Alberta has adopted the National Energy Code for Buildings (NECB) 2011 edition into its newest building code. The coming into force date for the new energy code is November 1, 2016 and it will have significant impacts on how buildings are constructed in Alberta, but not for the reasons you might think. While most people are aware of the changes, a majority still don’t realize the full impacts that the new building code will have on building designs. Fortunately for building owners and designers (and unfortunately for energy efficiency in Alberta), the energy and cost impacts of the code for the majority of building types are not significant.
There are three paths available to achieve compliance: prescriptive, and trade off (follow the prescriptive requirements but trade between them) and energy performance compliance.
The prescriptive path is definitely the easiest path to understand and requires the least amount of expertise, but also offers the least amount of flexibility. The prescriptive requirements (for all sections) must be followed exactly and might prove challenging to meet. For example, the energy code provides prescriptive requirements for the effective envelope thermal transmittance values which must be matched to achieve compliance, as seen in the chart (Edmonton and Calgary fall under Zone 7A).
Any keen observer will notice that the required thermal resistance values are about double that of what is typically constructed in Alberta at the moment (again, these are effective not nominal R-values). For this reason, we do not recommend using the prescriptive or trade-off paths (which do offer more flexibility but not nearly enough).
Energy Performance Compliance Path
The building energy performance path is definitely the compliance path that requires the most expertise (as it requires building energy modelling) but is also the most flexible and will likely be the path chosen by most design teams. For most projects this is the compliance path that will be the most cost effective compliance path. The reason for this is quite simple. While the envelope section of the code is very stringent, many other sections of the code (lighting, HVAC, glazing) are very weak. Because the performance path looks at the energy use of the entire building, any efficiencies (over the reference building) in the lighting, HVAC and service water heating sections can be used to offset the requirements of the envelope section (this isn’t allowed in the trade-off paths).
For example, the prescriptive requirement for the thermal transmittance of fenestration is 2.2 W/m2K. This equates to essentially a clear single pane window with aluminum frames. Clearly, this is not difficult to improve upon. So a typical dual pane window with an effective overall U value of 1.6-1.7 W/m2K (including frame) will be significantly better; this energy savings can be used to reduce the envelope requirements.
Similarly, the prescriptive lighting requirements are extremely weak from an energy perspective. For example, the reference lighting density requirement for an enclosed office is 11 W/m2. Even second generation T8 lighting can get below this level (10 W/m2). LED bulbs are becoming pretty standard now in most buildings which means that a realistic lighting level is closer to 6 W/m2. Therefore, a typical savings in lighting energy can easily be 40-50 per cent and as before, this savings can be used to reduce the envelope requirements. In fact, based on our analysis, some building types will meet the requirements of the code without changing anything at all. That being said, for some building types (warehouses, car dealerships) even those so called “performance path freebies” will not be enough.
It should be clear that the performance path will be the preferred path for most buildings. It allows the most flexibility in the building design and allows you to take advantage of efficiencies from other systems to offset envelope requirements. Because of the nature of the compliance path, energy modelling is a requirement for projects wishing to go this route. However, if the building is already going after LEED or other rating system compliance, the energy model used for the rating system compliance can be adapted and used for NECB 2011 compliance with relative ease; thus not requiring a brand new model.
Either way, energy modelling is the best way to guide a project to its energy target, and this is even more true now considering the implementation of the new energy code. Energy modelling from an early design stage is the best way to provide a cost-effective design under NECB 2011 and gives the design team much more flexibility in all aspects of the building design.
While this is mostly good news for building owners, it certainly is not great news for energy efficiency in Alberta. There are simply too many “performance path freebies” in the energy code to make real gains in the province’s energy efficiency. One might hope however, that because teams are driven to use energy models for compliance, they might start using energy modelling as a design tool, which is the best way to optimize building performance. This might just be the biggest change to the way buildings are built in some time, and this is very positive for the industry.
In terms of energy efficiency, one can only hope that future versions of the NECB are implemented quickly (NECB 2015 is already published) or that the province moves to a performance based standard similar to those used all over Europe (removing all or most of the prescriptive requirements and moving to an energy use intensity requirement of 80 kWh/m2 for example). Either way, at least Alberta has finally taken its first small step towards energy efficiency.
Jacob Komar, P.Eng. is a principal at Revolve Engineering Inc. and a specialist in high performance building design.