New regulations and incentives are making green roofs a staple in the Class A development playbook

The Environmental Protection Agency (EPA) defines green roofs as simply a vegetative layer growing on the roof. Green roofs have a long history on buildings owned by the federal government. The General Services Administration (GSA) maintains nearly 2 million square feet of green roofs in the U.S., with a long history of green roof construction and maintenance dating back to the 1930s.

Sometimes also called “plant roofs” Or “living roofs“green roofs provide shade, remove heat from the air and reduce the temperature of the roof surface and the surrounding air. According to the EPA, in some cases the temperature of a green roof can be 30 to 40 degrees cooler than conventional roofs. All of these factors help mitigate the heat island effect, a phenomenon that occurs when dense urban areas with a high concentration of sidewalks and buildings absorb and retain heat, raising the area’s temperature. The effect leads to higher energy costs for air conditioning, for example, increases air pollution levels and increases the number of cases of heat-related illnesses.

The composition of a green roof typically includes a waterproof membrane, a growing medium – usually soil – and vegetation. In addition to lowering temperatures and providing shade, green roofs also play a large role in stormwater management. In areas with a large number of paved or construction surfaces, rainwater is prevented from being absorbed into the ground. This causes excessive runoff, which deteriorates water quality by sweeping pollutants into water bodies. According to the GSA, green roofs reduce roof stormwater runoff by up to 65 percent and delay rainwater flow by up to three hours. Vegetated roofs can also provide new habitats for plants and animals in urban areas, increasing biodiversity. Green roofs are expected to last twice as long as traditional roofs.

In Manhattan’s Chelsea neighborhood, the Tishman Speyer Morgan North office building, formerly a USPS facility, has a two-acre green roof that also includes numerous break rooms and shared work spaces that are the focus of the facility’s marketing campaign: Morgan North’s website greets visitors with the tagline “An office space that is a breath of fresh air.

Considering all the environmental benefits, as well as attractive amenities for building tenants, it’s easy to see why rooftop gardens are a famous amenity that becomes even more attractive at a time when there is greater impetus for green activities than ever before. However, as with many things, the biggest barrier is often the cost of adding it. According to Manhattan-based RAND Engineering & Architecture, building a green roof has a large upfront cost that can range from $25 to $30 per square foot, including design, materials, labor and installation. It would also require constant maintenance, which is an additional cost to consider. However, there is an argument for ROI. In one case study conducted by GSA, a green roof paid for itself after 6 years with a 224% ROI thanks to extended life, stormwater benefits and additional energy savings. Over the past decade, many cities across the country have taken initiatives to encourage the installation of green roofs on buildings.

Read more: New regulations and incentives are making green roofs a staple in the Class A development playbook