Denver City Council adopted a new Green Building Policy on October 29th, 2018. The policy, among the most ambitious in the United States, will contribute to alleviating Denver’s substantial urban heat island, add green space to the city, provide water quality and storm water benefits, and reduce greenhouse gas emissions.

All new buildings over 25,000 square feet must now have a cool roof as well as either a green roof, green space anywhere on the site, solar panels, energy efficiency features, LEED Gold Certification or a combination of these options. When an existing building of this size replaces its roof it must install a cool roof as well as either a green roof, new green space anywhere on the site, solar panels, energy efficiency improvements or LEED Silver Certification.

The following is the story behind Denver’s new Green Building Policy. What began as a citizen-led ballot initiative requiring a limited range of green roofs and solar panels was broadened through a long stakeholder engagement process to have even more benefits, as well as more flexibility. Great cities and great places don’t happen by accident. They are planned wisely, which is what Denver sought to do here.

On November 7th, 2017 voters in the City and County of Denver approved a Green Roofs Ordinance. The ordinance was proposed by citizens who wanted to help the environment and improve their City. The ordinance took effect on January 1st, 2018. It required all new buildings over 25,000 square feet to install a green roof covering a portion of the roof, a green roof in combination with solar panels, or just solar panels covering the entire roof. It required all existing buildings over 25,000 square feet to cover a portion of the roof in a combination of a green roof and solar panels when the roof was replaced.

There were several problems and unintended consequences associated with the original Green Roofs Ordinance, including the inability of many existing buildings to support the weight of a green roof, the cost to large single story retail buildings for which the original coverage requirement was particularly burdensome, legal challenges surrounding rainwater retention requirements, and uncertainty over whether green roofs alone were the best tactic in Denver’s arid climate.

Denver City Council had the authority to amend the green roof ordinance after six months, but the City’s mayoral administration felt it was important to take the time needed to convene a solid task force of diverse viewpoints, obtain the input of experts, and circulate draft proposals for public input before making a final recommendation to City Council. Some people did not want Denver to touch the original green roofs ordinance passed last year and others wanted it repealed altogether. But it was clear that

Denver needed a more functional solution.

The author led the Denver Department of Public Health and Environment’s process to review the Green Roofs Ordinance for the City. The City formed the Green Roofs Review Task Force of stakeholders from academia, the real estate industry, government, and the creators of the original green roof ordinance. The Task Force’s mission was to recommend modifications, clarifications, and improvements to the Green Roof Ordinance through a collaborative, consensus-based process that honored the vote and the benefits that the ordinance would have achieved.

The task force met nine times from January 19, 2018, through June 7, 2018. Each meeting was three hours long with many hours of work and small group discussions between meetings. The task force circulated a draft proposal for public input during May 2018. In their final meeting, members reached consensus on a proposal they believed would take the ordinance in the right direction for Denver.

Good public policy is accomplished by having great people from diverse perspectives working on it. The Green Roofs Review Task Force was no exception. Two leaders on the task force were Brandon Rietheimer, of the Green Roofs Initiative, the lead proponent for the original ordinance, and Kathie Barstnar, Executive Director of NAIOP Colorado and lead opponent of the original ordinance.

After the task force reached consensus the two leaders co-authored an op-ed in The Denver Post, where they said, “After a democratic election, people on both sides of an issue can agree to work together to make public policy better. That’s where Denver is today with our city’s Green Roof Initiative, voted into law last November. One of us campaigned against the Green Roof ballot measure, certain that the proposal set goals that would be either unworkable or unaffordable for many. One of us initiated the campaign to add meaningful green space, reduce the heat island effect from buildings, improve water quality and increase the use of renewable energy. But we didn’t let those differences in perspective deter us from talking when the election ended; instead, through the Green Roof Review Task Force, we worked together to find a way forward that we both can support and that, we hope, those on both sides of the election can live with – one that respects the will of the voters, and provides solutions that can be implemented.”

Based on the Task Force’s consensus recommendations, City Council passed the new Green Building Policy on October 29th, 2018. Final rules implementing the ordinance should be adopted in February 2019.

While green roofs and solar panels are great options, this new and improved policy looks at development more holistically. It recognizes that the best, long-term approach to building a more sustainable city is to increase green space, improve water and storm water management, increase use of solar and other renewable energies, foster the design of far more energy-efficient buildings, and embrace national standards of green building, like LEED and Enterprise Green Communities Certification.

Conventional roofs in downtown Denver, prior to enactment of the city’s Green Buildings policy

Compared to the original ordinance approved by the voters, the new Green Buildings Policy has the following key features:

