Navigating Boulder’s Solar Shadow Ordinance: Tips for Homeowners and Builders

What is the Solar Shadow Ordinance?

Boulder's Solar Shadow Ordinance regulates the shading that new constructions and additions can cast on neighboring properties. The goal is to protect solar access for a four-hour period on December 21st, from two hours before to two hours after local solar noon, ensuring that neighbors receive adequate sunlight during the shortest day of the year.

Key Provisions and Their Impact

Solar Access Timeframe

• Solar access is protected from 10 AM to 2 PM on December 21st.

Shadow Angle Measurement

• Shadows are measured within a 30° angle east and 30° west of due north.

Solar Fence Concept

• Hypothetical “solar fences” at property lines, either 12 feet or 25 feet high, define the degree of protection.

• Solar Access Area I: Protected by a 12-foot solar fence, imposing stricter limitations.

• Solar Access Area II: Protected by a 25-foot solar fence, offering slightly more flexibility.

• Solar Access Area III: Includes remaining zoning districts not protected by a solar fence.

Solar Access Areas and Their Zones

Solar Access Area I

• Protected by a 12-foot solar fence.

• Includes properties in the RR-1, RR-2, RE, RL-1, and MH zones.

Solar Access Area II

• Protected by a 25-foot solar fence.

• Includes properties in the RL-2, RM, RMX, RH-1, RH-2, RH-3, RH-4, RH-5, MU-1, MU-3, and I zones.

Solar Access Area III

• Not protected by a solar fence.

• Includes the remaining zoning districts.

The Complexity and Restrictions of the Ordinance

Lot Orientation

• Lots running north-south, especially those along the mesas, tend to be more advantageous as they are less likely to cast long shadows on neighboring properties.

• East-west oriented lots may face more restrictions due to longer shadows during the critical time period.

Shadow Length Restrictions

• These restrictions can significantly limit what can be built on a property. In some cases, the limitations imposed by the ordinance can make certain projects unfeasible, leading some to refer to these restrictions as “project killers.”

Historical Context

The Solar Shadow Ordinance was passed in 1982 to protect access to sunlight for homeowners and renters. This ordinance limits the amount of shading that new construction can permit, ensuring solar access during the critical four-hour period on December 21st. This historical context highlights the city’s long-standing commitment to sustainable living and community well-being.

Strategies for Compliance

3D Computer Modeling

• To navigate these restrictions, many homeowners and builders create 3D computer models of their projects. By reverse engineering the shadow, they can determine the available building envelope and ensure compliance with the ordinance.

Design Adjustments

• Consider architectural modifications to minimize shadow impact. This might include reducing building height, changing the orientation, or using innovative design solutions to comply with the ordinance.

Consulting Experts

• Engage professionals who specialize in local zoning laws and solar access regulations. Their expertise can provide invaluable insights and help streamline the approval process.

Benefits of Compliance

Adhering to the Solar Shadow Ordinance not only ensures legal compliance but also promotes a sustainable and community-friendly environment. By protecting your neighbors' access to sunlight, you contribute to the overall well-being and harmony of your neighborhood.

Conclusion

Boulder's Solar Shadow Ordinance presents unique challenges for new construction and additions, but with careful planning and strategic design, compliance is achievable. Understanding the ordinance's intricacies and leveraging tools like 3D modeling can help you navigate these regulations successfully.

For more detailed guidance and support in planning your construction project in Boulder, contact Stonebrook Construction Group. Our expertise in navigating complex regulations ensures your project will be both compliant and considerate of your neighbors' solar access rights.