Passive Houses
Say hi to super efficient homes of the future
I was introduced recently to passive houses almost simultaneously by two cutting-edge architect friends who are into sustainable architecture, Montreal-based Morgan Carter (L’Oeuf) and NY-based Eve Lefebvre-Macdougall (Buck Moorhead Architect, Brooklyn Built). Both seemed convinced that passive houses could radically change how buildings are designed in the future.
Passive houses 101
The term passive house (Passivhaus in German) refers to “a rigorous, voluntary, standard for energy efficiency in a building, reducing its ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling”. (1)
Energy savings for passive houses can be up to an amazing 90%. This is particularly impressive considering that “76% of all electricity generated by US power plants goes to supply buildings”. Passive houses could have a major impact on combatting climate change. (2)
In 2012, there were 25,000 passive houses in Europe (mostly in Germany and Scandinavia), with only 13 in the USA. (3)
Passive House buildings aim to “maintain occupant comfort for more hours of the year without the need for mechanical temperature conditioning of the indoor air”. The approach is to “maximize your gains, minimize your losses”. (4)
Passive house can typically include some of the following features (5)(6):
- Passive solar design and landscape: Design of building to maximize solar passive gain and minimize house energy requirements.
- Superinsulation: Reduction of heat transfer through walls, roof and floor through superior insulation.
- Advanced window technology: Use of triple-pane insulated glazing with air-seals and custom-developed frames.
- Airtightness: Development of airtight building envelopes through air barriers.
- Ventilation: Use of passive natural ventilation.
- Space heating: Use of passive solar gain and heat from intrinsic sources (appliances, lighting or humans) in tandem with comprehensive energy conservation. Remaining heat demand is provided by an extremely small source.
- Lighting and electrical appliances: Use of energy-saving lighting forms like compact fluorescent bulbs or LED.
There is an interesting distinction with zero-emission buildings (ZEBs), who “rely predominantly on active systems to bring a building to zero energy” while passive houses “work with natural resources, free solar energy is captured and applied efficiently”. (7)
House in Four Fields
Morgan recently won the prestigious prize Canadian Architect Award for Excellence for 2012. No surprise, it was a passive house! Actually, the project was one of the first passive houses ever built in Quebec.
The project, called House in Four Fields, was erected on a site described as follows:
“The site is in the Rouge River valley, a gently undulating farmer’s field crossed by the meander of an ancient oxbow, structured by wire fences and surrounded by forest. The approach weaves through some aged agricultural and livestock buildings to the south and reveals a view of Mont Tremblant to the east”. (8)
Perhaps one of the most interesting aspects of this project is how the house seems to adapt to the four very different seasons in Quebec:
“The house opens to the summer winds, ventilating at central skylights and end gables, and lending itself to passive night-time flushing. Autumn draws use intensely to the terrace and kitchen for canning and preserving, and to the garden shed and storage basement. With winter, family activities refocus on the house, with picture views across the fields to the mountains east and south from the main living spaces. Discontinuous inhabitation in the early years and during the winter challenged the project, and in response the house is super-insulated and opens to the south — it is passively heated and cooled”. (9)
The jury had this to say about the House in Four Fields:
“This is an exemplary project in every way. The approach is guided by green design and is inspired by the traditional architecture and art de vivre Québécois throughout the seasons. The extreme simplicity of the architecture, the perfect merging of site and landscape, the richness of the indoor and outdoor spaces, the beauty of the house’s volume floating over the stone wall is significant. The result is a perfect example of a great coherence between form, sustainable design, high- and low-tech, and traditional methods”. (10)
5 Questions with Morgan Carter
Hailing from Eastern Canada, Morgan graduated from the Harvard Graduate School of Design, where he earned a GSD Green Design Scholarship. He is also a lecturer on architecture and design at McGill University, University of Montreal, Carleton and Harvard. He has previously completed projects on post-earthquake housing in Haiti and sustainable urbanism in the Persian Gulf. I met Morgan last year through the Harvard alumni club in Montreal. His current practice is rooted in an architecture of cultural and ecological sustainability — including the award-winning House in Four Fields project.
1. How did you get interested in passive houses?
As an architect, my primary interest is in understanding how design impacts the individual users of a building — and the potential that exists therein to inform broader cultural and technological change. What I find compelling about the passive house approach to design, is that it has the capacity to respond to both of these by addressing interior comfort, durability, urban design, and energy efficiency — without imposing a formal or stylistic agenda on the architecture itself.
