Solar Thermal Report-Spring 2012: Winning gold with solar
Harrisonburg, Va.-based Eastern Mennonite University, a small Christian university with roughly 1,500 students (of which about half are Mennonite), has the distinction of having the first residence hall in the state to achieve LEED Gold certification - one of only 33 across the country. Its 35,000-sq.-ft. Cedarwood dorm, which was the brainchild of a student task force on residential living and learning, achieved 45 LEED points. The minimum gold ranking for new construction requires 39 points.
EMU students play a big role in campus sustainability issues, such as organizing sustainability events and developing mini-grants for innovative projects. The student residential living group began work on a plan to demolish the old Oakwood dorm and replace it with a new, sustainable building in the fall of 2007, says Eldon Kurtz, EMU’s physical plant director.
Using an integrated design-build process, the construction team - architect, general contractor, and plumbing, mechanical and electrical contractors - was involved in the design process with the university from the beginning of the project, which broke ground in July 2008 and was completed a year later.
The solar thermal portion of the Cedarwood project was conceived when the construction was already halfway complete, says Hans Rosenberger, owner and founder of Altadena Energy & Solar (Altadena, Calif.).
“I knew Eastern Mennonite University and its emphasis on stewardship, and the ever-growing emphasis of putting this ethic into practice in building construction and operation,” he says. “Since I was aware of EMU’s intention to qualify the Cedarwood dorm as a LEED project, solar thermal appeared to be another area where additional energy savings and LEED points could be achieved.”
Rosenberger’s extensive experience with solar thermal systems in California and Germany’s RSF Solar, combined with his connection to EMU, made Altadena a natural choice to design Cedarwood’s solar hot water system.
“Hans’ family has been a longtime supporter of EMU, which gave immediate credibility to his offer to design and install a hot water solar system for our new dorm,” Kurtz notes. “At the time there were only a few contractors in the area installing solar domestic systems and few with the depth of experience that Hans was able to demonstrate. It also was helpful to have a single contact to design the system, source the components, supervise installation and ultimately provide the financial vehicle to take advantage of available incentives.”
Part of that financial vehicle is a power purchase agreement, typical in the solar energy industry, where Altadena Energy & Solar owns and maintains the solar thermal system and EMU purchases heat units from Altadena. The university doesn’t have the capital outlays of purchasing the solar panels and other equipment, yet can still realize tax benefits.
Existing building designThe primary goal was to have the dorm ready for the 2009-2010 academic year, with the secondary goal being the completion of the solar thermal system, Rosenberger says. Since the roof and mechanical room were already completed, the 1,000-sq.-ft., 1,100-gallon solar thermal system design needed to be adapted to the existing building for roof support, pipe chases, tank locations, etc.
“Estimation of the hot water demand and simulation of the system design were the two most challenging aspects of the engineering,” he notes. “Because the dorm was a LEED project, a lot of emphasis was placed on reducing demand, as well as meeting that demand with the most benign system design as is possible.
“For the solar design, this system was challenging because the physical layout of the system outstripped our solar simulation software. Our system is comprised of three fields (West, South, East) on two hydraulic loops (W-S, E-S) and multiple tanks. That situation could not be simulated exactly with our design software.”
Chris Mast, president of mechanical contractor Mast & Brunk, adds: “The issue of over-temperature mitigation is significant. A fan-coil unit for removing excess heat was considered during design planning, but has not been implemented as of yet. Currently, a solenoid drain-off valve is used to dump excessive hot water.”
The system was installed over the course of five months to avoid conflict with the dorm residents during the school year. The system started testing in spring of 2010, and was commissioned for service that July.
Mt. Crawford, Va.-based Mast & Brunk, which has worked with EMU and The Troyer Group on various projects for nearly 17 years, installed the 25 Sunearth EC40 panels for the indirect glycol system in about two days with a team of four to five men, says Mast. Mechanical systems installed in the dorm include: PAW pump stations; an AIC double-wall, brazed-plate heat exchanger; and two 500-gallon storage tanks arranged as pre-heat to three A. O. Smith Cyclone 90+ AFUE water heaters to supplement the solar domestic system. The system is operated and monitored remotely through a RESOL-based control system. A Mitsubishi City Multi VRF heat pump system is used for space conditioning.
“We designed the system expecting to replace about 50% of our natural gas requirement for domestic hot water production,” Kurtz remarks. “While the current payback is not very attractive because of today’s gas prices, we expect this system will be a valuable long-term investment that will eventually pay back. Not many years ago we were spending 4-5 times what we are currently paying for gas. Measuring the output of the solar system is essential since we’re billed on the basis of production.”
Sustainable stewardsAs part of the LEED certification process, Eastern Mennonite University worked with QA Graphics to develop an Energy Efficiency Education Dashboard for use in the Cedarwood residence hall. “We chose to do the building information display in the lobby as an educational tool for students and visitors,” Kurtz says. “We received an innovation credit for the display.”
The EEED is an interactive application designed similar to a website, which students can conveniently view online or on the lobby’s interactive display. They can learn about the campus’ sustainability initiatives by viewing the residence hall’s real-time energy and water use, as well as information about what makes the new building environmentally friendly. An animated demonstration illustrates how the solar panels help heat more than 50% of the building’s hot water.
Through this education, students and visitors can better understand how they too can be more sustainable and help make the campus more efficient. For example, more than 85% of Cedarwood’s construction waste was sorted and recycled, and some of the green features in the building include natural daylighting, low-flow water fixtures, reflective roofing, low-VOC adhesives and finishes, flooring made of natural and recycled materials, Blue Storm electric hand dryers, T-5 fluorescent lighting with motion and daylight controls, a bio-retention filtration system to manage stormwater runoff (which EMU received a grant for from the Virginia Department of Recreation and Conservation), and a bike shed with a student-designed, “green”-landscaped roof of thick soil and sedum plants.
In 2010, the university had another first as it installed the largest solar energy installation in Virginia on the roof of the Hartzler library (more than 100 kW). By last September, the array had exceeded its estimated output by 12%.
While solar thermal in Virginia is not on the same scale as the West Coast and Northeast, Mast believes that solar thermal installations will naturally gain ground along with solar photovoltaic installations.
“Because of equipment costs and the tax implications of depreciation, it takes both state and federal grants as well as power purchase agreements to formally take these projects from the conceptual stage to reality,” he explains. “When these elements all come together, it is a beautiful thing and makes all the sense in the world from the financial side.”
The solar thermal system installed at EMU’s Cedarwood dorm is providing high performance, high capacity and energy savings for the university, Mast says. Rosenberger agrees, noting it provides 50% to 70% of the dorm’s hot water needs during the school year, and nearly all its hot water during the summer when the dorm is used for conventions and sports camps.
“Production of the system has outperformed our expectations. In fact, we need to find more ways to use excess capacity in the summer when the dorm is not always filled,” Kurtz remarks. “We at EMU feel that implementing these types of sustainable initiatives is an environmentally responsible approach that saves money in the long term, while immediately signaling our commitment to sustainability to our students.”