Sustainable Home Design for Secondary Suites in Ontario

As the demand for housing continues to grow, particularly in the bustling urban centres of Ontario, the construction of secondary suites has emerged as a smart and practical solution to meet this demand. In fact, it's become such a useful solution, that we've written many articles about secondary suites already.

That being said, as we navigate this era of rapid urbanization (and environmental uncertainty), we must prioritize sustainable and eco-friendly choices in every aspect of construction--including the development of secondary suites.

In this article, we'll delve into the significance of making eco-friendly choices in your secondary suite construction. By the end of the post, you'll have a comprehensive understanding of why sustainable practices are crucial, and how to achieve your goals.

The Importance of Eco-Friendly Choices in Secondary Suites

Secondary suites play a pivotal role in promoting sustainable housing, particularly in urban areas where space is at a premium. By optimizing existing residential spaces, these suites provide additional housing options without the need for further land development, thus preserving natural habitats and reducing urban sprawl. Additionally, they offer a practical solution to housing shortages, providing affordable and sustainable living options for individuals and families.

But it doesn’t stop with just protecting against urban sprawl. Sustainability in the construction of secondary suites is important for a multitude of reasons. Firstly, sustainable construction practices help in conserving precious natural resources. By opting for recycled or sustainably sourced materials, we significantly reduce the demand on natural habitats and decrease deforestation rates.

Secondly, eco-friendly choices can lead to a significant ROI through the integration of energy-efficient appliances, smart design choices allowing for better natural light and airflow, and the utilization of high-quality insulation and materials that enhance the overall energy efficiency of the suite.

Lastly, sustainable construction practices contribute to healthier living environments. By choosing non-toxic, low-emission materials and ensuring proper ventilation, we can improve indoor air quality and create a living space that supports the well-being of its occupants.

Sustainable Materials for Secondary Suites

Selecting the right materials is crucial when constructing a secondary suite, so where do you start?


Bamboo stands out as an exemplary choice due to its rapid growth and durability, making it a sustainable alternative to hardwood. Cork is another great option, as it is harvested from the bark of cork oak trees without harming the tree itself. Recycled or reclaimed wood also provides a rustic and eco-friendly flooring solution by repurposing old materials for new use.


If new windows and doors are added—or more exterior updates are needed—sometimes the siding needs to be replaced. Fibre cement siding, made from a mix of wood pulp and cement, is long-lasting and resilient, requiring less frequent replacements and repairs. Additionally, recycled metal siding offers a durable and sustainable exterior option.


Green roofs, also called “living roofs,” which are partially or completely covered with vegetation, provide excellent insulation, reduce stormwater runoff, and help combat the urban heat island effect. Alternatively, metal roofing (especially those made from recycled materials) offers longevity and high recyclability at the end of its life.


Composite decking, made from a blend of wood fibres and recycled plastic, provides a durable and eco-friendly alternative to traditional wood decking.


Energy-Efficient Appliances Suitable for Secondary Suites

Outfitting a secondary suite with energy-efficient appliances is a straightforward and impactful strategy for diminishing energy usage and trimming utility expenses. Seek out appliances that boast the ENERGY STAR certification, as these appliances meet rigorous energy efficiency standards established by Natural Resources Canada. Whether it’s refrigerators, dishwashers, or washing machines, these appliances are designed to consume less energy and water, rendering them a prudent investment for both the environment and the homeowner. And if new appliances are not in the budget, purchasing good quality used appliances keeps them out of landfills before they've reached the end of their life cycle.

The Importance of LED Lighting and Its Advantages

Incorporating LED lighting is another pivotal aspect of creating a sustainable secondary suite. LEDs are significantly more energy-efficient than traditional incandescent bulbs, using up to 75% less energy and lasting up to 25 times longer. This not only reduces the suite’s energy consumption but also decreases the frequency of bulb replacements, further minimizing waste. Furthermore, LEDs have evolved to integrate seamlessly with smart technology, enabling the creation of customized atmospheres in various sections of the suite by adjusting their colour temperatures.

Benefits of Insulating the Exterior During Basement Finishing

If the secondary suite is located in the basement, exterior insulation is a key consideration. This practice involves adding insulation to the outside of the basement walls, which enhances the thermal envelope of the suite, leading to greater energy efficiency. Exterior insulation also helps to prevent moisture issues, a common concern in basements, ensuring a more comfortable and healthier living space. This upfront investment pays off in the long run through reduced energy bills and an increase in the suite’s overall value.

Mini-Splits for Heating and Cooling and Their Efficiency

Mini-split systems are an excellent heating and cooling solution for secondary suites, offering both efficiency and flexibility. These systems consist of an outdoor compressor/condenser and one or more indoor air-handling units, allowing for zoned temperature control. Mini-splits are incredibly energy-efficient, often resulting in lower energy bills when compared to traditional HVAC systems. Additionally, they are easier to install and do not require ductwork, making them a practical choice for secondary suites with limited space.

By integrating these sustainable building practices, secondary suites can become a model of efficiency and eco-friendliness, contributing to a greener future while providing comfortable and healthy living spaces.

Use MLI Select to Make Your Dreams of Green Come True

At its core, MLI Select prioritizes three critical aspects: affordability, accessibility, and climate compatibility. The program aims to make sustainable living spaces more financially accessible to homeowners, ensuring that more individuals can contribute to and benefit from eco-friendly housing. Furthermore, it emphasizes the creation of spaces that are accessible to individuals of all abilities, fostering inclusivity in sustainable living. Finally, MLI Select is dedicated to aligning rental construction with climate resilience practices, ensuring that these living spaces are built to withstand and adapt to changing climate conditions.

MLI Incentives

To encourage homeowners and builders to adopt sustainable practices, MLI Select employs a point-based incentive system. Under this system, points are awarded based on the implementation of various sustainable building practices, materials, and technologies in construction. The more sustainable the choices made, the more points accrued. These points then translate into tangible benefits for the homeowner or builder, serving as a direct incentive to prioritize sustainability in the construction process.

These incentives include:

Enhanced Leverage and Amortization:

For existing properties, the maximum leverage has increased from 85% to 95% loan-to-value. For new construction, the leverage remains at a generous 95% loan-to-cost. Additionally, the program allows for amortization periods to be stretched to 50 years, a decade longer than what MLI Flex permitted.

Reduced Insurance Premiums:

One of the standout features of MLI Select is the general reduction in CMHC insurance premiums, particularly for properties demonstrating strong social outcomes. This reduction in premiums acts as a financial incentive for property owners to invest in sustainable and affordable housing.

In Conclusion

The shift towards sustainable home design for secondary suites in Ontario is not just a trend but a necessary evolution in our approach to urban living and construction. Through the integration of eco-friendly materials, energy-efficient appliances, and innovative heating and cooling solutions, secondary suites can play a pivotal role in fostering a more sustainable and resilient urban landscape.

Ready to take the next step in creating a sustainable living space?

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