You may have heard something about “white roofs” in the news but you may not know how they can help our planet, or a maintenance budget. I’ll try to clear things up a bit.
First, A few definitions, for the purpose of this article only.
a. White roof: A roof that is white in color and has a high rate of reflection of the sun’s energy.
b. Green roof: Any type of roof that will help our planet. Most white roofs are considered to be “green”
c. Planted roof: A roof that actually has plants growing on it.
d. Black roof: Old style roofs consisting of asphalt, rubber, or a combination of the two.
Most all of the commercial buildings in the world use black roofs. Because they are black, they soak up the sun’s energy like a sponge.
That’s bad for several reasons. Commercial roofs and pavement are the major factors in the “heat island effect” in major cities. Black roofs are typically almost twice the ambient air temperature on a hot day. Much of that heat is transferred into the building and places a tremendous load on the air conditioners, which use enormous amounts of electricity to keep the building comfortable. Black roofs have been around for decades because there were no alternatives.
White roofs. You might think you could just paint a black roof white and be done with it. Unfortunately, roofs expand and contract constantly. White paint will crack and leak almost immediately. We use acrylic elastomeric materials for our roofing systems. These materials will expand and contract up to 300%. They also reflect up to 85% of the sun’s energy, including UV. This virtually eliminates the heat island effect of that building, and will typically save up to 50% of the energy needed to cool the building. The energy savings with this type of roof are why energy czar Chu is traveling all over the world promoting white roofs. The total amount of energy savings potential is incredible, especially on a world wide basis. Upfront cost is comparable to a black roof, but a white roof will typically pay for itself in 4-7 years with energy savings alone.
Planted roofs are becoming more popular every day for several reasons. Many metropolitan areas in the US are having huge problems with excessive rain run off. A planted roof helps because it will soak up a great deal of moisture before it becomes saturated. In some cities, they are even growing vegetables on the roof. The major problems with a planted roof are cost and weight. A roof can only hold so much weight before it will collapse. Black roofs are quite heavy already so the ideal solution is to have a lightweight membrane underneath the plants to seal the roof. Flat roofs have always been hard to seal, having plants on top may preserve the covered portion of the roof, but there are almost always walking spaces for servicing equipment on the roof. Having to remove all the plants to service the actual roof surface would be very expensive, so we recommend a modern elastomeric membrane underneath so there will be no maintenance for many, many years. Planted roofs are beautiful, the plants produce oxygen, they reduce the heat island effect, and they save even more energy than a white roof, and they help tremendously with run off water. But, they must be done right in order not to leak.
White roofs, green roofs, and planted roofs may qualify for various tax credit programs which will help make them more attractive to building owners.
We can convert virtually any roof to a green roof. From the smallest Mom and Pop store, to the largest buildings on the planet, anywhere in the US.
If you own a building, or know some one who does, have them contact us to see what we can do. We only have one planet, let’s make sure our kids and grand-kids have a place to live.