What do you get when you combine an energy intensive laboratory building, aggressive sustainability targets, and existing conditions that include low floor to ceiling heights? The beginning of a bad joke? Nope, the Conant Science Center at Bridgewater State University.
Bridgewater State University’s Marshall Conant Science Center stands as a cost-effective example of green building design, drawing upon a number of sustainable features and strategies which has led to a building with exceptional energy savings as well as coming in well below budget. The project has been designed for Silver certification under LEED 2009 for New Construction as an academic science and research building for undergraduate students. The building is part renovation – part new construction, with a new wing constructed adjacent to the original, renovated building. The entire building is approximately 212,000 square feet and includes a vegetated roof, solar thermal array, greenhouse, and rooftop observatory. Total site energy savings amount to 34%, with an estimated cost savings of 28.3%.
That’s all well and good, but what’s the secret to this success? The answer is quite simple – a good team and early alignment between the owner, contractor, architectural and engineering teams. The project’s kick-off meeting set the stage for what the project team wanted to do and made sure everyone was on board. Early in the project, concepts were explored that allowed the project team and owner to make informed decisions about sustainability. Simplified controls, reduced air change rates, staged exhaust, low pressure air drop system, reduced exhaust rate and cascading air systems were all ideas that made it through to the end due to continuous exploration and discussions of sustainability features throughout the project.
After investigating the benefits and limitations of an enthalpy wheel, it was decided to include this energy recovery device. Five, 30,000 cfm low pressure drop enthalpy wheels were installed in the project building. An enthalpy wheel is a total energy recovery device designed to transfer outgoing heat and humidity (energy) to the incoming air. Because the cost to remove moisture can represent a substantial cost for conditioning air, an enthalpy wheel offers more savings compared to a more conventional air-to-air exchanger.
One of the more difficult hurdles to overcome within the existing building was the low ceilings – running ductwork was almost impossible because the floor-to-floor height was so low at approximately 9- 10 feet. To overcome this and in lieu of a more standard HVAC system, displacement ventilation was utilized throughout the existing portion of the project building which ties into the operable windows. This particular system is very quiet and uses 100% outside air, resulting in a healthier environment for occupants as air is not re-circulated through the building. Not only did this system provide a healthier ventilation alternative but it does not require a return air system which resulted in considerable cost savings. Chilled beams were utilized in the new wing of the project. In the entry, there was no space to run duct work so a radiant floor was used with a chilled water system.
The project building also uses solar thermal heating for hot water used within lab spaces. A large cistern was buried near the project site which provides a space for reclaimed water to be kept for flushing. This combined with low-flow fixtures and a system designed to capture condensate and rainwater helped reduce water use.
Three main ingredients provided a successful project from an MEP point of view. First, a good working
relationship with the architect, Payette. Second, a great contractor that was involved early on, Barr & Barr. And finally, and most importantly, an owner that was readily accessible by the engineering team, willing to entertain new-to-them design concepts and set a realistic budget and objectives. As a result,the MEP portion of the project came in 20% under budget and Bridgewater has a wonderful new Science Center that fits their needs and is a showcase of sustainability.
This piece was contributed by Suzanne Robinson Suzanne heads up the Sustainability Department at Vanderweil Engineers.