Consulting-Specifying Engineer - March 2008 - (Page 32)

Our commissioning authority puts together a measurement and verification plan consistent with the International Performance Measurement & Verification Protocol tracking the first year of performance against baseline, and gives us the tool to continue to do so for subsequent years,” said Joseph Clair. of exhaust air at the system level caused by the general and toilet exhaust requirements. This system is not demand-controlled, but school designs from here on out will be, according to Clair. Occupant comfort is the primary concern in system design, so the engineers are controlling to temperature, with a dehumidification strategy if the space humidity is above ASHRAE 55 comfort levels. There are occupancy sensors, but they are currently only for lighting. CPS is moving toward incorporating them into Albany Park and future schools’ HVAC system as well as part of an effective ventilation and energy-efficiency strategy. Elementary schools like Albany Park within the CPS system do not get cooling towers, but the large high schools do. The package at Albany Park does not have variable primary chiller, as the system was designed in 2003, but future systems will, as well as variable-drive chillers. Commissioning made the big difference in efficiency of these systems. Though the engineers don’t have enough significant final performance data yet, the preliminary data suggest that commissioning has been the biggest boost to energy efficiency certification through the local gas and electric utilities. Energy models predicted that the facility would use around 700,000 kWh of electricity each year (for non-plug-loads) and 38,000 therms per year. The first full year of data suggests the usage at around 1 million kWh of electricity (including plug-loads) and 32,000 therms. The cooling system commissioning was not able to be completed during the first cooling season, so with further refinement, the expectation is that the electricity usage will come down. Compared with previous prototypes of similar size and use, Albany Park is performing at about 75% of the electricity usage and 75% to 80% of the natural gas usage. It is expected that the next generation of buildings will be able to significantly surpass this performance as design integration and technology improve the overall building performance. “Our commissioning authority puts together a measurement and verification plan consistent with the International Performance Measurement & Verification Protocol tracking the first year of performance against baseline, and gives us the tool to continue to do so for subsequent years,” Clair said. of the school year. Albany Park serves 720 students, though the building is only half-occupied right now, though it should be full within the next couple of school years. The school embraces all aspects of green and recently was certified at USGBC’s LEED Certification level. The 104,000-sq.-ft building has 26 classrooms and sits on a 4.5acre site. In support of Mayor Richard M. Daley’s effort to make Chicago the most environmentally friendly city in the nation, green building strategies are integrated into the design phase of each city project, including this school. Building excellence The HVAC system uses three condensing boilers, and each is sized for half of the load such that the failure of one will allow for 100% of the load to be serviced on a design day. The boilers operate at a range of temperatures from 160 F to 180 F based upon load, and cycle on and off as needed. These boilers are the primary part of the HVAC system, because the school is heated more than cooled throughout the school year. The boiler room, which houses three units, is on the third floor, reducing the stacks outside the building, set in a densely populated neighborhood. The school also has three variable air volume systems and two constant volume systems, with building automation systems attached to them. All five air-handling units (AHU) are capable of bringing in 100% outside air and are full economizing. Heat recovery was considered, but does not work due to the low amount 32 Consulting-Specifying Engineer • MARCH 2008

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Consulting-Specifying Engineer - March 2008 Contents Viewpoint Letters News M/E Roundtable Grade A HVAC When UPS and Gensets Have Issues Ignite Opportunities To Mentor Fire Protection Engineers Cooling People, Not Buildings Codes & Standards Case Study New Products Equipment Lifecycles Advertiser Index Green Space Pure Power Supplement Edison Institute Honors Recovery Efforts Canada Launches Clean Energy Software Climate Change Drives Increased Investment Critical Power for R&D Heating Calculations for Electrical Duct Bank Submetering for Energy Profiling New Products

Consulting-Specifying Engineer - March 2008

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