Building operation is one of the largest  sources of carbon emissions, accounting for around 40% of the global greenhouse gases generated each year. At the same time, we face a worsening housing shortage in the Greater Toronto Area. The ZeroHouse, a new partnership between Ryerson University’s Architectural Science Department and the Endeavour Centre, offers an exciting new solution aimed at eliminating high carbon emissions from buildings and offering a solution to the lack of affordable housing in the Greater Toronto Area. I asked Cheryl Atkinson, design architect on the ZeroHouse team, to explain this exciting project in more detail.


Tim Ehlich: What is the ZeroHouse?

Cheryl Atkinson: The ZeroHouse is a 1,100 square foot two-storey, net-zero energy demonstration 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:

  1. Zero net carbon emissions
  2. Zero net energy use
  3. Zero toxic construction materials
  4. Zero construction landfill waste
  5. 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.


TE: What makes the ZeroHouse different from other net zero energy houses?

CA: The ZeroHouse is a fully functional and sustainable home that’s different in 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 carbon dioxide.

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 with ground floor commercial space 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.

Illustration: Cheryl Atkinson and Matt Ferguson, Ryerson University Architectural Science Department

TE: In a multi-unit scenario, how can the ZeroHouse collect an adequate amount of solar energy?

CA: Stacking units 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 solar panels mounted to south-facing walls. To power the lower unit of the house, the southern facades of both ZeroHouse units incorporate building-integrated photovoltaics in addition to the roof. We used a unique 9-inch wide “peel and stick” photovoltaic laminate (PVL) that adheres to standard metal siding and is less visible than conventional solar panels.


TE: Why did you choose off-site fabrication or prefabrication for the ZeroHouse?

CA: 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 accurate panel sizing to minimize excess construction materials and offcuts. Effective management, separation and sorting of waste due to the distinct construction phases also reduces our impact.

Photo: Endeavour Centre


TE: Which certification standards or guidelines did you use?

CA: Unfortunately, no single certification standard encompasses all five priority areas for the project. However, we referred to multiple standards, 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.


TE: How does the ZeroHouse address housing needs in the GTHA, especially with regards to affordable housing and densification?

CA: Communities across the Toronto region 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-rise 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 land containing buildings that are only one and two storeys tall and unsuitable for high rise development. Using these for redevelopment strengthens existing communities and saves the costs associated with traditional new developments—while alleviating the affordable housing crunch.


TE: How far away are we from this being a market reality for consumers?

CA: 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 projects like ZeroHouse.

We know first hand that millennial buyers and architects are interested in the social advantages of denser and proximate urban living and are more aware and supportive of net zero energy and carbon neutral design. A number of large-scale residential builders, such as Great Gulf Homes’ Brockport pre-manufacturing factory, have invested in offsite timber frame panel construction. In addition, building codes have changed to allow for mid-rise wood ( six storeys) in Ontario and new, stepped building codes are heading towards 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 originally published on the The Atmospheric Fund’s 80×50 blog and is reprinted with permission.


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

Project Management

Jamie Fine, PhD Student, Ryerson Mechanical Engineering

Business Development

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