Sustainable Design – Think Metal Roofing…
FACT – steel takes the pressure off renewable resources

Great Metal Roof Systems
Sustainability can be defined as meeting the needs of the present without compromising the ability of future generations to meet their own needs all considering social, environmental and economic impacts of your actions. Sustainable Design on the other hand seeks to reduce negative impacts on the environment and the health and comfort of building occupants thereby improving building performance. The bottom line is that the built environment has a profound impact on our natural environment, economy, health and productivity. According to Energy Star, buildings in the US account for: 36% of total energy use/65% of electricity consumption; 30% of greenhouse gas emissions; 30% of raw materials use; -30% of waste output/136 million tons annually and 12% of potable water consumption.

School Project - LEED Silver
I was lucky enough to have been selected to speak at our national trade show recently about this exact topic and how it relates to Metal Roofing products. Metal Roofing is a great product for the environment as compared to its competitive roofing products which mostly contain asphalt and oil based ingredients. It won’t “off gas” greenhouse gases like its competitive asphalt products which ultimately contributes to climate change.
Recycled Content:
The basic facts is that metal roofs are made of recycled materials and can be recycled at the end of their useful life. More steel is recycled each year than all other materials combined. Two out of every three pounds of new steel are produced from old steel. According to the Recycle Steel Insitiute; steel has an average recycling rate in excess of 50 percent since World War II and over 60 percent since 1970. Last year, over 67 million tons of steel scrap were recycled in the United States. Using steel takes the pressure off renewable resources: a typical 2000-square-foot home requires about 40 to 50 trees, about an acre’s worth, to build with wood. With steel, only the equivalent of about six scrapped automobiles are needed.
Metal Roofs are COOL-
Surface temperature is a key indicator of how much heat energy will transfer into a building…makes complete sense? Sure…metal is a great conductor of heat as well as cold! Metal Roofs on the other hand use Infrared Reflecting pigments which actual reflect the heat energy (non visable heat energy) back into the atmosphere. Solar Reflectance is measured as a percentage {0=fully absorb heat to 100% zero heat gain) of reflected sun energy. So…let’s say you want a white roof…the Solar Reflectance is a 70%….this means the surface is reflecting 70% of the suns energy and absorbing 30%…the less absorbed the cooler! The general rule of thumb for every one point of increased SR the surface temperature drops by one degree F. The higher SR the better! The Energy Star program requires the SR to be a minimum of 25% to qualify for the tax credit (steep slope <2:12).
Solar Reflectance is only one of many components of cool roofing…emittance, system design and proper ventilation should also be considered especially if you live in cooler climates.
Thermal emittance works in tandem with SR as it’s a measure of how quickly a material emits heat energy back into the atmosphere. This is also measured as a percentage (0 to 100%)….again the higher the name the better. Bare steel products have a very low emittance (about a 10%) and most painted products have an 87%. The best way to think of emittance as it relates to roofing materials is the higher the number the quicker the roof will cool when the sun sets. Combine this with a SR and you have one of the most energy effiecent roof system. The key to metal roofs is that they retain 95% of the initial solar reflectance so you’ll enjoy years of energy savings.
I mentioned system design depending on where you are located…in cool climates you may want to consider adding an air space (3/8” minimum…ask your Drexel Metals contractor about a product named ENkamat/Colbond) between the metal roof and the roof deck along with proper ventilation at the eaves, gables and soffit.…air acts as a great insulator and will help the heated air to escape through natural convection in the summer and will help to keep your warm air in during the winter months. The use of a thermal barrier or a radiant barrier can also be considered.
Thanks for reading! Hope this helps to explain some of the great sustainable benefits of using metal roofing products. Make sure to visit our website www.drexmet.com to find an installer or request additional information about us. We’d be happy to help.