ASHRAE Journal - May 2011 - 46

Building at a Glance
Name: Mesa Community College – Physical Sciences Building Location: Mesa, Ariz. Owner: Maricopa Community Colleges Principal Use: education Includes: laboratories, classrooms, offices, and support spaces Employees/Occupants: 900 Gross Square Footage: 64,480 ft2 Conditioned Space: 62,000 ft2 Substantial Completion/Occupancy: Fall 2008 Occupancy: 100% National Distinctions/Awards: Metal Architecture – Sustainable Design Award, 2009, Arizona Masonry Guild Excellence in Masonry Architectural Awards, 2009, AIA Western Mountain Region, Distinguished Building Award, 2009.

Laboratory controls minimize energy and noise while ensuring ventilation rates and safety. The HVAC design takes advantage of the single pass air requirements of the laboratory spaces to provide increased ventilation for the office and instructional spaces as calculated per ASHRAE Standard 62.1-2004’s Ventilation Rate Procedure. All laboratory, office, and instructional spaces are served by a central HVAC system. Laboratory areas are exhausted, while office and common spaces are returned. When compared to a Standard 62.1-2004 compliant facility, the central HVAC system provides more than 30% increased ventilation, achieving the LEED Indoor Environmental Quality Credit 2. Select classroom and lecture spaces have the ability to function either as classroom or laboratory. In these areas, a wall switch enables an electrical outlet serving a portable demonstration fume hood. Note that portable fume hoods recirculate filtered air and are designed for specific chemical use. The building management system (BMS) monitors the status of the wall switch, and automatically changes the space from normally returned air to laboratory general exhaust when enabled. Exhaust outlets in these spaces are located at the front of the room (away from the students) as an additional measure of safety. The building air-handling units are capable of 100% outside air economizer operation, and use variable speed drives for energy efficient operation. Each airhandling unit is designed with nominal face velocities of 400 fpm (2 m/s), which translates to energy savings by way of reduced internal static pressure (pres46 ASHRAE Journal

sure drop varies with the square of the velocity). A variable air volume laboratory exhaust system allows the building to exhaust only the quantity of air required to maintain indoor air quality, and uses bypass outside air to provide dilution and maintain stack velocity. All laboratory spaces are maintained negative with respect to other spaces via airflow tracking. High efficiency low flow fume hoods are used throughout the facility. Fume hood operation varies based on location and intended use. Where the fume hood exhaust for a space is less than or equal to the minimum ventilation rate, the fume hood operates at a constant exhaust rate. If the airflow for temperature control exceeds the fume hood exhaust rate, an airflow tracking general exhaust valve is added to maintain negative space pressurization. With the fume hood exhaust in excess of the minimum ventilation rate, fume hood exhaust is modulated to reduce energy use. The approach to fume hood control was simplified based on two environmental factors: fume hood configuration and student-based learning. Fume hoods for student-based learning are either in use or not in use (sash at operating height or closed). Instead of modulating control, two-position control was provided. A potentiometer cable, or sash position sensor, monitors the height of the single vertical sash. With the sash height above 6 in. (150 mm), fume hood exhaust increases from minimum to design flows. Note
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that this distance was selected as it maintains minimum design velocities at NFPA 45 minimum exhaust rates. The HVAC systems are designed for quiet operation. Concerns were voiced during design relative to an instructional laboratory with 12 fume hoods. Three of the fume hoods (one for instructor demonstration, another for chemical storage, and one ADA student hood) operate at a constant exhaust rate to maintain minimum ventilation rates. The remaining student hoods are for experiments only (no chemical storage), and are controlled by a wall switch and sash position sensors. With the wall switch off and all student hoods closed, the exhaust to the student hoods is shut off. This approach both conserves energy and reduces noise levels.
May 2011



