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Making the grade – A look at Sheridan College’s district energy system

August 14, 2023 – Creating a sustainable energy system to heat, cool, and power an entire college campus is no easy feat. With the goal of lowering campus energy and GHG emissions by half, Sheridan College launched its Energy and Climate Master Plan in 2013.

The college understood it would have to transform its heating and cooling system to help meet those objectives. Sheridan looked to the Trias Energetica model—first developed in 1979—as a guide to developing a sustainable energy system that integrates heating and cooling functions and recovers energy that might otherwise be wasted.

“We wanted to position Sheridan as a role model on sustainability and follow best practices. This ties into our educational mission as well,” said Herbert Sinnock, Sheridan’s director of sustainability.

After an evaluation of the HVAC infrastructure in existing campus buildings, the college realized that the most effective way to make its heating and cooling operations more efficient was to install an entirely new system, using a district energy model, starting at its Trafalgar Campus in Oakville, Ont.

Implementing district energy

Sheridan began constructing its third-generation district energy system in the summer of 2016, burying 3.5 kilometres of pre-insulated pipes that carry pressurized hot water across the campus from a central plant to every building. Sinnock notes the pipe network is not installed very deep in the ground, which made it quick and easy to install.

The pipe systems come with integrated leak detection, helping operations teams quickly identify any problems to ensure the system operates at peak efficiency.

Reciprocating heat and power engines, installed in 2017 and 2018, generate baseload heating for the system, along with a modest amount of electricity. Supplemental boilers provide additional temperature lift on very cold days.

Centralized delivery uses less energy than a distributed system with separate boilers in each building. In the summer, the engines’ heat can be sent to an absorption chiller that feeds the chilled water network to several campus buildings.

Heat is transferred from the system’s primary loop to each building’s secondary heating system through a Danfoss energy transfer station. The ETS is an interconnected system of heat exchangers, valves, pumps, programmable controller, metering and piping that draws heat from the primary loop of pipes outside each building to control and feed the building’s secondary heat network.

A pressure-independent control valve on the primary side of the ETS ensures the heat exchanger operates efficiently, using an outdoor temperature sensor to modulate the heat transfer process for each building while allowing each building’s heating system to operate independently.

The ETS is a key component of the district energy system because it contains automated controls that provide continuous digital metering, and can monitor and adjust to the demands of the building, controlling critical temperatures and working to maximize the combined efficiency of the primary loop and the buildings.

A customized approach

In 2019, Sheridan began a three-year project to decommission a nearly 50-year-old steam plant serving six of its Oakville buildings, replacing it with the new hot water district heating system.

A steam-to-hot-water conversion requires replacement of all steam-generating equipment with a completely new system. That meant that the campus buildings would potentially be without heat during the installation period. Sinnock noted that while it was a challenge to coordinate both contractor schedules and the school’s academic calendar, the installation went smoothly.

Because each ETS arrived ready for start-up with factory-configured and pre-tested controls, they were able to control the heat exchange between the primary loop and the building upon first start. This meant that the period when buildings would be without heat could be minimized, and multiple buildings could make the transition to the new district energy system in quick succession.

“It only took a couple of hours per unit to start up the system,” said Sinnock. “The pre-programming and pre-testing helped make the transition seamless.”

Leading the community

Ultimately, the increased efficiency and decreased system operating temperature will lower the college’s carbon emissions, with the potential to contribute to decarbonization throughout the community.

Sheridan’s district heating system creates an energy network where heat can not only be recovered and reused within campus buildings, but can be recovered and supplied to buildings in the larger community.

At some point, Sinnock envisions connecting the college’s energy system to a larger municipal district energy network and sharing heat with multiple buildings in the community.

“We are excited to integrate and maximize our district energy architecture,” said Sinnock. For example, a local ice rink would be able to provide excess heat, as can the college’s glass-blowing studio.

“We wanted to be a community leader and educate others about district energy,” said Michelle McCollum, associate vice-president of facilities and sustainable infrastructure at the college. “When people see a district energy network in action, it becomes real. We are able to help make changes in community energy plans and embed a culture of sustainability.”

McCollum noted that a recent employee survey indicates that 95% of Sheridan employees are aware of the college’s efforts in sustainability and energy efficiency.

Achieving energy reductions

Sinnock admitted that reducing carbon emissions in heating is challenging, as is achieving a return on investment in system upgrades. Fortunately, Sheridan’s leadership and board of governors saw the value and supported the project.

Prior to the switch to district energy, the college’s steam plant was losing about 65% of the heat it generated. Following the conversion to the hot water system, natural gas consumption was reduced by 20%, which equates to an annual carbon reduction of 530 metric tonnes.

“We expect to see even more reductions in energy use and costs as we attach more buildings to this system,” said Sinnock.

— With files from Danfoss

Addendum: In 2021, Danfoss recognized Sheridan College as its 2020 EnVisioneer of the Year. Launched in 2010, the annual award competition recognizes North American OEMs, building owners, municipalities, contractors and end users that have introduced a new product, opened a new facility or invested in a building or system upgrade in the past 18 months using Danfoss products or solutions “to realize significant energy and environmental savings”.