Energy capture, storage, and distribution to achieve high solar-fraction housing

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Heating, cooling, and ventilating the built environment we live in, and providing the hot water, lighting, and appliance services we need, consumes tremendous amounts of energy.  This contributes significantly to environmental and energy security issues.  For example, housing accounts for 33% of all electricity and 24% of all natural gas consumed in Canada, and produces 13% of the country's greenhouse gas emissions.  Despite significant efforts made by governments and industry over the past 40 years, energy use by Canadian housing continues to rise. The solar radiation incident upon the exterior of an average-sized house (regardless of orientation) greatly exceeds the building's annual energy requirements.  In most cool and cold climates, space and water heating account for the majority of residential energy demand.  For example, more than 80% of all energy consumed in Canadian housing is for these two end uses, which can be serviced by a supply of low-grade (<80oC) heat.  Therefore, the majority of these energy demands could be met by exploiting the locally available solar resource, but this is greatly complicated by temporal supply-demand mismatches.  It is common to limit passive solar gains to buildings by restricting the area of south-facing windows, this to prevent overheating that can occur during a few hours on particular spring and summer days.  The strong seasonal mismatch between solar supply and building thermal demands is an even greater challenge: approximately 80% of the solar radiation incident upon an average-sized house occurs outside the principle space-heating period of mid-November through mid-March. The objectives of this research are to study and critically examine two related novel concepts aimed at maximizing the use of solar energy for providing space and water heating.  One concept involves the seasonal storage of thermal energy wherein the solar energy that is abundant during the summer is captured and stored for use during the winter.  The second concept involves capturing and storing excess passive solar gains that are admitted through south-facing windows using thermally activated building systems and heat pumps.  The goal is to find solutions that achieve solar fractions for space and water heating (the fraction of the thermal demands met by solar energy) in the order of 80%.  The widespread adoption of such concepts could lead to a two thirds reduction in the consumption of natural gas and electricity of Canadian housing.  This research will also provide new fundamental knowledge on heat transfer within seasonal thermal stores, heat transfer between buried thermal stores and their surrounds, and transient heat transfer within thermally activated building systems.