With the growing demand for environmentally friendly and sustainable roof design, many commercial roofing contractors are exploring different green roofing options. Products such as protective coatings, reflective membranes, and metal systems all fall under the green designation, but two systems stand out as innovative offerings — garden and photovoltaic (PV) roofing systems.

Garden roofing

Many in the industry treat garden roofing as a new and passing trend, but, in fact, garden roofs have been used in Europe, Canada, and Asia for years with great success. In the United States, many state and local governments are providing incentives for using garden roofs to reduce the urban heat island (UHI) effect, and through the Leadership in Energy and Environmental Design (LEED) Green Building Rating System, garden roofs may qualify for green building certification credits.

Garden roofs offer outstanding benefits, including: reducing heating and cooling costs; protecting the membrane against ultraviolet radiation, temperature fluctuations that can cause harmful contraction and expansion, and punctures; extending the life of the roof; and enhancing the aesthetics of a building. Because garden roofs are considered pervious building areas, an architect can specify an additional 20,000 square feet of building space, allowing a developer to maximize the design of the building.

Many cities, including Chicago, Seattle, Washington, and Portland, Ore., are leading the way by using garden roofs to proactively control their storm water management programs. A garden roof can reduce storm water runoff by nearly 75 percent, which is a large concern for cities big and small.

Available for use on nearly any building, garden roofing systems come in two distinct types: built-in-place (extensive) and modular systems (intensive). Built-in-place systems are constructed on the rooftop, whereas modular systems are assembled off-site and brought to the building ready for installation. With built-in-place systems, installation can be tedious, and more maintenance is required over time, which can become costly for your customer. Modular systems can usually be installed much quicker, with as much as 7,000 square feet installed a day, and require little maintenance — saving you time and your customer money.

To ensure the lifespan of a garden roof is long and worry-free, be sure to discuss with an architect/specifier which type of garden roof will work best for your customer's needs.

Photovoltaic roofing

A relative newcomer to the green market is photovoltaic (PV) roofing. Over the last 10 years, the solar cell technology of PV has continued to evolve. PV solar cells and panels channel sunlight and convert it into electricity, which, in turn, produces energy savings.

Solar roofing currently accounts for only two percent of the commercial roofing market despite the potential savings these systems offer in face of rising utility costs. Utility costs around the world are estimated at $1 trillion. As companies and building owners look to lower costs through a renewable energy source, such as solar power, there is a huge growth potential for PV systems.

Along with the benefit of increased cost savings, many states, such as California, New Jersey, and Connecticut, are now offering rebate programs for local businesses and schools interested in having PV systems installed on their roofs.

There are two PV offerings on the market now — amorphous and crystalline silicon systems. Amorphous systems have 9 percent efficiency, and their flexible, thin film allows the system to be installed directly over the membrane. Crystalline systems are much more efficient, with 34 percent efficiency, and can also be installed over the membrane. Some crystalline options require that the system be installed directly into the deck, penetrating the membrane, which may require extra waterproofing.

If your customer expresses interest in a PV system, you must evaluate how it will work with the roof and membrane. PV systems work best with fully-adhered membranes with protective walkway mats due to high traffic on the roof. Minimal maintenance is required for PV systems, including occasional cleaning of the PV panels. Work with your customer to set-up a customized maintenance plan.

Reaping the benefits

Although relatively new to the U.S. commercial roofing scene, garden and PV roofing systems are continually being specified and installed throughout the country. Both systems can offer contractors a lucrative business if the job is done right, and the potential of these systems will continue to expand as the industry sees more modifications in the future.

RIAZ HASAN is the accessories product manager for Firestone Building Products.