Dear All,

Our current project is an existing building renovation, where boiler and chiller in the 2 pipe fan coil system are retained, but the fan coil units are replaced with new ones. The mechanical contractor informs us that it is cost prohibitive to implement an Optimum Start functionality as required by ASHRAE 90.1-2007. How are we supposed to approach this in your opinion? Can we assume that this heating / cooling system is an existing system and therefore does not have to comply with the prescriptive requirements of ASHRAE 90.1-2007?