Our energy efficient coating has been applied to rooftop AC units for around 30 years.  I see those units by the hundreds everywhere as I am sure everyone else has as well.

A few weeks ago I asked the DOE if any agency knew, or at least had a rough idea, how many buildings in the US had rooftop metal units and units that also had exposed ductwork.


Here is the response they sent back.  Thought I would share it with anyone that might have an interest on this site.


Thanks to Mr Gentry and the DOE for the reply.

Hal Skinner







Today at 2:40 PM

Thank you for your May 19, 2014 email to the U.S. Department of Energy (DOE) regarding the how many buildings in the U.S. have rooftop units (RTUs) and exposed ductwork on the roof.  Your email has been forwarded to the Energy Efficiency and Renewable Energy Building Technologies Office (BTO), and this is our response.


There isn’t a good direct source for estimating the total number of RTUs and the energy consumption associated with them.  The DOEAdvanced Rooftop Unit Campaign states that RTUs are used in over 60% of U.S. commercial buildings (roughly 50% of conditioned area). That figure was derived from the 2003 Commercial Buildings Energy Consumption Survey (CBECS 2003).    CBECS 2003 is the most current survey; the 2008 had to discarded due to data collection issues. The 2012 CBECS is underway.


The 2.1 Quads was derived from Building Energy Data book, which states that total primary energy associated with cooling and ventilation is roughly 4.3 quads.  Energy consumption is assumed to directly proportional to the area;  thus, 50% of 4.3 is roughly 2.1 quads. The Building Energy Data Book is not currently being updated, but you can update any calculation by clicking on the reference links, which provide the latest data via the relevant Energy Information Administration report. Recalculations based on the current data and assumptions would result in roughly the same answer.


Thank you for your interest in energy efficiency. Should you have further questions, please contact me.






Randall Gentry

Energetics Incorporated

Under contract to the U.S. Department of Energy

Office of Energy Efficiency and Renewable Energy | Building Technologies Office

o: 202-287-1632


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