New Ontario Building Code
The updated OBC generally follows the green building standard outlined in ASHRAE 90.1-2010 with the ASHRAE 189 envelope requirements. This is a significant improvement over the codes in other provinces and in the US, which typically require the basic ASHRAE 2009 or earlier standards to be followed. In terms of building envelopes, ASHRAE 189 actually encourages the design of green buildings rather than just the "bare minimum" of energy efficiency and occupant comfort.
There are two ways to meet the updated OBC: the performance path and the prescriptive path. The performance path requires that a building be designed to achieve 25% energy savings relative to the Model National Energy Code (this is essentially the prerequisite energy requirement for LEED). This would likely be demonstrated through an energy model that indicates what building features are improvements over a conventional building (i.e., daylighting sensors, triple glazed windows, east-west building orientation). The prescriptive path will have some "real eye openers" for many design teams:
- no more than 40% glazing
- many common wall constructions, such as z girts and spandrel panels, will have challenges meeting the required insulation values
- heat recovery ventilation (whereby exhaust heat is used to preheat incoming fresh air) required in more building types
There are several potential challenges in enacting the new building code for officials and design teams:
- A typical new glass-walled tower has 70% window-to-wall ratio, while a punched window design often achieves 30-40%. Designers will say goodbye to many Toronto glass box tower designs, or take the energy modeling performance paths where mechanical/electrical improvements can be shown to compensate for the envelope performance.
- Although in the past year code officials have begun asking for more documentation to prove new buildings will meet existing code requirements, the current code is not well enforced. Will officials enforce the new, more stringent building code?
- Even if only half of new Ontario buildings choose the performance path, there will likely be a shortage of good energy modellers to help design teams prove their building is designed to achieve 25% (relative to MNECB) energy savings. Bringing an energy efficiency engineer onto projects as early as possible (before building massing) to provide design facilitation and suggest innovative, yet proven and low-cost technologies and design solutions will be increasingly critical.
Despite these challenges, the 2012 OBC is a significant step in the right direction for the province and a benchmark for other provinces and states looking to make a significant impact in the area of energy efficiency.
Learn more about how to meet the updated OBC here.