Can this be? Two of my favourite concepts in one building? In an urban setting like Brooklyn, yet. Cohousing is based on the idea of "intentional neighbourhoods" where people consciously commit to living as a community. Or as Meaghan wrote in our first post on the subject: "In some ways, they hark back to the ideas of a kibbutz, a co-op, or commune, but in a more modern, Euro-style, not-so-hippy way."
The basic principle of passivhaus design is simple: Minimize your losses (with a lot of insulation and sealing) and maximize your passive gains (with solar orientation.) In a renovation like the Brooklyn cohousing, it is like building a building inside a building. The American Passive House Institute writes:
A Passive House is a very well-insulated, virtually air-tight building that is primarily heated by passive solar gain and by internal gains from people, electrical equipment, etc. Energy losses are minimized. Any remaining heat demand is provided by an extremely small source. Avoidance of heat gain through shading and window orientation also helps to limit any cooling load, which is similarly minimized. An energy recovery ventilator provides a constant, balanced fresh air supply. The result is an impressive system that not only saves up to 90% of space heating costs, but also provides a uniquely terrific indoor air quality.
Because building to standards that outperform walk-in coolers is expensive, units tend to be smallish and squarish. Put a family into a space that tightly sealed, and it can get smelly and humid really quickly, so unlike in most of the US where the weatherizers will seal and insulate but not worry too much about air quality, in a Passivehaus they worry a lot. So it has continuous exhaust from the bathroom and kitchen, piped to a central enthalpy heat exchanger that recovers the moisture as well as the heat (and saves all the energy that is lost in the change of state of the water). What little bit of heat is still needed is provided by a ground source heat pump.
Tom Lane, "Solar Hot Water Systems: Lessons Learned 1977-Today."
Domestic hot water is provided by a solar thermal system on the roof. The cost of upgrading to Passivhaus standards is estimated to be $ 350,000, which is pretty cheap considering that it will save an estimated $ 66,700 per year, a payback of 5.25 years.
There is so much to love about this project; Cohousing is a great alternative way of living, especially as people age and can use a little support from their community. As they say in their introduction:
Our vision is to create an oasis of community amid the swirling intensity of New York City, and an antidote to the isolation and impersonality of contemporary life.
Passivhaus is a better way to build, as concerned about air quality and health as it is about energy savings. As they say at Passive House US:
How do we best square our building energy needs with those of our environment and of our pocketbook? In the realm of super energy efficiency, the Passive House presents an intriguing option for new and retrofit construction; in residential, commercial, and institutional projects.
Over at Brooklyn Cohousing (Copassivhausing?) they are working on the plans and there is not a lot to see yet, but this is one to watch. Brooklyn Cohousing
More on cohousing:
Cohousing for Gen X and Y
Start Your Own Cul-de-Sac Commune
Solar Row: Sustainable Housing In Boulder
More on Passivhaus:
A Passiv Haus in Urbana, Illinois
Passivhaus in the New York Times
It's Not a Passivhaus, It's a Plusenergihus
Aktivhaus Generates More Heat and Power Than It Needs
Passive Houses Get Good Graphic Explanation