Energy Management Information System Helps McGill University Cut Down On HVAC Energy Usage
One of the first steps taken by McGill to cut down on HVAC energy use was implementing an energy management information system.
The intent behind the EMIS was manifold: 1) monitoring improvements in day-to-day building operations; 2) documenting savings generated by the different programs of the plan; 3) prioritizing energy conservation measures based on savings potential. Documenting savings was a condition made by McGill’s administration to back up the plan. The different energy conservation measures are funded through a loan; energy savings, benchmarked against consultants’ estimates and measured with the EMIS, are used to repay the loan over amortization periods determined by McGill’s accounting department.
In 2010, the university invested $3 million to install close to 400 meters to monitor in real time the energy demand of the main buildings on campus. Three years later, 50 percent of the building portfolio is now monitored, amounting to 80 percent of the university’s energy consumption.
McGill also deployed a software solution to collect and organize meter data. Users of the software can plot energy demand against external factors (outside temperature and humidity, wind speed and direction, net solar radiation, etc.) as well as generate reports to track energy savings. The monitoring system also has the capacity to establish baselines and typical curves based on historical data, thus making it easy to track savings and pinpoint inefficiencies in real time.
The last component of McGill’s energy management information system is a multi-disciplinary team of experts. The team was set up to investigate inefficiencies detected by the monitoring software. For each case investigated, the team proposes a corrective solution to quickly solve the problem, and a preventive solution to prevent the problem from occurring again.
The team consists of staff from two units — utilities and energy management plus building operations — and includes energy managers, HVAC managers, control technicians, building op to quickly solve the problem, and a preventive solution to prevent the problem from occurring again. The team consists of staff from two units — utilities and energy management plus building operations — and includes energy managers, HVAC managers, control technicians, building operators, and unit directors.
When initially set up in 2010, the team started on analyzing monitoring data every second week. At that point, the team was striving to reduce the number of systems operating 24/7 on campus and adapt HVAC hours of operation to the actual use of the buildings. Three years down the road, the HVAC operations of more than 40 buildings have been reviewed; 18 have been modified so far with annual savings of $180,000.
In 2011, the team investigated a strange case. The University’s bookstore consumed as much steam in the summer as in the winter. What’s more, there was no correlation between steam demand and outside temperature, but, surprisingly, a clear correlation between steam and rainfalls could be seen.
After analyzing the control sequence of the system, it appeared that this building was using free cooling in the summer months. However, the trigger was on dry-bulb outside temperature only. As a consequence, during cool but humid days, the intake air enthalpy was actually greater than the return air enthalpy, thus forcing the system to cool the air and then de-humidify it using a steam heating coil. The problem was solved by installing an enthalpy sensor and controlling free cooling based on outside enthalpy instead of dry-bulb temperature only. This measure, together with a review of the HVAC system operation hours, resulted in savings in steam cost of more than 60 percent per year.