||City of Chicago, Department of Environment
||Mechanical - IBC Engineering
Electrical - Spectrum Engineering
||Commercial office, Industrial, Assembly
||$5,400,000 (excluding land cost)
||Typically occupied by 35 people, 50 hours per person per week; and 100 visitors per week, 2 hours per visit
||City of Chicago Building Codes
Mixed Mode System
|Mixed Mode Strategy
||Concurrent system. As a 1950s office building,
the structure had been designed for natural cross ventilation as well as
daylighting using narrow wings extending out from a common circulation
core. The renovation took advantage of this existing condition to retain
operable windows while adding a mechanical cooling system. The primary
strategy relies on cross ventilation rather than stack effect or other
techniques to maintain natural ventilation.
|Natural Ventilation Details
||Operable windows are awning type, crank
operated set below fixed vision glazing. Insulated, spectrally selective,
low-e glazing was installed throughout the facility.
|HVAC System Details
||A ground-source heat pump system provides
all space cooling and most of the space heating. System includes 28 vertical
wells drilled to a depth of 200 feet. Although a cooling tower was incorporated
to assist during the cooling season, it did not operate at all during the
first summer, all cooling came from the wells. At the beginning of the
cooling season, glycol from the earth entered the heat pumps at a cool
55∞F allowing them to run at very high cooling efficiencies. By the
end of the summer, this glycol was still below the 90∞F threshold
that would have required cooling tower operation. During the winter months,
heat from the heat pumps is subsidized by heat from a natural gas-fired,
high-efficiency, condensing hot water boiler.
A run-around heat recovery loop, tied to the heat pump system, recovers
heat/cool energy from exhaust air and uses that energy to preheat/cool
incoming ventilation air. Extensive daylighting displaces the need for
some artificial lighting. A 25% savings in lighting energy is expected
over standard systems. At times of high-electric demand (such as hot summer
days), the building management system is programmed to prevent demand spikes.
It reads the load required and temporarily offsets mechanical startups
to save demand costs.
The building is divided into seven (7) zones. One (1) zone is a large assembly
area and each of the other six (6) zones is an office area. Operable windows
were not a factor in selecting the zones. Zones were selected based on
activities and exposures (North, South, East, West).
Duct distribution design was determined by air volume requirements, displacement
ventilation requirements (many diffusers are located under desks), and
space restrictions (this was a retrofit of an existing shell). Operable
windows were not a factor since the system has to provide complete heating
and cooling when the windows are closed. Peak heating and cooling demand
tends to occur during extreme weather when windows should be closed. Windows
are used for providing additional ventilation during days where the outside
air conditions are comfortable; therefore, they don't really affect system
sizing. Windows may actually increase peak heating and cooling demand because
of leakage around the seals. For this building the effect was probably
The building surpasses the American Society of Heating, Refrigerating,
and Air-Conditioning Engineers (ASHRAE) Standard 90.13 by 405, which means
that the Center uses 40% less energy than a minimally code-compliant building
of the same size, saving an estimated $29,000 each year.
|Configuration & Control
||The building has a complete building automation
system which takes information from building thermostats, the ground loop
temperature, and the peak electric demand to optimize the running of the
heat pumps. The building operator has complete control of the HVAC from
a PC station located in his office. There is no active or passive connection
between the windows and the mechanical system. Occupants are free to open/close
windows at their own discretion.
|Building Design Process
||The U.S. Green Building Council's LEED
Rating System was used in setting goals for the project before the design
commenced. The LEED Platinum rating was identified as the final objective
by Owner and influenced all choices of major components including mechanical,
electrical, and ventilation options.
||DOE-2 software was used for energy analysis.
Energy modeling expects the building to surpasses ASHRAE 90.1 by 60%, an
energy savings of approximately $21,000 per year. These savings are generated
through a combination of the heat pumps, solar shading, controls, daylighting,
and building envelope.
||Commissioning was provided by IBC Engineering,
the mechanical engineers for the project. The mixed-mode strategy was identified
in the first design intent and remained constant through the project. The
minor changes in the execution of the ventilation system that took place
during construction and commissioning were necessitated by code requirements
||When air conditioning is provided in commercial
buildings, the City of Chicago code requirements do not allow for natural
ventilation to be included in total ventilation requirements. Mechanical
ventilation systems are therefore designed as if no natural ventilation
existed. During construction the City code inspectors required additional
through-the-wall powered vents be provided in those spaces identified for
light manufacturing. While not necessary for the natural ventilation design,
they in effect provide for an additional economizer cycle when windows
are opened and the wall vents are activated.
||The site is adjacent to a commuter rail
route, but due to the density of the rail system in Chicago this is not
an uncommon occurrence and users are relatively habituated to the noise.
