These choices, among other smaller modifications, enabled the building to get very close to zero net embodied carbon. In total, these changes reduced over 185 tonnes of total carbon emissions, with the building having a minimal carbon intensity of just 60 kg CO2e/m2.
The estimation above did not include any carbon storage in the timber products in the building, which included wall, roof and floor framing and the charred wood siding. After securing local and/or certified wood for the project, we calculated the carbon storage using the methodology and calculator from World Wildlife Fund’s Biogenic Carbon Footprint Calculator for Harvested Wood Products. This tool does more than just reckon the actual amount of carbon atoms in wood, but accounts for carbon emissions and forest regrowth to come closer to a real understanding of the climate impact of using different types of wood products. It’s not a perfect methodology (much work is being done in the sector to close in on a better understanding of forest carbon flows), but we used it as the best available and transparent resource available. With a percentage of the wood carbon storage recognized, the Trent Forensic Crime Scene facility tips over into net carbon storage.
In addition to material choices, the design team pursued a high degree of energy efficiency, with insulation levels upgraded (R-100 attic, R-42 walls, R-28 foundation and slab) and a highly air-tight enclosure (meeting the Passive House requirement of 0.6 ACH50). Heated and cooled with an air source heat pump and with a 43 kWh solar array on the roof, the building has very low energy consumption requirements and is able to meet these on an annual basis with on-site generation.
Trent University and the design team achieved a unique result: a real zero carbon footprint building, or as close to the goal as is possible with today’s data and materials.
With the exception of the solar array and its attendant gear, the costs associated with the project were within the typical range for an institutional project of this type. Enough carbon storing materials were available in the market to allow the project to meet its goals. Material sourcing, supply chains and construction experience with new materials were obstacles that this team was able to overcome, but provide insight into the pinch points that currently may prevent more projects of this type from being realized.
The barriers to creating buildings with a true zero carbon footprint are low enough that we should be pursuing this type of result as the new normal, and not only on one-off projects.
Architect: Christopher Z. Tworkowski Architect
Contractor: Gerr Construction
Mechanical: ZON Engineering
Electrical: Berthelot Engineering
Structural: Building Alternatives
Zero carbon consultant: Endeavour Centre