Vol. LXIV, No. 2
Wednesday, January 13, 2010
Princeton University students in a civil and environmental engineering class featuring design for sustainable development focused on the property at 190 Witherspoon street, making recommendations for energy-efficient designs that would also conserve resources. They presented their findings on Monday to a packed Community Room at the Public Library at an event scheduled as part of the Environmental Film Festival.
Students and long-term residents, as well as local environmentalists and the curious were all in attendance. Alex Gasner, a senior majoring in mechanical engineering explained that climate and energy usage are, along with sustainability, the primary concerns in designing for a carbon-constrained world.
Taught by Visiting Professor Bob Harris, the class analyzed the 190 Witherspoon property, which is comprised of a 6,000 square foot warehouse in the back, with two front buildings on either side that have retail spaces below, with housing on the second floor. Mr. Gasner noted that the four design exercises involved a whole building energy analysis, a look at geothermal heating and cooling for the site, the possibility of rainwater harvesting, and indoor air quality.
Fourth-year undergraduate Catherine Cleary noted that the energy analysis was performed with the assistance of software called Green Building Studio. Form and construction, internal systems, and on-site renewable energy sources were all examined.
Ms. Cleary asked those present to consider whether minimal results in terms of energy efficiency would be worth a significant extra cost with respect to insulating materials.
Bob Hillier (a Town Topics shareholder), the developer and owner of 190 Witherspoon Street, plans to install clerestory skylights on the roof that will let in natural light and allow for decreased usage of the lighting system inside, Ms. Cleary said.
Installing photovoltaic cells on the roof proposed by the current plan would result in a reduction of 12 percent of the electricity demand and cost $34,000 to install, Ms. Cleary noted, estimating a payback period of seven years. Solar panels on the entire roof would mean a 200 percent reduction in lighting use, making the building not just carbon neutral, but carbon negative, she said.
Another senior in Environmental Design, George Lederman explained the process by which the class assessed the possibility of installing a geothermal heating and cooling system that would utilize ground temperature or groundwater to assist in controlling temperature.
A closed-loop groundwater system would involve an initial capital expenditure of $82,000, and a yearly cost of $3,500, whereas an open loop system would total $25,000, and $3,100. By contrast, the regular yearly heating, ventilation, and air condition (HVAC) was calculated at $4,111. Currently there are concerns about space constraints and installing wells at the site, so more analysis would be needed, Mr. Lederman said.
Mr. Gasner emphasized that water management strategies are important in green design, particularly because New Jersey and 35 other states face freshwater shortages by 2013 on a local basis.
Storm water runoff from impervious surfaces, like paved roads, contributes to erosion, municipal wastewater overflow, and generally degrades water quality, Mr. Gasner noted.
University student Jon Bradshaw noted that the proposed green roof at 190 Witherspoon would absorb storm water, thereby reducing runoff, and that there might be tradeoffs between rainwater harvesting for use in non-potable water sources within the building. He did recommend installing low-flow and high-efficiency water fixtures that could reduce water usage by 30 percent.
The student analysis of Consumer Product Safety Commission tests revealed that formaldehyde is found in certain batches of drywall manufactured today. Mr. Harris called the findings an unfortunate eye-opener, since the exposures theyre finding exceed both the acute and chronic safety levels.
Christina Nolfo, a graduate student in Civil and Environmental Engineering spoke about indoor air quality as it is affected by building materials, and suggested using only tested and certified drywall. Though there are known contaminants of indoor air present in certain building materials, no federal standards currently exist.
Mr. Hillier, who was present at the talk, commended the students and noted that many of their recommendations have been or are being incorporated into the designs of 190 Witherspoon.
Mentioning the controversial housing he proposed for Bunn Drive, Mr. Hillier said that the 140 units of senior housing on the 20-acre site, with the inclusion of various sustainable elements like a green roof, cisterns, and gray water, have completely eliminated the need for a retention basin. Such a basin, which was in previous plans for the site, would have caused the destruction of three acres of woodlands, he said.
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