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Benchmarking Using Average Monthly Temperature

Created 8/31/2011 by James White
Updated 5/15/2013 by James White
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A tremendous amount of information about a building's energy usage can be gained from monthly billing history.  The average kW usage and average monthly temperatures can be determined from the monthly kWh and meter read dates:

Avg. kW = [Billed kWh] / [Days in Billing Period] / (24 Hrs/Day)

Average kW readings can be further normalized to Average Watts/Ft2 by dividing by the square footage:

Avg. Watts/Ft2 = [Avg. kW] x 1000 Watts/kW / [Building Sq. Ft.]
or
Avg. Watts/Ft2 = [Billed kWh] x 1000 Watts/kW / [Days in Billing Period] / (24 Hrs/Day) / [Building Sq.Ft.]
Watts per Sq Foot vs Average Temperature
A graph of building's normalized energy use in terms of Watts/Ft2 is shown above.
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Comments (3)
Mark Wiser on 08/31/11 on 04:31 PM (Pacific Time)
We use this tool to help customers with high bill concerns. These charts indicate whether the bill is in fact high, heating or cooling related, the result of a heating system failure, a HP thermostat set on emergency heat, high base use. We also use it to verify energy savings, which can be seen after the next meter read following measure installation. After running nearly 400 of these benchmarking charts we have consistently seen that electric resistance heat uses about 3.5 W/Ft2 at 20 degrees average temperature. A HP runs about 2.5 W/Ft2.
James White on 10/10/11 on 12:59 PM (Pacific Time)
We also used this benchmarking method to document actual energy savings during our Reduce Your Use contest.  The winner saved 35%, and all combined, the nine contestants reduced their 2010-2011 winter energy consumption by 19%.
James White on 05/15/13 on 01:36 PM (Pacific Time)
It surprises me that more people do not use this methodology for analyzing the energy use of commercial and residential buildings.
1. It is free
2. It is powerful
3. It uses readily available billing data (monthly kWh consumption)
4. Determines opportunities, quantifies improvements, and tracks persistence.

I wish there would have been a presentation on this methodology at the Energy Efficiency Connections.