Partisans of the Mission District’s famous Zeitgeist Beer Garden won a victory Thursday when the Planning Commission voted to shave five feet off a proposed condominium building that critics said would have blocked some of the precious sunshine that makes the bar’s backyard one of San Francisco’s most popular al fresco drinking spots. The five-story, 28-unit condo development at 198 Valencia St., currently the site of an automobile oil changing shop, will likely cut the ceiling height in the ground floor retail space from 15 feet to 10 feet to conform to the commission’s decision. The commission also directed the developer to make the building’s rooftop parapet transparent, which will further reduce the shadows it casts. While chopping five feet off of the building only decreases the amount of shadow cast on Zeitgeist by 2 percent over the course of a year, that 2 percent would have shaded about eight large picnic tables during the late afternoon and early evening hours, when the beer garden is at its busiest, according to Zeitgeist. The vote was noteworthy because state environmental laws only require cities to analyze shadows cast on public spaces, not private beer gardens. Project architect David Sternberg said the transparent parapet would be more expensive and that the reduced ceiling height would make the retail spaces less attractive to tenants. [...] with dozens of newly built retail spaces sitting vacant in housing developments across the city, commissioner Rich Hillis said the emphasis should be on helping a longtime business.