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Archive for 'Technical'

QII HERS Credit Now Allows Open Cell Spray Foam

QII HERS Credit Now Allows Open Cell Spray Foam

Posted on 19. Dec, 2011 by .

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This news flash about a seemingly obscure topic is of immediate importance to all our architect Title 24 clients -and it’s good news for a change. The Quality of Insulation Installation credit is a HERS test that can help design projects to achieve Title 24 energy compliance, and we’ve had a couple of nasty surprises with it in the past.

Apparently, up until around yesterday, the California Energy Commission did not officially recognize the QII test as valid for open-cell spray foam. Our insulation expert James Morshead of SDI Insulation actually sent me an urgent email yesterday with the news, saying:

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Water Heating Efficiency and Residential Title 24 Compliance

Water Heating Efficiency and Residential Title 24 Compliance

Posted on 29. Sep, 2011 by .

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OK, I’m the first to admit that I know next to nothing about water heaters. Aren’t they those white cylinders that live in garages, as far as possible from the kitchen and the shower? Well… yes and no. In our Title 24 work, which is architect-designed custom single-family projects, the water heater is usually the last thing on anyone’s mind. However, on many of our analysis projects, the quickest, cheapest way to comply with California’s stringent energy-efficiency requirements has been to upgrade the water heater – and sometimes, to include a solar hot water credit.

This article explains how to assess water heater efficiency numbers, including the use of a handy lookup database at the California Energy Center’s web site.

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CALGreen, GreenPoints, and Title 24 – What’s the Deal?

CALGreen, GreenPoints, and Title 24 – What’s the Deal?

Posted on 31. May, 2011 by .

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California’s Green Building code went into effect this last January, and recently we had questions from another residential designer about CALGreen – how’s it different from GreenPoint Rating, how does it fit in with Title 24 energy standards, how it works. To answer his questions, I read through the code manual. In addition to the CALGreen code book itself, there’s a very handy cheat sheet that compares CALGreen, GreenPoints, and LEED, for low-rise residential projects. (This version’s probably a little out of date, being from 2010, but you get the idea.) The Q&A below is based partly on that conversation, with special thanks to Doug Hensel of the California Department of Housing and Community Development, who reviewed a draft of this article.

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The Devil is in the Details – Energy Model for Home with Custom Field Built Windows

The Devil is in the Details – Energy Model for Home with Custom Field Built Windows

Posted on 31. May, 2011 by .

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Remember last week, when we were talking about glass houses? Well, here’s another Title 24 case study on a 4,500 SF house, also from Swatt|Miers Architects. This house had almost 60% glazing to floor area, much of it custom built on site: 564 square feet of single paned butt glazed corner windows, 540 square feet of frameless glazing, a steel framed window, a 30 foot tall translucent window in a stair tower, 300 square feet of skylights, and a custom built wood screen interspersed with glass panels. That’s almost 2,700 square feet of glass.

And, to make the challenge that much more… piquant… it was in California climate zone 2 (Sonoma – HOT)… AND, they needed to beat California’s Title 24 energy standard by 15% because of local ordinances. It was the combination of all that single glazed area with the climate zone that concerned us the most. But, we had a reputation to maintain, and our motto to designers was, “We’ll never tell you that you have to shrink your windows.”

(Above image courtesy Swatt|Miers Architects.)

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Can Glass Houses Be Energy-Efficient?

Can Glass Houses Be Energy-Efficient?

Posted on 23. May, 2011 by .

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Actually the real question is whether an all-glass pavilion can still comply with the new version of California’s Title 24 energy code. Although Title 24 has been around since the 1970s, it is only now that designers are feeling the pinch. Given the increasing strictness of the energy code, what can an architect do if he (or she) wants to create designs with dramatic glass curtain walls?

The “glass house” shown on the cover image is, of course, Philip Johnson’s famous Modernist masterpiece, also called the Glass House. Even that house could, with the right high-performing window system, comply with Title 24 requirements – I tested it out. But, let’s talk about some more current designs for our case study.

