Water Heating Credits (Table R406.3 Option 5)
Category 5 of Table R406.3 covers water heating efficiency. For many builders, a heat pump water heater is one of the most cost-effective ways to earn credits — up to 3.0 credits from a single piece of equipment that you need to install anyway.
Category 5: Water Heating
The water heating category offers several sub-options, each worth different credit values depending on system type and efficiency. The key sub-options are:
| Sub-option | Description | Credits |
|---|---|---|
| 5.1 | Solar water heating system Solar thermal collectors — panels on your roof that heat water directly using sunlight. Different from solar PV panels that generate electricity. | 1.5 |
| 5.6 | Electric heat pump water heater, NEEA Tier III qualified A standard heat pump water heater — looks like a tall tank with a compressor unit on top. Pulls heat from the surrounding air to heat your water, using 2–3x less electricity than a conventional electric tank. Needs to be in a space with adequate air volume, typically a garage or utility room. The NEEA specification is the technical standard — you don’t need to read it, but your plumber or supplier will use it to confirm the equipment qualifies. | 2.0–2.5 |
| 5.7 | Electric heat pump water heater, UEF ≥ 2.9, split system A split-system heat pump water heater — the compressor/heat exchanger sits outside (like an AC unit) and connects to an indoor storage tank. More efficient than the all-in-one version and doesn’t cool down the room it’s in. Requires outdoor unit placement on the site plan. | 2.5–3.0 |
Credit values vary by climate zone. CZ5 typically earns the higher value in each range. Check the full Table R406.3 or use the wsec.ai wizard for your specific zone.
Addon vs Primary
You can only select one option from sub-options 5.3 through 5.8 — these are mutually exclusive primary water heating selections. However, sub-options 5.1 (solar) and 5.2 (drain water heat recovery) are addons that can be combined with any primary selection. This means you could pair a NEEA Tier III heat pump water heater (5.6) with a solar preheat system (5.1) and stack the credits.
Practical Note
A heat pump water heater (HPWH) typically costs $2,000–$3,500 installed, depending on brand and capacity. At 2.0–3.0 credits per unit, this is often the best credit-per-dollar value in the entire R406 table. Compare that to upgrading your entire wall insulation assembly or installing a solar PV system — the HPWH is frequently the cheapest path to closing a credit gap.
Frequently Asked Questions
What’s a heat pump water heater?
A heat pump water heater uses the same technology as a heat pump HVAC system, but applied to water. Instead of generating heat directly with an electric element, it pulls heat from the surrounding air and transfers it to the water tank. This makes it roughly 2–3 times more efficient than a standard electric tank water heater. Most units also have backup electric elements for high-demand periods.
Where do I put it?
A HPWH needs access to a reasonable volume of air — manufacturers typically recommend at least 700–1,000 cubic feet of surrounding space. A garage or dedicated utility room works well. Keep in mind that the unit produces cool, dehumidified air as a byproduct, which is a bonus in a garage during summer but something to plan for in conditioned spaces.
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