Three U.S. Projects Are Passivhaus Award Finalists
Germany's Passivhaus Institut selects a townhouse project in Philadelphia and a brownstone in Brooklyn as the only U.S. residential finalists for the 2014 design awards
Two residential projects in the United States have been named finalists in an international design competition sponsored by the Passivhaus Institut: a three-unit townhouse in North Philadelphia and a renovated brownstone in Brooklyn, N.Y.
In making the announcement, the Passivhaus Institut said a total of 92 eligible projects were submitted, half from Germany and half from 20 other countries. The winners will be announced on April 25 at the 2014 International Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. Conference in Aachen, Germany.
Details about each of the three projects are available at the Passivhaus Institut's website. They've also been published in an easier-to-understand format in The Greenest Home: Superinsulated and Passive House Design, a book by Julie Torres Moskovitz. She is the prinicipal of Fabrica718, which designed the Brooklyn project.
North Philadelphia townhouses
The three-unit townhouse project, called Belfield Homes, was completed in 2012, the first certified Passivhaus houses in the city. Plumbob, the architectural arm of the design-buildCompany that handles house design and construction. Since both services are provided by the same firm, integrated design can often be more easily achieved. firm Onion Flats, designed the project as a model for low-income urban infill housing. (For more information on Onion Flats, see Passivhaus Townhouses Are Underway in Philadelphia.)
Onion Flats later worked on a 27-unit townhouse project elsewhere in the city called The Stables.
The Belfield townhouses were assembled from modules constructed offsite and are equipped with 5-kW rooftop photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow. arrays for net-zero energyProducing as much energy on an annual basis as one consumes on site, usually with renewable energy sources such as photovoltaics or small-scale wind turbines. operation (or "net-zero capable," as the firm says). The townhouses are insulated with a mix of dense-packed cellulose and foil-faced polyisoPolyisocyanurate foam is usually sold with aluminum foil facings. With an R-value of 6 to 6.5 per inch, it is the best insulator and most expensive of the three types of rigid foam. Foil-faced polyisocyanurate is almost impermeable to water vapor; a 1-in.-thick foil-faced board has a permeance of 0.05 perm. While polyisocyanurate was formerly manufactured using HCFCs as blowing agents, U.S. manufacturers have now switched to pentane. Pentane does not damage the earth’s ozone layer, although it may contribute to smog. insulation and are heated and cooled with a heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump..
According to Ted Singer of Plumbob, the townhouses are equipped with monitors that measure energy produced and energy used, among other things. One of the units is close to net-zero operation, he said, while the others are not operating as efficiently, due mainly to occupant behavior. The homes are owned by a non-profit and rented to families who do not pay their own utility bills, Singer said via e-mail, adding, "The lesson here is that occupants need to be financially responsible for their energy use in order to provide the necessary incentive for them to be energy [conscientious]."
An 1899 brownstone makes the list
The other residence to be named a finalist is Tighthouse, a renovated brownstone originally constructed in 1899 and rebuilt in 2012. It was the first certified Passivhaus house in New York City.
The building is insulated with a mix of medium-density spray foam, EPSExpanded polystyrene. Type of rigid foam insulation that, unlike extruded polystyrene (XPS), does not contain ozone-depleting HCFCs. EPS frequently has a high recycled content. Its vapor permeability is higher and its R-value lower than XPS insulation. EPS insulation is classified by type: Type I is lowest in density and strength and Type X is highest. and foil-faced polyiso. It uses Shüco windows, a Zehnder energy-recovery ventilator(ERV). The part of a balanced ventilation system that captures water vapor and heat from one airstream to condition another. In cold climates, water vapor captured from the outgoing airstream by ERVs can humidify incoming air. In hot-humid climates, ERVs can help maintain (but not reduce) the interior relative humidity as outside air is conditioned by the ERV., and a Mitsubishi air-source heat pumpHeat pump that relies on outside air as the heat source and heat sink; not as effective in cold climates as ground-source heat pumps..
The house has a 2.5-kW solar array and a rainwater collection system. Domestic hot water is provided by rooftop solar collectors plus electric tank backup.
The rear facade of the brownstone is new, as is a third-floor addition with an angled roof for solar thermal and PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow. panels, Fabrica 718 said. All lighting is LED or fluorescent. Air-tightness was measured at 0.38 air changers per hour at 50 pascals.
- Onion Flats
- Sam Oberter
- Hai Zhang
- Ty Cole Photography