Denver’s Green Roof Ordinance is the only green roof initiative in North America that goes beyond new construction to include existing buildings. The Denver Metro Building Owners and Managers Association participated in a collaborative task force, with the city and other stakeholders, to review and make recommendations to improve the practical application of the ordinance. BOMA’s focus was to mitigate the financial impact to existing buildings and new buildings, while meeting the intent of the ordinance.
Fast forward to today and the ordinance has been revised and approved by Denver City Council. BOMA helped develop performance-based alternatives to a prescriptive-based ordinance. International Building Codes and Standards have evolved over the decades into performance-based solutions. This became the umbrella of our approach to refining and improving the ordinance. Our goal was to improve flexibility and give existing and new buildings more cost-effective options. This obviously had to be done while honoring the vote and achieving the benefits of the original ordinance. Keep in mind, maintaining the status quo was not an option. The task force consisted of a wide range of competing interest groups. None of the interest groups, including BOMA, walked away with everything they wanted for their members.
The revised green roof standards include installing a cool roof. This typically is done with a white roof membrane 45 to 90 mils thick (the thicker, the better, in my experience). Light colors reflect (rather than absorb) solar energy to reduce urban heat island effect. Dark-colored roofs can increase heat-island effect (outdoor temperatures) 5 to 7 degrees. In addition to a cool roof, one of five options must be implemented to either decrease energy use/greenhouse gas or increase green roof/green space. The energy reduction option is a direct offset of what would have been achieved by installing solar photovoltaic panels on the roof. We all know by now that reducing energy saves money. This isn’t a new phenomenon. Many building owners have been doing this for decades. Like anything else, it must be done cost-effectively.
Most existing buildings (25,000 square feet and larger) will need to do a cool roof, plus one of the following compliance option:
- Green space on the roof, terraces or podiums; or payment for off-site green space.
- Percentage of new on-site solar (some existing solar installations might comply).
- Enroll in a flexible energy program achieving similar energy reductions as on-site solar.
- Third-party green building certifications (LEED BD&C or O&M Silver, and others).
If the third option – to enroll in a flexible energy program – is selected, the building should enroll before a roof replacement and use a baseline year from the last five years, then get credit for energy improvements made before the roof replacement. If this is done, the enrollment is valid for 20 years or through the roof replacement, whichever is longer.
There are several partial exemptions also available, in which case the building must still do a cool roof, but it is not required to meet any of the energy program options. Three (of several) examples include:
- Roof recover (defined as installing a new roof covering over the existing roof covering), which is different from roof replacement.
- Emergency wind or fire damage (not hail damage).
- Hail damage with insufficient insurance coverage (only through Nov. 2, 2019).
The hail damage exception obviously is designed to alert buildings they need to get the proper updated insurance coverages, which meet the provisions and potential costs of the new ordinance. It would be wise to call your insurance broker now to get the proper advice and insurance coverages.
There is a full exemption for all existing buildings if an annual roof replacement is 5 percent or less. This makes annual repairs and maintenance more important than ever. This has always been fundamental to properly managing a building. Good repairs and maintenance go a long way in extending the “useful life” of roofs, heating, ventilation and air-conditioning equipment, parking garage concrete, fire alarm systems, etc.
I like to emphasize “useful life” of a piece of HVAC equipment or a roof might be 20 years, but its actual life could be 25 to 40 years with good, consistent repairs and maintenance. I also must emphasize the importance of quality repairs and maintenance performed by quality roofing contractors. Property managers and building engineers need to properly prequalify these vendors by developing some level of a request for qualifications. The RFQ should specify various requirements for vendor’s including industry training and experience levels of personnel. I prefer to use a highly qualified roof consulting firm to help write the RFQ for roofing contractors.
The city held an open house Nov. 15 to educate building owners on how to comply with the ordinance. There are two very up-to-date and informative slide decks available on the city’s website: https://www.denvergov.org/content/denvergov/en/denver-development-services/commercial-projects/green-roof-initiative.html.