LEED® Silver Student Housing Benefits from VRF Zoning Capabilities, Controls Network

The state of California is home to some of the most demanding energy standards in the nation. The standards dictate improved energy efficiency, enable demand reductions during peak periods and allow for future technologies to enter the market. The Suites on Paseo (Suites), San Diego, is a new student housing complex that followed these standards, resulting in LEED® Silver certification and 287 very comfortable students. Variable Refrigerant Flow (VRF) zoning technology from Mitsubishi Electric US, Inc. Cooling & Heating Division (Mitsubishi Electric) played a large role in meeting the state’s standards.

Challenge: Selecting an HVAC system that could meet the demands of both California’s tough energy standards and local students’ high expectations.

Suites serves San Diego State University students and was developed by Village Lindo Paseo, LP (VLP). The Preiss Company (Preiss), Raleigh, North Carolina, operates the complex, managing its three adjoining buildings and 98,000 square feet of space. VLP wanted that space to be not just energy efficient, but energy efficient enough to merit LEED certification from the U.S. Green Building Council (USGBC). To achieve this lofty goal, VLP called in TTG Engineers (TTG), Pasadena, California.

Edgar Pagdanganan, mechanical department manager, TTG, guided the energy conservation effort. His recommendation: VRF. Pagdanganan said, “I was working in Singapore 14 years ago and I discovered this remarkable VRF technology that was popular in Asia long before it came to the U.S. There is no conventional HVAC system today that can touch the energy savings of VRF zoning systems.”

The California Center for Sustainable Energy (CCSE), San Diego, was called in to advise on a VRF-based HVAC design that would support the goal of LEED certification. Michael Bigelow, LEED certification specialist and owner of Bigelow Energy, LLC, Las Cruces, New Mexico, worked for CCSE at the time. Bigelow said, “I was thrilled to discover VRF engineering from Mitsubishi Electric. The technology is impressive for its energy-conserving design. Instead of the fans running 24/7 like a conventional HVAC system, they run only when students call for cooling or heating.”

Pagdanganan agreed that Mitsubishi Electric VRF was the right choice for the job. “Mitsubishi Electric is an industry leader in this technology,” he added. He was particularly impressed by the system’s independent zone control, small footprint and reduced number of outdoor units. Pagdanganan also noted Mitsubishi Electric’s “excellent tech support.”

With the system specified, installation began and quickly finished. The startup was easy and “even the commissioning of the system went rather quickly,” said Lee Rich, building maintenance supervisor, Preiss. Rich also referenced the simple maintenance since installation: “Every three months, I clean the washable filters, coils and squirrel cage in all of the indoor units. This is part of our preventative maintenance program. I like this Mitsubishi [Electric] system because it is user friendly and easy to maintain. Everything works well and I have had very few complaints from the students here.”

The system’s smooth operation is also due to the advanced controls network. Suites has 300 separate zones across its three buildings, all controllable from a central computer. Rich said, “From the computer in my office, my Mitsubishi Electric controls network allows me to override every single fan coil on this property. That’s impressive.”

Solution: A VRF system from Mitsubishi Electric offered impressive energy savings and unprecedented levels of operational control.

Rich said Mitsubishi Electric’s controls network is ideal “not just for daily student comfort but for handling energy alerts,” a component of meeting the state’s energy codes. The new HVAC system receives alerts directly from the utility company and can be set to notify the manager or respond automatically, enabling a more effective and environmentally friendly use of energy. He added, “During such an energy alert, I like the fact that I have total control of the entire system.”

For Suites, total control translates into significant energy savings. Bigelow worked with several simulations during the design process, comparing potential options to a baseline as part of LEED certification. Bigelow said, “Without the onsite generation from solar PV and fuel cells, our design was 32 percent more cost efficient than the baseline. When we look at just the cooling system, including the fans, the system provided a 40 percent annual kWh savings. This foundation allowed our all-in design to beat the baseline by 46 percent, which got us 11 out of 10 LEED points in the v2.2 system. Yes, there’s a bonus point in there.”

Such energy savings and overachieving, a mark of Mitsubishi Electric’s VRF zoning technology, will make Suites a comfortable, healthy place for students to live for years and years to come.