‘Good Bones' Support Upgraded Laboratory
A growing number of college students and researchers around the country toil away in outmoded laboratory facilities that date back decades. Increased competition to attract students and faculty to science curricula has spurred institutions to upgrade and/or expand these facilities incorporating the latest in technology. An important decision in this process is whether decades-old buildings can be upgraded to provide a state-of-the-art environment for teaching and research.
Several years ago, Mount Holyoke College in South Hadley, MA, faced that conundrum. Existing science buildings were more than 50 years old, and the college sought to include them into an ambitious $34.5 million plan to create a unified science center that would foster intellectual exchange and interdisciplinary research among all science departments - astronomy, chemistry, biological sciences, biochemistry, mathematics and statistics, physics, computer science, and earth and environmental studies - and serve to attract the curiosity of non-science majors.
An evaluation of existing facilities found that they could be upgraded and reused as lab and science spaces. Mount Holyoke's unified science complex now encompasses a new 40,000-sq-ft, four-story building that connects to three existing laboratory and science buildings, with 76,000 sq ft of renovated space. Kendade Hall, the new building, was completed in 2002; renovations to existing facilities were completed in 2003.
Carr LaboratoryOne existing facility was the three-story, 47,000-sq-ft Carr Laboratory Building, which housed undergraduate chemistry courses. Constructed in 1952, Carr provided students access to sophisticated instruments for pursuing research, but in an outdated environment. Initially, there was concern over whether Carr could be upgraded to incorporate the latest scientific facilities and building systems. An evaluation found that it had ‘good bones' and could be renovated to support modern teaching and research labs. But with its low floor-to-floor heights and reinforced concrete columns, beams, and slabs - its good bones - it would take a creative approach to incorporate the necessary, highly sophisticated HVAC, electrical, data, and communications infrastructure into the building.
ProgrammingInitial programming affirmed that the chemistry laboratories and department would be housed in the new building. As planning progressed, it became clear that the budget would not allow a large enough new building to house all of the chemistry department with its required adjacencies. Examining Carr, it was determined that it could incorporate the ideal 20 ft by 30 ft planning geometry needed for chemistry facilities. The decision was made to keep all chemistry facilities in Carr.
To get the most construction out of each dollar spent by the college, the design team aggressively pursued a "zero phasing" option. This solution required a complete shutdown of chemistry lab instruction and research for 12 months. Potential disruption was minimized through advanced planning and coordination. Because the shutdown was scheduled to occur from one December break to the next December break, each class year of students only missed one semester of instruction. Evening labs were held in the semesters prior to and after the shutdown to make up for the loss of laboratory instruction. Additionally, some critical research projects and facilities were temporarily relocated.
Outdated SystemsMany of the systems in Carr were marginal and past their useful life. The majority of the piping was original to the building. Through-wall air conditioners, unit ventilators, radiators, and fin tubing were used to cool, heat, and ventilate Carr before the renovation. This made it difficult to create and maintain the pressure zones needed in the labs and hard to maintain constant temperatures.
The majority of the building was ventilated by classroom-type unit ventilators located at exterior walls sometimes in conjunction with AHUs located in prep labs or on the roof. AHUs were controlled in sequence with unit ventilators in an attempt to provide makeup air for fume hoods. The makeup air handlers served two adjacent labs and, if one lab wasn't in full operation and the other was occupied, makeup air handlers were forcing the unoccupied lab into a positive pressure situation.
Existing main fume hood exhaust fans were located within two mechanical penthouses on the roof. These fans and their location had been problematic for some time. The fans and their duct systems had deteriorated, resulting in fumes being discharged into the mechanical rooms. On calm days, lab exhaust odors often were noticeable at grade in the building's courtyard.
Once the new building was completed, work on Carr began in earnest, with the building stripped down to its structural elements. All systems, windows, piping, and even the foundation slab were removed. Much of the demolished material was set aside for reuse, as part of a major LEED™-qualifying initiative.
HVAC SolutionCarr's low ceiling heights and the concrete structural elements were challenges to running systems through the building horizontally. But they also served as an impetus for the design team to think creatively. The decision to run numerous HVAC chases vertically down from a new rooftop mechanical penthouse into the corridors was one key decision that made the renovation possible. This vertical distribution concept allowed a minimum of horizontal ductwork to be run from the corridor chase into each lab along pockets between exposed concrete beams.
The facility's 42,000-cfm custom AHUs (100% outside air) reside in penthouses at each end of the roof. They are cross-connected by a header duct within a rooftop enclosure. This allows the two units to act as a single system, provides a degree of back up or maintenance should one unit fail (although each unit is sized to 50% of the maximum design load), and reduces overall supply fan annual energy usage. The VSDs run at identical speeds under duct static pressure control. When total supply airflow falls below 35% of design airflow, one of the AHUs is taken off-line, and the AHU's supply air flow is increased to pick up the current building load. This is done to guard against unstable fan and coil operation during reduced airflow conditions.
Laboratories and related rooms in the building are VAV controlled, including the fume hoods. In typical labs, fume hood air quantities are reset based on sash position (with minimum hood airflows applying). General room exhaust valves and supply air valves track so they always provide the required air pressure relationship to its adjacent space. Room temperature sensors also control the supply air and hot water reheat coil valves.
A below-grade utilidoor was developed beneath the building to provide a route for mechanical and central services to enter and exit the building. This utilidoor incorporated a series of piping racks and allowed the main utilities to enter and exit the building without running through laboratory space. This limited the congestion within laboratories and kept the service associated with these systems from disrupting teaching and research environments.
