Practicing ArchitecturePracticing Architecture
A Suburban Philadelphia Fossil Fuel-Guzzler Slims Down into an Energy-Neutral Performance Machine
John Hubert Architects fills the Kahn House with natural light, ventilation, and sustainable materials, and in turn, the house starts re-filling the client’s wallet
By John Hubert, AIA
This renovation and additions project to a 1960s-era residence paired high performance building design with sustainable construction practices in an attempt to meet Energy Star and/or LEED for Homes guidelines for residential renovation projects.
By improving the thermal and moisture barriers of the structure, incorporating photovoltaic and geothermal systems, and designing the renovations around a passive solar collector, this project was able to achieve energy neutrality and LEED Platinum certification while greatly improving the livability of the interior and exterior spaces.
The client purchased the property specifically because of its south facing orientation, the inherent thermal benefits of a partially submerged basement and garage, and its proximity to public transportation. The existing structure relied heavily on fossil fuels for heating, cooling, and cooking, used a tremendous amount of water, and had annual utility/fuel costs in excess of $4,000.
As such, the initial objective was to overcome as many of these environmental deficiencies as possible using cost effective measures, which also supported the big picture vision of the renovation. To meet this requirement, the exterior walls and roof were reinsulated to the greatest extent possible, most of the windows and exterior doors were replaced with Energy Star products, and attic and crawl spaces were properly ventilated. Exterior penetrations were also caulked, and a polyethylene membrane was installed on the unfinished crawl space floor.
A site-specific passive solar collector was designed to maximize the daylight harvesting potential during the least productive day of the year (the winter solstice), while supporting the reorganization and consolidation of interior spaces and a centralized living space to circulate around and through. The unique ability of the collector to harvest daylight throughout the year while limiting the heat gain during the summer is achieved through the application of a nano-ceramic film applied to the interior surface of the glass. The addition of the film eliminates all ultraviolet rays, reduces 40 percent of infrared heat gain, reduces sun glare, and reduces heat loss by an additional 40 percent, while simultaneously decreasing the energy load on the photovoltaic and geothermal systems.
The western (master bedroom) end of the residence was redesigned to further reduce heat gain and solar glare during the afternoon. Solar tubes and skylights were installed on the north side of the roof to bring natural daylight into several otherwise dark spaces, including two second floor sleeping areas, a master bedroom closet, the entry foyer and main stair, the dining room, and kitchen.
The energy system includes a 7.92 kWh photovoltaic collection system, a Sunny Portal Web data collection system, two 225-foot geothermal wells, a three-ton geothermal ground source heat pump, Intellizone four-zone interactive system controller and an energy recovery system to harvest latent heat and provide fresh air for the circulation system. In addition, Energy Star equipment and appliances, LED/CFL lamping, dual flush toilets, and ultra low flow showerheads and faucets are also used throughout.
To meet LEED Platinum certification and further reduce the environmental impact on the site, an existing pool and apron, as well as approximately 10 percent of the existing impervious ground coverage were removed. Ninety-five percent of all grasses were removed and replaced with drought tolerant plants and ground cover. Roof gutters, down spouts, and site drainage were redesigned to redistribute storm water more evenly throughout the property.
In combination, the passive solar collector, the photovoltaic and geothermal systems, the improved thermal envelope, and the incorporation of water conservation strategies produces a high performance structure which significantly decreases its reliance on non-renewable energy sources and wasteful water consumption, while creating a more integrated relationship between the building and landscape. After 12 months of operation, the system is producing more electricity than required, and the projected rate of return on the investment (including rebates, tax credits, and depreciation) is projected to exceed the client’s original target.
LOCATION: Wyncote, Pa.
CLIENT: Dr. Sidney Kahn
ARCHITECTURE: John Hubert
BUILDER: John Hubert Associates
ENERGY CONSULTANT: Energy