Development and Analysis of Approaches and Strategies to Facilitate the Conversion of Canadian Houses into Net Zero Energy Buildings

Abstract

Conventional building design is not aligned with modern housing requirements. Growing energy demand, international pressure to reduce greenhouse gas (GHG) emissions and increasing cost of energy motivate the building energy research community to provide alternative solutions to improve traditional housing. One of the most popular options for housing is the adoption of net zero energy building (NZEB) concept, which is defined as a building that exports more or equal energy than it imports. So far, majority of research efforts have been focused on finding solutions for the design, construction and operation of new NZE houses. Since the renewal of the housing stock is slow, the impact of introducing NZEBs into the housing stock would not be significant for many years, making the conversion of existing houses into NZE or near NZE buildings an important objective to reduce energy consumption and associated GHG emissions. Canada has numerous climatic and geographical regions and the Canadian housing stock (CHS) is diversified in terms of vintage, geometry, construction materials, envelope, occupancy, energy sources and heating, ventilation and air conditioning system and equipment. Therefore, strategies to achieve NZE and near NZE status with the current stock of houses need to be devised considering the unique characteristics of the housing stock, the economic conditions and energy mix available in each region. Identifying and assessing pathways to converting existing houses to NZE or near NZE buildings at the housing stock level is a complex and multifaceted problem and requires extensive analysis on the impact of energy efficiency and renewable/alternative energy technology retrofits on the energy use and GHG emissions of households. To develop and analyze techno-economically feasible approaches and strategies to support the conversion of Canadian houses into NZE and near NZE buildings by implementing energy efficiency and renewable/alternative energy technology retrofits, the Canadian Hybrid Residential End-Use Energy and GHG Emissions Model (CHREM), a state of the art residential sector energy and GHG emission model statistically representative of the CHS, was expanded and used. For this purpose, a wide range of energy efficiency and renewable/alternative energy technology retrofits including envelope modifications, appliance/lighting upgrade, internal combustion engine and Stirling engine cogeneration, solar combisystem, air to water heat pump, solar assisted heat pump and building integrated photovoltaic and thermal system architectures were developed/adapted and models were incorporated into the CHREM. The impact of the retrofit measures on the energy consumption and GHG emissions of the CHS was investigated. Numerous retrofit scenarios involving various technologies were developed for each province and post-retrofit source energy intensity and GHG emission intensity of houses were determined to evaluate the performance of the retrofit scenarios to achieve NZE and near NZE status for Canadian houses. The results indicate that substantial energy savings and GHG emission reductions are techno-economically feasible for the CHS through careful selection of retrofit options. While achieving large scale conversion of existing houses to NZEB is not feasible, achieving near NZE status is a realistic goal for a large percentage of Canadian houses.