Today, if you call a roof a “Green Roof”, you are probably referring to any number of environmentally-friendly type of roofs.
Commonwealth Roofing is familiar with almost all types of green roofs including white reflective roofing, energy generating system like photo-voltaics (PV) or wind generators, or a system that is literally green vegetative roofing.
Cool White Reflective Roofing
The most common and affordable way to be environmentally responsible when choosing a roof system is to select a heat-reflective system such as our most popular white PVC roof, Duro-Last. This simple consideration of the color of a membrane can have a major affect on the air-conditioning cost and comfort level in a building and accounts for a simple formula: “Green = White.”
You may ask, “Doesn’t the beneficial heat that’s lost in the winter to a white roof cancel the benefit of the harmful heat that’s avoided in the summer?” Very good question! Fact is, because of the reduced amount of daylight and the reduced sunlight angle in the winter plus the increase in winter cloud cover, the beneficial heat gain of a black roof in winter accounts for only about 10% against the benefit of a white roof’s reflectivity in summer.
So, considering that many heat-reflective white systems cost no more than comparable black membranes, this plus the simple addition of more insulation board can often be the easiest way to “go green” on a re-roof project.
Energy Generating Systems
There have been steady improvements in the efficiency of energy generating systems like photo-voltaics (PV) and windmills. These can often be integrated into the roof system of a building with good results, but one must be careful that the system is properly engineered and installed. For instance, there are some windmills that require more energy to manufacture, ship, and install than they will ever create during their useable lifespan.
Likewise, if a PV system is designed to produce a payback in 25 years, but the effective lifespan of the photo cells is only 20 years, can it be justified? This is not to say that PV and wind energy is a bad idea but that one needs to be careful of the timing and development level of a project before diving in. Commonwealth Roofing can help make these determinations, and once an energy generating system is determined, we can help make sure it gets installed right. After all, the primary purpose of a roof is still to dependably keep the weather out.
One type of green roofing that would work well in the Kentucky, Southern Indiana area would be the “living” or “vegetative” roof.
A vegetative roof or live roof is just what it says it is, a roof made up of living things which are usually plants. In other words, a roof of a building that is partially or completely covered with plants rooted in soil planted over a waterproofing membrane.
This does not refer to roofs which are merely colored green, as with green roof shingles, and it must be a well-engineered system to include components like root barriers and drainage and irrigation systems. The structural capacity of a building must also be considered when designing a live roof, as some of these systems can be quite heavy, especially during and after a rain.
Living roofs serve several purposes for a building, such as absorbing rainwater, providing insulation, and helping to lower urban air temperatures and combat the heat island effect.
In Louisville and Southern Indiana, the benefits of vegetative roofing are usually not well understood. In Europe however, these technologies have become very well established. Such support recognizes the many tangible and intangible public benefits of live roofs. They not only provide the owners of buildings with a proven return on investment, but also represent opportunities for significant social, economic and environmental benefits, particularly in cities.
While rather a new concept, Commonwealth Roofing can help you decide if a vegetative roof is right for you.