Storm-Water Retention:

During heavy rainfall events, runoff in commercialized areas is inevitable due to all the impervious surfaces such as pavements and rooftops. In the Washington DC Metro area management of this storm-water is a serious issue. In most big storm events the sewer systems simply cannot handle the amount of incoming water. This results in an overflow and pollution to our local water sources however green roofs can alleviate this issue pressure on the storm-water infrastructures by retaining up to 75% of the rainfall. Also The District offers a green roof incentive program for residential and commercial owners. Performance: Retain >1" rainwater with sub-watershed bonus incentives with a maximum reward available for 1.2" retention. The reward amounts are $7 per SqFt district wide, $10 per SqFt targeted watersheds; $15 per SqFt residential properties in Floodgate subwatershed <2,500 SqFt. Northern VA as well as MD also offer incentive programs for greens roofs, check out some of the helpful links for more information.

Reducing Energy Consumption:

Green roofs are great insulators for your building. This will help reduce peak energy demands by lowering cooling costs in the summer months and heating costs during winter months. During the summer the temperature of a green roof tends to be about 20% lower than the ambient temperature. Putting this into perspective, on a 100 summer day your rooftop will be about 80 versus a conventional roof that could get up to 150 degrees in these conditions. Also not to mention your HVAC is located on the roof and pulling directly from the ambient air just above your roof, thus making your HVAC run 20% more efficient with the cooler air intake. On average owners see a 20-30% savings on cooling costs during the summer and around 10% reduction in heating costs during the winter.

Reducing the Urban Heat Island Effect:

Typically a city is much hotter than its surrounding environments. The ambient temperature can be as much as 10 hotter, which makes cities much hotter and puts a strain on the grid during peak energy demands.   More green roofs and fewer dark roofs equal a cooler city. While dark roofs retain heat, plants naturally cool their surrounding environments through evapotranspiration cycles. Reducing this urban heat island effect will be huge moving forward as it will be a good way to help regulate rising temperatures in cities and can also help a building owner earn LEED points.

Waterproofing Membrane Protection:

Every green roof has some form of waterproofing involved in the construction process. Soprema is one of the best in the game when it comes to waterproofing membranes that are time tested even without a garden on top. However adding the green roof helps to protect the membrane from damaging from damaging UV rays, freeze-thaw cycling and repeated foot traffic, extending its lifespan. There are some green roofs in Europe that have lasted more than 40 years without being replaced.

Improved Air Quality and Habitat:

Plants are one of the best carbon dioxide sequesters on the planet that only nature can provide, by taking sunlight and carbon dioxide then producing oxygen. Having a green roof will improve the air quality around your building. This improves the air quality being pulled into your HVAC systems, which tenants breathe, everyday. And additionally green roofs have been found to provide habitat for animals and insects of all kinds. Studies have shown green roofs can provide habitat for 100’s of bird species and 1000’s of insect species which is astounding.

LEED and Green Globes:

The U.S. Green Building Council's (USGBC) LEED program and the Green Globes system were developed to assist in the design and construction of high-performance, sustainable buildings. These programs can offer tax incentives to building owners who meet defined criteria. Green roofs contribute to certification in both programs.

Sound Insulation:

Soil and plants have been found to be effective sound insulators. This can help to reduce incoming noise pollution outside of the building.

Aesthetics:

Green roofs are visually stimulating and can make great areas for recreation and pleasure. Some studies have shown increased productivity out of employees that can utilize, or have a view of a green roof over those with a conventional.

Increased Property Value:

A green roof has so many benefits to society and installing a green roof can increase property value by providing a valuable building asset. Whether it’s more utilized building space, a section to help manage stormwater runoff, or help with your heating and cooling costs, green roofs are becoming major asset moving forward to make our cities healthier for their inhabitants as well as increase property value.