New revisions to the British Columbia 2018 Building Code has been approved and will take effect on Dec. 12. This includes changes to BC Energy Step Code requirements that will affect residential buildings, buildings outside Climate Zone 4, and public sector buildings. Climate Zone 4 includes the lower mainland and southern Vancouver Island.
In Part 9 of the Building Code, there will now be two options to address building envelopment requirements: revised thermal energy demand intensity (TEDI) metrics and a percent-better approach. TEDI measures the amount of annual heating energy needed to maintain a building’s stable interior temperature.
After the first revision, builders working in colder areas had difficulty meeting the TEDI targets for Part 9: Residential Buildings in their designated climate zone. The adjusted scale will now be based on heating degree days (HDD) rather than a single value for an entire climate zone.
This will result in higher TEDI targets for all locations with HDD’s that are higher than the HDD at the lower range of each climate zone.
Currently, the TEDI target is used to demonstrate how builders have met the B.C. Energy Step Code envelope performance requirements. An alternative approach is being considered for the model National Building Code that compares annual space heating requirements for a proposed house to a reference house. It will require a percent better improvement in the efficiency of the building envelope.
In some buildings with unique design features (such as cathedral ceilings or multiple articulations in the roofs or walls), modelling results can show significant improvements to overall energy performance. Yet, the same buildings may not meet the requirements for the current TEDI targets. This change will ensure fairness across a greater range of building designs and provide an alternative way to demonstrate that buildings are meeting energy objectives, say B.C. code officials.
The next step will include additional guidance materials for builders, energy advisors, and building officials. The Building and Safety Standards Branch will work through the Energy Step Code Council.
Public sector buildings
The 2018 B.C. Building Code contains targets for buildings in all climate zones for occupancy groups C (residential), D (business and personal services), and E (mercantile). However, the current targets don’t differentiate among the different climate zones. This means that there is one thermal energy demand intensity (TEUI) and TEDI target that applies to the entire province. Changes will be made that establishes TEUI and TEDI targets based on climate zones to reflect colder climate conditions. TEUI measures the building’s heating needs, primarily influenced by insulation and airtightness.
Public sector buildings are currently not included amongst these occupancy groups. Hospitals, care centres, schools, recreation centres, libraries and colleges have now been introduced in the B.C. Energy Step Code.
This will include requirements for energy modelling that conforms to Part 8 of the National Energy Code for Buildings (NECB) and air leakage testing for these building types. Specific energy intensity targets are not included for these public sector buildings. Further review and stakeholder engagement will be conducted to guide and inform the development of future targets.
The Building and Safety Standards branch is also considering possible amendments to the Energy Step Code targets for houses and small residential buildings. This will focus on Climate Zones 5 and 6 (including Kelowna, Kamloops, and Prince George). These possible changes are still in development and will not be part of the current public review.