Built in 1789 as a summer home on the Schuylkill River for renowned lawyer and abolitionist Judge William Lewis, Strawberry Mansion is the largest of seven historic Fairmount Park houses open to the public and one of the most celebrated homes in Philadelphia. Fairmount Park is one of the largest and oldest urban parks in the U.S., established in 1855. Today, Fairmount Park is part of Philadelphia Parks & Recreation Department’s extensive park and recreational system, which consists of 166 parks and 11,073 acres.
Challenge: To identify an energy-efficient HVAC solution that would have an unobtrusive impact on the fabric of a historic house built in the 1800s.
In 1930, the Committee of 1926 (the Committee), an all-volunteer group of civic-minded women, restored the historic mansion and opened it to the public as a museum – a collection of 18th- and 19th-century antiques, textiles, fine art and collectables. Eighty years later, in 2009, in an effort to preserve the Mansion’s legacy and collections, the Committee closed the house for four years of extensive renovation.
Finding a Green Building Solution for a 224-Year-Old Mansion
One of the most pressing needs of the rehabilitation process was a complete replacement of the 1930’s radiators, steam and condensate piping in favor of a new central heating and air-conditioning system.
Beth Kowalchick is the 1926 Committee president. “With 10,000-square-feet on four levels, 23 rooms and masonry-bearing walls, it was a challenge to find an advanced cooling and heating system that would have an unobtrusive impact on the fabric of this historic house,” Kowalchick said. “The museum had never been centrally air-conditioned and it badly needed climate control for our significant antique collections. In addition, the Greenworks Philadelphia Plan, [a six-year plan launched in 2009 with the goal of making Philadelphia the greenest city in America], meant there was a strong desire on the Committee’s part to find an inventive, green building solution to this challenge.”
Mark B. Thompson Associates, Inc., Philadelphia, designed a closed loop geothermal system using water source heat pumps with a 4-pipe system to deliver either hot or chilled water to fan coil units throughout the building. The existing steam boiler, radiators and piping system were also to be restored to provide backup heating.
The Committee awarded the restoration contract to W.S. Cumby, Inc., a general contracting firm in Springfield, Pa. W.S. Cumby asked Carter Mechanical, Paoli, Pa., to bid the 4-pipe system as designed. Carter advised the W.S. Cumby team that the 4-pipe water based system was not practical to install – the 200-year-old stone walls could not accommodate many of the 24 inches wide by 8 inches deep chases required for the 4-pipe design. In many areas there was no space for ductwork or for pipe routes perpendicular to structural elements.
Jeff Harper was Carter’s project engineer. “As soon as we saw the job, it was obvious that it was a perfect application for the 2-pipe Variable Refrigerant Flow [VRF] zoning system from Mitsubishi Electric [US Cooling & Heating Division (Mitsubishi Electric), Suwanee, Ga.].”
2-Pipe VRF System Saves $50,000: Having completed a number of other installations together, Carter and W.S. Cumby were familiar with Mitsubishi Electric’s air source systems. They liked the exceptional efficiency of the VRF zoning design. Since this project already included the geothermal well fields, the Mitsubishi Electric water source VRF zoning system allowed the team to offer the owners an even greater leap in efficiency.
Solution: A water-source VRF zoning system provided a modern heating and cooling solution that preserved the architectural integrity of the mansion.
Not only would this system operate more efficiently with the existing geothermal field, but would also save the owners $50,000 upfront, compared to the 4-pipe proposal. Cumby took these suggestions to the Committee, who agreed after thoroughly researching the Mitsubishi Electric technology and similar installations.
Taking Energy Efficiency to a New Level
Mitsubishi Electric’s VRF zoning system was able to meet the unique needs of Strawberry Mansion. “The 2-pipe system and discrete indoor units could easily fit in the old chase walls and ceiling where there was no space for ducting. The extraordinary flexibility of the refrigerant lines and diversity of indoor units were perfectly adaptable for the restrictions posed by the 224-year-old structure,” Harper said.
“There is no HVAC system and technology better suited to historic preservation and adaptive reuse,” Harper continued. “In addition to the non-invasive piping and wiring, no manufacturer offers such a wide diversity of indoor air handlers and flexibility of refrigerant line configuration. Where there was no space for a ducted indoor unit, Mitsubishi Electric offered us a floor-mounted air handler that we could build into a bookcase or a convenient wall-mounted unit. No one knows it is there because the operation is so quiet. In many cases, we were able to fit the small refrigerant piping inside existing pipe chases where four larger water pipes would not fit.”
The design team placed the two water source heat pumps in the basement. They are specifically engineered for closed water loop systems and efficiently interact with Strawberry Mansion’s existing 12-well geothermal field. Designed to fit in small spaces, these units take up little room and are flexible enough to cool or heat up to 50 individual zones maximizing energy, equipment and installation efficiency.
Switching to the Mitsubishi Electric system also allowed for four water distribution pumps required by the original design to be completely eliminated. This opened up much more space in the basement and eliminated all of the electric usage those pumps would have created, significantly reducing the annual maintenance requirements.
“I Love This System”: A Remarkable Difference
The restoration project was a $1.2 million model of public-private partnership between the Committee and the Philadelphia Department of Parks & Recreation. “I love our new system!” exclaimed Kowalchick. “You have no idea what a remarkable difference it makes. Our collection has suffered from decades of no air conditioning or humidity control. After a few months, I could see a noticeable difference in the appearance of our textiles, prints, antique furniture, fine art, and especially in our invaluable collection of 18th-century wax dolls.”
Emily Afflitto is Strawberry Mansion’s site manager, responsible for daily operations of the building. “This system is perfect,” she said. Afflitto was impressed with the advanced features of the system, including the central controller that allowed her to monitor and control the temperature in any room in the museum from her desk. “In addition to the vital preservation of our collection, I am most impressed with the fact that a property this old can be turned into a model of 21st century sustainability and ecological responsibility. This advanced engineering is not lost on our visitors. For the first time, we are taking our guests to the basement to witness the efficiency of a geothermal field and our water source heat pumps.”