A white paper from The Roof Coatings Manufacturers Association examines the effect of reflective roof coatings have in mitigating peak energy demand.
The paper provides a comprehensive overview of base use and peak demand of electricity and shows how to calculate peak demand savings.
The findings from the roofing paper also include the following conclusions:
Savings are found in all climates and conditions
The total value of base plus peak energy savings offered by a reflective roof is significant, averaging more than $1000 annually in most climate zones for a typical commercial building.
Savings are important for both “old” and “new” levels of insulation. Cool roofs can offer a significant opportunity for net energy savings even at the highest levels of roof insulation mandated by the latest building codes. The savings value of cool roofs is further reinforced because modern cool roofing membranes frequently cost no more that darker non-cool roofs.
Related: How Cool Roofs Can Reduce Water Use
All of the savings identified in the analysis tend to drop to the bottom line without any additional cost problems.
New insulation delivers peak savings
Differences in the level of new versus old insulation appear to have a significant effect on the amount of base use savings. In most cases, base use savings using the lower R-value levels of old insulation are reduced by half or more by the addition of the higher R-value levels of new insulation.
This condition does not appear to hold for peak demand savings. In most cases, the savings available using either old or new insulation levels appears to be significant for all climate zones.
Even more: 3 Vital Roles of Roofing Insulation
Therefore, it would appear that significant reductions in peak demand cost could not be done simply by increasing insulation levels without also installing a cool roof covering.
Peak demand drives savings
One of the most striking results from this analysis according to the white paper is that the estimated savings due to peak energy demand reduction provide a substantial majority of the net energy savings throughout all climate zones studied.
According to the data, peak demand savings account for over 50% of total savings in the warmest climate zones up to 100% in the coldest climate zones. While base use savings tend to vary widely by climate zone (even falling to negative values in the coldest climates), peak demand savings tend to more significant and consistent throughout all climate zones. Consequently, the analysis clearly suggests that any estimate of cool roof savings that neglects to include peak demand reduction has little chance of providing an accurate estimate.