Designing Complex Mechanical Systems for Laboratories

Published April 13, 2016 on labdesignnews.com

In this month’s column for Lab Design News, we explore the ideal way to design a mechanical system for laboratory buildings using our Amherst College New Science Center as a successful example.

Designing laboratory buildings requires consideration of complex mechanical systems. This consideration is compounded when the aim is to design a sustainable lab build and even more so when targeting low Energy Use Intensity (EUI). In practice this can be challenging as architectural intent may be in opposition to sustainable strategies. When making decisions, which priority takes the lead: mechanical systems or architectural intent? Ultimately, for beautifully executed high-performance buildings, neither priority can be compromised. Our design team worked to embody both in the New Science Center for Amherst College. Throughout the design process, the design of the mechanical system and design of the architecture were valued equally, and work to support one another.

The building is organized into five building elements; two laboratory wings tucked into the hillside along the east edge of the site, and three pavilions set in the landscape to the west. The lab wings and pavilions open to a glass enclosed atrium space, nicknamed the Commons, which promotes a community of science and is a destination for the entire campus. The Commons is then tied together by a symbolic unifying element of a floating roof.

Early Goal Setting
Early in concept design, the owner and design team set clear goals for the project. One of those goals insisted that the building be an environmentally responsible project. Related to energy efficiency, the agreed upon measure of success for the project was a target EUI of 99 kbtu/sf-yr. This aggressive target for a lab-intensive research and teaching facility could only be met with a commitment from all stakeholders involved in the project. 

Program Zoning and Building Massing
The massing of the New Science Center is organized by 3 discrete elements: a pair of laboratory bars set behind three smaller pavilions nestled in the foregrounded landscape, all tied together by a shared atrium space. Architecturally, this massing allowed for key programmatic zoning coupled with different mechanical demands. The larger laboratory bars contain high-energy, intensive research and teaching spaces, whereas the smaller pavilions contain low-energy, dry programs. This separation of program coincides with the separation of mechanical systems. Mechanically, this arrangement allowed for the two high-energy laboratory bars to be off a dedicated laboratory air system and the three pavilions of low-intensity program, served off the non-lab air system. For purely aesthetic reasons, this separation was critical because it allowed the atrium to be an unobstructed space, free of ductwork. The program zoning and massing were two moments of synergy between the mechanical system design and the building program in the design.
 
High energy / low energy diagram

The Roof and Penthouse
With the building site located at the base of a large hill, the roofscape is highly visible from other parts of campus. We viewed the rooftop mechanical spaces as a design element and determined that a traditional mechanical penthouse was not a viable option for our design intent. In an effort to avoid a visual “forehead” of a mechanical penthouse, we decided to only locate essential equipment on the upper level, and much of the traditional lab-building systems were relocated to the mechanical basement. Working with the project’s engineers, penthouse equipment was limited to only lab-exhaust units, the glycol heat recovery system and atrium smoke exhaust fans. Mechanically, these systems remained at the roof level as they all are part of the exhaust stream and are required to be discharged as high as possible. The glycol coil system was chosen both for its compact size and because it allows for the complete separation of supply and exhaust airstreams. The heat recovered from the exhaust stream at the penthouse is then brought back down to the mechanical basement and used for pre-heating the outside air at the lab air handlers. At just 8’-0” high, the penthouse still functions efficiently, while remaining a design element that frames the landscape beyond and unifies the atrium below.

View of the roof and penthouse from upper campus

Passive Transfer Air
Air transfer is part of the overall mechanical air strategy and is implemented through architectural detailing. The strategy is a passive transfer, as air will naturally move from areas of high pressure to areas of lower pressure. For example, air will move from the office and classroom spaces to the atrium and laboratory spaces. The transfer details embodied three goals: 1.) execute without the use of any mechanical equipment, 2.) architecturally conceal the locations of transfer air and 3.) maintain the desired acoustic separation between spaces. Acoustically, if we merely provided a transfer grille on each side of a wall, the design would not satisfy the required sound rating. Integrated designs were achieved by transferring air through architecturally perforated wall panels and through reveal details. Furthermore, the acoustic demands required new methods of transfer that varied throughout the building. Transfer was executed by using “Z” ducts in walls, concealed acoustical lovers, and through utilizing mechanical bulkheads as sound buffers.

Transfer air section

In laboratory building design it is critical that the mechanical systems, particularly the air system, be integrated with the architecture. It’s too important, especially when trying to achieve a reduced EUI. By setting goals early, building stakeholder buy-in and looking for synergies between the architectural intent and the building systems throughout design, a beautiful, energy efficient building is possible. The New Science Center at Amherst College kicked off construction in early 2016 and is scheduled to reach in early fall 2018. We are currently tracking an EUI of 91 kbtu/sf-yr and through an architecturally integrated mechanical design, hope to achieve an even lower EUI in a beautiful building.

The full article can be found on labdesignnews.com and will also be featured in the March/April print edition of Lab Design.