Discussion on cool roofing peak energy demand

by Jennifer Wilson | May 13, 2016 9:45 am

In our February 2016 edition we published an article, “Results may vary: Reducing energy usage with cool roofs[1],” by Craig Tyler. Kurt Shickman of Global Cool Cities Alliance wrote in to comment on what he calls an “inaccurate down-portrayal of roof reflectivity and peak energy demand reductions.”

We shared his comments with the author and now present them here:

The article, “Results may vary: Reducing energy usage with cool roofs,” by Craig Tyler, published in the February 2016 issue of The Construction Specifier, included a section in which the author inaccurately downplays new research linking roof reflectivity and peak energy demand reductions. Most commercial consumers pay a peak demand charge, which is often a substantial (30 to 50 percent or more) portion of their bill. The good news is that research—including the paper cited by the article’s author—shows these charges can be significantly reduced with reflective roofing. Further, there are trusted online tools that factor in peak demand charge savings to help commercial energy consumers determine how much they can save with reflective roofing.

The author dismisses peak demand charges as an obscure utility rate practice most businesses would not need to pay. In fact, a simple Google search reveals that utilities in all 50 states have a demand charge for commercial/industrial users. You can see if you are being charged differently for peak usage on your own bill. The charge will appear in kilowatts, rather than kilowatt-hours. Medium to large commercial companies are almost certainly paying a peak demand charge every month.

The author states that cool roofs may only have “some effect on certain building owners with peak energy demand charges.” This phrasing downplays the potential to reduce demand charges by installing cool, reflective roofing. The savings on demand charges is large, and up until very recently, a largely hidden benefit to the commercial energy consumer. The paper[2] the author cites shows significant demand charge savings accruing when cool commercial roofs are installed. That paper evaluated new buildings in every climate zone using a conservative demand charge and base rate. The demand charge savings outpace the base rate savings in every zone and, in the coldest climates, make cool roofs a net economic benefit to buildings. In short, understanding and capturing the demand charge impact of cool roofs is critical to an accurate cost/benefit analysis.

With the peak demand savings version of the Department of Energy (DOE) Roof Savings calculator[3]  mentioned in the paper, it is possible to easily calculate the effects of cool roofs on peak demand charges. It is free and it comes with links to additional energy information that can help a building designer make the best design decisions for any situation. This tool could actually increase the value that the building professional brings to the table in establishing the ultimate roof design.

 

Source URL: https://www.constructionspecifier.com/discussion-on-cool-roofing-peak-energy-demand/

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