Hot Water Heat Pumps Solve Title 24 Code Challenge
Changes to California’s Title 24 code allow heat pump waters to perform as a prescriptive option, balancing overall energy use for a home.
The 2019 Title 24 added two rules not found in previous codes. The first new item is Community Shared Solar or Battery System. This allows for a common shared system to offset any solar and/or battery requirements of a building.
The second important change is the way builders show compliance in the performance approach. 2019 uses Energy Design Rating (EDR). Currently, it is TDV (Time Dependent Valuation). The EDR rating is scored on two aspects:
- Performance of heating, cooling, and domestic hot water systems
- Performance of heating, cooling, and domestic hot water PLUS appliances, lighting, plug loads and PV.
So it might play out like this: A builder could design a high-performance home, but not include PV. The first goal is passed, but because he doesn’t have the necessary PV production required by code, the house will fail. In another situation, say a builder puts up a home that has lots of windows but offsets their energy use with a huge PV system. While he will clear goal two, he will be wildly out of compliance with goal one, and the house will fail. The idea behind the two goals is that the CEC is looking for a balance of energy efficiency and PV production. (Additions and alterations will still be rated via TDV and not subject to the PV or use of appliances and receptacles rules).
A new way (as of 2019) to hit the Title 24 benchmark is with heat pump hot water heating. This technology drops the overall energy load for the home significantly, making it easier to hit the necessary balance between PV production and power use.
“When you consider the schemes to get compliance and the flexibility with the heat pump water heaters, it is amazing,” adds Gina Rodda, principal of Castro Valley, Calif.-based Gabel Energy. “If you want extra windows or something else you can get a demand response utility rate by allowing utilities to charge the water heater during the day, which helps manage the grid.”
(This example Rodda gives could be done through a performance software strategy coordinated with local utility and demand response controls allowing communication between utility and home.)
"Heat pump technology is tried-and-true technology we know well,” explains Greg Holladay, with Bradford White Water Heaters. “We’ve taken that technology and adapted it to our water heater and run it in reverse from how a refrigerator works. You take a little bit of warmth—anything above 35 degrees F—and you can use that to heat your water up to a maximum of 140 degrees.”
Holladay says the education process for contractors is ongoing, but that making the case for the superiority of heat pump technology is simple. It comes down to technology and cost savings. “Electric heat pump technology is more efficient because it is moving heat, not generating heat. It comes in at 3.39 UEF. A higher UEF will decrease your cost and result in a faster payback.
“It’s a product that helps homeowners,” Holladay summarizes. “It’s bigger than the product itself. Heat pump water heating is the best green technology out there because it pays for itself so quickly.”