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Windows and Home Energy Performance

Windows and Home Energy Performance

Posted on 26. Apr, 2011 by .

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Many architects have yet to realize how much a window’s energy performance can impact their projects, especially under the new Title 24 energy code. Ordinary glass is great at letting in daylight but it’s a terrible insulator. It also does little to block the sun’s heat in the summertime. Windows lose heat through the glass, and they can also leak air around the edges of the frame.

Here are a few analogies to understand the different ways that windows can lose both heating and cooling energy. If you wear a big holey sweater in the wind, it doesn’t keep you very warm. That’s air leakage. Now, imagine just wearing a single sheet of clear plastic on a winter day. It’s a better windbreaker than that holey sweater, but you’ll still feel pretty darn cold. That’s because a thin sheet of plastic, like a single sheet of glass, is a poor insulator. And remember what happens to your car parked in the summer sun? It gets 20 degrees hotter than the outside, or more – if you have black vinyl seats, you’ll scream when you sit on them in your summer shorts. That’s solar heat gain.

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Home Insulation and Title 24

Home Insulation and Title 24

Posted on 21. Feb, 2011 by .

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Everything you think you know about insulation is wrong. That’s in a nutshell what I got from talking with James Morshead of SDI Insulation, Inc. in Burlingame, CA.  SDI is a full-service green insulation contractor offering “sustainable” versions of several common insulation types, including blown-in, spray foam, and fiberglass batts. I wanted to know about high-performing insulation products that would fit into small building cavities, because that’s often something we have to recommend for Title 24 performance modeling. But it’s one thing to say that a project has to fit R38 worth of insulation into a 4-inch roof space, and it’s quite another to find an affordable product that’ll actually do it – and where using that product’s self-reported rating is also acceptable for demonstrating Title 24 compliance.

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New Ventilation Systems for Today’s Airtight Homes

New Ventilation Systems for Today’s Airtight Homes

Posted on 31. Jan, 2011 by .

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A few months ago, we interviewed Bronwyn Barry of Quantum Builders on the Passive House standard. When I called her again to ask about ventilation, she recommended Zehnder, a Swiss company, because their products are Passive House certified and if there’s anyone who knows about ventilation, it’s the Passive House folks. Passive Houses need state-of-the-art ventilation because they rely so heavily on an airtight building envelope, and their stringent energy budgets also mandate the most energy-efficient motors available.

I spoke with Barry Stephens of Zehnder America, the U.S. subsidiary. Zehnder has over 100 projects all over the U.S., including some larger residential complexes. Two-thirds of their projects are Passive House projects, but the company also works with other types of energy retrofits. You can see a great animation of their system here. Barry then referred me to his brother Charlie Stephens of the Northwest Energy Efficiency Alliance, who’s an energy research expert.

We asked both of them some general questions about ventilation principles, along with specific questions for Barry about the Zehnder product line. Most of the discussions here reference the Passive House standard, because it’s so far ahead on ventilation. In fact, if you’re looking for a good ventilation consultant, finding someone with Passive House certification wouldn’t be a bad place to start.

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Building Science for Residential Architects

Building Science for Residential Architects

Posted on 18. Jan, 2011 by .

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We all know that every home in California’s going to be Net Zero by 2030, right? Actually, it’s every NEW home built after 2030 – the old homes can go on being inefficient, until the next time someone needs a building permit. At that point, serious attention may need to be paid to bringing the home up to date. And, increased enforcement now occurs at many different points throughout the project, making it harder to do swaps during construction.

The truth is, architects can’t rely on the builder anymore to specify and install systems and materials as an afterthought, because that’s far too late in the process; to make the right decisions, designers will have to start thinking in terms of building science. And, they’ll have to start paying closer attention to builder execution as well, because in many cases the builders will cut corners if left to their own devices – and this can lead to problems, regarding both regulatory compliance and the owners’ daily operational costs.

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