Initiative 300 (I-300), commonly referred to as the Green Roof Initiative, has been in effect since January 1st, 2018. The Initiative succeeded with just over 54% of the vote despite significant outspending by an opposition coalition of developers and real estate businesses.

Green roof legislation has long been implemented in Europe but interest has been growing within the United States. Many cities, such as PhiladelphiaChicago, and Portland, offer incentives and bonuses for developments that incorporate green roofs. On January 1st, 2017 San Francisco became the first U.S. city to mandate living roofs and solar energy collection on new construction. Now Denver is the second U.S. city with mandatory green roof legislation and is posed to strengthen its position as a sustainable and resilient city.

Denver Green Roof Initiative Details:

The mandate requires every new building, building addition, or roof replacement with a gross floor area of 25,00 square feet or greater must include a green roof or a combination of green roof and solar energy collection. The area required to be a green roof is scalable starting at 20% coverage for 25,000 to 50,000 ft2 of the gross floor area and increasing 10% for every additional 50,000 square feet up to 60% coverage. Solar energy collection can be used to fulfill up to 70% of the area required to be a green roof. There are modifications and exemptions to these requirements that are dependent on characteristics such as building structure and planned use. For example, existing buildings that require a roof replacement only need to meet I-300 requirements up to the amount of roof coverage possible without requiring major structural alterations.

The rules on how the Green Roof Initiative will be carried out require further discussion and clarification. There are many opportunities for public involvement during this process. A Technical Advisory Group (TAG) has been created to help guide the Community Planning and Development Department through this process. In addition to the TAG, the Denver Department of Public Health and Environment is leading a stakeholder engagement process to review and suggest modifications to the ordinance. They will be holding meetings open to the public lead by a team of appointed stakeholders. The Community Planning and Development Department will also hold public meetings for proposed changes to the municipal code related to initiative. Changes to the Initiative require a super-majority from the Denver City Council and cannot be implemented before mid-2018. See the link below for updated information on upcoming public meetings.

What does Denver stand to gain from the Green Roof Initiative?

Prior to the passing of I-300 a cost benefit study was conducted by The Green Infrastructure Foundation and Green Roofs for Healthy Cities to provide a financial analysis of what a Yes Vote would mean for Denver. The study found that by 2058 there would be an estimated 57.5 million square feet of green roofs built with $1.85 billion generated in savings. Some of the benefits contributing to the total savings include:

  • Added jobs in construction, maintenance, and food production
  • Direct energy savings
  • Locally produced food
  • Savings from a reduced heat island effect.

The study found that the costs of green roof installation and maintenance for a typical office building are more than offset by energy, storm water, and real estate value benefits. Green roofs prove to be cost effective on an individual building scale but their significant community wide benefits should also not be overlooked. These benefits include flood risk reduction, wildlife habitat, and air quality improvements. The next blog entry will explore these community benefits in greater detail.

Links About the Denver Green Roof Initative:

  • The full text of the I-300 ballot submission is available here.
  • You can download the full Cost Benefit Study here.
  • Updates from municipal departments and public meetings is available here.