A Case Study on Energy Efficient Roof Material

By DECRA Metal Roofing. 

Metal or concrete? One homeowner’s sustainable story of cutting energy use and switching to a metal roof. 

There are many variables that can influence your buildings efficiency, making it difficult to calculate the right roofing option. Air temperature, humidity, windows, doors, attic insulation, even the amount of people in your home, can alter the energy efficiency of a roof. The best roofing choices are case by case, read ahead to see how one homeowner saved money and energy by switching to a stone-coated metal roof.  

Enter a homeowner from just outside of Sacramento, California. In April 2007, they installed a DECRA Villa Tile roof in Pompeii Ash, anxious to see if the metal roof would be more energy efficient than the concrete tile. The previous roof was a grey concrete tile on a batten system, so the homeowner wanted to keep the overall appearance of the concrete grey color. 

No changes were made in the venting method between the two installations and while DECRA Villa Tile is a direct to deck product the 3-1/4-inch barrel height on the product provides an offset from the roof deck. 

Oak Ridge National Laboratories conducted a study on roof assemblies and identified the benefits of offsetting a roofing product from the deck. In its study, a counter-batten/batten installation method was used. The airspace created between the roofing material and the deck increases the airflow across the deck and assists in pulling heated air away from the conditioned space. Less heated air in the attic equates to less stress on the cooling system and lower energy consumption. 

As mentioned, DECRA Villa Tile is not installed on counter-battens/battens, but rather direct to the deck. Nonetheless, the high barrel height allows for the movement of air beneath the panel and simulates a counter-batten/batten installation. 

Four years later, the homeowner contacted DECRA with data (2006 to 2009) summarizing the number of kilowatt hours used during the five hottest months in Northern California: June, July, August, September and October. Some variables were noted by the homeowner throughout the four years— the number of children at home over the course of the summer and instances of humidity. After reviewing the average daily temperature during the months of the years in question, it was noted overall the temperature was consistent with only a couple of outlying temperatures in 2006 and 2009. 

With this said, the average number of kilowatt hours used in 2006 from June to October, when the concrete tile roof was installed, was 941. The Villa Tile roof was installed in 2007 and the average number of kilowatt hours used in 2007 was 748, in 2008 was 833 and in 2009 was 810. During this time, there has been a 15% lower use of kilowatt hours for 2007 through 2009, than were used in 2006. 

This is not an exact science, nor is it a study conducted by scientists, it is just one homeowner looking to cut his energy use by switching to a metal roof— a stone coated steel roof. With consumers focusing on reducing energy costs, DECRA Villa Tile is a great choice for the homeowner. In addition to being energy efficient, DECRA Villa Tile has upwards of 25 percent post-consumer recycled steel, is easy to use with rain catch and solar panel systems, has a long-life cycle and is low maintenance. All of these characteristics and benefits add up to an enduring, sustainable, roof. 

 Have a question? AskARoofer. 

Find your local roofing contractor in the RoofersCoffeeShop® Contractor Directory.