No, ENERGY STAR scores are NOT affected by other properties in Portfolio Manager.
ENERGY STAR scores are developed based on the data in the Commercial Building Energy Consumption Survey (CBECS) conducted by the Department of Energy’s Energy Information Administration. This national survey gathers data on building characteristics and energy use from thousands of buildings across the United States. EPA uses this building data to build statistically representative models to compare your property against similar properties from the survey, and determine the scores.
EPA updates the scores as new CBECS data becomes available (approximately every 4 years).