Passive.
This word means many things to many people in a myriad of contexts. In the context of real estate and architecture, it has the ability to easily confuse. However, it is important for us to clear the air because passive building is about to be the trend everyone is talking about. There are currently only a handful of properties in Philadelphia that represent this foreign and rare form of design. The newest plan for Pemberton Street in Philadelphia was just approved by the Bella Vista Zoning Committee last night. Live Love Philly talked about passive construction with Laura Blau of BluPath Design and GreenSteps Consulting who is handling the Pemberton project.
Above: Original plan for Pemberton that has been modified.
For nearly a decade, Laura Blau and Paul Thompson have worked together at BluPath Design to design simple, elegant and environmentally sensitive spaces. After meeting their clients for Pemberton Street through the Meredith School Silent Auction, they started working towards designing this new residential property to passive construction speciifications. What does that mean? The following is information Ms. Blau provided Live Love Philly.
PASSIVE HOUSE CONCEPTS
Passive House buildings, residential or commercial, meet a rigorous energy standard developed in Europe. They are extremely energy-efficient and comfortable, with excellent indoor air quality. They are also better built and more durable, with lower utility costs than most buildings. The Passive House concept slashes heating consumption of buildings by up to 90%. There are over 40,000 Passive Houses worldwide as of 2012. Passive House buildings use the following strategies:
SUPERINSULATED WALLS: In a Passive House, the entire envelope of the building- walls, roof and floor or basement- is super-insulated, depending on the climate and project size. Insulation varies from 6” for California to 16” for Minnesota.
NO THERMAL BRIDGES: Heat flows out of a building on the path of least resistance, through a building element that conducts heat efficiently- a ‘thermal’ bridge. PH construction minimizes or eliminates thermal bridges.
AIRTIGHT CONSTRUCTION: Airtight construction reduces or eliminates drafts and heat loss through exfiltration and infiltration, reducing the need for space conditioning. The airtightness of a building is measured with a ‘blower door’ test. PH construction is very ‘tight’, and is confirmed by multiple blower-door tests during and after construction.
ENERGY RECOVERY VENTILATION: A house and its occupants need to breathe. The ventilator provides a constant supply of fresh air while conserving most of the energy already used to condition the building by using a balanced air-to-air energy recovery system. PH buildings have excellent indoor air quality, whether you open the windows or not.
HIGH-PERFORMANCE WINDOWS AND DOORS: Passive House windows and doors are chosen based on the transmission values of both frame and glazing. PH windows, usually triple pane, are 5+times more efficient than typical windows. Typical windows have a thermal resistance value equivalent to R2, EnergyStar windows may be as much as R3.5 whereas PH windows are R5 to R13 and perform more like a standard building wall. No more drafty windows or leaky doors!
PASSIVE SOLAR DESIGN AND INTERNAL HEAT GAINS: Passive House designs utilize well-known and proven passive solar design principles- building orientation, window size, type and location, sunshading- to manage energy gains and losses. Because of the exceptionally low levels of heat loss from the building envelope, heat generated by appliances, electronic equipment, lighting and people are a significantly source of heat in a Passive House building.
PASSIVE HOUSE PLANNING PACKAGE: Passive House Planning Package (PHPP) is a proprietary energy-modeling tool that helps the designer integrate each of the building elements so the final design will meet the Passive House standard. It has a proven accurate track record.
PASSIVE HOUSE STANDARDS
Passive House standards are met when:
- Space heating and cooling requirements are less than or equal to 4.75kBtu/ft 2 /yr for new construction and 8.0kBtu/ft2/yr for retrofit. [US commercial building average is 33.00kBtu/ft2/yr, from US EIA 2003 Commercial Buildings Survey]
- Total primary energy use of the design is less than or equal to 38.1kBtu/ft 2 /yr (120kWh/m2a)
- Airtightness of the building is verified to be at or below 0.6ACH @50Pa, 1.0ACH@50Pa for retrofit.
(ACH = air changes per hour, Pa = Pascals, unit of pressure).
So why passive? A passive building achieves overall energy savings of 60-70% and 90% of space heating without applying expensive actives technologies. Energy losses are minimized, and gains are maximized. The heat/energy recovery ventilator helps keep energy that has already been generated in the house instead of venting it out. Pemberton Street in Bella Vista is trail blazing the way for more properties to be built that exhibit this extraordinary energy efficiency. Passive is in.
For more information, feel free to contact Laura and Paul of BluPath at 267.519.3564 or at info@blupath.us.
South Philadelphia News and Updates – 1.7.13
