A Large Corporate Headquarter Retro-Commissioning: How Changes Produced Significant Energy Savings

The investigated facility is the world headquarter of a large corporation located in New Jersey. The facility is an 866,020 square feet (80,456 m(2)) campus with four commercial office buildings and a global network center building. The energy usage rate was high for this type of facility. A retro-commissioning project was approved in the fall of 2010. Energy conservation measures include adapting variable frequency drives on constant-speed fan and pump motors, changing control mode, optimizing fan and compressor control for air-handling units, conversion of constant-volume system to variable-volume system, re-commissioning and control optimization for the whole campus HVAC systems. Savings measurement and verification was performed from fall 2011 to fall 2012. As a result, over 4,510,110 kWh electricity and 3,718 MMBtu (1,090 MW) natural gas was saved annually. Comparing the weather normalized post-retrofit data against the pre-retrofit data, annual electricity consumption is reduced by 18% and gas usage is reduced by 6%. The total source energy savings is reduced by 17% after weather and billing period calibration. The overall payback was 2.4 years and reduced to 1.3 years with the rebate provided by NJCEP incentive program.