Estimating Savings

So how do you estimate savings? Let's look back at our example.

This utility helped this customer install high-efficiency lighting. Using the lighting survey worksheets, we compute the overall Connected Lighting Load (installed lighting power density in units of W/sqft) for the before and after case. These are entered as shown:

The lighting loads are entered as the connected load averaged over the entire building. Based on the lighting survey done at the time, the old facility had 2.05 W/sqft of connected lights. The efficeint lights averaged 1.10 W/sqft. There were some outdoor lights that were not changed. These worked out to a connected load that averaged 0.17 W/sqft based on the indoor (not the outdoor) square footage. (Note the plug loads and usage factor have been adjusted to match the actual bills as explained later.)

A "X" pops up in column A to reminds us that there is something different bewteen the two cases -- this helps us keep track of any conservation measures.

What do the results look like?

The Proposal report documents the conservation savings expected. First, a table summarizes the current usage and potential savings.

 Energy Usage Index (EUI)

Weather adjusted consumption is 76 kBTU/ft2 per year for this facility.

The low, median and high ranges of consumption are 19, 86, and 219 kBTU/ft2 per year for facilities of this type.

Potential Conservation Savings
 

	Annual Energy Consumption, kWh	Average Demand, kW per Month	Annual Energy Consumption, Therms
Base Case	151,184	46	0
With ECMs	122,046	40	0
Savings	29,139	6	0

Then there is a picture of the assumed end uses over the year.

 Then a graph showing how the annual end uses compare between the two cases analyzed.

 Then an estimate of how the monthly bills will change.

All of these graphs and tables can easily be cut-and-pasted into other applications to generate standard reports. EZ Sim does not compute the dollar value of the savings because there are so many different rate schedules. But EZ Sim provides the results in a table that can easily be used to compute the dollar value if the rate schedule is known.

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