Qualifying For Solar Incentives With NSHP – Case Study

Posted on 22. May, 2009 by in Case Studies, Designing for Compliance, Solar

A principal in a local architectural firm approached us for T24 on a new house in Sonoma County that he was designing for himself and his partner. They needed Title 24 documents for their permit submittal, but beyond that, he wanted to qualify for solar rebate credits through California’s New Solar Homes Partnership Program (NSHP). He also wanted the house to be as “green” as possible, just because.

What do we need to do to get a rebate through California’s New Solar Homes Program?

Part of qualifying for California New Solar Homes Partnership Program (NSHP) is that the home’s Title 24 must exceed the baseline by 15%. As it turns out, the New Solar Homes Program has two tiers. Tier 1 is 15%, and requires Energy Star appliances. Tier 2 is 35%, requires Energy Star appliances, and you must demonstrate a 40% reduction in cooling load, presumably recovered from solar energy.

Well, the two buildings together were 15%, not 35. The main house was passing with flying colors, but the guest house was just squeaking by. So the question was, whether and how to modify the design aggressively enough to qualify for the higher Solar Homes tier. Since NSHP is tied to Title 24, there was some confusion over which features counted in which program.

Lessons Learned

Photovoltaics don’t count towards Title 24, but solar hot water does. However, using Solar Water Heating yields only small gains in the Title 24 results, not enough to make a difference in the Solar Homes incentive. Even without regulatory gains, though, adding solar hot water is relatively inexpensive, while PVs for electricity are not.

We also noted that the Solar Homes incentive has diminishing returns in the upper tier, because photovoltaics are expensive to buy and install, and can take many years to yield meaningful savings. Photovoltaics do count towards the solar credit, at $2.50 per watt, or 1500 watts for $3750. An additional incentive of $3.50 per watt or another $5,250 is available if you go for Tier 2. So, a Tier 2 home with 1500 watts of PV paneling would get a $9,000 rebate. But… it would cost $18K for the panels, plus installation.

Do we need a HERS rater?

When specific items are installed (Ducting, Solar P-V, certain EER-rated equipment etc.), these must be verified by a HERS rater who is a certified inspector with CalCerts, CHEERS, etc. When you have solar water heating or photovoltaics, it must be verified by an inspector who is specifically approved for the California New Solar Homes Program (aka “Title 24 HERS rated”).

What appliances count towards this credit under Energy Star?
Windows, heaters, lighting, fridge, freezer, dishwashers, washers, and dryers can earn Energy Star. Water heaters can be rated as High Efficiency under the Energy Star system, but they don’t “count” here towards the NSHP credit.

Where do Energy Star appliances get factored in for Title 24 compliance?

Umm, nowhere. Don’t confuse Title 24 calculations with the NSHP incentive. However, EnergyStar appliances count for plenty of other things – LEED for Homes, GreenPoints (which is strongly encouraged in some jurisdictions). And, of course, they contribute towards lower energy bills.

How much do you want to spend to improve the design?

Generally, adding more thermal mass, using fewer square feet of glass, using ultra low E glass, and adding a thermal envelope will all contribute towards improved energy performance, and all of these items are factored into the Title 24 calculations. But get it in before August 1, when the 2008 Title 24 requirements go into effect that are 15% more efficient than the old Title 24. With this added restriction, the main house would still comply, but not a 15% anymore, and the guest would not pass.

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