Position Statement - Massachusetts Residential Code Requirements
780 CMR EIGHTH EDITION AND MASSACHUSETTS RESIDENTIAL MECHANICAL CODE FAN EFFICACY REQUIREMENTS
It has come to our attention that the 780 CMR Eighth Edition and Massachusetts Residential Code fan efficacy requirement of 2.8 cfm per watt that is required for bath fans and air handlers is incorrectly being applied to energy recovery ventilators (ERV). This misinterpretation of the code mainly arose because REMRateTM, the most commonly used rating software to show compliance to the residential code, had incorrectly applied the fan efficacy requirement for bath fans and air handlers to ERV. PRODUCT Residential Heat Recovery Ventilators (HRV) and Energy Recovery Ventilators (ERV). DISCOVERY/INTERPRETATION Upon further research into this problem, we discovered that the bath fan and air handler fan efficacy requirements were never intended to apply to ERV’s and do not apply to ERV’s. Furthermore we also learnt that NORESCO, the third party developer for the software, was contacted by the person who authored this portion of the code, who indicated he was seeking a clarification from ICC based on his stated intent for that section. On this basis, NORESCO has removed the fan efficacy requirement for HRVs and ERVs in version 15.0 of the REMRate software. The figure below is the software enhancement version history for v15.0 of the REMRate software that shows that the application of fan efficacy requirements do not apply to ERV’s have been removed from the software. Figure 1 - REMRate Software Version History Note CONCLUSION The fan efficacy requirements of the 780 CMR Eighth Edition and Massachusetts Residential Code only apply to bath fans and air handler and do not apply to energy recovery ventilators. Additionally REMRate nce to the Code. Bath fans and Air Handlers use energy to move air, ERV’s save energy over and above the energy used to move that air.