the US Department of Energy. This project reports an average cost of $3500 per home retrofitted, with a distribution of 57%, 14%, 29% to homeowner incentives, contractor incentives, & administrative costs respectively. In the commercial domain, the Energy Star Program by EPA aims to reduce the carbon footprint of buildings. According to this initiative, owners benchmark their buildings on a scale of 1–100. Those scoring 75 & above receive 'Energy Star' designation; while the others are encouraged to follow upgradation strategies for a better performance. Nearly 500,000 properties, representing about half of US commercial building floor area has been benchmarked as of 2016, with a grand total 29,500 buildings receiving the 'Energy Star' rating to that point. The retrofitting industry is steadily on the rise. Some major obstacles in its path include as found by Carine et al.: High initial investment. Complexity of retrofits. Lack of awareness regarding retrofitting. Shortage of affordable financing. Notable case studies The Empire State Building The Empire State Building is undergoing a deep energy retrofit process that is projected to be completed in 2013. Upon completion, the project team, consisting of representatives from Johnson Controls, Rocky Mountain Institute, Clinton Climate Initiative, Jones Lang LaSalle, and NYSERDA will have achieved an annual energy use reduction of 38% and $4.4 million. A notable achievement of the project is that instead of replacing the chillers as originally planned, the design team were able to first reduce the building's required cooling capacity by 1600 tons, allowing for a chiller retrofit instead of replacement which would have been $17.3 million more in capital costs. The Indianapolis City-County Building The City-County Building recently underwent a deep energy retrofit process that is projected to be completed in September 2011. Upon completion, the project team, consisting of representatives from the Indianapolis Marion County Building Authority, Indianapolis Office of Sustainability, Rocky Mountain Institute, and Performance Services will have achieved an annual energy reduction of 46% and $750,000 annual energy savings. Market sizing United States A business case study by The Rockfeller Foundation sizes the potential of retrofitting market in the USA. Retrofitting offers a burgeoning business market for entrepreneurs, engineers, investors in the USA. It offers a $279 billion investment opportunity. The residential sector, followed by commercial and institutional sectors, offers the largest business impact. Scaling up retrofitting efforts can create 3.3 billion direct and indirect cumulative job years in the United States. Criticism