(apologies to Dr. M and practitioners of the Dental Sciences everywhere…it’s not you, it’s me…really)
In general, when it comes to knowing and not knowing stuff, most people would rather be in the know…however, there are more than a few things that…well, nobody really needs to know about…if you know what I mean.
During these dog days of summer, it’s more important than ever to stay cool. If you’ve followed this blog, you know air conditioning is one of the most energy-intense parts of a building, with lighting paling (dimming?) by comparison.
You can’t have sweaty surgeons or feverish patients, so cool we must. And while we cool, we’re always looking to save energy and reduce greenhouse gases at the same time.
Enter a made-in-Ontario solution called Deep Lake Cooling, which you may remember from posts by Chad and Mike. We’ve had it at Toronto Rehab, and now we’re chilling out with it at Toronto General Hospital! Thanks Cecille Agmata for bringing all the info together in one cool package …
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:
Keep reading for more details and photos.
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.
Part Load Performance of Old 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.
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.
New Chiller
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)
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.
New Cooling Tower Being Hoisted Into Place
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):
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!
A comfortable temperature is quite a balancing act, and a good thermostat is key. This is not even touching individual preferences … think how many arguments at home start with one person shivering while the other one sweats bullets ? 🙂
Old-school Pneumatic thermostats were widely installed in buildings over 30 years old. Pneumatics use the energy in compressed gases to make things move or work. Despite the fact that more and more projects have a centralized building automation systems, many buildings still rely on pneumatic thermostats to control individual heating, ventilation and air conditioning (HVAC) for individual zones to address the occupants’ comfort.
With energy efficiency standards continuing to improve and facility management requirements getting more detailed, pneumatic thermostats could not meet the demand.
Disadvantages of pneumatic thermostats:
Yikes!
It is not easy to convert a pneumatic controlled room to Direct Digital Control (DDC). It’s expensive and it’s disruptive to the people working in the area. In the last few years, wireless pneumatic thermostats emerged on the market and are a good solution for old buildings. They save installation time and cost.
For those interested in the nuts and bolts tech side, Wireless Pneumatic Thermostats (WPT) include an electric temperature sensor and convert the electrical signal to a pneumatic transducer. All signals are relayed to BAS via wireless router. With WPT, facility managers and building operators are able to know the details on how the rooms and floors are operating. Furthermore, energy optimization could be put in place with all these inputs.
Typical energy optimization includes:
BAS could now adjust the setpoint based on the condition of the occupancy.
With the information of room temp, setpoint and pneumatic pressure, duct static pressure reset can be implemented in the AHU control. Duct static pressure setpoint could increase when more rooms are calling for cooling.
And that should keep everyone more comfortable.
So, it was about a year ago that I started, after a 10-ish year hiatus, cycling to work again (aka re-cycling?)…and while I’m still not at the point of cycling around town for day-to-day living (I’m more of a walker) or hopping on a bike when travelling (aside from the occasional beach ride to get ice-cream), I have over the past few months collected a number of random thoughts and observations:
During our Earth Week extravaganza, we collected ballots filled out with people’s favorite Green Team Ideas and the bin fact that they found most surprising. Over the course of the week, hundreds of ballots were collected. Excitingly enough, 5 people joined the Green Team on the spot! Without further ado…
Speaking of bins, that brings me to my next topic: the waste stream. At UHN, waste goes through a specific process to ensure that it ends up in the right place. All of the hospitals have mixed recycling except for Toronto General (TGH) and Princess Margaret Cancer Research Tower (PMCRT) who have separated recycling. Mixed recycling is when all of the recycling goes in one bin. Separated is when there is a bin for metal/glass/plastic items and a separate bin for paper/cardboard products. Regardless, these bins are lined with clear bags so that recycling and garbage can be distinguished (Ed. 1 exception: TRI uses black bags in garbage).
Housekeeping collects the bags and takes them to the waste room where it is then picked up by waste handlers and taken to the loading dock. At this stage, it can look like recycling is being lumped together with the rest of the garbage. However, the clear bags allow it to be separated out again once it reaches the loading dock. It is important to note that heavily contaminated recycling will interfere with the sorting process down the line, so it must be considered garbage. This is why it is so important to throw your waste into the right bin.
At the loading dock, each bag is sorted into the appropriate bin or compactor. Depending on the site, and what kind of recycling it has, there may be many or few different compactors. For example, these photos taken at TGH, showcase many different recycling bins.
Below we have the general waste compactor and the organics bins. The bin with the yellow lining is an empty hazardous waste bin, about to be taken to a waste station near a unit. There are special processes for dealing with hazardous waste depending on what type it is (eg. biomedical, cytotoxic) and they are kept completely separate from the rest of the waste stream. From here the waste is picked up on garbage day and taken where it needs to go. To see the next stage, read our deep dive into waste streams.
I hope that a better understanding of the waste disposal process will help make UHN a greener place.
Happy recycling!
Now that the weather is warming up, it’s a great time to dust off your bike and ride. For many of our readers, there’s never not a good time to ride, even on the chilliest winter day. Good for you if you fall in that category.
Whether you’re hardcore or fair weather, we have something for you this BikeMonth.
Alex and Lisa on bike to work day
For everyone: Bike month always kicks off with “Bike to Work Day”, a day where we ride our bikes to work, and can enjoy a group ride and breakfast event at Nathan Phillips Square. Register to participate in Bike to Work Day at http://www.bikemonth.ca/biketoworkday and you’ll qualify to win 1 of 3 prize packs of $500 gift card to MEC and $500 voucher from VIA Rail!
For everyone: Online course to learn everything cyclists need to know about biking with confidence in Toronto. Topics include: equipment and bike fit, safe riding techniques, rules and responsibilities, interactions with others, choosing your route and more. Register here.
For UHN Staff: Live/in-person demo/workshop at Toronto General Hospital. Expert bike mechanics will provide an in-depth focus on up to two topics, identified in advance, such as fixing a flat tire, repairing a chain and/or crank, replacing or repairing brakes, or adjusting derailleurs. Bring your bike for hands-on learning. Register here
For everyone: Online course to learn about cyclists’ rights and responsibilities when interacting with others on the road in this interactive quiz-style workshop. Topics include: laws and fines that apply to both cyclists and drivers, sharing space with pedestrians and other road users, common misconceptions about turns, parking, passing, right of way and more. Register here.
For UHN Staff: Live/in-person session to learn about cyclists’ rights and responsibilities when interacting with others on the road in this interactive quiz-style workshop. Topics include: laws and fines that apply to both cyclists and drivers, sharing space with pedestrians and other road users, common misconceptions about turns, parking, passing, right of way and more. Workshop at Princess Margaret Cancer Centre. Register here
If you drive regularly, wanna do it smarter?
The Smart Drive Challenge is a free (we like that price) national program that teaches you to drive so you get better gas mileage. Not only will you save big bucks, your car will emit less of those nasty greenhouse gases which cause climate change. Bonus, it makes for a safer and smoother ride. SmartDriveChallenge.ca has online courses, tips and tools on smarter driving techniques, low and zero emission vehicles and alternative modes of transportation.
So, if you want to save fuel, money and reduce your greenhouse gas emissions, get with the program. Did we mention free?
And we can’t mention cars without a plug for carpooling and a plug for EVs (which requires an actual plug). 🙂
