Page E1.2 . 08 June 2011                     
ArchitectureWeek - Environment Department
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  • AIA Top Green Buildings 2011

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    Center for Neighborhood Technology



    The building uses 50 percent less energy per square foot than a new building constructed to standard codes thanks to a combination of holistic strategies, including a below-grade thermal ice-storage system that efficiently cools the building using off-peak energy.

    The thermal ice-storage system uses a storage tank filled with four-inch- (ten-centimeter-) diameter spheres made from a high-performance polyethylene. Filled with water, the spheres are either cooled to form ice or thawed by a glycol-based solution. During off-peak hours, typically at night, the glycol solution is pumped from a chiller that has lowered the liquid's temperature enough to turn the water in the spheres to ice and circulated through the spheres.

    Since the chiller runs at times when systemwide demand for energy is low, the Center avoids high electrical rates and does not add to systemwide demand spikes, which often lead utilities to build additional generating capacity solely to address those peaks. When the building is occupied during the day, the chiller can be shut off and the "ice balls" alone provide air conditioning and process cooling.

    A roof-mounted photovoltaic system supplies the building with over five percent of its energy needs; 50 percent of the remainder is offset by purchase of renewable energy certificates that fund new wind-energy projects. Energy use is reduced by new insulation in the walls and roof, efficient equipment and, most important of all, the constant monitoring of interior and exterior conditions for temperature, sunlight, carbon-dioxide levels, humidity, and time of day to adjust heating and cooling automatically. Large skylights and operable windows, adjustable lights, and indoor plants all contribute to indoor environmental quality and reduce dependence on artificial lighting and mechanical ventilation.

    Client Perspective

    Since 1978, the Center for Neighborhood Technology (CNT) has worked to show urban communities locally and all across the country how to develop more sustainably. By combining thoughtful data analysis with creativity and innovation, well before the term sustainable development was even widely used, CNT has been demonstrating its unique brand of sustainable development: development that is good for the economy and the environment; makes better use of existing resources and community assets; and improves the health of natural systems and the wealth of people — today and in the future... Our... building demonstrates how we work — from innovation to implementation — within a framework that values places. CNT web site (January 2009)

    Old is Bad, New is Good? Misperceptions

    It is widely assumed that the older a building is, the more energy will be required to use it comfortably. The data about commercial buildings say otherwise.

    Because they incorporate design for passive survivability, many older buildings use less energy than more-recent buildings. In Canada, commercial buildings built before 1920 have a lower energy use per square meter than any period until 2000-2004. The worst performance groups were built in 1960-1969 and 1980-1989.1 The U.S. Energy Information Administration confirms a similar pattern in the United States.

    It is possible that the oldest buildings use the least energy because they have not been modernized — although this runs contrary to the belief that old buildings are energy hogs unless "leaky" windows are replaced. Studies by government agencies comparing modern applications and expectations of comfort within large and diverse real estate portfolios verify that the oldest buildings use the least energy per unit of physical area and, in some cases, by function.

    A 1999 report by the U.S. General Services Administration found that the historic buildings in its portfolio (although it did not separate them by age) used seven percent less energy than nonhistoric buildings; 98 percent of them matched or used less energy than the industry standard, while only 86 percent of nonhistoric buildings met industry standards.2

    A 2007 UK Ministry of Justice study on energy usage in 256 court buildings in the United Kingdom found that the oldest buildings (pre-1900s) have the lowest energy use per square meter, and only the buildings of the 1990s and 2000s matched their performance in energy efficiency per building area. However, the modern buildings use significantly more energy per courtroom (68 percent) to "provide the identical function of justice" because the new courts are so much larger than the old.3

    Discuss this article in the Architecture Forum...

    Jean Carroon, FAIA, LEED AP, leads the highly regarded preservation practice at Goody Clancy in Boston, Massachusetts. She has earned national recognition for her expertise in applying sustainable design technology to historic buildings, including more than a dozen National Historic Landmarks. She has directed the adaptive reuse and preservation of signature buildings in a broad range of sectors, including educational, civic, and cultural projects, for clients such as Harvard University and the National Park Service. Carroon has been overseeing renovation of more than 50 historic structures on the St. Elizabeths Hospital west campus in Washington, D.C., to house the Department of Homeland Security. A member of the National Trust for Historic Preservation Sustainability Coalition and the Advisory Group of the AIA Historic Resources Committee, she helped draft the Pocantico Proclamation on Sustainability and Historic Preservation.

    This article is excerpted from Sustainable Preservation: Greening Existing Buildings by Jean Carroon, copyright © 2010, with permission of the publisher, John Wiley & Sons.


    1. National Round Table on the Environment and the Economy, and Sustainable Development Technology Canada. Geared for Change: Energy Efficiency in Canada's Commercial Building Sector, Figure 7. 2009.
    2. Bradley Wolf, Donald Horn, and Constance Ramirez. "Financing Historic Federal Buildings: An Analysis of Current Practice." U.S. General Services Administration, May 1999.
    3. Jon Wallsgrove. "Age Energy Research: A Study of the Energy Usage of Buildings Relative to Their Age." HMCS Estates Ministry of Justice, May 2007.

    Project Credits

    Project: Center for Neighborhood Technology renovation, 2003 (Chicago, Illinois)
    Architect: Jonathan Boyer (now of Farr Associates)
    HVAC Engineer: EME Consulting Engineers
    General Contractor: Phoenix Builders
    LEED Consulting and Commissioning: J.T. Katrakis & Associates


    ArchWeek Image

    A side yard adjacent to the Center for Neighborhood Technology (CNT) offices serves as a small sliver park, while also providing shade for the building and permeable surfaces for stormwater filtration.
    Photo: © Center for Neighborhood Technology Extra Large Image

    ArchWeek Image

    The CNT building cooling system uses water-filled plastic balls as a heat sink. Here, a storage tank for the system is being buried next to the building during renovation.
    Photo: © Center for Neighborhood Technology Extra Large Image

    ArchWeek Image

    The water-filled balls are frozen at night, when systemwide energy demand is low. They are then used to cool a food-grade-glycol-based solution, which is circulated through pipes to cool the building on hot days.
    Photo: © Center for Neighborhood Technology Extra Large Image

    ArchWeek Image

    Axonometric drawing of the CNT building showing the interior layout.
    Image: © Center for Neighborhood Technology Extra Large Image

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    A list of some of the sustainable design elements of CNT's 2003 renovation.
    Image: John Wiley & Sons Extra Large Image

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    Site regeneration at the CNT building created a compact oasis connecting with the neighborhood.
    Photo: © Center for Neighborhood Technology Extra Large Image

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    Axonometric drawing of the Center for Neighborhood Technology building. The light-colored roof reduces heat absorption and keeps the interior air temperature lower. A roof-mounted photovoltaic system meets about five percent of the building's energy needs.
    Image: © Center for Neighborhood Technology Extra Large Image

    ArchWeek Image

    Sustainable Preservation: Greening Existing Buildings by Jean Carroon.
    Image: John Wiley & Sons Extra Large Image


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