March 24, 2017
It is now possible to design, construct and warranty homes that are more energy efficient than the minimum building code (and homes that are more comfortable) and at less cost than prescriptive building code measures would dictate. There are now three ways of meeting and exceeding the new energy efficiency levels within the 2017 SB-12 standards with each alternative providing more flexibility and cost effectiveness than the default (and often difficult) prescriptive path. The Building Knowledge Canada team has been working with numerous designers and builders across Ontario reducing the energy use of their home designs to meet new building code standards -and doing it at no extra cost!
Option 1: Performance Path (No Air Test)
In this option, Building Knowledge Canada evaluates and optimizes each homes enclosure design, e.g. insulation, air tightness and mechanical performance using energy modeling software. Using this method many designers and builders are often surprised to find their current specifications meet or exceed even the new Ontario Building Code requirements. Most notably this compliance method (energy modeling) allows the designer and builder to create their own energy solutions, taking advantage of local best practices, better air tightness levels and/or better performing building products and equipment. As an example, a designer may struggle to fit more insulation into the above grade walls due to loss of internal square footage or inability to accommodate garage and stair clearances. By eliminating the "prescriptively" required 1" to 2" of continuous exterior insulation and increasing the efficiency of the mechanical equipment and upgrading the window performance specifications, the designer maintains the valuable square footage and eliminates the clearance issues. More importantly the design now uses less energy (lower utility bills and better comfort) than even the original prescriptive requirements.
Option 2: Performance Path + an Air Test
This is the same as option one, with the exception that an air test is performed on the home prior to closing. The prescriptive compliance packages of the OBC assume homes have a normal-to-high air leakage rate e.g. 3.0ACH50 for singled detached and 3.5ACH50 for attached homes. Most designers and builders are constructing homes that have robust air barriers which perform far better than the Ontario building code assumed minimum levels. Builders also know that air leakage and infiltration can add 20% to 30% more heating / cooling load to a home. Builders can quantify or test their homes (through 3rd party energy evaluators) using a blower door test. In validating better air tightness e.g 2.5ACH50 on Singled detached/3.0ACH on attached, the designer and builder can remove other specifications from the home which do not provide any noticeable benefit to the occupant.
With this energy efficiency measure achieved, Building Knowledge will use software to model your design, to determine what additional energy efficiency improvements, such as triple pane windows, energy recovery ventilation, underslab insulation and domestic hot water heat recovery are required to beat the SB-12 reference design.
If you can prove the building is airtight, you can drop some of the other energy efficiency requirements. More importantly, the efficiency of the home will be increased, operating costs will be reduced, comfort issues can be eliminated and long term effects of air infiltration (condensation inside of walls) can be controlled.
Option 3: ENERGY STAR® for New Homes Certification
We've saved the best for last (in our opinion). For those of you that are already certifying to ENERGY STAR®, congratulations! All your years of hard work constructing comfortable and durable homes is paying off.
For everyone else, this truly is a no-brainer, cost-effective choice. The preferred rating system for energy efficiency in homes, ENERGY STAR® homes are 20% more efficient than the building code. The funny little blue label has a consumer recognition rate of 90%+! The blue ENERGY STAR® label helps buyers feel confident they are getting a well-built home that is 3rd party tested and inspected. If you choose to certify to ENERGY STAR®, you should expect to design to requirements like this:
Attic/Ceiling : R50/R31
Walls: R20+R5 sheathing
Windows: Zone 2 ENERGY STAR®
Furnace: 95% afue
Hot water: 0.80/ 90% TE
HRV: 65% SRE
DWHR: 42% serving one shower
Fireplace: spark ignition
Air tightness test: 2.5ach detached /3.0 ach attached
If you're choosing this route, remember to have your houses enrolled with ENERGY STAR® by September 1, 2017 and built out and inspected by August 31, 2019. That gives your Building Knowledge consultant plenty of time to review your go forward path on the recently released ENERGY STAR® - Ontario 17 version.
So there are your options! We hope this helps you make an informed decision, but rest assured, moving towards a more air tight, better performing design is always a plus in the long run. Get in touch to discuss which path works best for you.