BOZA grants solar-access exception for Longwood Avenue remodel despite limited new shadows

The Boulder Board of Zoning Adjustments unanimously approved a solar-access exception (docket BOZ2025-00005) for 3585 Longwood Avenue to permit alterations to the upper story roof that will increase interior headroom and create a small amount of new shading on nearby properties.

Staff recommended approval after detailed shadow analysis and review against the solar-exception criteria in the Boulder Revised Code (staff referenced §9-9-17). The board voted 5-0 to grant the exception.

The property owner proposes to “square off” a portion of the upper floor to create habitable space. Planning staff explained the lot is steep — with a roughly 20–33 foot drop toward neighboring properties — which lengthens winter shadows and makes the site uniquely likely to cast long shadows even for modest modifications. Staff identified three directly affected neighboring parcels: 3555 Longwood (west), 3130 Cottrell Court (northwest) and 3140 Cottrell Court (north). Support letters from 3555 Longwood and 3130 Cottrell were included in the application; 3140 Cottrell did not provide support or opposition.

Robbie Wyler, BOZA liaison, and principal city planner Lisa Hood explained the solar-access analysis uses the winter solstice (December 20) worst-case sun angles at 10 a.m. and 2 p.m. to produce the longest shadows. Staff’s calculations showed new shading of under roughly 150 square feet in total; some limited shading was also removed by the project in other small areas. Staff concluded that the new shadows fall primarily on steep, partially wooded portions of neighboring yards and do not materially affect neighboring rooftops or south-facing walls where rooftop-mounted solar or south-wall solar panels would typically be placed.

Architect Lisa Larson, representing the applicant, described a roughly 150-square-foot interior reconfiguration and said the design preserves the existing ridge height while extending roof form to improve headroom on the west/upper stair element. Larson noted a seven-foot wildlife easement on the north property line and said the project avoided adding roof area that would extend further north toward Cottrell Court. Larson also said two of the neighboring parcels already have rooftop solar arrays (staff flagged panels on 3555 Longwood and another Cottrell address visible in aerials).

There were no public speakers at the hearing. Board members asked technical questions about the shadow calculations, how staff validates the analysis, and whether the shaded areas are suitable for solar installations. Wyler explained the analysis relies on surveyed elevations, architectural elevations and a standard “adjusted shadow” method that compares proposed shadows to a 12-foot hypothetical fence in Solar Access Area 1. Staff concluded the change met the code’s multi-part exception test (9-9-17(f)(6)(a)–(i)), and further found the proposal would cause at most an “insubstantial breach” of solar protection.

Following discussion, Ben Doyle moved to approve BOZ2025-00005 as presented. The roll call recorded yes votes from Sean Haney, Drew Eisenberg, Katie Crane, Ben Doyle and Chair Nikki McCord.

The BOZA decision allows the applicant to proceed with the subsequent building permit process; staff will verify final elevations and building coverage at permit review.