Ventilation and VRF for Multi-functional Campus Buildings

Set to officially open in July 2018, George Mason University’s Global Center is the home of INTO Mason, a language and academic preparation program designed for international students. Originally a hotel, the seven-story, 102,000-square-foot space houses 270 students year round, hosts a full-service dining facility as well as classrooms and administrative offices. Now that the former hotel rooms have turned into dorm rooms, the school is putting the final touches on the academic spaces. As with any educational space, ensuring the proper amount of outside air and student comfort was critical to the building’s renovation.

GMU selected Mitsubishi Electric’s CITY MULTI® Variable Refrigerant Flow (VRF) technology and PremiSys Fusion DOAS for its cooling, heating and ventilation needs. We spoke with the project’s contractor and HVAC engineer who explained why these systems were the right choice.

Why CITY MULTI VRF?

“We knew that zoning was going to be optimal for a building like this with both offices and classrooms. Mitsubishi Electric is also the only brand that could easily accommodate future HVAC additions. With their two-pipe system, it’s easy to attach another unit to the branch controller box in case the school wants to expand in the future. Other brands using three pipes don’t offer that. In addition, for this project, the previous hotel was LEED certified, and using Mitsubishi equipment made it easy to maintain that certification.”

Why PremiSys Fusion?

“The building originally had a dedicated outside air system (DOAS) but with VRF’s efficiencies, it ended up being oversized.The PremiSys Fusion unit was also ideal for meeting the Virginia Energy Code for educational facilities. We used one PremiSys Fusion DOAS unit for the administrative spaces and will use another for the classrooms. Using this unit actually reduced the amount of ductwork needed.”

Why CITY MULTI VRF?

“The school already had a lot of Mitsubishi Electric equipment in other buildings so it makes sense it was specified here as well. VRF is very quiet which is why it works so well in the classroom especially compared to VAV boxes or fan coil units…the noise levels are low. Aireco was especially helpful in getting us started with the CITY MULTI equipment for this job as well. They’re cost-effective and friendly.”

Why PremiSys Fusion?

“There are two reasons why the PremiSys DOAS works well for this kind of project. It has the same controls platform as the VRF system and can be tied to the front-end interface unlike if we were to use a different brand’s DOAS system. Secondly, these units are extremely energy efficient. With PremiSys, there’s an energy recovery wheel. Instead of using 100 percent outside air, the system brings in exhaust air and mixes it with outside air which is then used by the outdoor unit. This allows for efficiency and humidity control.”