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EWChillerPlant is the first in a series of EnergyWitness™
optimization modules. When optimizing a chiller plant you need to
work towards a goal—something you can measure and verify. Of course, that goal is to reduce energy
consumption and operate at the lowest
cost, but always maintain space comfort. EWChillerPlant provides
hourly operating costs for the chiller plant, each sub-system, and
each component—updated every 15 minutes. You can see exactly how well your plant operates
on a cost basis, and immediately
see the impact of control changes or other maintenance work.
Operators can move through time (1), and see data for each system and the entire plant (2).
Bypass flow (3), energy rates (4), and weather data (5) are shown. A tab (6) switches
the view to show the underlying models. Gauges show total cost in $/hr and $/ton-hr (7). |
Chiller Plant Cost Speedometer
The first of two views of the chiller cost data is the cost
speedometer. It provides a summary report of the hourly cost of
operations for the whole plant and each major sub-system (chiller,
cooling tower, etc.). The system recalculates each cost every 15
minutes based on the plant's operational data for that interval.
The speedometer also supplies unit-based measurements (kW/ton,
$/ton-hour) that provide additional at-a-glance
information. For example, two identical chillers running at very
different costs/ton may point to an issue that needs attention, or,
if running gas and electric chillers you can instantly see which is
more cost effective on a per-ton basis.
The Cost Model
Each facility's plant is different, and so EWChillerPlant is
configured for each installation. IDS works with each client to
build the model in Excel using a template. This ensures the model is
a complete and accurate representation of the plant. The models
account for every piece of equipment from chillers and cooling
towers down to fans and pumps.
Models include a series of engineering calculations, such as
chiller efficiency, evaporator BTUs, condenser BTUs, motor brake
horsepower, motor energy, steam energy, make-up water BTUs, and
more. The cost calculations are then based on the client's utility
rates, taking into account on/off peak rates and changing fuel
prices. Each calculation not only drives the speedometer, but is
saved as historical trend data.
Historical Cost Trends (and other calculations)
Powering the snapshot view of the speedometer is a complete
set of trends. Each value displayed in the speedometer report, every
equation in the underlying Excel models, and a few other
calculations made along the way, are all stored in
EWDataWarehouse, providing
historical trend data for all the engineering formulas and operating
costs.
Cooling tons output shown at 15 minute intervals for each chiller.
In this case, chiller 1 (green line) is well below its rated
capacity. |
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The cost/ton calculation shows, in this case, chiller 1 (gas,
light blue) costs about 35% as much to operate as chillers 2, 3,
& 4 (electric, dotted) during peak hours. |
You view and interact with these trends in EWViewer, just like
any other data points. Combine them with any other data from the
warehouse. Move through time. Easily see daily/weekly/monthly
patterns. Use them within your diagnostics and monitoring efforts.
That's actionable information! And once you do take action, you'll begin to see at the
next 15 minute interval how you've affected efficiency and cost.
That's right, immediate feedback on how control changes,
maintenance, etc. affects operating cost.
Speedometer tab showing systems that make up the plant, and property box showing
equipment details for the item selected in the data tree (a York gas
chiller). |
A data tree tab is devoted to the speedometer calculations. Each
site will be unique based on the equipment configuration and building
automation system(s). In the example on the right you can see
folders for each chiller, cooling tower, secondary pumping system,
and the total plant. Available trend calculations within each
include items such as pump brake horsepower, efficiencies, flows,
tons output, cooling tower fan kW, cooling tower makeup water, and of course, costs.
Hourly operating cost data exists at three levels—the chiller
plant total cost, a total for each system within the plant, and
finally at the component level. For Chiller 1 you can see hourly
costs for the chiller engine, chilled water pump, and condenser
water pump in addition to the total for that chiller..
The Power to Optimize
It's a whole new way to monitor, manage, and optimize your
chiller plant. Engineers don't have to spend hours or days
collecting the underlying data and running spreadsheet calculations
(although if you do have some favorites we don't cover, you can drop
the data into Excel and go to town or add your Excel models to
EnergyWitness through its plug-in architecture).
EWChillerPlant calculations often make smaller problems readily
apparent, for example, a production balance equation that generates
impossible numbers likely indicates sensor problems that
might have gone unnoticed looking at the point data (we've seen
clients put projects on hold until they could service all the
sensors that needed to be fixed or recalibrated).
All the data and
tools are there for diagnosing issues
by drilling down through the underlying calculations and individual points to find
the root cause of the inefficiencies. Some people would call this
data mining or business intelligence. We call it
results.
Show Me How I can Optimize My Chiller Plant
Want to see what it looks like to know exactly how efficiently
your chiller plant runs, and just how much it costs to run? Give us a call at 617-744-1091, or send an e-mail to
info@intdatsys.com to arrange a demo.
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