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As you may have noted, the main factor in what makes one of these Alternatives pay for itself over the other, is of course the equipment that’s selected and, of course, the cost of said equipment. The factor that, mathematically speaking, makes the largest impact is actually the building load profile. For instance, if these chillers were hooked up to some processed load that was the same, 24 hours a day, 7 days a week, 365 days a year - if they were running on a load like that, we might actually want to create the custom load profile, which we actually can do. We go to “actions” and “modify load profile.” We have our monthly loads, and this is our cumulative ton hours per month, and our heating load per month, but we can go to our hourly loads, and we can go ahead and change one of these at a time, and the way that chiller plant analyzer works with the day types, there’s not actually 8,760 hours in a year, which would be 24/7/365. There’s actually 1,440 data points here.

The explanation of that is covered entirely in our Trace 700 course. It’s probably something that you don’t necessarily need to know, but what we can do is export from here. We can export our hourly loads and our monthly loads. Of course, the monthly loads are basically the integration of the hourly loads, so the hourly loads is really where all of the data’s at. We can go ahead and we can add the hourly load. We can add some tons - say, 50 tons this hour or something like that. We can increase the load that way. Or we can decrease the load, and that will actually impact every single hour of the year. In my opinion, editing this way is sort of useless. If you really want to get into the nitty-gritty of it, you’ll actually want to import from Excel.

In order to import from Excel, you probably want to take one of these and export to Excel first, so that you have a template that you can edit and you export the hourly loads, and then you can import that from Excel once you make your changes. It’s not something that we really need to do right now, because I don’t have a specific example to give you. However, if we did that, and we have a chiller that ran at 1200 tons year-round, we might very well find that the single large chiller uses less energy over the duration of the year than the two smaller chillers operating in Series or Parallel - I suppose that would be the same thing - Series or Parallel, if they were indeed operating at full, 100% operation.

In reality, if they were running at 1,000 tons on 1,200 ton capacity, that would also change things, because we would be at a different point on the unloading curve. To get the math exact, if you’re running at 1,000 tons year-round, that’s 83%. We can look at the graph here. At 82%, we’re at approximately 80% of the full power, so we gain slight efficiency at that exact placement.

Now, if we had two chillers operating at 500 of 600 tons, of course that comes out to be the exact same in terms of the math, and in such a case, the cost, among other factors, would be important. But, the load profile, again, has the biggest impact on our net energy, and it works based off of these unloading curves. This data is typically determined in a lab by the chiller manufacturer. We also have the ambient relief curve. This just has to do with the ambient temperature, and how of course when it’s colder outside, the chiller operates more efficiently because the cooling tower delivers cooler water.