In other words, passive houses have the potential to address a wide range of individual and collective aspirations — without hampering our capacity as architects to develop creative and culturally relevant solutions to design problems. And while I am invested in addressing the ecological and climate change imperatives we face — as an architect, I will never surrender my fundamental responsibility to design projects which reflect clients’ needs while simultaneously responding to the urban, territorial, and cultural contexts in which we live.
2. What were some of the challenges to planning/building the “House in Four Fields” project or passive houses in general?
The first challenge for a passive house project is to find the right clients. Because passive houses require more time and more investment than conventional houses, it is essential that the clients and the architect establish common ground at the outset so that they are able to develop a vision for the project and see it through to the final detail. The relationship we have had with the House in Four Fields clients was exemplary in this respect, as we established a strong set of shared values at the outset which guided the project forward and allowed it to develop in unexpected ways.
The second, and in some ways more daunting challenge, is to finding competent builders and sub-contractors who have either the experience or the willingness required to build a passive house project. Though the passive house movement is gaining momentum — with thousands of built examples worldwide to draw lessons from — it is still a very novel approach to design and building in North America, and there are only a handful of professionals and tradespeople who have the experience and/or competence to take on passive house projects.
3. Does it make sense to retrofit a house to become passive?
Unlike LEED — which relies on a point system from which a designer can pick and choose “sustainable” criteria for a given project (in which energy-efficiency criteria are typically the most difficult to obtain and therefore least often pursued points) — the passive house institute has a single standard for new homes and a single standard for retrofits, which you either make or don’t make — based entirely on energy-efficiency.
Whether it makes sense or not (i.e. the viability of a retrofit, or even a new passive house) has everything to do with the clients and the project(s) they have in mind. And while some projects are clearly better suited than others — because of either solar orientation, the project schedule, or a clients’ willingness to invest in high quality windows and doors — the passive house approach is still relatively new in Canada, which means that those wishing to be ahead of the curve will pay more for a passive house than for a conventional house (just as those who purchased a prius, i-pad, or blu-ray player did when those technologies arrived on the market). So while it is true that a passive house will cost you more money up front, energy savings of 90% for new construction and between 75% and 90% for retrofits, represent real and dramatic decreases in energy consumption that will continue to gain traction in the years to come.
4. In 25 years, will every house be passive?
As an architect and urbanist with a tremendous appreciation for the heterogeneity of our built environment, I hope that we never arrive at a point in which all houses are based on universal norms and methods… That being said, I view the passive house approach as being more akin to a national building code than any stylistic or formal typology. In this sense, it is unlikely that the passive house approach would represents a real threat to urban diversity and its’ architectural heritage — but I would nonetheless be very surprised to see an across-the-board change in the built environment given the capacity of developers and contractors to resist change.
I am, however, convinced that we will see a great deal of change in our building and design culture as we move toward the examples of Germany and Austria, where cities and regions now require that many new buildings — including schools, offices, social housing, recreational facilities, and government buildings — be designed and built to passive house standard. So while I doubt that we will see an overnight or across-the-board change in how we build cities in Canada, the move toward passive house and other energy-efficiency standards is inevitable — and will largely be driven by architects, builders, and enlightened clients and developers given the government’s reluctance to take a strong position on climate change and sustainable urbanism.
5. What are you working on now? What’s next?
Along with the hard work we are doing to complete the House in Four Fields (which will be one of the first passive houses built in Québec), we are also scaling up the passive house approach by applying it to larger projects, including a social housing project we are currently designing in Laval. As a research-based practice, we have enjoyed being pioneers of the passive house movement in Québec, and have already developed a set of methods and tools which allow us to monitor and evaluate the performance of new building technologies and their application in Québec’s extreme climate.
In terms of future work, I would say that we are more interested in finding the right clients than the right projects per se. And by right, we don’t necessarily mean those with the biggest budgets or broadest ambitions — but rather, those who represent the potential to become partners in building cleaner, smarter, denser, and more culturally dynamic communities. In other words, we are more interested in collaborating with progressive people than we are in any specific type or scale of project. In our experience, partnering with the right clients, consultants, and other project stakeholders is a better indicator of the architectural outcome than any other single factor. And while there is no doubt that the buildings we design must meet our clients’ needs and stand the test of time — it is the ideas within our buildings that feed our collective imagination and hold the greatest potential to address questions related to ecological and cultural sustainability.
