Ontario home builders are in the process of making changes to the way houses are constructed in order to comply with the upcoming implementation of energy efficiency changes to the Ontario Building Code. First established in regulation back in 2006, the changes take effect January 1, 2012 and will apply to any permit applications after that date. The changes to the regulations mandate higher levels of energy efficiency but offer builders two ways (performance and prescriptive) to accomplish the task.
Under the performance method, computer modelling software is used to assess energy consumption of a proposed house design. After the house is built, a blower door test confirms airtightness. In order to comply with the Building Code, the house must meet or exceed a score of 80 on the EnerGuide scale. For the techies: the Code only references version 9.34 of the Hot2000 computer modelling software.
The prescriptive method, on the other hand, allows builders to choose from 37 methods outlined in accompanying tables in the Code. For a gas-heated house in Southern Ontario, there are 13 prescriptive methods available. Using a prescriptive method means the house meets Code and is deemed to reach an equivalent of EnerGuide 80 without the need to provide backup documentation or airtightness verification.
Michael Lio, President of Home Ratings Ontario, says the 2012 Code gives builders a lot of choice. Custom builders who want to demonstrate that their homes are above the EnerGuide 80 standard will likely want to choose the performance method. However, he expects most builders will concentrate on finding a prescriptive option as it demonstrates compliance without the need for verification.
One builder choosing the performance path is Doug Tarry Jr. of Doug Tarry Homes in St. Thomas. Tarry, who is the First Vice-President of OHBA, says the performance system offers advantages to custom builders who want to attract customers looking for a high-performance home. Tarry says his concern is that, without testing and verification, there is no way to demonstrate to the purchaser that the home meets the minimum EnerGuide 80 standard.
Regardless of which method a builder chooses, there are advantages and disadvantages to both.
Verification & Testing
As mentioned previously, the performance method requires the home go through a computer modeling process before a building permit is issued. Once the house is built it must pass a blower door test and meet or exceed EnerGuide 80 standards set out by Natural Resources Canada. The cost of hiring a consultant to model the house design is estimated at $150 to $200 and the follow-up blower door test will range around $350.
Using the prescriptive method, the house relies solely on standard municipal inspections during construction and, provided all requirements of the Code are met, it is deemed to meet EnerGuide 80. There are no additional costs beyond what the Code requires.
Trades & Training
Using one of the prescriptive methods offers builders a system that will work across many jobsites employing different trades at each site. It allows companies to set up methodologies so that trades on each jobsite are following the same system. Superintendents on each jobsite can ensure the work is carried out according to the new specifications.
Either method will require builders to increase supervision, education and training for both their own employees and their trades.
Airtightness
Regardless of method, the Code changes will result in homes becoming more air tight. The Code will require 3.1 air changes per hour.
Most builders consider improved wall assemblies and the use of exterior rigid foam insulation to be the most cost-effective way to meet the new standard. Estimates indicate that improved insulation and wall assemblies will add about $2,000 to the price of a home, but those prices could decrease as manufacturers and contractors adapt to the new rules.
Adding an HRV system, which is common in the performance method, will add about $1,500 to the cost. Some builders fear that increased mechanical costs could create an affordability issue for homebuyers.
Inspection
Some builders are concerned that using the performance method might create delays at municipal building departments as there will be a learning curve while municipalities and contractors develop new ways to manage homes built to the performance standard.
Under the prescriptive method there should be fewer variables, easier inspection protocols and communication between municipal building inspectors and builders.
Increased Costs
In price-sensitive markets, builders fear that passing price increases along to the homebuyer will affect affordability and sales.
A common concern expressed by many builders is that homebuyers still prefer to spend money on interior finishes rather than systems that increase a home’s energy performance. Several experts have noted that builders who choose the performance method will be better equipped to manage construction costs. Allowing each home to be modelled using the Hot2000 software before the design ever heads to construction provides a builder with the opportunity to trade off certain elements for others. This balancing act will demonstrate savings if the builder and design consultant work closely.
The prescriptive method may save money initially for builders who have never attempted a high performance home before and just need a simple answer on how to get the job done quickly and efficiently. At the end of the day, which method a builder chooses will be at his discretion and comfort level.
To purchase a copy of Ontario Home Builder - Summer 2011, click here.
Even using the performance based method, if the homeowner simply installs a 600 CFM range hood fan all calculations are thrown out of proportion and the house in effect becomes leakier.
The Prescriptive method is a builders' 'Get out of jail free' card. All testing should be performance based. This would certainly make the lazy builders I have worked for and others much more diligent and serious about building a more airtight and energy efficient home.