Landmarks Preservation commissioners approved the $1.3 billion Domino Sugar Refinery redevelopment in Brooklyn today. After commissioners rejected a five-story rooftop addition to the complex’s landmarked refinery building in March, its developers decided to scale it down to four stories on the left of the smokestack and three stories on the right. The signature Domino Sugar sign will now be preserved atop the three-story rooftop addition. The project is expected to break ground in fall 2009. Thirty percent of the 2,200 residential units were slated to be affordable, but the developers told the Observer that some could be lost because of a 20,000-square-foot reduction in size.