbonise housing
Date of First Compliant Deposit: 1 November 2018
Last Modified: 07 Nov 2019 03:22
URI: http://orca.cf.ac.uk/id/eprint/116221

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