Thursday, 27 June 2019

Building Energy-Efficient Homes

It takes a lot of energy to heat the average home, especially during Saskatchewan’s cold winters, but it doesn’t have to. We have the knowledge, techniques, and materials to build energy-efficient homes. All we need is the political will and public interest to improve our building standards.

The Saskatchewan Conservation House in Regina was completed in 1977 and combined superinsulation, airtightness, and a heat recovery system. Over the years, a number of people have pushed the Saskatchewan government to introduce more stringent building standards with little success. That has begun to change. The Government of Saskatchewan introduced energy efficiency standards in January 2019 and recent interest in passive house design has resulted in several energy-efficient residential buildings in Saskatoon (Temperance Street Passive House, Radiance Cohousing).

Michael Nemeth, engineer and Passive House Canada instructor, provided an overview of the current provincial legislation, its strengths and weaknesses, and the direction he believes we should be taking.

Current Saskatchewan Legislation 
The Saskatchewan government has adopted the National Energy Code of Canada for Buildings 2017 (commercial) and Section 9.36 – Energy Efficiency of the National Building Code 2015, Energy Efficiency (residential) for any permits issued after January 1, 2019. Under the new standards, builders are required to measure energy efficiency based on 3 possible paths or models:

The prescriptive path sets specific values that must be met for building materials, insulation, and heating equipment. For example, residential windows and doors must have a maximum U-Value of 1.60 W/m²K .

The trade-off path allows builders to substitute a less energy-efficient feature in one area so long as another feature exceeds requirements. For example, if the windows are of a higher standard, the insulation in the walls can be of a lower standard.

The performance path measures the overall energy efficiency of the building rather than measuring individual features. The efficacy of this model very much depends on what you are using as a reference model. For example, a building with small windows can have a lower energy rating if it’s compared to a building with large windows.

Requiring an energy model raises awareness and Michael hopes this will encourage builders to raise their standards. Overall, however, the standards set a low threshold for energy efficiency and Michael suspects they will remove bad behaviour and poor building practices but fail to increase energy efficiency. Both the prescriptive and trade-off paths focus on individual elements rather than looking at how the building functions as a whole. The performance path measures overall energy efficiency; however, by substituting one feature for another, builders can continue most of their current practices.

BC’s Energy Step Code
In 2017, British Columbia introduced the Energy Step Code as an alternative to the prescriptive approach. The Step Code establishes higher standards than the national code, requiring both an energy model and an airtightness test. It offers a stepped approach to allow municipalities to improve energy efficiency on a gradual basis. The lower steps are fairly easy to meet, while the upper steps are more ambitious, empowering “builders to pursue innovative, creative, cost-effective solutions” and “incorporate leading-edge technologies as they come available.” The province’s goal is to have everyone at passive house or net zero ready standards by 2032.

The stepped approach provides flexibility as municipalities can choose the step which best suits their community’s current capacity, although Michael believes it would be more efficient in the long run for builders to retool immediately to meet the optimum standards.

As of September 2018, 14 local governments referenced the Step Code in a policy, program, or bylaw, and 30 were consulting on the Code. Together with the City of Vancouver, which has set its own energy efficiency targets, the communities represent 61% of BC’s population. The majority are considering and/or implementing the lower steps, particularly for houses and small buildings. Some communities have introduced incentives for voluntary adoption of the Step Code or to encourage builders to achieve higher steps.

Measuring Overall Heating Requirements 
Michael firmly believes that the best approach for ensuring energy-efficient buildings is to set overall space heating targets. Space heating measures the energy required to heat a square metre, taking into consideration the characteristics of the building, the heating system, solar gains, and external weather conditions. (The Canadian average is 150 kilowatt-hours per square metre (kWh/m²). whereas passive house certified homes are at 15 kWh/m².) This comprehensive approach acts as an incentive for increased research and development into more energy-efficient products (e.g. windows) and provides builders with increased flexibility when developing their plans.

A good example is Souls Harbour Rescue Mission in Regina, a 4-storey facility housing emergency shelter for 24 men, soup kitchen, free clothing store, daycare, and 17 low-income residential units. The building will come very close to meeting passive house certification standards with space heating at 22 kilowatt-hours per square metre.

Building an energy-efficient home doesn’t have to cost more money, but it does require rethinking standard models. For example, Souls Harbour Rescue Mission saved $180,000 on mechanical equipment by replacing a more traditional boiler with four furnaces and a very high-efficiency ventilation system. The savings were invested in energy-efficient insulation, windows, and doors with an added bonus of reduced maintenance expenses with furnaces rather than a boiler.

Energy-Efficient Retrofits 
Raising standards for new builds isn’t sufficient. Government needs to introduce incentives to support energy-efficient retrofits of existing buildings. Michael points to PACE, Property Assessed Clean Energy, as a useful financing model. PACE programs provide homeowners with the upfront capital to finance renewable energy or efficiency upgrades to their property. This is already happening in Alberta and some US states. With minor changes to the Cities Act, Saskatchewan municipalities could finance a PACE program through property taxes. Monthly cost of living in these homes would be lower with ongoing energy savings, and the homes would be more attractive with improved thermal comfort and sound attenuation. Homeowners could also recoup the cost of the retrofits when selling their home as the expense would remain embedded in the property taxes.

Energy Monitoring 
Constructing or retrofitting an energy-efficient home is only the first step. Consideration must also be given to how much energy is being consumed within the home by appliances. Energy monitoring, using a system such as Sense, can improve occupant behaviour by increasing awareness of how much energy is consumed by the refrigerator, television, and other devices.

See also: 
Passive House: Comfortable, Energy-Efficient Homes 
Temperance Street Passive House: Saskatoon’s First Passive House

Photo credit: Souls Harbour Rescue Mission, Michael Nemeth