I don’t mean to rub it in to the rest of the country, who have had heinous winter weather to deal with this season. But here in Northern Cal it’s mid-February and we have had a string of weather with days of mostly high 70’s. Bad for skiing and the water table, but days like this make me think that Bernard Maybeck, 1882 – 1957, the great Californian Architect, was right. The best house for California is a bunch of small rooms scattered around a garden. Who needs heat or AC? Maybeck was inventive and responsible for the earliest tilt-up concrete panels. I’d like to think he would appreciate SIP construction.
But I digress. I am here with Katy Hollbacher of Beyond Efficiency Inc, an Energy Efficiency specialist and a Certified Passive House Consultant, to discuss CalGreen and Title 24 from 2011 on and what it means to Californian Architects, Developers, and Builders.
Oz – ” Hello Katy welcome to my little green blog”
KH – ” Thanks, I’m honored to be here! “
Oz – ” So, Katy let’s cut to the chase. We just started the CalGreen mandates. I’ve read through them, and I’m confused like everyone else, but I see a lot of green building standards that were already required in some municipalities, like Build It Green and others, that have been incorporated into CalGreen. Do you see CalGreen supplanting these Green Programs?”
KH – “I think it’s anyone’s best guess as to exactly how CalGreen will or won’t impact Build It Green’s GreenPoint Rated program, LEED or others. But first, it’s important to understand that GreenPoint Rated, as well as any other voluntary program, will by design always be “beyond code”. In fact, when CalGreen went into effect January 1, a new version of the GreenPoint Rated checklists that incorporate the mandatory CalGreen measures were ready & waiting. I think there will continue to be sellers and buyers in the marketplace looking for a third-party “seal of approval” of the greenness of a building, and that programs solely dedicated to that role, such as GreenPoint Rated, will continue to fill that need. “
Oz – ” CalGreen has 2 building classifications, residential and non-residential, 2 sections, mandatory and voluntary, then 2 levels of voluntary achievement called Tier One & Tier Two. How do these compare to, say, Silver, Gold, or Platinum LEED standards? ”
KH – ” You might be able to do an analysis of points only and find typical correlations, but I haven’t done that comparison. There’s a very helpful summary of low-rise residential measures that compares CalGreen with GreenPoint Rated Single Family and LEED for Homes—I’ll give you the URL to share with your readers. (See following) But points aside, I think that attempting this comparison is a little misleading because of the verification differences between CalGreen and the others. CalGreen does have a field inspection requirement, but I don’t think anyone can honestly argue that building departments will have the resources to fulfill that role as thoroughly or as well as a specially trained, dedicated third-party Rater. It will be interesting to see how many local jurisdictions choose to outsource CalGreen verification to outside Raters. “
Oz – ” When you are analyzing a building for the required Title 24 report how do SIPs perform over stick framing? ”
KH – ” SIPs assemblies do great in Title 24 calculations: as a quick example, a 6” SIP wall gives you an overall assembly R-value of 18.5, while a 2×6 stud wall with R-19 batts gives you just R-13.5. This improved performance of almost 30% can do wonders for your Title 24 compliance margins and associated California Advanced Homes incentives. And as for what it means to the building, less heat loss really adds up and can hugely impact the size of your HVAC systems, let alone comfort and utility bills. “
Oz – ” What about the incredible tight exterior envelope you can achieve with SIPs. How does this help in Title 24? ”
KH – ” One of the available Title 24 compliance credits is for reduced envelope air infiltration. Just about any building assembly can be made very tight, but it takes a lot more work to detail a stick-framed assembly for airtightness. With SIPs you really only need to deal with splines, connections to sill and top plates, and penetrations through the panels. “
Oz – ” You know the question was coming. How do you see SIPs as a solution to address Title 24 energy efficiency standards? ”
KH – ” SIPs building assemblies can be a major contributor to the overall energy efficiency of a building and achievement of Title 24 energy efficiency standards. It’s essential to think whole-systems, though, and be sure you’re getting other measures right such as optimal orientation of the building, proper selection and placement of windows, high-efficiency equipment, and on and on.
Oz – ” I know we both have a small contribution to Clarum Homes‘ Lemon Ave project, one of the first Certified Passive House projects in California. You are performing the energy analysis and Premier is providing the SIPs. How are SIPs helping you to achieve the 80-90% reduction in space heating demand as called for in Passive House standards? ”
KH – ” For anyone who isn’t familiar with the Passive House building energy standard, let’s just say it’s a REALLY high bar for energy-efficiency and incorporates a level of precision and scientific analysis rarely attempted for huge buildings, let alone homes. In real life <stick framing> you don’t have an R-19 wall, but more like R-14, or about 25% worse performance—and that’s not even accounting for air leakage or improper insulation installation (which sadly is usually the rule, not the exception). 25% of the typical stick-framed wall is filled with wood, and that obviously displaces insulation and reduces average R-values—but on top of that we get additional losses from 2-dimensional heat flow effects called thermal bridging in areas adjacent to the wood members. So how does SIPS help ease the Passive House challenge? There’s much less wood in the overall assembly, the panels are already very airtight and don’t need much sealing work in the field after installation, and the insulation’s already perfectly installed! “
Oz – ” Thank you very much Katy. I know you haven’t told us all you know, so hopefully, we’ll have more questions for you and can have you back.”
KH – ” Anytime! Thanks for having me. “
Readers related resources:
CalGreen code: www.bsc.ca.gov/CALGreen
CalGreen vs GreenPoint Rated: http://goo.gl/dyYHH
CalGreen, GreenPoint Rated & LEED Homes measures compared: http://goo.gl/fB3E9
Passive House California: www.passivehouseca.org
Beyond Efficiency: www.beyondefficiency.org