As the 2019 code cycle brings new requirements that make compliance more challenging, there also will be new HERS-verified alternative systems and devices that can be incorporated into your building design for some positive compliance credit. Listed below is one new mandatory requirement plus some optional features that can be used as tradeoffs in your projects.
Kitchen Range Hoods
Newly installed kitchen range hoods will now require mandatory verification by a HERS rater. The HERS rater will verify that the installed kitchen range hood is certified with the Home Ventilating Institute (HVI), and that it is rated to meet the required airflow of 100 cfm minimum and a noise level of 3 sones or less. Kitchen range hoods exhausting more than 400 cfm at lowest speed are exempt from this requirement.
Drain Water Heat Recovery
Choosing to install a drain water heat recovery system (DWHR) is a new compliance option that can provide you extra “bonus points” in Performance method energy calculations. As shown in the picture, a cold water line is connected to the DWHR device, with a copper coil wrapping around the shower drain. DWHR systems reclaim the heat from the hot waste water going down the shower drain, preheating the cold water line going into the water heater. This device does not use any moving parts and can be an easy install by a licensed plumber. DWHR systems are great for families and are best located at the shower used most.
When a DWHR system is modeled for Performance method compliance credit, a HERS rater must verify that the installed DWHR system and installation criteria match the compliance documents. They also need to check that that the values modeled for the system have been certified to the Energy Commission.
Graphic from a presentation by Roy Eads and Russ King of CalCERTS
Central Fan Ventilation Cooling
A central fan ventilation cooling (CFVC) system is a Performance method alternative to the Prescriptive whole-house fan (WHF) requirement in climate zones 8 through 14. These are typically hotter climate zones with larger cooling loads. A CFVC system is typically tied into the HVAC system, and automatically senses the moment when the outdoor air temperature falls below the indoor air temperature. The CFVC system will then bring in cooler outside air through the duct system and into the home, and send the home’s warmer air into the attic. The warm air exhausting into the attic will push out the attic’s even hotter air out through the attic vents to the outside. Unlike a WHF, a CFVC system does not require the occupant to open the doors and windows and manually turn on a switch, and can run without any action from the occupants.
When a CFVC system is modeled for Performance method compliance, a HERS rater must verify that the installed CFVC system ventilation rate (cfm) and fan efficacy match the values in the compliance documents.
Graphic from a presentation by Roy Eads and Russ King of CalCERTS
Small Duct High Velocity Systems
Small duct high velocity (SDHV) systems are very similar to traditional HVAC systems. The benefits with a SDHV are the smaller two inch diameter ducts, which can be great for retrofit situations or buildings that may not have enough space to place traditional duct work. These systems move air very quickly through the conditioned area, and get the space to the desired temperature much sooner than typical systems. The HERS tests for SDHV systems are the same as standard systems, just with different airflow and fan watt targets.
Unicosystems.com graphic from a presentation by Roy Eads and Russ King of CalCERTS
Article written by Francis Villapando, Energy Analyst
First published in the Gabel Energy Summer/Fall 2019 Newsletter