ASHRAE Journal - May 2011 - 48

When the demonstration period is over and the instructor is ready to begin experiments, the wall switch in this instructional laboratory is turned on. With the wall switch on and all student hoods closed, the student hoods operate at their NFPA 45 minimum exhaust rate. With the sash of any student hood above 6 in. (150 mm) (regardless of wall switch position), the student hood exhaust rate increases to its design flow to ensure student safety. The supply airflow varies based on the use of the student hoods. High capacity radial flow supply diffusers complement this installation, operating quietly and promoting containment at the fume hoods. High efficiency lighting is provided throughout the facilities. Occupancy sensors regulate lighting, and relay information to the BMS via a secondary contact at the occupancy sensor. The BMS uses this occupancy information (with an adjustable time delay) to increase the range of temperature drift when the space is unoccupied, saving energy and reducing operational costs. The use of daylighting and adjustable light levels in classrooms and laboratories promote learning and a connection with the environment. The occupancy sensors also provide a way to monitor for excessive fume hood energy use. As the majority of these fume hoods are for student-based learning, their sashes are either open or closed. With a staged fume hood open and the space unoccupied (after a fixed time delay), an energy waste alert can be sent to the lab users. A similar approach is used for the classroom and lecture spaces that can function as laboratory spaces (with the portable fume hoods) to save energy. This building complies with ASHRAE Standard 55-2004 for thermal comfort. The building air-handling units reset the supply air temperature based on building load, while local variable air volume terminal units modulate airflow rates for temperature control. A primary-secondary hydronic heating system with high efficiency gas boilers provides for local heating when required. Diffusers with high induction rates were selected for
48 ASHRAE Journal

classrooms, offices, and laboratory spaces. Radial flow diffusers are provided in laboratories with high airflow rates, reducing air velocities and promoting containment at fume hoods. Carbon dioxide sensors monitor high occupancy spaces to ensure minimum ventilation rates are maintained.
Month February March April May June July August September October November December January Total Electricity (kWh) 65,095 72,781 82,865 79,326 80,023 78,911 69,008 78,774 70,963 81,191 84,152 76,494 919,583

Table 1: From February 2010 to January 2011, this building saved 35% compared to an energy cost budget (ECB) building (1,415,198 kWh).
Natural Gas
(Therms)

Space Heating Domestic Hot Water

6,682 616 Total 7,298

Table 2: Proposed natural gas consumption. Because of the campus metering, it’s not possible to break down this building’s actual natural gas use. However, the calculated EUI for this lab building is 57.5 kBtu/ft2·yr (653 000 kJ/m2·yr). The majority of buildings on the MCC campus are designed for outside air economizer use, allowing the campus central plant to shut down during various portions of the year. The air-handling units serving this building also shut down when the building is scheduled unoccupied, though
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laboratory exhaust is maintained at minimum levels. Select spaces are monitored for temperature when the building is unoccupied. If the temperature in these spaces goes out of range, the air-handling units are restarted for a fixed period to restore temperature. Certain spaces within the building (such as electrical, telecom, and equipment rooms) require continuous cooling. With the air-handling units shut down, and chilled water unavailable during certain portions of the year, an alternate cooling source was needed. A variable-refrigerant system using environment-friendly R-410A refrigerant was selected to serve these spaces. This approach provides for energy-efficient operation, minimized equipment servicing requirements, and limited the rooftop noise in the vicinity of the astronomy program’s rooftop star gazing platform. BIM was used in design and during construction to coordinate utilities. Weekly meetings were held with the MEP disciplines and coordinated by the mechanical contractor. Design was brought in at key milestones to ensure design intent and assist in resolving modeling conflicts. The process allowed for offsite prefabrication and the minimizing of construction waste. Recycling efforts diverted more than 726 metric tons or 77% of the construction waste from landfills. More than 37% of the materials used in the construction of this project contain recycled content. Low flow plumbing fixtures and waterless urinals result in a 56% reduction in potable water use. The use of native vegetation allowed for a further 62% reduction in potable water use for irrigation. Throughout the design and construction process the Maricopa Community Colleges emphasized the importance of student safety. One area of concern was relative to natural gas use in laboratory spaces. As instructors may not always be present, they wanted a way to ensure the safety of their students. The solution was to provide a local gas solenoid valve, control panel, and dedicated occupancy sensor at each laboratory space with natural gas.
May 2011

ASHRAE Journal - May 2011

Table of Contents for the Digital Edition of ASHRAE Journal - May 2011