ASHRAE Journal - May 2011

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

ASHRAE Journal - May 2011
Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
Seismic Restraint
Plug Load Design Factors
Technology Award Case Studies:
State-of-Art School
Green School Lab
Eco-Friendly, Affordable, School
Building Sciences
Special Section
InfoCenter
Solar NZEB Project
Emerging Technologies
IAQ Applications
Washington Report
International Column
Products
People
Classified Advertising
Advertisers Index
ASHRAE Journal - May 2011 - Intro
ASHRAE Journal - May 2011 - ASHRAE Journal - May 2011
ASHRAE Journal - May 2011 - Cover2
ASHRAE Journal - May 2011 - 1
ASHRAE Journal - May 2011 - 2
ASHRAE Journal - May 2011 - Contents
ASHRAE Journal - May 2011 - Commentary
ASHRAE Journal - May 2011 - 5
ASHRAE Journal - May 2011 - Industry News
ASHRAE Journal - May 2011 - 7
ASHRAE Journal - May 2011 - 8
ASHRAE Journal - May 2011 - 9
ASHRAE Journal - May 2011 - 10
ASHRAE Journal - May 2011 - 11
ASHRAE Journal - May 2011 - 12
ASHRAE Journal - May 2011 - 13
ASHRAE Journal - May 2011 - Letters
ASHRAE Journal - May 2011 - 15
ASHRAE Journal - May 2011 - 16
ASHRAE Journal - May 2011 - 16a
ASHRAE Journal - May 2011 - 16b
ASHRAE Journal - May 2011 - 17
ASHRAE Journal - May 2011 - Meetings and Shows
ASHRAE Journal - May 2011 - 19
ASHRAE Journal - May 2011 - Seismic Restraint
ASHRAE Journal - May 2011 - 21
ASHRAE Journal - May 2011 - 22
ASHRAE Journal - May 2011 - 23
ASHRAE Journal - May 2011 - 24
ASHRAE Journal - May 2011 - 25
ASHRAE Journal - May 2011 - 26
ASHRAE Journal - May 2011 - 27
ASHRAE Journal - May 2011 - 28
ASHRAE Journal - May 2011 - 29
ASHRAE Journal - May 2011 - Plug Load Design Factors
ASHRAE Journal - May 2011 - 31
ASHRAE Journal - May 2011 - 32
ASHRAE Journal - May 2011 - 33
ASHRAE Journal - May 2011 - 34
ASHRAE Journal - May 2011 - 35
ASHRAE Journal - May 2011 - State-of-Art School
ASHRAE Journal - May 2011 - 37
ASHRAE Journal - May 2011 - 38
ASHRAE Journal - May 2011 - 39
ASHRAE Journal - May 2011 - 40
ASHRAE Journal - May 2011 - 41
ASHRAE Journal - May 2011 - 42
ASHRAE Journal - May 2011 - 43
ASHRAE Journal - May 2011 - Green School Lab
ASHRAE Journal - May 2011 - 45
ASHRAE Journal - May 2011 - 46
ASHRAE Journal - May 2011 - 47
ASHRAE Journal - May 2011 - 48
ASHRAE Journal - May 2011 - 49
ASHRAE Journal - May 2011 - 50
ASHRAE Journal - May 2011 - 51
ASHRAE Journal - May 2011 - Eco-Friendly, Affordable, School
ASHRAE Journal - May 2011 - 53
ASHRAE Journal - May 2011 - 54
ASHRAE Journal - May 2011 - 55
ASHRAE Journal - May 2011 - 56
ASHRAE Journal - May 2011 - 57
ASHRAE Journal - May 2011 - Building Sciences
ASHRAE Journal - May 2011 - 59
ASHRAE Journal - May 2011 - 60
ASHRAE Journal - May 2011 - 61
ASHRAE Journal - May 2011 - 62
ASHRAE Journal - May 2011 - 63
ASHRAE Journal - May 2011 - 64
ASHRAE Journal - May 2011 - 65
ASHRAE Journal - May 2011 - 66
ASHRAE Journal - May 2011 - 67
ASHRAE Journal - May 2011 - InfoCenter
ASHRAE Journal - May 2011 - 69
ASHRAE Journal - May 2011 - 70
ASHRAE Journal - May 2011 - 71
ASHRAE Journal - May 2011 - 72
ASHRAE Journal - May 2011 - 73
ASHRAE Journal - May 2011 - 74
ASHRAE Journal - May 2011 - 75
ASHRAE Journal - May 2011 - 76
ASHRAE Journal - May 2011 - 77
ASHRAE Journal - May 2011 - Solar NZEB Project
ASHRAE Journal - May 2011 - 79
ASHRAE Journal - May 2011 - 80
ASHRAE Journal - May 2011 - 81
ASHRAE Journal - May 2011 - 82
ASHRAE Journal - May 2011 - 83
ASHRAE Journal - May 2011 - 84
ASHRAE Journal - May 2011 - 85
ASHRAE Journal - May 2011 - 86
ASHRAE Journal - May 2011 - 87
ASHRAE Journal - May 2011 - 88
ASHRAE Journal - May 2011 - 89
ASHRAE Journal - May 2011 - Emerging Technologies
ASHRAE Journal - May 2011 - 91
ASHRAE Journal - May 2011 - 92
ASHRAE Journal - May 2011 - 93
ASHRAE Journal - May 2011 - 94
ASHRAE Journal - May 2011 - 95
ASHRAE Journal - May 2011 - IAQ Applications
ASHRAE Journal - May 2011 - 97
ASHRAE Journal - May 2011 - 98
ASHRAE Journal - May 2011 - 99
ASHRAE Journal - May 2011 - 100
ASHRAE Journal - May 2011 - 101
ASHRAE Journal - May 2011 - Washington Report
ASHRAE Journal - May 2011 - 103
ASHRAE Journal - May 2011 - International Column
ASHRAE Journal - May 2011 - 105
ASHRAE Journal - May 2011 - 106
ASHRAE Journal - May 2011 - Products
ASHRAE Journal - May 2011 - 108
ASHRAE Journal - May 2011 - People
ASHRAE Journal - May 2011 - Classified Advertising
ASHRAE Journal - May 2011 - 111
ASHRAE Journal - May 2011 - Advertisers Index
ASHRAE Journal - May 2011 - Cover3
ASHRAE Journal - May 2011 - Cover4
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