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Classroom Utilization Studies Prove Energy Savings Potential of Events2HVAC

Mar 22

Written by:
3/22/2018 9:04 AM  RssIcon

Many colleges and universities strive to achieve 67% classroom utilization during the core hours of 8 am to 5 pm, Monday – Friday. Which means classrooms must be used for 30 hours of the total 45 hours/week (Classroom Use and Utilization, APPA, p. 12). Even if they achieve their goal, classrooms are empty and running HVAC at occupied settings 33% of the time. But most of them fall short of the 67% mark, making their potential savings with Events2HVAC schedule integration even greater.

Consider this 2016 study by the State of North Carolina that summarizes classroom utilization for public universities, community colleges, and private universities in North Carolina. They determined the average weekly room hours of instruction in classrooms on each campus and summarized the results in the following table.

 

 

The study states that the University of North Carolina standard is 35 hours of instruction per classroom per week, or 77% utilization (p. 20). According to the table above, the UNC campuses were well short of that goal in 2016 with an average of just 23.3 hours of instruction or 52% utilization. The North Carolina community colleges and private colleges fared much worse, averaging 10.9 hours (24% utilization) and 12.3 hours (27% utilization) of instruction per classroom per week, respectively.

If the average classroom at UNC is occupied 52% of week, that means it is empty 48% of the week – yet it is still running HVAC at occupied setpoints. Setting HVAC back to unoccupied setpoints between classes is generally not done because it is too labor intensive to schedule each individual classroom in the HVAC controls. Instead, facility managers typically schedule HVAC based on daily building schedules, and many college and university buildings are not set back to unoccupied setpoints until 9 or 10 pm.

Some colleges and universities are trying to use occupancy sensors to control HVAC. But occupancy sensors cannot predict occupancy – they can only react to it. Therefore, rooms are often uncomfortable at the start of classes and events; and HVAC is often triggered by a person acting alone rather than a scheduled event. Do you really want to heat a 300-seat auditorium for 2 hours because a single student sits down to study between classes?

Events2HVAC solves these problems by integrating room scheduling systems (EMS, Ad Astra, CollegeNet R25 and 25Live, etc.) with HVAC controls to automatically return HVAC equipment to unoccupied setpoints between each scheduled class. It includes pre-start times for each zone, so rooms are always comfortable when classes and events begin – and HVAC will not be triggered by unscheduled use of a room. Events2HVAC is a simple Windows-based software application hosted on campus. It saves energy without sacrificing comfort, and eliminates the need for exception schedules for holidays and weekends.

Let’s take the UNC data and determine the potential runtime savings. Runtime savings is the number of room-hours the HVAC equipment would be returned to unoccupied settings with Events2HVAC.

If HVAC is scheduled 8 am-5 pm, Monday-Friday (45 hours total), and classrooms are empty 48% of the time, then you have runtime savings of 21.6 hours per classroom per week.

45 hours of HVAC/week x 48% empty room = 21.6 hours/classroom/week runtime savings

Multiply that by 52 weeks, and you have 1,123 hours of runtime savings per classroom per year for HVAC equipment.

21.6 hours/classroom/week runtime savings x 52 weeks/year = 1,123 hours/classroom/year runtime savings

But many college classroom buildings are run longer into the evening; and classroom utilization generally goes down in the summer months too.  Therefore, 1,123 hours of HVAC runtime savings per classroom per year is probably a conservative figure for UNC.

For example, if the building schedule is 6 am-10 pm, then HVAC is running 112 hours per week. If a classroom is used 35 hours per week (UNC standard), then HVAC is running in an empty room 68% of the time, and we can calculate runtime savings with Events2HVAC as shown below.

112 hours of HVAC/week x 68% empty room = 76 hours/classroom/week runtime savings

76 hours/classroom/week runtime savings x 52 weeks/year = 3,952 hours/classroom/year runtime savings

Building schedules will vary across campus. Some will run closer to the first example, while some will run closer to the second. Most of them will probably fall somewhere between the two examples. Depending on the pre-start times set in Events2HVAC for each event, consecutive use of classrooms, and other factors, a campus may lose 10-15% of that runtime savings. But when you consider all the classrooms on campus, you can quickly see why universities that are using Events2HVAC report significant energy savings, such as $1 million/year at Minnesota State University Moorhead. (See MSUM Case Study.)

In case you are thinking that North Carolina universities and colleges have particularly low classroom utilization rates, here are some similar studies from other universities:

  • Space Utilization and Optimization, University of Colorado Boulder, 2014 (p. 15, classroom utilization 43%)
  • Instructional Space Utilization, Purdue University, 2015 (p. 1, classroom utilization 59.7%)
  • University of Oregon Classroom Space Utilization Study, 2017 (p. 1, classroom utilization 78%)
  • University of Washington Learning Space Assessment, 2014 (p. 85, classroom utilization 54%)
  • Arkansas State University Utilization and Space Needs Analysis, 2012 (p. 14, classroom utilization 53%)
    • Looking at the studies above, the University of Oregon is the big winner with 78% classroom utilization. But even that high number leaves HVAC running in unoccupied rooms 22% of time. If they used Events2HVAC to integrate room schedules to their HVAC controls, they could save a significant amount of energy and money – and eliminate the need for facility managers to manage HVAC building schedules or set exception schedules for holidays and special events.

      I have been examining classroom utilization data because it’s easy to find. But Events2HVAC is also used in student unions, event centers, K-12 schools, churches, government agencies, and corporate conference rooms. See energy- and labor-savings results from several of these in our Case Studies.

      Any facility or campus that has rooms with varying schedules can benefit from Events2HVAC.

      If you would like to schedule a demo of Events2HVAC or receive a proposal for your campus, please contact sales@events2HVAC.com or call (888) 320-4277.

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Founded in 1998, Streamside Solutions provides software products, solutions and services for the building automation industry.


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