Closing Loopholes for The Next OBC Iteration

Ontario is making headway in building efficiency with changes to the Ontario Building Code’s (OBC) Supplementary Bulletin 12 (SB-12). As of January, an increase of 15 percent efficiency was mandated for all low-rise residential buildings. This is a good start, but….
The Ministry of Municipal Affairs and Housing (MMAH) can legislate all the increases it wants, but unless we close the loopholes, they won’t reach their energy reduction targets with the existing system. The chief obstacle to greater energy performance of Part 9 buildings lies with enforcement at the municipal level.
Projected vs Actual Energy Savings

Planning for the next building code iteration starts by identifying loopholes in the existing system that lead to compliance deficiencies, and closing them to align projected and actual energy savings. The process needs to be fixed so that more efficient, comfortable and durable buildings get built. Here’s our list of demands for municipalities and the MMAH for the next OBC iteration:

Plans Examiners:

  • Enforce the window-to-wall ratio: Policing the window-to-wall ratio that’s stated on the Energy Efficiency Design Summary (EEDS) is a must because some designers tend to round down – significantly. We suggest a policy of calculating 10 percent of all submissions randomly and enforcing the two thresholds of 17 percent and 22 percent window-to-wall ratio. This is a tedious calculation if done manually, but the better way would be to have designers include the AutoCAD .DWG file as part of their submittals. That way plans examiners can quickly and easily receive the building statistics.
  • Quality Control check 20% of all energy models: The SB-12 Performance path requires an energy simulation be done by a qualified energy modeler. As the old saying goes, “Garbage in = Grbage out”. Good energy modelers are hard to find but the sad truth is that we suspect very few energy models are checked for accuracy, because plans examiners a) don’t receive the energy model, b) aren’t trained in the software used to create the energy model. That’s a huge problem. Experts like RDH’s John Straub suggest that most of the commercial and high rise buildings in particular constructed today using SB-10, don’t meet the energy code becuase of workarounds in approved software or manipulation of the software. We suspect the same can be said of SB-12 where nobody from the municipality or the MMHA is guarding the energy efficiency “hen house” from naive and in many cases astutely duplicitous energy modelers who are not complying with the OBC.
  • 3rd party field test required? Does the design take advantage of promised energy efficiency gains due to low building air leakage rates? Both the EEDS (misplaced only under SB-12 Performance, see below) and the mechanical design for the home (see example below) allows the designer to take advantage of high quality, more air tight enclosures and the lowest threshold of either has to be forwarded to the building inspector. Air leakage rates used to be defaulted at 4.5ACH50, but as of 2015, CAN-CSA F280 allows mechanical designers to “right size” mechanical equipment by specifying the buildings projected air leakage rate. Few are aware of this allowance buried in the mechancial design.
  • Flag rooms with accelerated heat loss: Develop a rule of thumb that insists if one room has more than three exposed surface areas and/or has over 30 percent window-to-wall ratio, the room needs to be thermostatically controlled and zoned with the central heating system or at the very least supplemented with a separate electric resistance heater. We receive too many calls from home owners complaining about discomfort in glass rooms that run off a centrally controlled Ground Source Heat Pump that can’t keep up with demand.
  • Edit your EEDS forms: A maximum allowable air leakage rate is stipulated under the “SB-12 Performance” heading, but it needs to be added under the “Building Specifications” heading because of credits afforded in Tables (see below). Further, this has to be cross checked with the Mechanical Design mentioned above. Whichever air leakage rate is specified, the lowest one gets input under the heading.

Building Inspectors:

  • Need the EEDS for windows!: Just because the EEDS mandates a maximum U-Factor of 1.6 for windows doesn’t mean the installed product meets it. We need factory labelling for each window and inspectors have to demand it. Either the EEDS document is onsite with the Project Manager’s permit set drawings, or the sheet is on file so the inspector can compare required specifications to the actual installed products that include windows, furnaces, HRVs, hot water heaters and envelope insulation levels throughout. Check, check, check! This is especially crucial for window performance. Too many unrated windows are being installed right now in Ontario. The factory applied energy rating stickers must stay on the windows until the occupancy permit is issued. Forget cleaning them off for the Pre-delivery Inspection (PDI)!
  • Where’s the air leakage test?: With your newly edited EEDS, check to see if an air leakage test is required. If the builder doesn’t have a lot of experience on detailing air barriers or if the house is geometrically complex; test early and test often if an air leakage rate below 2.5ACH50 is required. We highly recommend that a pre-drywall air leakage test be done, otherwise the house will be finished and may not meet the design criteria. This is a liability to be avoided by municipalities. So check for to see if envelope substitutions were permitted using Table and or C (see SB-12 excerpt below), which requires the building be 3rd party tested to meet 2.5 ACH50 or 3.0 ACH50. Ask for the air leakage report before signing off on occupancy permit.
  • Get trained on HRVs and ERVs: To avoid these mistakes, which happen in the City of Toronto, building inspectors need technical training. With homes getting more air tight, and the increased investment in balanced mechanical ventilation systems, there’s a prescient need for more attention to how ERVs and HRVs are installed.
  • Give the spray foamer some room!: Flex your muscle and insist that bulkheads, stair case risers and ductwork on exterior walls go on AFTER the spray foam and insulation’s been installed especially is the prayed foam is part of the Air Barrier System.


  • Hardwired ventilation: I’m not sure where the practice of using an extension cord to plug in a vitally important ventilation machine began, but it has to stop. Too often, HRVs get unplugged because of noise, misunderstanding (i.e. thinking open windows provide adequate ventilation), and lack of maintenance or lack of good controls. I’d highly recommend that these ventilation units be hard-wired on the same circuit as a hall light so that ventilation machines can’t be turned off without complicit knowledge of shutting it down. This has two ramifications for the builder: select a quiet ventilation machine with good controls and educate the home owner on the unit’s importance.


  • Love your stickers: Keep the energy performance stickers on everything, including the windows, furnace, hot water heater, HRV and skylights. Wash around the sticker for now if you need to clean, but don’t take them off until occupancy.
  • PDT not PDI: forget Pre-delivery Inspection; think Pre-Drywall Test! You can improve the comfort and durability of the home by testing the air barrier system before the drywall is applied. If the test doesn’t turn out well, you are in a position to fix the air barrier system and your client will be happier for it in the long run.

The yellow highlighted area shows how the updated CAN/CSA F280 takes advantage of more precise building air leakage rates for sizing equipement more accurately. In the example above, the mechancial designer assumed the building would leak no more than 1.5ACH50, which is a wild assumption for a new building if it’s not being tested. If the builder’s never had anything tested before, assume it won’t make the cut.


The OBC’s SB-12 allows the builder some efficiency tradeoffs with the above Table which necessitates a 3rd party air leakage test to confirm that the air leakage rate isn’t greater than one of either 2.5ACH50 or 1.26cm2/m2 or 0.93L/s/m2 for a detached home.