See post-occupancy evaluation results below.
||The University of California Berkeley Center
for the Built Environment performed a web-based occupant Indoor environmental
quality (IEQ) survey at the Chicago Center for Green Technology. The survey
addressed general building satisfaction, general workspace satisfaction,
office layout, office furnishings, thermal comfort, air quality, lighting,
acoustic quality and cleanliness and maintenance.
Occupants reported being satisfied or very satisfied with all categories
but with more neutral comments in thermal comfort and acoustic quality.
Thermally responses showed that occupants often find the building too cool
in both warm and cool seasons particularly in the afternoon. This dissatisfaction
was attributed to a lack of accessibility and control of thermostats. In
acoustic quality the responses showed that the open plan cubicle workspaces
were not providing enough privacy for occupants.
|Actual Energy Data
|Additional Building Features
||• Located within 1/2 mile of a Metro
Rail station and within 1/4 mile of two bus lines.
• Majority of the material accumulated on the site was recycled or
salvaged for reuse.
• Bike storage, showers, and changing facilities for
• Recharging stations for electric vehicles
• Preferred parking for carpools.
• The brownfield site, which had been turned into a dumping ground
for construction and demolition materials, was cleaned by the city at a
cost of nine million
||• Four water-storage cisterns catch
rainwater used for irrigation, reduce flow into sewers, and have a combined
capacity of 12,000-gallon.
• Native plants minimize maintenance and water needs
• Green roof on a portion of the project also reduces stormwater runoff.
|Energy and Atmosphere
||• Extensive daylighting displaces
the need for some artificial lighting
• Expected 24% savings in lighting energy over standard systems.
• Insulated, spectrally selective, low-e glazing.
• Heat and air conditioning registers are located near occupants with
low velocity output.
|Materials and Resources
||• No CFCs are used in any building
materials or systems.
• No HCFCs are used in any building materials.
• Recycling center encourages occupant participation.
• 100% of the original building's structural shell was retained in
• 84% of all construction waste was diverted from the landfill.
• 36% of all building materials have recycled content, including:
drywall, cellulose insulation, linoleum, ceiling tiles, rubber flooring,
fill materials, steel, tile, MDF board, and fireproofing.
• Over 50% of the building materials (excluding mechanical and plumbing
systems) were manufactured or assembled within 300 miles of the construction
• The elevator runs on canola oil.
|Indoor Environmental Quality
||• A construction indoor air quality
management plan was designed and implemented by the contractor .
• Low-VOC materials.
||Farr Associates, Architecture and Urban Design
53 West Jackson Blvd., Suite 650
Chicago, IL 60604
|Mechanical, Electrical and Fire Protection Engineer
217 Wisconsin Avenue, Suite 300
Waukesha, Wisconsin 53186
633 Skokie Boulevard, Suite 305
Northbrook, IL 60062
505 N. LaSalle, Suite 250
Chicago, IL 60610
||Tylk, Gustafson, Reckers, Wilson, Andrews
407 S. Dearborn, Suite 900
Chicago, Il 60605
||Site Design Group
8 South Michigan, Suite 1007
Chicago, IL 60603
||Construction Cost Systems|
200 West Lombard, Suite 209
Lombard, IL 60148
|Construction Waste Management
||Micheal Roy Iversen Architects|
144 N. Lombard Ave
Oak Park, IL 60302
|Computer Energy Modeling
||Prisco, Serena, Sturm|
3351 Commercial Avenue
Northbrook, IL 60062
|Efficient Lighting Design
||Sieben Energy Associates
333 N. Michigan Avenue, Suite 2107
Chicago, IL 60611
|Public Health/Indoor Air Quality
||O'Donnell, Wickland, Pagozzi and Peterson|
111 West Washington, Suite 2100
Chicago, IL 60602
||• USGBC LEED Platinum Rating (2003)
• 2003 AIA Top Ten Green Building Award
• 2003 Chicago Building Congress Green Building Award
||• Green Technology Center to Open:
Collaborations Build Environmental "Brightfield" on Chicago's
Industrial West Side by Middendorf, Bobbye Conscious Choice (April 2002).
• Chicago Green Tech Center Receives Platinum LEED Rating from U.S. Green
Building Council (November 14, 2003) This press release, available on-line,
announces the presentation of a LEED Platinum award to the Center for Green
Technology. The release includes comments from Mayor Daley and a description
of the project.
• Emerald City by Kamin, Blair Chicago Tribune (May 6, 2002).
Spire Solar Chicago Celebrates the Opening of Its Plant At Chicago Center
for Green Technology (May 6, 2002).
• How Green Can You Get? by Harold Henderson Chicago Reader (May 3, 2002).
• U.S. Department of Energy High Performance Buildings Database.
Farr Associates Architecture and Urban Design
53 West Jackson, Suite 650
Chicago, IL 60604