The Board of Zoning Adjustments approved a solar-access exception for 3585 Longwood Avenue that allows changes to the upper story roofline that staff said will create only a small amount of new wintertime shadow on three neighboring properties (3555 Longwood and 3130 and 3140 Cottrell Court). The motion passed by unanimous roll call.

Why it matters: Boulder’s solar-access rules in “solar access area 1” are intended to protect neighbors’ ability to collect solar energy in south yards, south walls and rooftops. The board's decision permits an owner to increase habitable headroom on an upper level in a way staff concluded will not cause a significant loss of solar potential for the impacted properties.

Staff findings and measurements: Robbie Wyler, BOZA liaison, described the lot as steep—dropping roughly 20 to 30 feet toward properties to the north—so the house projects long winter shadows. Staff said the project produces a small net increase in shaded area (staff estimated under 150 square feet of additional shadow, after accounting for some shading reductions elsewhere) and that those new shadows fall mainly on areas staff considers unlikely to be ideal locations for ground-mounted solar arrays. Wyler explained that solar-shadow calculations use December 20 (the winter solstice period) at 10 a.m. and 2 p.m. to model worst-case shadow lengths and noted that some existing shade will be removed elsewhere on the site. As Wyler summarized on the record: “we feel that 6 a through I are being met in full as it has been presented by the applicant.”

Applicant presentation and neighbor outreach: Lisa Larson, the project architect, told the board the changes are modest (about a 50-square-foot modification to provide habitable headroom) and that the property’s grade change—about 33 feet from the top of the main floor to the adjacent property line—drove the dramatic shadow profile. Larson said the owner had reached out to neighbors; two impacted neighbors submitted written support (3555 Longwood and 3130 Cottrell) and one directly impacted property (3140 Cottrell) did not provide a written response.

Board discussion and vote: Board members said the topography made the lot unique, that the proposed change does not increase building coverage beyond city limits, and that the additional shadows are narrow and limited in extent. Ben Doyle moved to approve BOZ2025-00005; Drew Eisenberg seconded. The roll call was unanimous in favor (Sean Haney — yes; Drew Eisenberg — yes; Katie Crane — yes; Ben Doyle — yes; Nikki McCord — yes).

What’s next: With BOZA approval, staff told the board the applicant may proceed to finalize building-permit plans and return the project to the planning and building-permit process for verification of numerical standards.