Monday, May 1, 2017

Energy Efficiency in the Building Code. 9.36: Opportunities and Challenges


The Alberta Building Code (ABC) has gone through one of its biggest overhauls ever in the last year. The final piece to that code change, Section 9.36, came into effect on Nov 1, 2016.  This long awaited piece of legislation will move the Alberta construction industry forward, making for more energy efficient buildings and homes across the province.

9.36 is a large section of the Code that has been written to bring together all elements relating to the energy performance of low rise buildings.  9.36 includes requirements for the envelope insulation, windows and doors, air tightness, as well as mechanical and ventilation systems. While the details of safety and durability remain in specific sections earlier in the code, 9.36 is the one stop shop for all things relating to Energy Efficiency.

The first major piece of 9.36 provides rules on navigating the section.  This is important as 9.36 is the first piece of Building Code that has allowed multiple pathways for compliance.   Builders now have the choice of:
     - Prescriptive Path
     - Prescriptive with a Trade-Off Path or
     - Performance Path.
This flexibility provides new opportunities for builders and architects to navigate the Code, providing a custom fit application to particular projects.  For the first time in Building Code History, Albertan's have the choice to find the best fit application of code requirements.

The Performance Pathway option is an entirely new approach to code compliance, using a computer energy simulation to show compliance with the intent of the Building Code without having to meet the requirements of every specific measure.  The energy simulation, also known as an energy model, takes a holistic view of the home's energy efficiency and allows builders to use whatever strategies they wish to meet the equivalent performance of the Reference House.  The Reference House is an identical energy model built using the Prescriptive (Code minimum) Pathway.   Reductions in glazing percentage, improvements in mechanical systems, and enhanced insulation all are calculated together to show the overall performance of the proposed house and that it meets or beats the code minimum Reference House.

The Performance Pathway option provides projects extensive flexibility, rather than limiting them to prescribed limits in the design of wall assemblies, windows or mechanical systems.  Once the home has been modelled and is shown to meet Code Compliance, a report, or Letter of Compliance, is submitted to the AHJ for review along with Development Permit submission.

CaseStudy - Lowering Wall Insulation
The new Code substantially increases the minimum R-value requirements for wall assemblies.  For some projects, this may not be a cost effective option, given their current building practices.  Instead, by using the Performance Pathway and energy modelling a house before it is built, a project team can find other areas in which to make up for the energy losses from a reduced R-value in the wall systems.  This could be achieved by a combination of:
     - Decreased window to wall ratios (FDWR)
     - Improved ventilation efficiency with an Heat Recovery Ventilator (HRV)
     - Improved furnace efficiency
This recognition of alternative measures to meet the intent of the Building Code allows for builders, designers and homeowners to make the choices that make the most sense for their particular project.

4 Elements has been doing performance modelling and reporting for residential construction since 2008.