1. General information
2. Objectives of the intervention
Goals of the intervention
Portland’s ecoroofs are largely designed to aid with stormwater management (Ref. 2,4,12), in broader efforts to increase the City’s resilience to natural hazards, disasters, and climate change (Ref. 3,9).
Stormwater management principles are used to protect the City against runoffs and flooding, and to maintain the health of the city’s watersheds (Ref. 7,12).
The City prioritizes the use of vegetation and infiltration to meet stormwater requirements because it improves resilience to changes in hydrology anticipated due to climate change (Ref. 7).
Furthermore, ecoroofs are incorporated into green building design to provide a ‘sustainable alternative to conventional roofing’ and ‘reduce the negative impacts from buildings on air, water, energy and the earth’ (Ref. 8).
Stormwater management principles are used to protect the City against runoffs and flooding, and to maintain the health of the city’s watersheds (Ref. 7,12).
The City prioritizes the use of vegetation and infiltration to meet stormwater requirements because it improves resilience to changes in hydrology anticipated due to climate change (Ref. 7).
Furthermore, ecoroofs are incorporated into green building design to provide a ‘sustainable alternative to conventional roofing’ and ‘reduce the negative impacts from buildings on air, water, energy and the earth’ (Ref. 8).
Quantitative targets
The City’s Grey to Green Initiative in 2008 laid out a goal of constructing 43 acres of new ecoroofs between 2008 and 2013 (Ref. 13).
As of 2018, for new buildings with a net building area of at least 20,000 square feet, there must be an ecoroof that covers 100% of the building area; at least 50% of the ecoroof vegetation must be an evergreen species; the vegetation should be hardy and achieve 90% coverage within 2 years of planting; the roof must reduce annual runoff volume by 50%; the roof must have at least 4 inches of growing media (Ref. 2).
As of 2018, for new buildings with a net building area of at least 20,000 square feet, there must be an ecoroof that covers 100% of the building area; at least 50% of the ecoroof vegetation must be an evergreen species; the vegetation should be hardy and achieve 90% coverage within 2 years of planting; the roof must reduce annual runoff volume by 50%; the roof must have at least 4 inches of growing media (Ref. 2).
Monitoring indicators defined
% of ecoroof coverage on buildings, % of evergreen species in ecoroof vegetation, % vegetation coverage, % runoff volume reduction, inches of growing media (Ref. 2), area of ecoroofs (Ref. 13).
Sustainability challenge(s) addressed
Climate change adaptation: What were the goals of the NBS?
Climate change adaptation: What activities are implemented to realize the conservation goals and targets?
Please specify "other Habitats and biodiversity conservation activity"
Create and use scientific knowledge for conservation, regarding avian monitoring (Ref. 14,15).
Habitats and biodiversity conservation: What types of conservation goals are / were defined for the NBS intervention?
Habitats and biodiversity conservation: What activities are implemented to realize the conservation goals and targets?
Implementation activities
- From 2008 to 2012, subsidies of $5 per square foot were provided for projects meeting the following criteria: ‘be in the Portland city limits, be designed to manage stormwater, and be feasible and buildable within two years of receiving funds’. Projects were also evaluated on ‘cost estimates, size, ratio of green roof to total roof area, visibility, innovation, and the opportunity to engage diverse communities’ (Ref. 5).
- From 2018, the following criteria are mandated: ‘new buildings with a net building area of at least 20,000 square feet must have an ecoroof that covers 100% of the building area; at least 50% of the ecoroof vegetation must be an evergreen species; the vegetation should be hardy and achieve 90% coverage within 2 years of planting; the roof must reduce annual runoff volume by 50%; the roof must have at least 4 inches of growing media’ (Ref. 2).
- Energy conservation & avian monitoring studies were conducted on ecoroofs (Ref. 14,15).
- Support from the City has been provided, including providing classes, tours, events, technical assistance, and online resources for DIY ecoroofs and professional ecoroof service providers (Ref. 1,4,12,13).
- From 2018, the following criteria are mandated: ‘new buildings with a net building area of at least 20,000 square feet must have an ecoroof that covers 100% of the building area; at least 50% of the ecoroof vegetation must be an evergreen species; the vegetation should be hardy and achieve 90% coverage within 2 years of planting; the roof must reduce annual runoff volume by 50%; the roof must have at least 4 inches of growing media’ (Ref. 2).
- Energy conservation & avian monitoring studies were conducted on ecoroofs (Ref. 14,15).
- Support from the City has been provided, including providing classes, tours, events, technical assistance, and online resources for DIY ecoroofs and professional ecoroof service providers (Ref. 1,4,12,13).
3. NBS domains, ES and scale
4. Governance and financing
5. Innovation
Type of innovation
Novelty level of the innovation
Please specify novelty level of the innovation
Green roofs have been implemented in other parts of the world, but it is more novel in the US (Ref. 8).
Replicability/Transferability
Please specify Replicability/Transferability
Unknown
