New Chiller Plant Saves “Tons” of Energy at UHN’s Bickle Centre

With recent string of extremely high temperatures, it’s the perfect time to talk about how Bickle’s new chiller plant is saving us energy and improving reliability. For those less interested in the story and pictures, here are the cold, hard results:

  • Annual Electricity consumption savings: 647,000 kWh (equivalent to about 65 houses in Ontario)
  • Electricity demand savings: 188kW (equivalent to about 2,350 flat screen TVs running simultaneously)
  • Huge electricity consumption savings of 78% over the old chiller system!

Keep reading for more details and photos.

Old Chiller Plant

Similarly to the project at UHN’s Lyndhurst Center, Bickle still had the original chiller plant that was installed when the building was constructed in the 1970s. This plant was in poor condition, with the chillers typically requiring costly repairs at the beginning of every cooling season. The system was unreliable, inefficient, and ran so loudly that it disrupted the staff on the floor above. Here are a few photos:

In order to measure the performance of the older system, an energy meter was installed on each of the old chillers for a period of one month during cooling season to generate a part load performance profile. Spot measurements were done on constant speed equipment, including chilled water pumps and cooling tower fans. These meter readings were combined to produce an average power consumption of the plant for various outside air temperature (OAT) ranges.

old plant

Part Load Performance of Old Chiller Plant

New Chiller Plant

Key technologies employed in the new chilled water plant included chillers with magnetically levitated bearings, variable speed pumps and cooling tower fan motors, and new control sequences. Pumps and fans were also downsized where appropriate.

Chillers

The new chillers installed use compressors that have magnetically levitated bearings. A major efficiency gain is achieved because the system is frictionless (picture a hover board instead of a skateboard). Unlike Bickle’s new chillers, chillers with standard bearings need to be lubricated, which can eventually lead to oil migration into the refrigerant stream and fouling of the condenser/evaporator tubes. The new chillers also employ variable frequency drives meaning that the compressor motor can run slower, using much less electricity, at part loading.

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New Chiller

Pumps

The old cooling plant had one chilled water pump, one condenser water pump, and one standby pump with a convoluted valving setup to allow the standby pump to operate as a backup for either pump. To accommodate this, the original chilled water pump appeared to have been oversized, wasting energy. The new plant employs three smaller chilled water pumps (one per chiller plus one standby) and two smaller condenser water pumps. Even if a chilled water and condenser water pump failed, we would still be able to operate both chillers. The project also added a separate connection that could be used to to connect an external source of chilled water if power was lost for an extended period. In addition to these resiliency improvements, we added variable frequency drives (VFDs) on all the pumps so that they can ramp down at lower periods, saving significant energy.

Photos of the new pumps (left) and VFDs (right)

Cooling Tower

The new cooling tower is made of fiberglass instead of the standard galvanized steel. Fiberglass does not corrode and should provide a longer life expectancy than a standard tower. The tower has 6 smaller fans replacing the 4 large fans of the old tower. The 6 fans are controlled by a VFD to maintain condenser water temperature. The new control sequence resets the condenser water temperature lower when outdoor conditions allow to take advantage of higher chiller efficiency at lower condenser water temperatures.

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New Cooling Tower Being Hoisted Into Place

Plant Performance

As mentioned at the beginning of the article, the new plant runs using almost 80% less electricity to provide the same amount of cooling as the old plant. It is much easier to track the performance of the new plant over time because the chillers and pump/fan VFDs directly report power consumption back to our building automation system. The new part load performance is shown below (compared to the old plant):

old vs new

Part Load Performance of New Chiller Plant

As you can see, performance is especially strong during lower demand times when outdoor air temperatures (OAT) are mild. This is important because most hours of the cooling season tend to be at milder temperatures between 10-25C. We are also saving over 60% on power consumption during peak times. Power consumption is so low during the 10-15C bin because we are now automatically shutting down the plant at these temperatures, whereas the old plant did not have this control capability and was often left running over night or over the weekend “just in case” of high temperatures.

