It's Easy Being Green
Chicago City Hall is an imposing structure that has stood in its downtown location for more than 100 years. The 11-story building contains 500,000 sq ft and is home to numerous government offices, including the mayor and Chicago City Council. Given its age and size, it's no surprise that City Hall has not been the city's most energy-efficient building, but thanks to the Mayor Richard M. Daley, that is changing.
Under the mayor's direction, the city of Chicago has been implementing a new approach to the design, construction, and operation of public buildings that seeks to create healthy, high-quality structures in a manner that is both fiscally and environmentally responsible. This approach results in "green" buildings that enhance occupants' health and well-being, cost less to operate, and require fewer resources to build and maintain.
To that end, the city of Chicago has adopted the Chicago Standard, which is a new set of construction standards for public buildings that is derived from the LEED® Green Building Rating System developed by the USGBC. These standards were closely followed during the recent - and ongoing - renovation of City Hall, which included the installation of a new BAS to keep energy use under tight control.
Out with the OldIn 2003, it was realized that City Hall could not become a showcase of energy efficiency until it ridded itself of its proprietary DDC system, which was cumbersome to maintain and support. A redesign process began, which culminated in the installation of a new BAS, as well as energy-efficient motors, VSDs, and numerous other upgrades throughout the building.
"We started looking at the HVAC systems and controls in the building, but the project escalated in scope to include life-safety, security, and metering after evaluating the entire building and our operations," said Roger McGinty, chief engineer of Chicago's City Hall. "The controls were obvious, because we had problems controlling the building. We had numerous occupant complaints about comfort, and my staff was constantly servicing the units."
The city of Chicago opted for a new BAS, and after considering several alternatives, decided on the "Niagara" framework. This framework is a fully open, Internet-enabled distributed architecture that provides real-time access, automation, and control of devices and systems. In addition, it offers connectivity to many industry standard communications protocols including LonWorks®, BACnet®, Modbus®, OPC, and SNMP, as well as legacy products. This was crucial to McGinty, who was adamant that the system be 100% open. "I didn't want to be locked into any company," he said. "This system is totally open and has allowed us to get the level of integration of security, HVAC, lighting, video, and fire that we wanted."
Environmental Systems of Chicago (ESI) created the new system design, which included control and automation applications, as well as graphic displays for the Web browser interfaces. A high-speed Ethernet network was installed to connect the various floors and areas where mechanical equipment is located. In each of these areas, network controllers were added to support LonTalk communication trunks to the various LonMark devices. In addition to LonTalk, each network controller can support BACnet, Modbus, and many other protocols, providing the city of Chicago with numerous options for future expansions.
"The type of integration being done here isn't anything new or unique," said Paul Oswald, president of ESI. "It's the level of technology that's being implemented, combined with the applications and operating training, that make this system a model for what technology can do to improve the safety and comfort of the building occupants, as well as the overall operations and energy efficiency of the building."
Take, for example, the fire system. When an alarm goes off, the software will initiate a video feed, so firefighters can see what's happening before they ever get to the necessary floor. The software also triggers the paging system, so in the event of a fire, the page goes directly to the building engineer through the BAS, telling him the exact location of the fire.
The entire system is monitored from a centralized engineering room, which came about after McGinty attended a conference concerning homeland security. "I talked to other engineers who have had incidents in their buildings, and they said they have saved more lives when everything is more centralized. We were able to integrate the security, life safety, HVAC, and lighting systems into the engineer's office and centralize all of our building operations."
What this means is that one person in the engineering room at City Hall can operate every aspect of security, fire, BAS, and video. The system monitors wind speed and direction, so in the case of an airborne contaminant or other hazardous agent being released, the engineer will know how long it will take for the contaminant to reach the building. Personnel would not have to shut down each fan unit individually. Instead, the engineer can push a software-based "kill" button to safely and simultaneously shut down the entire ventilation system, effectively sealing the building.
This system also helps meet Mayor Daley's visions for centralized control of all city buildings. "Mayor Daley envisions a global building monitoring system, and City Hall is the benchmark. In the event of a crisis, the response team would be able to pull up the videos of each of the 485 city buildings to see what's going on. If we can do it in a 100-year-old building while saving energy, then we can do it at any building," said McGinty.
Growing ProjectThe first phase of the renovation involved the installation of the new BAS, as well as the replacement of approximately 90% of the building's motors. "Some of the existing fan motors dated back to 1947, so they were replaced with premium-duty motors, and all of the constant volume fans were converted to variable-frequency drive," stated McGinty.
VFDs are installed everywhere throughout City Hall, and parts of the building also benefit from VAV. Depending on the budget, McGinty is hoping to convert the rest of the building from constant volume to VAV over the next 10 years.
Installing the new BAS, motors, and VFDs generated a great deal of energy savings, which are well documented by the "Energy Profiler," an application built on the Niagara framework. This Web-based energy analysis tool allows the city to have numerous reports that show the building's energy consumption in a number of different ways. McGinty estimates City Hall is running at roughly 60% of the energy consumption that it was prior to the first phase of the renovation.
With a new BAS in place, extra funds were used to update the heating and cooling systems as well. On the cooling side, the chilled water valves were rebuilt and new chilled water coils were installed in eight of City Hall's main air handlers. To further drive efficiency in the chiller plant, new control schemes were devised. "We actually started from scratch on the application logic for every one of the air-handling systems and the chiller plant and the pumping systems," said Oswald. "Not only was the control system replaced, but the project team sat in front of a white board and diagrammed out how we wanted these units to be controlled."
