Father Michael McGivney is a winner
Two high schools located north of metro Toronto: both are roughly the same size of building; roughly the same number of students. Both schools should consume roughly the same amount of energy each year to heat and cool, but they don't.
Father Michael McGivney High School uses almost half the energy of the other facility in the York Region Roman Catholic Separate School Board, and pays $10,000 a year less in annual energy costs.
One hundred and ten earth energy units are coupled to the ground through 45 km of pipe (360 vertical boreholes, each of which is 70 m deep). A mixture of water and methanol is pumped through the array by two 50-HP circulating pumps, and extracts sufficient heat from the ground to warm the 2,400 students, faculty and staff in the 17,000 m² building. Ninety of the units are water-to-air modules for heating air; the other 20 are water-to-water modules for heating water. Total capacity is 1,400 kW (rated at 410 tons).
Just a few kilometres away, Holy Cross High School was opened three years earlier with 350 m² less space, but that building consumes 4.3 million kWh of natural gas and electricity each year ... compared to 2.5 million kWh at the earth-coupled McGivney. While Holy Cross burns more than 220,000 m3 of gas in boilers to heat its classrooms and water, and uses chillers and a cooling tower to provide air conditioning during the summer, McGivney uses the school's playing field as a giant solar panel to supply heating and DHW requirements and to meet the cooling load in summer.
On a yearly average, McGivney consumes the equivalent of 19.6 kWh of energy per square foot of space ... compared to 24.2 kWh at Holy Cross. The average energy consumption throughout the entire York Region RCSSB is 29 kWh/ft²/year.
Conventional heating systems in most high schools consume about 2.22 kWh/m² per year, but the McGivney installation uses about 1.3 kWh/m²/a. With annual maintenance costs of $1.40/m², this ground-coupled heat pump installation had a simple payback of less than five years.
It is never inexpensive to provide space conditioning system in a Canadian school, regardless of which energy source is selected. Total cost for McGivney was $2.6 million, but a conventional heating/cooling system with boilers and chillers would have cost $2.5 million, with an additional $225,000 in construction costs to raise the height of the ceilings.
The earth energy units are located in the ceiling space above the classrooms, which allowed the School Board to shave 600 m² from the space for the school's mechanical room, thereby maximizing the grants from the provincial Ministry of Education.
"These sheets are made possible through a contribution from Natural Resources Canada."