Kohler Environmental Center, Choate Rosemary Hall School
Engineering firm: Kohler Ronan, LLC
2013 MEP Giants rank: 100
Project: Kohler Environmental Center, Choate Rosemary Hall School
Address: Wallingford, Conn., United States
Building type: School (K-12)
Project type: New construction
Engineering services: Electrical/Power, Fire & Life Safety, HVAC
Project timeline: November 2009 to October 2012
Engineering services budget: $230,000
MEP budget: $230,000
The goal of the Kohler Environmental Center (KEC) at Choate Rosemary Hall was to create an environmental immersion program and corresponding facility in which students would live, learn, and take responsibility for their individual environmental impact. In so doing, each student would develop a sense of stewardship toward the natural world, one which would serve as an example for his peers, while the facility itself would become a model for academic institutions—if not all sustainable buildings across the country. As part of this goal, the owner envisioned a facility designed to the utmost in green building standards, a facility of net-zero energy usage with the capacity to provide an interactive experience where systems offer its occupants feedback regarding energy consumption and building performance. The new building would in effect be a living laboratory and serve as an integral component of a thoughtful interdisciplinary program.
Kohler Ronan’s engineering challenge was clear: how to achieve the ambitious sustainability goals of a LEED Platinum, net-zero, interactive educational facility in a cost-effective manner—without sacrificing occupant comfort or happiness. To successfully meet this challenge, environmentally advanced systems needed to be designed unlike others seen in American secondary schools to date. Further, the systems needed to engage students and encourage full participation and commitment to maintaining an energy self-sufficient environment; without that commitment, the project’s goals could not fully be realized. The Kohler Environmental Center is the first teaching, research, and residential environmental center of its kind in U.S. secondary education. The associated engineering systems needed to be of the same caliber. Inspired by the challenges inherent in this project, Kohler Ronan regarded the new facility as an opportunity to create a truly unique, impactful engineering design.
Kohler Ronan selected an integrated design process as the best means to achieve a successful result for the KEC. To meet the project’s sustainability challenges, all disciplines and members of the design team would need to work together seamlessly, sharing ideas and critical information from the project’s start to its finish.
Kohler Ronan’s energy modeling team took the lead. Using advanced industry software such as IES-VE, Trace, LoopDA, Radiance and GLD, the firm’s modelers conducted countless energy simulations used to evaluate greater than 120 design scenarios. With rapid turnaround, modelers were able to inform design team decisions and ensure OPR compliance. The team determined the building’s best performance based on innumerable variables including orientation, envelope, window and door placement, insulation, type of equipment, daylighting, natural ventilation, and other factors.
Extensive investigation of passive load reduction strategies indicated that the building’s optimal performance would be achieved if constructed facing south. The site of the 31,325-sq-ft facility, which would incorporate dormitory rooms, faculty apartments, common spaces, classrooms, laboratories, and a state-of-the-art research greenhouse, consisted of over 260 acres of undeveloped land adjacent to the Choate campus. The acreage provided ample space for the building’s preferred orientation as well as a 294 kW photovoltaic array. Large windows were also designed south-facing to capitalize on natural light and heat. Envelope optimization resulted in an overall building weighted U-value 50% better than baseline values. The team went on to perform multiple iterative simulations demonstrating the relative value of various energy conservation measures (ECMs). Earth duct simulations, sizing, and performance assessments determined that a 15 F temperature differential could be achieved enabling passive preconditioning of the outdoor air. Coupling earth duct systems to energy recovery ventilators brought design outdoor air temperature up from 9 F to 53.2 F. This represents a 75% reduction in ventilation related peak heating demand and an 86% reduction in heating related energy consumption. Corresponding energy cost savings would be significant.
Other system features include roof-mounted evacuated solar tubes. These tubes circulate and heat water which is piped to the basement for storage. The greenhouse is heated by a boiler using waste cooking oil from the school’s kitchen, while a cistern was attached to the greenhouse to collect rainwater for its plants. The facility was designed to perform 50% more efficiently than ASHRAE 90.1-2004 energy standards and operates at 34 kBtu/ft2/yr. Water performance standards include a >60% reduction in the use of potable water and receipt of all LEED WE credits. The facility is also 2030 Challenge Compliant.
Fulfilling the second part of the challenge, students are able to track this performance via highly specialized dashboard monitoring systems accessible online via large wall-mounted monitors in the common room or via their personal smartphones. Based on the information related to heating, cooling, water consumption, and carbon footprint, students can then alter their living habits to affect energy efficiency. Students are invested in the facility’s performance and become committed to living as efficiently possible. Kohler Ronan is delighted to have designed the sophisticated MEP/FP systems for this groundbreaking facility.