On July 14, 2017, the Ministry of Municipal Affairs announced the replacement of the Ontario Building Code, effective January 1, 2019. The changes are being made to include new requirements supporting the government’s Climate Change Action Plan (CCAP) of June 2016, with a view to reducing GHG emissions and implementing energy-efficient measures in new homes and large buildings. The concept is to bring these structures closer to being “net-zero energy buildings” (NZEB) – where the energy used by the building is equal to the amount of renewable energy created on site. Affected parties including designers, builders, contractors, and installers should take note of these significant changes being considered.

Requirement of “Solar-Ready” Roofs and Conduits

One of the major themes from the proposed changes is to institute requirements during the installation stage of new houses and large buildings that will make them ready to be “net zero” in the future. There are two amendments with this objective in mind: (i) adding a loading requirement to roofing designs for all new large buildings that makes possible the future addition of solar technology; and (ii) the requirement of a conduit on all new houses and large buildings to facilitate the installation of a photovoltaic system or a solar domestic hot water system.

The current version of the Building Code does not require these facilitating measures be in place. The rationale for these proposed changes is that, currently, when solar voltaic panels are added to an existing building, the construction costs can be huge. These amendments would require that certain upfront costs be incurred during the construction phase – ensuring large building roofs are able to support a larger dead load allowing for the weight of a future installation of a PV or solar hot water system, and of installing conduits on all new houses and buildings.

The loading requirement for roofing designs will only be waived in circumstances where the solar collection system is not practical, including roofing areas occupied by mechanical equipment, vegetative or high-reflectance roofs, roof area that is largely shaded, roof area that is sloped or oriented to make solar collection impractical, and roof area used for paths of travel.

National Resources Canada partnered with the Canadian Solar Industries Association to explore this “solar-ready” concept and created Solar Ready Guidelines.[1] Builder-led pilot projects were done to explore the solar-ready concept. The findings were that a few simple, inexpensive design modifications made “up front” in the design and construction phase of a new home enabled building owners to significantly save on future installation costs of a solar domestic hot water system or photovoltaic system. Specifically, it found that for an average home, homeowners could expect to save about $1,000 on the installation of a solar domestic hot water system or a solar PV system in a home built “solar-ready” versus a home without these features.[2]

Reduction of Trade-offs between Building Envelope and Heating Systems for Energy Efficiency Compliance

Another significant proposed change is with regard to the energy efficiency requirements under the Ontario Building Code, as set out in the Supplementary Standard SB-12 “Energy Efficiency for Housing.” The change would reduce, starting in 2020, the possibilities for trade-offs between components of building envelopes and heating systems, eventually eliminating the practice of these trade-offs altogether by 2022.

Currently, houses can meet the energy efficiency requirements by following either the prescriptive-based approach or the performance-based approach in SB-12. Prescriptive compliance means that the thermal performance and energy efficiency of both the building envelope and the mechanical equipment (including space heating equipment, hot water heating equipment, and heat recovery ventilators) must conform to a certain compliance package with specified requirements for each component. Performance compliance means the builder must only ensure that the overall energy use of the house does not exceed the amount of energy it would use if it was designed according to a select prescriptive compliance package; but how this is distributed amongst the various components is up to the builder to decide. This greater flexibility thus allows builders to make trade-offs between building envelopes and mechanical equipment, which often results in the substituting of a highly energy-efficient heating system with a poorly-performing building envelope.

A recent Globe and Mail article entitled “Ontario Looks to Close Loophole on Energy Standards for Buildings” discussed that many condominium and apartment building developers are exploiting the flexibility provided under the current rules.[3] Developers are able to meet energy targets by installing ultra-efficient mechanical heating and ventilation systems as a “trade-off” against the use of one of the least energy-efficient materials for its building envelope – floor-to-ceiling windows. This practice has the effect of undermining the energy efficiency of these new large buildings which are able to “squeak by” the energy efficiency standards, but whose building envelopes are overall low-performing in thermal and energy efficiency.

The proposed amendment will reduce the potential for these trade-offs with the view that it will highlight the critical role of the building envelope in making new buildings as efficient as possible in terms of energy use and GHG emissions. As of 2022, these trade-offs will be altogether eliminated, so that builders can only substitute building envelope components for other building envelope components. For example, a window with a lower-than-required performance level can be substituted for insulation that has a higher than required R-value but it cannot be substituted for a higher performing heating system.

Requirement of Heat or Energy Recovery Units in all Buildings

Another amendment, to be in effect by 2022, is that all apartment buildings and condominiums will be required to have a heat or energy recovery unit as part of their ventilation system. The rationale for this change is that due to recent efforts at reducing air leakage in new buildings, air tightness in new homes and buildings has significantly increased to the extent that air leakage, as well as the supply air for exhaust ventilation systems, is now reduced. A heat or energy recovery ventilator can address these issues as it provides a controlled amount of fresh air through a mechanical ventilation system. The purpose of a heat recovery unit is to remove moisture and provide fresh air to buildings in order to maintain good indoor air quality. Air quality is important not just for human health reasons, but also for energy efficiency and cost-savings, as it reduces heating costs by not heating excess water vapour in the air (heating moist air eats up more energy). Although there will be upfront installation costs for these units, it is expected that the saved heating costs over time will make them cost-efficient and have a payback period shorter than their expected lifetime.

Encouraging Greywater Reuse Systems

One of the proposed changes to the Building Code is to facilitate greywater reuse systems. Greywater systems are a form of decentralized water reuse where the system is maintained by the property owner or manager and the collected water is reused on site.[4] There are cost benefits for the user, as there will be lower payments for water, system benefits, as the re-used water does not have to be transported through the water infrastructure (the sewage system), and environmental benefits, as there is, obviously, lower water source withdrawal, as well as lower energy use.

“Facilitation” of these systems in the new Building Code will be in the form of adopting a new standard for greywater reuse created by the Canadian Standards Association – the CAN/CSA-B128.3 Standard – which references the quality of water required for greywater reuse systems. The current Building Code only references one CAN/CSA standard, which is focused mainly on the design and installation portions of greywater systems.

The hope is that with implementing such a standard controlling the quality of water, users’ and consumers’ concerns about health, safety, and sanitation with Greywater reuse systems will be allayed, and these systems will become more commonplace.

A recent study done by the Priority Green Clarington demonstration project and reported on by the Environmental Commissioner of Ontario in its 2016/2017 report found that compared to other water-saving technologies, the Greywater system delivered the largest water savings – at 13 litres per person per day, providing more than 50% of the water needed for toilet flushing.[5] Unfortunately, such systems are not yet cost-efficient, due to their high upfront cost, including installation of a dual plumbing system.[6]

It is unknown whether this addition of a new water quality standard will be enough to encourage users to install and retrofit these expensive greywater systems. This change is to be in effect in 2019, although it is anticipated that there will be a negative reaction to this initiative from municipalities, who based their capital expenditures on water and wastewater treatment systems on the current model of water usage.

Other potential changes proposed for the new Building Code include: continuous insulation requirements; energy-efficient windows and sliding doors requirements; and air leakage testing and air tightness requirements.


The Ministry is encouraging comments to be posted on their site during the 77-day comment period, which closes September 29, 2017. Following this period, Technical Advisory Committees of Building Code experts will meet to offer advice on the proposals, which are anticipated to begin coming into effect as of January 1, 2019. However, with a provincial election scheduled for spring 2018, it is unknown whether some or all of these changes will actually be put in place.