The Canada Green Building Council (CAGBC) is aiming to simplify the criteria for complying with its zero carbon design standard, while also pushing forward with more rigorous performance goals. The newly released version 3 of the zero carbon building (ZCB) design standard relaxes the earlier thermal energy demand intensity (TEDI) target for projects that eliminate gas-fired systems for space heating, and introduces a new prerequisite related to embodied carbon.

The trade-off on TEDI in favour of electrification gives more budgeting flexibility for project proponents to prioritize either HVAC or building envelope options. However, in all cases, the updated standard consigns combustion heating to backup status with the requirement that it only be used when outdoor temperatures fall below minus 10 Celsius — a threshold reflective of the functional capability of most currently available heat pump products.

The new prerequisite for embodied carbon gives project proponents the option of choosing an absolute target or relative improvements over a baseline figure. The updated standard also promises “more flexibility to better recognize smart design choices” in calculating energy performance.

“These updates to the ZCB-design standard are informed by two years of market and project feedback, as well as changing market expectations of operational and embodied carbon emissions,” reports Thomas Mueller, the CAGBC’s president and chief executive officer.

“The intent is to reduce the cost and effort required to achieve the desired outcomes of certification, and to open the standard to as many projects as possible,” concurs Doug Webber, principal and co-founder of the consulting engineering firm Purpose Building, and chair of the zero carbon steering committee.