Norgen Consulting Group is developing a master plan for a major NYC developer to comply with LL97 2050 goals of 80% reduction of carbon emissions and Boston Emissions Performance standard of zero carbon in 2050. The two 40-story plus office buildings being studied are heated by district steam. The buildings open in 1909 and 1992 respectively. This plan is being developed through NYSERDA PON 4498 "Empire Building Challenge". The master plan is intended to be applied across the portfolio of tall buildings including those resent builds in the last five years. This 30-year plan will require significant investments in the buildings shell and mechanical systems. The plan also has to be flexible and completed in increments using existing technology.