Buildings are the largest source of carbon emissions in the Greater Toronto and Hamilton Area. At the same time, we face a worsening housing shortage. The ZeroHouse, a new partnership between Ryerson University’s Architectural Science Department and the Endeavour Centre, offers an exciting new solution to tackle both carbon emissions from buildings and the lack of affordable housing. We asked the ZeroHouse team to explain this exciting project in more detail.
Q: What is the ZeroHouse?
A: The ZeroHouse is a 1,100 square foot two-storey, net-zero energy home. It contains blown-in cellulose and straw bale insulation and is clad with maple plywood on the inside and prefinished steel siding on the outside. We had five key net-zero design targets:
- Zero net carbon emissions
- Zero net energy use
- Zero toxic construction materials
- Zero construction landfill waste
- Zero cost premium over a standard construction home of the same size
Ryerson University developed the architectural, interior, and urban design concepts, along with mechanical and electrical system simulation. The Endeavour Centre conceptualized the assembly design, coordinated industry sponsorships, and led the construction of the home.
Q: What makes this different from other net zero energy houses?
A: The ZeroHouse is a fully functional and sustainable home that’s different in it what it achieves and how it looks and feels. It’s completely non-toxic, comes at no cost premium over comparable homes and exceeds the zero embodied carbon target by actually sequestering over 24 tons of CO2.
Beyond these advantages, we wanted to create feasible, attractive housing that could integrate into existing neighbourhoods and is sustainable from the ground up—everything from design and materials, to systems, technologies and construction processes. Most current net-zero housing projects are designed as single family homes. In contrast, the ZeroHouse prototype is designed as the upper unit of a stacked row-house that would exist as part of a mid-density urban development.
Carbon emissions from the manufacturing of construction materials for homes are often substantial. So we approached the ZeroHouse design from a lifetime carbon perspective, including the use of natural plant-based materials that allow the ZeroHouse to store carbon instead of emitting it. For speedy construction and high quality, we relied on prefabricated construction techniques. We used almost all natural materials and some new technologies, including building-integrated photovoltaics instead of conventional solar panels.
Q: In a multi-unit scenario, how can the ZeroHouse collect an adequate amount of solar energy?
A: Stacking units effectively reduces the available roof area for solar panel mounting. However, research shows that there is adequate low altitude daylight in Canada to generate energy from vertical facades. To power the lower unit of the house, the southern facades of both ZeroHouse units will incorporate façade-integrated photovoltaics in addition to the roof. We used a unique 9” wide “peel and stick” photovoltaic laminate (PVL) that adheres to standard metal siding to be less visible than conventional solar panels.
Q: Why did you choose off-site fabrication (prefabrication) for the ZeroHouse?
A: Compared to conventional builds, on site construction time for this 1,100 square foot home was reduced from the average 20-50 weeks (depending on the season and materials used) to just four weeks after the foundations were prepared. By minimizing site construction time through prefabricated construction techniques, we can significantly reduce the time, travel, noise and labour costs. In one working day, a crane assembled the custom insulated floor, walls, and roof panels with pre-installed windows and doors. It only took another six days to install prefabricated stairs, interior wood wall paneling, roofing, exterior metal panels, and kitchen cabinetry.
Lastly, we can reduce landfill waste through the use of sustainably packaged construction materials and panel sizing to minimize waste and offcuts, and effective management, separation and sorting of waste due to distinct construction phases.
Q: Which certification standards or guidelines did you use?
A: Unfortunately, no single certification standard encompasses all five priority areas for the project. However, we referred to many standards, e.g. by including Passive House software for the net zero energy modeling and the Living Future Institute’s Red List of Chemicals. We eliminated all foam insulation materials, manufactured wood products, vinyl windows, most brands of paints, etc. Instead, we used alternatives such as fibreglass windows, plywood, natural oil finish for the floors, and included cork flooring.
Q: How can the ZeroHouse address housing needs in the Greater Toronto and Hamilton Area, especially with regards to affordable housing and densification?
A: Toronto, the Greater Toronto Area and Hamilton all suffer from what is commonly referred to as the “Missing Middle”—a lack of townhouses, triplexes, duplexes, or any housing that isn’t high rise or single family detached housing. Costs of both high and detached housing have skyrocketed in recent years, dramatically lowering the availability of affordable housing across the GTHA.
ZeroHouse puts families in existing and desirable urban neighbourhoods in an affordable and sustainable way by adding additional housing over existing low-rise space on main streets. This concept is adaptable to a variety of housing types from townhouse to walk-up flat to stacked townhouse, which provides significantly higher densities than single family homes while maintaining the desirable streetscapes of mid-rise housing along these often wide streets.
Current planning policies in the region recognize that there are extensive amounts of currently well serviced and affordable land along commercial corridors that are available for infill development. We are talking about buildings that are only one and two storeys tall and unsuitable for high rise development. Using these for development reinforces existing communities and saves the costs associated with traditional new developments—while alleviating the affordable housing crunch.
Q: How far away are we from this being a market reality for consumers?
A: We are at a moment where a combination of awareness, need, product development, and regulatory support is creating momentum for this idea. The market, industry, developers and government are rapidly approaching a tipping point of widespread adoption of a project like ZeroHouse.
We know first hand that millennial buyers and architects are interested in the social advantages of denser and proximate urban living and more aware and supportive of net zero energy and carbon neutral design. A number of large-scale residential builders support offsite timber frame panel construction for the last years by investing in large manufacturing facilities.
Building codes have changed to allow for mid-rise wood (6 stories) in Ontario and new stepped building codes are heading towards to the net zero standard by 2030. Government initiatives like CMHC’s EQuilibrium project have supported experimental builds of net zero single family homes since 2006.
So there is much support and research for this initiative, and with more integrated research and development between industry, developers, architects, academia and government, we firmly believe this will be a market reality within the decade.
This interview was conducted by email by TAF Communications Manager Tim Ehlich and edited for length and clarity. Photo credit for the top image (ZeroHouse interior): Tom Arban.
ZeroHouse Project Team
Architecture : Design and Research Team
- Cheryl Atkinson, Associate Professor DAS Ryerson, Atkinson Architect
- Matthew Ferguson, Graduate Student, DAS Ryerson University
- Chris Magwood, Director, Endeavour Centre
- Shane MacInnes, Design and Instructor, Endeavour Centre
- Tim Krahn, Building Alternatives Inc.
Systems and Design Consulting
- Danilo Yu, Ryerson Electrical Engineering
- Kyle Valdock, Seneca College
- Dr. Alan Fung, Professor, Ryerson Mechanical Engineering
Jamie Fine, PhD Student, Ryerson Mechanical Engineering
Dr. Phil Walsh, Professor, Ted Rogers School of Management
Construction and Management
- Chris Magwood, Endeavour Centre
- Shane MacInnes, Endeavour Centre
- Jen Feigin, Endeavour Centre
Endeavor Centre Student Team
- Britta Anderson
- Dave McDonnell
- Ella Bronstein
- Mateo Thomlinson
- June Saunders
- Kailee Marland
- Michele Deluca
- Natasha Danenhower
- Olivia Keddy
- Bill Andersen