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HERS Raters Can Credit Drain Water Heat Recovery Systems to Lower HERS Index Scores

Feb 22, 2016

The ANSI/RESNET/International Code Council Standard 301 incorporates new water heating efficiency calculations, including Drain Water Heat Recovery (DWHR) in calculating a home’s HERS Index Score.  RESNET accredited HERS Rating Software programs were to incorporate the new standard in their software tools beginning on January 1, 2016.  As a result of inconsistencies in incorporating the new standard, the RESNET Board of Directors moved the date that HERS Raters must use the revised software programs to July 1, 2016.

Despite this delay, HERS Raters can still credit DWHR systems through the Innovative Design Request that RESNET has adopted to calculate energy savings for DWHR systems and provide an appropriate HERS Index score credit where these systems are properly installed in homes.

The RESNET Drain Water Heat Recovery Innovative Design Request will remain in effect until the revised HERS rating software tools go into effect.

For information on how to incorporate DWHR systems into a HERS rating along with an example of completed determination of DWHR Systems for HERS Index credits go to RESNET Innovative Design Request on Drain Water Recovery