There is no right or wrong answer to this question!
The first thing you will need to decide is if you want to benchmark the entire campus as a multi-building property, each individual building as its own single-building property, or both. Any option is allowed, you need to do what is best for you. Learn more about the options for benchmarking a campus.
If you choose to benchmark each individual building, then you will have to be careful with how you measure the common heating and cooling. Probably, your heating/cooling system is located in one building and sends steam, hot water, or chilled water to the others.
Let’s suppose you have a three building campus (Buildings A, B, and C). You have a boiler in Building A that takes natural gas as an input fuel and creates steam, which is distributed to all three buildings. You will need to submeter the following:
- amount of natural gas that goes into your boiler
- amount of steam used by each building (A, B, and C)
Then, you have two options:
Option A (Recommended): Enter the energy consumption of each building according to its proportion of the natural gas that you purchased.
Suppose you purchase 120 kBtu of natural gas, which is converted to 100 kBtu of steam.
1) Measure the steam usage for each building:
- Building A uses 30 kBtu
- Building B uses 50 kBtu
- Building C uses 20 kBtu
2) Figure out the percentage of the steam used by each building:
- Building A uses 30 kBtu -> 30% of the total steam produced
- Building B uses 50 kBtu -> 50% of the total steam produced
- Building C uses 20 kBtu -> 20% of the total steam produced
3) Take those percentages (30%, 50%, and 20%) and apply them to the input fuel, 120 kBtu of natural gas.
- Building A uses 30% of the Natural Gas (30% * 120 = 36 kBtu of Natural Gas)
- Building B uses 50% of the Natural Gas (50% * 120 = 60 kBtu of Natural Gas)
- Building C uses 20% of the Natural Gas (20% * 120 = 24 kBtu of Natural Gas)
4) Update the Natural Gas Meters for Building A, B, and C with 36, 60, and 24 kBtu respectively.
5) In this example, you would enter a natural gas meter for each individual Building. You don’t have to enter the steam meters into Portfolio Manager. You can if you want, but make sure you don’t include them in your energy metrics.
This may sound complicated! And you have to repeat this calculation for each month/bill so that the percentages used are still correct. To help you, we have a technical reference document that walks through similar examples for both chilled water and CHP, and we also have a negative meter calculator which can help you to do these calculations. If you’re unsure what to do after looking at those calculations, contact our customer support team and we’ll help you.
Option B (Simpler): Enter the steam that goes into each building. This option is easier for you because you don’t have to compute percentages, but, Portfolio Manager will treat the steam as if you purchased it from your local utility. If you make efficiency improvements to your steam plant you should be able to produce more steam with the same amount of natural gas – but if you’re benchmarking the steam (instead of the natural gas) then you won’t see the benefits of those changes in your metrics.
Using the same example as above, where you purchased 120 kBtu of natural gas, which is converted to 100 kBtu of steam.
1) Measure and report the steam usage for each building in Portfolio Manager:
- Building A uses 30 kBtu of steam
- Building B uses 50 kBtu of steam
- Building C uses 20 kBtu of steam
2) In this example, you would enter a steam meter for each Building. You don’t have to enter the Natural Gas Meter into Portfolio Manager. You can if you want, but make sure you don’t include it in your energy metrics.
IMPORTANT NOTE: Make sure you are doing an “apples to apples comparison.” You cannot enter Building A using a positive natural gas meter that captures all purchased gas along with two negative steam meters to capture what is distributed to Buildings B, and C. If you need to subtract the energy that goes to Buildings B and C then all meters have to be of the same type (natural gas), otherwise your metrics will be wrong. Please refer to our FAQ on negative meters.
Finally, while both options above are presented using a “steam” scenario, the exact same concept would apply to Chilled Water, Hot Water, or even electricity if you were producing your own electricity, for example through a Combined Heat and Power (CHP) plant. You may want to refer to the examples in our technical reference on negative meters, which has diagrams for each of those scenarios.
Click here for more information about what constitutes a campus.