Benefits For The Owner

LEED Credits
Green roofs can earn LEED credits in the following
categories of the USGBC's green building rating system:

PART 1: SUSTAINABLE SITES
Reduced Site Disturbance, Protect or Restore Open Space
Reduced Site Disturbance, Development Footprint Credit
Landscape Design That Reduces Urban Heat Islands

PART 2: WATER EFFICIENCY
Storm Water Management
Water Efficient Landscaping
Water Use Reduction
Innovative Wastewater Technologies

PART 3: ENERGY & ATMOSPHERE
Optimize Energy Performance
Renewable Energy
CFC and Ozone Depleting Substance Reduction

PART 4: MATERIALS & RESOURCES
Storage and Collection of Recyclables
Recycled content materials

PART 5: INDOOR ENVIRONMENTAL QUALITY

PART 6: INNOVATION IN DESIGN

City of Portland Eco Roof Incentive
The city of Portland offers a grant of $5/sf for ecoroofs.

Increase in Roof Lifecycle
Because green roofs protect the waterproofing membrane from the UV rays of the sun and other elements, green roofs can last 2 to 3 times longer than conventional roofing systems, often 50+ years.

Increase in Building Value
According to, Green Roofs: Sustainability from the Top Down by David Stater, green roofs increase the value of the property and the marketability of the building as a whole. For example, American and British studies show that "good tree cover" adds between 6 to 15 per cent to the value of a home. Green roofs offer the same visual and environmental benefits.

Energy Savings
Environment Canada found that a typical one-story building with grass roof and 10cm (3.9 inches) of growing medium would result in a 25% reduction in summer cooling needs. In the winter, the additional insulation provided by the growing medium helps to decrease the amount of energy required to heat the building.

Floor Area Ratio (FAR) Bonus (Portland)
The bonus requires that Bureau of Environmental Services certify the design of the eco roof and that a covenant be executed with the City to ensure the installation, preservation, maintenance, and replacement, if necessary, of the eco- roof. The Eco-Roof Bonus provides additional development potential at the following rates:

Eco-roof is 10 – 30 percent of the building’s footprint, one square foot of additional floor area, for each square foot of eco-roof.

Eco-roof is 30 – 60 percent of the building’s footprint, two square feet of additional floor area, for each square foot of eco-roof.

Eco-roof is at least 60 percent of the building’s footprint, three square feet of additional floor area, for each square foot of eco-roof.

Sound Insulation
The growing medium of an eco roof will insulate against lower frequencies of sound and the plants will insulate against the higher frequencies of sound. According to Design Guidelines for Green Roofs by Steven Peck and Monica Kuhn, 5 inches of growing medium alone can reduce sound by 40 db.

Fire Resistance
Measurements by the FMPA of Germany found that the burning heat load of a green roof is only 3 KWH/m2, while a conventional roof with three layers of Bitumen has a value of 50 KWH/m2. Also, Sedums, which are a common choice for eco roofs in the Northwest, are well known for their fire retardation.

Food Production
For example, the rooftop garden at the Fairmount Hotel in Vancouver serves as a training garden for chefs, saves approximately $30,000 per year in food costs for the hotel, and provides amenity space for hotel patrons.

Project: Olympic Peninsula Project
Location: Olympic Peninsula, WA
SolTerra Provided: 3,500 sf semi-intensive green roof.
Project Description: This project is unique as this beautiful home is built like a high end barracks. The green roof was designed to tie the structure into nature as almost all the plants on the roof are native of the Pacific Northwest. Part of the project also included a separate garage that flows right into the hillside.

Benefits For Society

Improved Air Quality
According to Green Roofs for Healthy Cities, a green roof will not only absorb heat, decreasing the tendency towards thermal air movement, but will also filter the air moving across it. For example, 1 m2 (10.76 ft2) of grass roof can remove 0.2 kg of airborne particulates from the air every year. Also, 16.15 ft2 of uncut grass produces one years worth of oxygen for one person.

Storm Water Retention
The plants on a green roof capture rainwater and then through evaporation release the water back into the atmosphere. According to the City of Portland Bureau of Environmental Services in their 2003 paper, Storm Water Monitoring Two Ecoroofs in Portland, Or, USA, a green roof can retain 69 percent of rainfall from a storm. This is a huge benefit for cities because it puts less strain on the storm water management system and reduces the number of pollutants that harm watersheds and stream beds.

Water Filtration
Green roofs filter the water run-off of green roofs and moderate the temperature of the water, which is important for fish habitat in local streams.

Creation of Habitat
Green roofs provide a natural habitat for birds and act as a stepping-stone between our cities and the more natural surroundings. Furthermore, low maintenance green roofs can serve as protected habitat for sensitive plants.

Urban Heat Island Effect
This can be described as the difference in temperature between the city and the surrounding countryside. Green roofs prove to provide a huge benefit in reducing this effect. For example, research conducted on the Chicago City Hall green roof found that on days when the temperature on the paved half (black asphalt) of the building reached 169 degree Fahrenheit, temperatures on the green roof side of the building only reached 91-119 degrees Fahrenheit (directly over the greenery).

This is important because, as research by Environment Canada has suggested, greening a mere 6 percent of rooftops in Toronto, Canada, would reduce the urban heat island by one to two degrees Celsius, a reduction that would save well over $1 million per year in energy costs and remove 30 metric tons of pollutants directly from the air.