Changing the control scheme definitely worked, as McGinty stated that he did not have to raise his chillers over 80% during last year's long hot summer. Other efforts to conserve energy have been initiated by the mayor's office. "We now have a more stringent protocol that states we are not going to start up the main system for one person. An employee would come in on the weekend, and we would turn on the chillers," said McGinty. City Hall utilizes steam and hot water reheat, and on the steam side, all the valves were rebuilt, and a new control strategy was put in place so that the main steam valves will not open until an outside temperature of 10°F is reached. Last winter, the building was heated without opening any of the steam valves on the air handlers: All heating was accomplished with baseboard radiation, body heat, and lighting.
Four domestic hot water pumps were replaced and new VSDs were installed. Today, one pump runs the entire building at 38%, which obviously saves a great deal of energy. The system is also tied into the BAS, so engineers can make necessary adjustments in the case of an alarm.
Life Safety AdditionsYet another phase of the City Hall renovation involved adding steam and electric metering, in addition to an integrated card access system that controls 60-plus doors. A video system was also installed, as well as the fire system, which encompasses several thousand points.
While the fire system is interfaced through simple dry contacts, the access control and video systems are tightly integrated into the Niagara framework. With this deep level of integration, the question of interoperability arises, but according to McGinty and Oswald, there are no problems whatsoever. "Everything is functioning and working together," said Oswald. "We've got Lon frequency drives talking to BACnet controllers and BACnet controllers talking to Lon VAV controllers, and there is metering coming in via Modbus. The access controllers are conveying information via XML and video files are displayed in the same graphic along with all the other real-time data, and it all works."
McGinty added that not everything worked perfectly from the moment the power switch was flipped on, but all the wrinkles have been ironed out, and the system is working as planned. "When Lon, Modbus, and BACnet are talking, it's like French, Spanish, and English - there are going to be communication gaps, but those gaps were filled, and the system works great."
Teams and TrainingMcGinty is quick to point out that the reason why the renovation project has been such a success is that he has been able to work with a fabulous team at all stages of the design and installation process. "I had a lot of input on the design, but the design itself was a team effort. It wasn't just one person who came up with what we had," said McGinty. "The team we had was, by far, one of the best teams I've worked with."
The team's objectives included saving energy through the selection and installation of the best possible equipment, as well as training building engineers to use all parts of the system effectively. McGinty felt this was extraordinarily important, because if the people aren't trained, the system just won't work.
"Our engineers are well trained through Local Union 399 of the Operating Engineers, which gives them a good base of knowledge. This fundamental training, combined with the system training, gives them the skills they need to effectively operate the building," said McGinty. He added that they are able to take part in multiple hours of flexible training, which allows his staff to use the system for a while, then bring any questions or concerns to the additional training. "The beauty of this system is that the people who are trained here at City Hall today will eventually be able to go over to another city building and pick right up on that system, because it's going to be the same," said McGinty.
The long-range plan is for every city-owned facility to have the same basic user interface and the same mechanism by which engineers and operators can interact with the BAS. It won't necessarily matter what type of controls or system a building has, because the presentation and interaction will be the same. Operations efficiency should increase, because engineers will be able to confidently move from building to building, as the interface will be the same. This will reduce training costs and also shorten the learning curve for employees who are transferred.
This focus on selecting the best possible equipment and fully training the employees contributes to the entire goal of achieving system sustainability. Mayor Daley and the engineering staff at City Hall want to make sure the system selected today will still be there 10-plus years from now. As Oswald noted, "From our perspective as a systems integrator, that's one of the more unique things about dealing with the city of Chicago: Too often, clients don't take the long-range view of their facilities and operations that the city of Chicago does."
Nobody has a crystal ball, but the city of Chicago hopes that by choosing a system that is open and built from a sustainable design, there's greater assurance that they're going to get the maximum value over the course of its life cycle. ES
Roof Tops Off This Green DesignChicago City Hall is not only green on the inside, it is also environmentally friendly on the outside, thanks to the construction of its green roof. First planted in 2000, the City Hall rooftop garden was conceived as a demonstration project - part of the city's Urban Heat Island Initiative - to test the benefits of green roofs and how they affect temperature and air quality.
The garden consists of 20,000 plants of more than 100 species, including shrubs, vines, and two trees. The plants were selected for their ability to thrive in the conditions on the roof, which is exposed to the sun and can be windy and arid. Most are prairie plants native to the Chicago region.
Like all green roofs, the goals of the City Hall rooftop garden are to improve air quality, conserve energy, reduce storm water runoff, and help lessen the urban heat island effect. The garden's plants reflect heat, provide shade, and help cool the surrounding air through evapotranspiration, which occurs when plants secrete or "transpire" water through pores in their leaves. The water draws heat as it evaporates, cooling the air in the process. Plants also filter the air, which improves air quality by using excess carbon dioxide to produce oxygen.
The rooftop garden mitigates the urban heat island effect by replacing what was a black tar roof with green plants. The garden absorbs less heat from the sun than the tar roof, keeping City Hall cooler in summer and requiring less energy for air conditioning. The garden also absorbs and uses rain water. It can retain 75% of a 1-in. rainfall before storm water runs off into the sewers.
It's difficult to quantify exactly how much energy the green roof has saved City Hall, but Roger McGinty shares his own experience. "On a 90ºF day our roof is about 86º, and our adjoining building, which is a duplicate of ours and has a black roof, often has a temperature of 116º."