Passive House Extraordinaire
Paul Kando
In 2007, Paris became one of the first municipalities to adopt a climate action plan, setting goals for greenhouse gas emission reductions beyond those recommended by the European Union. The eco-district Clichy-Batignolles is a former rail yard being turned into an urban park surrounded by energy-efficient buildings to house 7,500 residents and provide places of employment for more than 12,000 people. The development is a laboratory for testing what’s possible in climate-sensitive development and evidence of the city’s commitment to minimizing its carbon footprint. The project, now 30% complete, is slated to be completed in 2020.
photo credit: PBA-Vectuel-Studiosezz
Architects, urban designers, government officials and environmental engineers worked together for years to plan this project. The mandate to meet ambitious goals and incorporate as many best practices in contemporary green design as possible challenged them to experiment with technologies in new ways.
To keep building footprints small and maximize indoor space, Paris waived its longstanding height limit of 120 feet to allow 10 buildings to rise to 160 feet tall. And the new Palace of Justice will top 520 feet.
Overseen by a city-owned public company, developers must follow strict guidelines for building energy consumption. For heating, annual energy use cannot exceed 15 kWh per square meter (about 1.4 kWh per square foot) of floor space, the aggressive limit set by the Passivhaus Building Standard. Maximum insulation and airtight construction are combined with high-performance windows oriented toward the sun to capitalize on natural heat and light. High-density materials store and release excess heat to aid heating and cooling. In fact, apartment dwellers report their heat coming on but a few times all winter.
Several buildings have green roofs that offer not only insulation but also garden space and habitat for wildlife. The walls of the elementary school building are covered with plants that both insulate and add biodiversity.
Much of the district’s heat and electricity comes from renewable sources. A neighborhood-scale geothermal heating system taps into the water table beneath the park, drastically reducing heating energy needs. To heat incoming tapwater, some buildings recycle heat from graywater drained from sinks, tubs and washing machines, saving 58% of the energy typically required for water heating. Wherever possible, solar panels have been installed on roofs and façades. More than 380,000 square feet of panels will generate 3,500 MWh per year, roughly 40% of the electricity used in the development.
To cut carbon emissions further, the district’s layout encourages walking and the use of mass transit. Space for cars is kept limited. Roadways are restricted to 12% of the total surface area. Low speed limits help privilege walkers over cars. To help maintain air quality, a fleet of electric vehicles performs all deliveries from a central drop-off site a kilometer (0.6 mile) away.
In addition to retail and office space, the district has four schools, medical services, daycare facilities, gyms, and an activity center for teens with performing arts spaces and a practice kitchen. A multiscreen movie theater and community gathering place will open soon.
Residential units are priced for buyers with a range of incomes. Different-sized apartments, some rent-capped, meet the needs of families, couples and those living alone. Some buildings are designated for students, another houses a nursing home.
Innovative measures minimize the eco-district’s climate impact. These include pneumatic tubes beneath the development that collect trash and recycling, reducing traffic and cutting greenhouse gases associated with waste disposal by an estimated 42%. Recyclables are sorted, then shipped using an adjacent rail line. Nonrecyclable waste goes to an incinerator that burns trash to produce heat and electricity.
The buildings encircle the 25-acre Martin Luther King Park, a key element of the development’s climate adaptation strategy. Its trees, plants and water features help lower the air temperature on hot summer days. Permeable surfaces let water soak into the ground. An underground tank collects rainwater for irrigation to minimize water use. A pond provides habitat for waterfowl and other wildlife, and also cools the surrounding area by evaporation. To ensure biodiversity nearly 500 plant species have been planted in the park.
An additional 70,000 square feet of private green space and 170,000 square feet of green roofs offer further opportunities for outdoor living, wildlife habitat, cooling and rainwater collection. Residents can grow their own food and compost food waste in two community gardens.
A €4.3 million European Union grant finances smart-grid technology development for end users to monitor and manage energy to help their buildings realize their CO2 reduction potential. Clichy-Batignolles is an urban project, but it is also a veritable tool catalogue for anyone interested in carbon-neutral community design.