C43 -- How Much Retrofit is Enough?

The government of Canada has established the emission reduction target, promising to reduce greenhouse gas (GHG) emissions by 40-45% below 2005 levels by 2030, and by 90% by 2050. Buildings are responsible for 17% of the total national GHG emissions. In Canada, over 50% of residential buildings are more than 30 years old, and over 20% are older than 50 years. Older buildings generally have higher energy demand since they were not built to modern energy codes. Building retrofits can improve energy efficiency and the well-being of occupants. Building retrofits have been mostly studied to cope with climate change and the need for energy demand reduction. However, to achieve the emission reduction target, not only should the retrofit rate increase, but the retrofit strategies should be optimized to include trade-offs between the environmental, social, and economic impacts of building retrofits. Currently, there is no Canadian standard or code available on how to calculate the embodied and operational carbon emissions related to a construction project. Different performance paths are being used in academia, industry, and government departments. Embodied and operational carbon present distinct challenges and opportunities. Balancing these two sources of GHG emissions is essential in developing effective retrofit strategies. This paper explores the critical question that ought to be posed when determining the optimal level of retrofit required to achieve GHG emissions reduction in existing buildings, and why energy efficiency is still important. The main aim of this paper is to create a holistic framework to answer the main question: How much retrofit is enough to achieve the goal of a greener and more sustainable built environment?