University of Northern British Columbia


Prince George, BC

UNBC is a leader in the post-secondary sector in terms of commitment and action towards energy management and sustainability.

A significant contributor towards this statement is that of the central campus bioenergy heating system which offsets natural gas consumption and lowers greenhouse gas emissions significantly. However, when this bioenergy system was integrated with the existing natural gas fired central heating plant, limited consideration was given to how the two heating plants (bioenergy and natural gas) would interact with one another from a controls perspective.

Prism reviewed the existing system and developed a strategy for improved control of the campus heating plant that allows the bioenergy plant to contribute as much as possible to campus heating.

After an extensive review, we identified several recommendations and prepared a new sequence of operation for control.  In summary, our recommendations included:

  • Resetting campus heating hot water supply temperature setpoint;
  • Using historical performance data to determine whether bioenergy can meet the load alone, and if so, allow the campus heating loop more time to give bioenergy a chance to meet the load;
  • Limiting the rate of change of return water temperature to the biogas boiler;
  • Establishing a low limit for return water temperature to the biogas boiler;
  • Installing a bypass around the natural gas boilers;
  • Adjusting the trip limits on the Nexterra bioenergy plant, and;
  • Increasing cleaning frequency of biogas boiler.

UNBC is currently in the process of reviewing and implementing these changes to improve the effectiveness of their campus bioenergy heating system.