Passive House Design: A frontline perspective
Ever since the first OPEC oil crisis of the early 1970s, I have been fascinated by the concept of the “urban farmhouse”—an urban yet off-grid, self-sufficient entity. In the urban farmhouse, all the fundamental elements required to support life are incorporated into one ecosystem, including greenhouse food growth, composting, and the harvesting of rainwater and energy provided by the sun and the wind.
Over the course of time, I discovered the work of Malaysian architect Ken Yeang, a pioneer of ecology-based architecture. I studied Ken’s work in considerable detail, reading and studying his treatise on designing sustainable intensive buildings (The Green Skyscraper, 1999). In the late 1990s, I had the fortune of not only meeting Ken Yeang but collaborating with him on the Canadian High Commission in Kuala Lumpur (completed in 2001). And while in Malaysia, I visited several of his projects which further intensified my interest in the role that architecture plays in ecology.
Nearly five years ago, my business partner Tony Mancini returned from a conference lecture and excitedly told me about passive energy and the theory that one can heat their home using only a hair dryer. It was then that I was compelled to explore the world of passive energy and quickly discovered the International Passivhaus Institut (PHI) based in Darmstadt Germany. A few months later, after taking all of the available PHI training, we began a Passivhaus renovation (EnerPHit) of a small 19th century farmhouse in Prince Edward County.
Passivhaus—or Passive House—is not about complex technologies. It’s about changing how we build, integrating low energy design criteria into projects from day one. There are five key Passive House principles.
First: massively insulated, thermally broken airtight envelope. Second: triple-glazed airtight, thermally broken windows. Third: optimized orientation. Fourth: mechanical ventilation energy recovery. Fifth: optimized functional design. A Passive House design allows for the building to heat and cool itself most of the time, providing significant occupant comfort for 90 percent less energy compared to conventional building methods. In a Passive House, you can sit next to a window in the dead of winter and not feel a draft, and then sit next to that same window at the height of summer and not feel overheated.
I have had the chance to work on a number of Passive House projects that vary in scale and complexity. The project examples below will allow me to illustrate what I’ve observed: the size of a Passive House project does not necessarily determine its complexity.
Last summer my team and I simultaneously launched two projects in Prince Edward County, Ontario: a Passive House renovation using the EnerPHit-Standard, and a new custom-designed, multi-generational residence on a greenfield site. In addition to these two residences, we were completing a Project Output Specification (POS) for a new, large-scale mixed-use student residence project at the University of Toronto Scarborough (UTS) campus. The three projects demanded an intensive study of Passive House process while simultaneously developing the in practice, each with their own typologies and scales. In order to achieve certification, the criteria had to be executed using slight variations to accommodate each project’s unique challenges.
The Reach Guesthouse (Small scale, high complexity)
Like most renovations, this project was a journey. Yet despite the slow progress of the project, we managed to create a systematic combination of “archaeological” discovery, preservation, encapsulation and architectural re-interpretation. The original building was reduced to its barest hand-hewn wooden structure, meticulously cleaned, and then sealed inside an airtight skin. We then added a new jacket of R43eff Structural Insulated Panel (SIP) based insulation to the walls and roof. (The “eff” designates “effective” R-values of the wall assemblies as opposed to the suppliers’ nominal values per layer of material.) One of the many challenges was to get an airtight seal around the existing structure. To achieve this, we had to lift all ground level floorboards, insert an Oriented Strand Board (OSB) layer and then relay. We had to pry loose the old board-and-batten walls, working progressively around the building so that we could seal the floor to the air/vapour barrier wrapping the house. The front gable window was intentionally oversized to allow a glimpsing view of the original house within the new house. This year, an electric “hair dryer” (actually a tiny electric heater purchased at a yard sale) has been maintaining temperatures comfortably despite the minus 25 degrees Celsius temperatures outside. This renovated farmhouse will be a guesthouse to the future “great house,” which will be perched on the top of the adjacent waterfront escarpment overlooking Adolphus Reach. Our firm’s newly acquired knowledge was immediately put to use creating another guesthouse for another future “great house,” also in Prince Edward County, this time overlooking Prince Edward Bay.
Endymion (small scale, moderate complexity)
Endymion is a 3,400-sq.-ft. multi-generational house that will enable four families to occupy the house at one time. Since it is a new building on a 3.5-acre site, we were able to select prime south-facing orientation and choose an efficient and simple form. We also selected an idyllic placement for the house so that it can be easily heated by the sun in winter and efficiently shaded in summer. It resulted in an elegant three-level house, its upper floors facing south over lavender gardens and lowest floor facing east and west and opening up to private courtyards.
Endymion is designed to be an R43eff Insulated Concrete Form (ICF) structure with large-format porcelain ceramic tile cladding. Windows and doors are triple-glazed, and the house is ventilated by two Energy Recovery Ventilation (Jablotron Futura ERV) units. Heating, if required, will be provided by two thermostatically controlled gas fireplaces. Walls are typically 500mm thick and the south facing wall has been framed out to 1M to allow a sculpting out of deeply recessed windows to achieve shading without resorting to applied sunshades.
As relatively small Passive House buildings, both the Reach and Endymion rely heavily on the sun to supply most of the heating. Siting, orientation and window placement are thus vital to the success of these projects.
UTSC Student Residence (large scale, high complexity)
Comprising approximately 280,000 sq. ft., with a transient population of roughly 1,000 people at any given time, a full commercial kitchen, a dining facility, 750 students with their own micro-refrigerators and computers, this Passive House building performs quite differently from the two smaller examples above.
With all the internal heat gains—generated within the building by people and equipment—this building, unlike The Reach and Endymion, is not relying on the sun to supply most of its heating. On the contrary, the internal heat gains are such that this building will largely require cooling. The building envelope is designed to achieve an R41eff insulation value, be airtight, free of any thermal bridging that would allow unwanted heat transfer, and have triple glazed windows that can be effectively shaded and not add to the heat load.
The exemplar design demonstrated compliance with Passive House standards in all but the commercial kitchen. Upon further analysis of the demands of a commercial kitchen serving thousands of meals per day to a multi-ethnic population, the International Passive House Institute is reconsidering the qualifying standards for such a facility in North America.
Based on these experiences, Kearns Mancini Architects will integrate Passive House standards for all future project assignments, where feasible. We understand the significance of Passive House design methodology. True sustainability comes from the measures and practices we set to limit our impact on the earth—practices that support us and help us to live better and do not set out to diminish our livelihoods, our health or our ability to develop as people, cultures, nations.
We look forward to seeing high performance buildings become the normal way to build. Not only is Passive House a better way to build, it should be the only way we are permitted to build. It is not a brand; it is a building standard, balancing energy efficiency, occupant comfort, and affordability. As more people become committed to Passive House, additional certified materials will become readily available, which will in turn make it less of a specialty commodity and reduce the overall cost. The Passive House Standard should not be a privilege; it should be a right.
Jonathan Kearns, FRAIC, is a co-founder and principal of Kearns Mancini Architects in Toronto.