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If you are a building owner or considering a new project in the city of Denver, you may be affected by the city’s new Green Building Ordinance. But what makes a building “green,” and why does the city require it?


The introduction of a green building ordinance is something that many forward-thinking cities across the US and the world are doing for a variety of reasons. The buildings we all live, work, and shop in are a major source of greenhouse gas emissions and generate significant demand from the grid. By requiring buildings to be constructed and operated using materials, methods, and design schemes that are less consumptive of energy and more efficient, these municipal, state, and national governments are helping to create a more sustainable future.

Green roofs, in particular, have become a hot topic for larger cities as they offer many benefits. A green roof is basically the inclusion of low maintenance plant systems on your roof and is a key aspect of the wider “green infrastructure” movement. By implementing a green roof on your building, you can reduce heating and cooling costs, help manage stormwater runoff, and provide a green space for your building’s occupants or employees to enjoy. Additionally, a green roof is a simple and effective way to earn points toward LEED certification if you are pursuing a green building.

The key to understanding why municipalities are implementing green building ordinances, however, lies in the wider benefits of green roofs. In addition to localized benefits, green roofs provide benefits to the wider community and environment in which they are required. Stormwater management is often a major issue in modern cities. The abundance of impermeable surfaces gives water nowhere to flow but downstream in a city, causing huge surges and washouts in the nearby streams and rivers along with a cascade of related ecological issues. By requiring green spaces, cities are attempting to increase the infiltration of water, and thereby slow the flow during rainy times. Increasing plant life in a city also helps to improve air quality and combats the “heat island” effect that can cause cities to be several degrees warmer than surrounding areas.

Stormwater management, rising temperatures, energy consumption, and poor air quality are frequent issues in major US cities. By requiring green roofs, all three can be addressed to the benefit of people, planet, and profit. Since not every single roof can be converted to a green roof, many green building ordinances offer the option to instead install solar panels or pay into a green building fund in order to help fund other projects designed to mitigate these issues.



As of November 1, 2018, the Denver Green Building Ordinance (GBO)—a revised version of the Green Roof Initiative (GRI)—became effective in Denver, Colorado. This law affects all newly constructed buildings over 25,000 sqft., any new building additions over 25,000 sqft., and roof permits for existing buildings over 25,000 sqft.

The Denver GBO gives affected building owners several ways of meeting the requirements of the law. These options include adding green space or a green roof, on-site solar power production, purchase of off-site solar power, payment to the Green Building Fund, other energy conservation methods, or some combination of the above approaches.


Green Space or Green Roofs
  • 10% of building or addition’s GFA OR
  • 60% of total roof area OR
  • All available* roof area
Payment to Green Building Fund
  • $50/sq. foot of green space required but not provided
Solar Power
  • Onsite: 70% of total roof area OR
  • Generate 100% of the building or additions annual estimated electricity use OR
  • Purchase of 100% of building electricity use

As construction and population in Denver grow at a breakneck pace, the GBO could not have come at a better time. This is the latest version of the Denver GBO, but there have been rules in Denver requiring some sort of green roof for new construction for some years. In 2017 the people of Denver voted 54% to 46% in favor of a Green Roof Initiative. This original vote required roofs of buildings over 25,000 sqft. in Denver to install a green roof or solar panels. However, the original wording of the rule made the process difficult for some building owners, and so the new ordinance was passed to shore up the language and provide alternative options for buildings not able to bear the weight of solar panels or a green roof.
“The new ordinance looks at development holistically and has an array of green space, energy conservation, renewable energy, and other great options to choose from,” said Bob McDonald, executive director of Denver’s Department of Public Health & Environment (DDPHE) and the City’s Public Health Administrator. “We are excited by what this means for Denver.”


The Denver Green Building Ordinance has been updated to allow for alternatives to green roofs and solar panels that still offer community and environmental benefits. Some examples include reducing the urban heat island effect with “cool roofs” or providing off-site solar capacity for roofs without the structural capability to add solar panels themselves. This change has made the law easier to comply with while honoring the intent of the original ballot initiative and the will of the people of Denver. However, the most effective way to comply with the law for most building owners or new project owners is still some combination of planted green spaces and solar power generation on the roof.

Whether to opt for green spaces, solar panels, or some combination of the two depends on the particular needs and qualities of your building. Green roofs can be less expensive in the short term and offer beautiful spaces for building occupants or visitors to enjoy. They also have the strongest potential for reducing the heating needs of the building. Green roofs are great for reducing your carbon footprint by reducing the demand for energy in heating and cooling but will not produce any energy or resources (other than flowers or perhaps vegetables).

Solar panels, on the other hand, are more expensive upfront than a green roof, but will almost certainly pay for themselves in saved utility and other operational costs in a short time. Structural considerations and aesthetics can play into the viability of rooftop solar panels and reinforcing or redesigning a roof can be costly. One excellent way to mitigate installation costs for solar panels is through C-PACE, or Commercial Property Assessed Clean Energy.


C-PACE is a financing structure available to commercial and multi-unit residential buildings for investment in clean energy and other energy efficiency solutions. The Colorado C-PACE program is offered in many Colorado counties, including Denver County, and offers long-term (up to 20 years) financing for solar panels and accompanying costs such as roof reinforcement.

Often a C-PACE loan covers 100% of clean energy investment and is designed to be offset by energy cost savings. This structure is designed to encourage investment in clean energy and can be effectively zero cost to a project initiator. Learn more about the C-PACE program in Colorado.

Getting the most out of the Denver GBO comes down to figuring out what’s sustainable in the long term for a given project. That being said, the best option, in general, is a mixture of green roof space and solar panels. A combination of 18% of the total roof area devoted to green space and 42% for solar panels is sufficient to satisfy the Denver GBO. This means you can reap the benefits of both the green spaces and solar power generation while maintaining 40% of your roof space for other necessary building uses.

Overall the Denver Green Building Ordinance is a powerful tool in pushing the city towards sustainability. For those that choose to opt-out of the most efficient and sustainable option, they are able to pay $50 per sq. foot into a Green Building Fund. For the rest of us, the city of Denver has a bevy of options and combinations that allow for nearly any new building, addition or update to a building to become better for the building occupants, the Denver area community, and the planet at large.

For more information on solar in Denver, call Independent Power now at (303) 443-0115.