If you have been a regular blog reader of ours, you might recall the August 2019 post I wrote about NRCan Existing Building Commissioning (EBCx) fund approval for Toronto General Hospital (TGH) and Toronto Western Hospital (TWH). It’s been almost two years, and I have an update for you. The investigation phase is complete, some of the recommendations have already been implemented, and the rest will be carried out gradually.

Environmental Stewardship, including the efficient use of energy, water and other resources, has been part of the UHN for over 20 years. The Energy and Environment (E&E) team of UHN has taken a lead in continuously improving mechanical systems from an energy efficiency standpoint: managing energy saving retrofit projects, ongoing retro-commissioning, BAS control upgrade and scheduling, and in general, lowering UHN’s carbon footprint.

Retro-commissioning and BAS upgrades are an ongoing mission of the Energy and Environment team. Our experienced internal BAS experts do this kind of work, though for large-scale EBCx projects, we typically hire a third-party consultant. As such, led by E&E, UHN retained two consulting firms to collaborate with in-house operations staff to complete the recent studies. 

The initial scope of the EBCx for both sites was very broad, including different mechanical systems, the district steam supply system from Enwave for TGH and detailed Air Handling Units (AHU) study for both sites. Due to budget limitations, we had to exclude the Enwave steam system study from the scope and narrow down our AHUs to 10 per site. This sample of AHUs illustrated the overall condition of AHUs in the building. Even after revising the scope, the project cost still came in almost 25% higher than expected due to some unforeseen challenges such as a global pandemic.   

Energy and Cost Savings

The study pertained to HVAC Retro-Commissioning at Toronto Western Hospital and District Energy Retro-Commissioning at Toronto General Hospital. The total investment for these two studies has been more than $170,000. By implementing the recommended measures, we expect a minimum energy cost savings of $280,000 for TGH and $70,000 for TWH. The potential energy saving, GHG emission reductions and simple payback for each site would be as follows:

*only 10% of chiller potential savings counts as an RCx saving and the rest counts as a major capital investment project


The World Health Organization (WHO) has recognized climate change as the greatest threat to human health in the 21st century. Energy management plays a key role in mitigating the causes and impacts of climate change. The majority of the identified measures in the EBCx study improve the performance of energy use within the hospitals, so they will have a positive impact on global warming and the health of all Canadians. Below are the other benefits of this project:

  • Reduced utility costs, allowing funds to be spent toward other initiatives in the building portfolio/healthcare.
  • Increased comfort level for building occupants and tenants.
  • Improved day-to-day operations; reduced service calls brought about by under-performing and inefficient systems that require high levels of reactive maintenance.
  • Improve performance of Enwave cooling and heating system.

Currently, some buildings at Toronto General Hospital have poor delta-T on chilled water. We must operate a chiller to boost temperatures to meet Enwave requirements. By implementing the identified measures in the chiller study, we can improve delta-T to reduce the operation of the chiller and save electricity. We may also be able to reduce overall cooling demand by reducing simultaneous heating and cooling. Since Enwave operates steam-driven chillers in the summer, this could contribute to reducing GHG emissions.

Lessons Learned

One of the most important lessons learned throughout this project is to be as detailed as possible in defining the scope of work from the initial stage of the project, especially when hiring a consultant for the investigation phase. Always clearly outline each party’s responsibilities and expected outcome of the study in terms of the level of details, the accuracy of the results, saving calculation method, etc. You may get very high-level recommendations from the consultant which can be found through a simple Google search if you do not define the scope and the expectations of the result properly.

Another item to keep in mind is that the system owner typically has the best knowledge about the system, how and why it works this way and the history of issues. Transferring this knowledge to a third-party consultant for investigating the root cause of the existing issue is a time-consuming effort. Depending on the situation, it might be more beneficial to work internally rather than hiring a consultant. 

In the end, I would like to thank NRCan for providing the EBCx study funds and my E&E team collaborators for their support.