  • A greater urban heat island reduction from having cool roofs on all buildings instead of black roofs partially covered in green. Requiring cool roofs is good policy. A cool roof is made of a highly reflective material (usually a reflective covering or reflective tiles/shingles) so it reflects more sunlight and absorbs less heat than a standard roof. Cool roofs are a simple way to reduce the urban heat island effect. A dark roof surface absorbs sunlight during the day, converts it to thermal energy, and then re-emits it mostly at night, preventing the city and its residents from cooling down at night. This is a major factor in why Denver is getting hotter, not just in the day but most significantly at night. Cool roofs can be installed at a minimal cost, and last as long or longer than dark roofs because the reflective surface sustains less sun damage.
  • Green space allowed to be provided on the ground as well as on the roof, so not only will Denver have up to 3.5 million more square feet of green space by 2050, it will be more accessible for residents and wildlife to enjoy.
  • The same greenhouse gas emission reductions as the old version, but with more design flexibility.
    • Using solar energy is a major piece of this policy, but property owners will have choices on whether to install solar, use community solar, purchase solar from Xcel, or use another equivalent renewable energy source altogether. Another option is to improve the building’s energy efficiency so much so that it achieves an equivalent reduction in emissions.
  • Greater flexibility in building design and a lower overall cost of meeting requirements by about 20%.
    • Some may consider the new policy to be too complex, but it’s because the task force wanted to make sure people have a range of options from which to choose what works best for them, from pursuing a recognized national standard like LEED Gold to designing tighter, smarter buildings that use significantly less energy overall. Altogether, there are 8 different paths for new buildings and 5 for existing buildings.
    • The task force calculated that total compliance costs are at least 20% lower for the green buildings ordinance than the green roofs ordinance, and many buildings will see only a small fraction of the original costs. For projects that choose a more expensive compliance path, there is usually a return on investment available.
  • Improved water and storm water management through on-the-ground spaces that can often filter and detain storm water even better than a green roof might.

Who does the new policy apply to?


  • Parking garages
  • Temporary or air-supported structures
  • Greenhouses
  • Single-family homes, duplexes
  • Multifamily residential buildings that are three stories or less
  • Emergency roof replacements

There are other exemptions based on technical feasibility, character-defining features, and existing green roof or renewable energy systems.

Cool roof only

  • Roof recovers on buildings of 25,000 square feet or more
  • Multifamily residential buildings (apartment and condo buildings) over 25,000 square feet that have 5 stories or fewer and are less than 62.5 feet in height

Cool roof + compliance option

  • Six-story or more apartment and condo buildings that are over 25,000 square feet
  • All new commercial buildings that are 25,000 square feet or more
  • Additions of 25,000 square feet or more
  • Any existing building or 25,000 square feet or more that is replacing at least 5% of its roof or roof section

Options for new buildings

New buildings must include a cool roof plus one of eight compliance options:

  1. A green roof or green space anywhere on the site.
  2. A financial contribution for off-site green space.
  3. A combination of green space and solar panels.
  4. A combination of green space and energy efficiency measures.
  5. Solar panels covering 70% of the roof.
  6. Designing a building that is at least 12% more energy efficient than current energy codes require.
  7. LEED Gold or equivalent certification.
  8. Enterprise Green Communities Certification.
Denver’s new Green Buidling Policy

Options for existing buildings

Roof replacements on existing buildings must include a cool roof plus one of five compliance options:

  1. A green roof or green space anywhere on the site.
  2. A financial contribution for off-site green space.
  3. Onsite solar panels.
  4. LEED Silver or equivalent certification.
  5. Enrollment in an Energy Program to achieve emission reductions similar to those achieved by the onsite solar option. The program includes options to buy community solar or to improve the building’s energy efficiency in a way that makes the most sense for that building.

What counts as green space?

This will be outlined in the implementing Rules and Regulations, currently under development, but is likely to mean any area containing trees, groundcover, shrubs, urban agriculture, natural grass/turf, or vegetated roofs.

What is the financial contribution for offsite green space? (“Fee in Lieu”)

To opt out of providing green space, buildings would need to pay a fee of $50 per square foot of green space coverage required but not provided. This amount was determined by a rate study that sought to account for the overall cost to the city for providing equivalent amounts of green space off site.

The rate study showed that the fee in lieu should be $50-90 per square foot for the city to have enough money to supply equivalent benefit. While $50/square foot is higher than the $25/square foot amount from the voter-adopted ordinance, it is the lowest amount deemed feasible for providing the equivalent green space benefit.

Historic buildings

There are several ways for historic buildings to meet the Green Buildings Ordinance without compromising their unique character. This includes purchasing renewable energy from the local investor-owned utility, Xcel Energy, instead of electricity generated from non-renewable sources, and enrolling in the new Energy Program. Notably, historic buildings are as, if not more, energy efficient than many other existing buildings.

Green Building Fund

The fee in lieu money goes into a Green Building Fund managed by Denver’s Department of Public Health and Environment (DDPHE). The fund must be spent on the following purposes, with priority given to low-income areas, high-impact projects, and green spaces located near the buildings that paid into the fund:

  • Green space acquisition and improvement (ecosystem protection and restoration, such as native plantings or native plantings as part of invasive species control)
  • Water quality improvements and green infrastructure
  • Urban forest protection and expansion
  • Installing green roofs in partnership with land owners/developers
  • Driving rooftop solar or community solar adoption among low-income and affordable housing developments

DDPHE will report on funding and its uses to City Council every 2 years and will establish a long-term management plan.

By working closely with both the creators of the original ordinance and real estate industry stakeholders, Denver is confident that it’s created a new and improved policy that can truly work for the community.

To read all about the new Green Building Policy go to To learn all about the task force’s work and their final proposal click on “Learn more about the origins of Denver’s innovative green buildings ordinance.”


Katrina Managan

Climate Smart Buildings Team Lead for Denver Department of Public Health and Environment. She leads programs that help the City to achieve long-term climate goals in private sector commercial and multifamily...

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