Calare Properties, a Hudson-based real-estate investment company that co-owns the former Evergreen Solar factory in Devens, recently acquired a 51,500-square-foot flex/office building at 205 Burlington Road for $2.3 million. In a press release, Calare officials said they plan to employ a "significant capital-improvement program," including a new roof, faade enhancements, seal/stripe of the parking lot, new signage, landscaping upgrades, and new interior common areas.