The lab fume hoods and general exhausts are ducted up to rooftop headers and then to a bank of four mixed-flow, upblast, direct-drive exhaust fans. They sit on a common plenum located on the roof. Automatic outdoor air-bleed dampers hold necessary suction pressure as the number of fans running varies and the exhaust air from the labs vary (one exhaust fan is fed with standby power). The combination of high discharge velocity and high dilution rates help prevent contaminates settling out at grade. The effective stack height of this system is over 80 ft above roof level. The fans are located at the highest point of the building, which also helps with its discharge and was used as an architectural feature of the building.
In the corridors, HVAC systems were hung and run above a dropped ceiling composed of wavy perforated metal. Cable trays were incorporated into the ceiling structure along the sides using the same perforated metal panels. This metal ceiling system was chosen for several reasons. It provided a means to conceal the mechanical/electrical systems, it enabled supply pressurization to be distributed through the ceiling at strategic locations, it provided an acoustical benefit, and it delivered a machine aesthetic that the architectural design team felt reflected the systems-heavy reality of the building.
Intense CoordinationOnce the conceptual HVAC system design was set, a crucial part of the project was successfully coordinating all systems to avoid conflicts and to fit them into tight or exposed spaces. The space constraints resulted in unusually tight tolerances for chases and runs of supply and exhaust air ductwork, for data and communications cable trays, for lighting and electrical equipment, for plumbing, and for safety systems.
The first step in the coordination process was to marry the HVAC concept with the building's pragmatic requirements. A conceptual estimate was completed comparing all the airflow requirements for each of the building's spaces. Since the concept required that all of the supply air system within each lab be placed between the existing structural beams, the lab partition layout was matched to the structural bay spacing.
The design team then was confident that the HVAC supply system for each lab space would match the required number of structural bays needed to deliver the airflow. As it turned out, some lab spaces would require only one supply-air duct assembly, while others would require several. This decision was based more on the type of lab than on its physical size.
For example, a typical chemistry laboratory would require more airflow than a typical biology laboratory, but their programmatic required floor areas could be the same. After the HVAC system concept was developed, the lighting, electrical, and plumbing systems were incorporated into the design. This was the next logical step, as the HVAC system took up the majority of space. The lights, piping, and data cable tray were designed to be at a level just below the duct system.
After the engineering systems design was completed, a 3-D computer model was developed to serve two very important functions. It was used to cross-check coordination throughout the project, and it was used to show the building owner what the lab space would look like when completed. This latter use was extremely important as all of the engineering systems are exposed to view, something that is unfamiliar to most building owners.
Lab DesignThe design of the labs was also an important factor to Mount Holyoke College. Could modern equipment be incorporated? Could pre-lab lecture space and a fume hood intensive laboratory be incorporated in one lab? Mount Holyoke has been in the forefront of a movement to micro-scale chemistry laboratory instruction - using reduced quantities of chemicals through smaller instrumentation. This had been difficult to accomplish in its outdated facilities. The new labs incorporate the equipment, systems, and space needed for leading-edge micro-scale techniques, while still providing room for traditional techniques to be taught.
The new teaching labs in Carr vary greatly from the old ones. In the old building, the fume hoods were located on the interior corridor walls. Students using the hoods would have their back to the classroom and to all shared benchtops. When the hoods were not in use and had no hazardous chemicals stored inside, the hood fans were turned off, resulting in zero ventilation through the hoods.
The new teaching hoods incorporate a custom designed fume hood that is constructed of see-through glass panels on all sides, giving the instructor and students better visibility in the lab to foster a stronger learning environment. All of the lab spaces were designed with a minimum rate of six ach for an occupied lab and four ach for an unoccupied lab (nights and weekends). The full flow occupied lab air change rates for some labs approached 20 ach.
The Computer AgeTechnology and computer systems have changed dramatically since Carr was originally built. The use of computers, and now the Internet, plays a key role in keeping a laboratory a safe and comfortable environment. The new four-building unified sciences complex is controlled by two DDC systems working together. One system controls all critical airflows and pressure relationships, and the other controls temperature. These systems communicate with each other through a common language (BACnet).
The entire system is viewable and controllable through a computer setup with an Internet connection. With the correct password, building engineers can check airflows, temperature, safety alarms, etc., for each lab from any computer with Internet access and from anywhere around the world. This provides a measure of real-time supervision that was non-existent only a few years ago.
Vibrant CrossroadsAnother college goal was to find a way to capture the diversity of science education at Mount Holyoke and to interest and intrigue non-science majors at the school. The design and siting of the new building helped achieve this. The new science building, Kendade, sited within the U-shaped complex parallel to the long side of Carr Laboratory, provided the opportunity for a dramatic public atrium space between buildings. The play between the three-story Carr down slope from four-story Kendade created a two-story clerestory window along three sides that bathes the space with natural light. This atrium serves as a living room for informal gathering and socializing - for the entire college, not just for science-focused students and staff. It also serves as the pathway via crosswalks to other buildings in the science complex and to other parts of the campus.
In one dramatic four-story space, the science disciplines are on display for science and liberal arts students alike. As you rise up, activity on each of the floors is transparent through window walls. A lunch café, advanced bio labs, lively physics labs, and group-study rooms all look out onto the atrium. Activity is happening wherever you look.
Mount Holyoke's unified science center - a pastiche of new building, dramatic atrium space, and rejuvenated older buildings with hardy "old bones" - symbolically brings together not only the sciences, but an entire academic community. ES