Building Retrofits

Photo by Paul Hanaoka from Unsplash.com

Urban growth simulations modelled on the Hillside Quadra neighbourhood of Victoria, BC, shows ways that medium-sized cities can leverage different technologies and urban planning strategies to reduce their greenhouse gas (GHG) emissions, and meet climate targets. 

Pursuing growth strategies such as distributed density infill, corridor-focused growth along main thoroughfares, or higher density neighbourhood centres all reduced building energy consumption and emissions by 2040, according to researchers for the PICS Energy Efficiency in the Built Environment (EEBE) project in their report, Community Solutions: Hillside Quadra Case Study Report. Surprisingly perhaps however, there was little difference in GHG reductions between these options.

Each growth scenario reflects Victoria's "missing middle" strategy of gentle densification, which prioritizes dwelling types between single family homes and apartments. That includes attached dwellings such as rowhouses and townhomes, secondary suites and duplexes.

The corridor growth scenario offered the most residents close access to amenities, encouraged active transport, reduced demand for vehicle trips, and was far more effective for transit, said EEBE project lead Ron Kellett, a professor and director of the School of Architecture + Landscape Architecture at UBC.

“Any city with the density to operate a convenient transit system will be well advised to look at consolidated or nodal growth strategies,” said Kellet.

However, complementary building technologies and infrastructure are crucial.

By far the most potent tool for reducing GHG emissions in the Hillside Quadra simulation was switching buildings from oil and gas for heating and cooling to electricity, which reduced emissions by roughly 80% in all three growth scenarios.

Deep retrofits, including upgrades to roofs, insulation and windows, produced emission reductions between 21% and 27% across the different growth models. Technology upgrades, such as equipping HVAC systems with heat pumps, produced results similar to shell upgrades.

“Because Victoria still uses a lot of fuel-oil at residential scales, the effect of fuel-switching was more dramatic than we might find in other communities,” said Kellett. “These results should embolden other cities to look at any strategy that enables switching to low-carbon fuels and encourages retrofits.”

The stacked bar charts on the right show total CO2e savings by fuel switching.
Figure 4.4. Emissions savings from fuel switching. The stacked bar charts on the right show total CO2e savings by fuel switching.

The Energy Efficiency in the Built Environment: Community Solutions: Hillside Quadra Case Study Report is the second in a series of three studies of the climate impact potential of policy options available to communities in BC. The first focused on Prince George (low density, low growth, cool climate), the second on Victoria (medium density, moderate growth, temperate climate) and a third on Vancouver (high density, high growth, temperate climate).

In British Columbia, the built environment, including buildings and transportation, is responsible for 55% of greenhouse gas emissions, making urban growth policy and building performance standards crucial to meeting the cities' aspirational energy and emissions goals and the provincial climate action timeline. Victoria’s size and growth rate make it a valuable test case for other middle-sized cities in B.C.

The Elements Lab created a virtual “sandbox” approximation of the Hillside Quadra neighbourhood that replicates the land-use, population, housing stock, building ages, and current technology to run a series of what-if policy experiments. The researchers used the Community Energy and Greenhouse Gas Emissions Forecasting Tool developed by SFU’s Energy and Materials Research Group to project uptake of policy options.

The experiments blended multiple projections for population growth, new construction, building replacements and building retrofits with Victoria’s policy options for land use and anticipated infill with “missing middle” dwellings. New transit and active transport options were derived from the City’s current and anticipated transportation policies.

The researchers found that meeting BC Energy Step Code objectives could be achieved by retrofitting existing building stock. Also, improved access to frequent transit and active transport options encouraged by a corridor or neighbourhood centre growth scenario led to moderate transportation emission reductions, while dispersed growth led to fewer.