Note: The “Peak” kW is lower than the highest temperature range because it uses a Toronto Hydro formula that averages the peak over longer time windows that include lower temperature periods.

Thanks to the following people who made this project possible: Val Cadar, Angelo Suntres, Jana Jedlovska, Eoin Kane, Joe Angione, and Allan Wu!

 

Mike at Home: The Sequel

When Ontario is giving out free smart thermostats, you know it’s time for a blog! Most of my recent blog posts have been about projects at UHN, so this time I’m going to change it up and talk about a couple of neat technologies I’m using at my apartment to save energy. Both of these savings ideas were mentioned in my previous Mike at Home Blog, but these new technologies really help to put those ideas into practice in a convenient way. There are many ways to save energy at home, even if you are a renter like me!

Smart Thermostat

I already had a programmable thermostat which was helping to save energy, but I wasn’t able to maximize savings for a couple of reasons. One way I typically try to save power is by setting back the thermostat if I’m away for a weekend or longer vacation, however this often led to an uncomfortably cold temperature for a few hours upon return. When energy savings lead to discomfort it can be difficult to maintain the energy savings behavior and I may have been less consistent in doing the temperature set back as a result. With my old thermostat on the fritz, I took the opportunity to upgrade to a web-connected thermostat.

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New Thermostat (source)

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You down with DCV at KDT? Yeah you know me!

Whether you want to send a car to space or implement an energy project, you must measure and track results! One of the biggest things we do here at the Energy and Environment team is to measure and track project results because it gives us real world information that we can use to accurately evaluate similar projects in the future. This post is about the recently completed demand controlled ventilation (DCV) project at the Krembil Discovery Tower (KDT). This project follows in the footsteps of similar projects that we worked on with UHN Research at the Princess Margaret Cancer Research Tower (PMCRT). Since we had such good proof of concept results from PMCRT, it made for a much easier decision to proceed with the project at KDT. Let’s take a look at the project and results!

Here’s a preview of the savings for those that don’t have time for all the details:

  • Electricity Demand Savings: 310.6 kW (equivalent to about 630 window AC units)
  • Electricity Consumption Savings: 1,433,353 kWh (equivalent to 161 typical Canadian houses annual consumption)
  • Natural Gas Savings: 418,343 cubic meters (794 tons of CO2, equivalent to taking 169 cars off the road)
  • Utility Cost Savings: $241,337
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Krembil Discovery Tower (Image Source)

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The Sixth Sensor – I See Live People!

Looks like I might be starting a trend referencing old 90’s movies on the Talkin’ Trash blog. This time, with Halloween fast approaching, we are taking a spookier turn as we look at the recent stairwell lighting project at TRI University Centre.

6th sense quote

If you want to hear something really scary, Continue reading

Bike Like Mike

There is no better time of year than now to ride your bike to work (or to the gym, or to the grocery store, or just for fun)! Fresh crisp air and cool morning temperatures help to ensure you won’t end up a sweaty mess on arrival. Biking regularly can help you get in shape, feel better, improve your health, and it’s just plain fun! Check out this TED Talk about the awesome ways that biking can change you.

Bikeshare

I’ve been meaning to write a blog on biking ever since the large expansion of Toronto’s Bike Share system this summer. Continue reading

Taking a Megabyte out of our Energy Bills!

I never thought such huge savings would be possible from a replacement of a ten year old computer system, but here we are. Normally when I think of energy savings opportunities, I think of HVAC equipment replacements, Variable Speed Drive installations, improvements to control sequences, lighting upgrades, and even electric vehicles. So, when I spoke to a company that said we could achieve big savings by upgrading computer infrastructure I was intrigued.

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Spring Greening

Now that we are groggily emerging from our hibernation of sitting on the couch in a Snuggie and binge TV watching while eating cookie dough ice cream, it’s time to think about spring cleaning. On second thought, sweeping the garage, sorting old junk, and throwing mittens in a drawer sounds awful – let’s talk about spring greening instead! Here are a few tips for an energy efficient spring and summer: Continue reading