air sealing

Air Leakage at Electrical Switches and Outlets

Posted on March 03,2015 by ab3 in ADA

One thing that invariably surprises people when I walk them through a house during their first blower-door test is how much air leaks in through the electrical switches and receptacles. On a recent Friday, we went out to do the last home energy rating in our latest HERS rater class, and we got to see something even better. But first, let's talk about that air leakage. We have a number of surprises waiting.

Blower Doors Have Become Essential

Posted on March 03,2015 by user-1048334 in air barrier

Blower doors are spoken of in reverential tones in energy circles. Or at least they were a few years back. Now you can’t throw a manometer without hitting a contractor setting up a blower door. Which is a very, very good thing. With the incorporation of air leakage standards into various housing codes, blower doors are becoming essential. In fact, I tell customers that a simple shorthand for whether your insulation contractors grok building science is whether they own/use/understand blower doors.

Major Thermal Bypasses

Posted on March 03,2015 by user-1048334 in air leaks

First, a bit about my writing: I write in longhand, whenever I have some spare time. Between audits, at lunch, after the gym, when stopping for a coffee. Then I type the notes up. The thing is that I find a lot more spare time in my walking-around day than at the home or office. To say there is a bottleneck getting these notes into electronic form is a disservice to good-flowing bottles everywhere. This is by way of explaining an upcoming sentence.

Heat Loss from Air Is No Big Deal, Right?

Posted on March 03,2015 by user-1048334 in air barrier

No, it’s a huge deal. The photo (right) is of air streaming through recessed lights in a cathedral ceiling. I often and exhaustively speak about air sealing as if it were a universal good. And it is, right up there with brown ale and Avengers movies. My audit customers often look confused when I address their insulation questions by bringing up air barriers and air leakage. I mean, “Why are you talking about air leaks when I asked about the insulation?”

How to Insulate and Air-Seal Pull-Down Attic Stairs

Posted on March 03,2015 by user-1048334 in air leak

Pull-down attic stairs are super-sized attic hatches that just beg homeowners to store more stuff in their attic. Besides the air-leakage and insulation problems stemming from having a particularly large hole in your ceiling, pull-down stairs creates a potential storage headache. For homeowners, a storage problem usually means “not enough space.” For energy auditors, a storage problem means using space that ought to filled with insulation for Timmy’s guitar, his old bike, Legos, his new bike, and the unpacked remains of twelve previous moves.

Green Basics Air Barriers

Test Driving the New Brattleboro Food Co-op Building

Posted on March 03,2015 by AlexWilson in air leakage

The new Brattleboro Food Co-op building with affordable housing on the top two floors is nearly completed, and we’ll be shopping there in just a week or two. So, how did the building turn out? Were the goals achieved? Are the mechanical systems going to work as intended? How effectively was the building envelope constructed?

How to Insulate and Air Seal an Attic Hatch

Posted on March 03,2015 by user-1048334 in air leak

There’s a subset of issues in the realm of home efficiency that falls into the category “out of sight/out of mind.” The boiler in the basement, how much insulation is in the attic … as long as these issues stay out of your view, no problem. So what’s up with attic hatches, then? Even though attic hatches can be huge air leaks and sources of radiant heat loss, they are rarely fixed. An attic hatch is usually located in a hallway or closet where the homeowners see it daily. Yet...

How Much Air Leakage in Your Home Is Too Much?

Posted on March 03,2015 by ab3 in air leakage

Whether you want to build a new home or fix an old one, the way to ensure that you get the best performance is to do the building envelope right. That means installing the right amount of insulation and installing it well, and it means having an air barrier with minimal leakage. But how do you know when you've done enough air sealing? How tight is tight enough?

How to Choose Insulation

Posted on March 03,2015 by CarlSeville in air sealing

[Editor's note:This is an excerpt of the “Insulation and Air Sealing” chapter of Carl's new textbook, Green Building. Carl's publisher, Cenage Learning, has allowed us to make the whole chapter available as a free download.]

Cape Cod Style Homes Are Difficult to Heat

Posted on March 03,2015 by user-1048334 in air barrier

One of the great ironies in construction (I bet you didn’t even know that construction could be ironic) is that Cape Cod style houses perform pretty poorly on Cape Cod. The year-round sea breezes wash right through a Cape building frame, making them chilly and uncomfortable in the winter months. How did Cape Cod style houses (which perform not-so-great in the winter) become popular in New England? Maybe the name was a marketing scheme? And how can we address the air leakage and heat loss issues to make Capes more comfortable?

Service Cavities for Wiring and Plumbing

Posted on March 03,2015 by user-756436 in air barrier

Conventional wood-framed walls perform many functions. Exterior walls are supposed to support the roof load, resist racking, and provide insulation. They must also provide space for routing electrical cables and (in some cases) plumbing pipes or even ductwork. If the walls are built properly, they should also include an air barrier.

European Products for Building Tight Homes

Posted on March 03,2015 by user-756436 in air sealing

A new distributor of building products from Europe has set up shop in Brooklyn, New York. The company, called Four Seven Five, was recently founded by a trio of Passivhaus consultants: Floris Keverling Buisman, Sam McAfee, and Ken Levenson. Four Seven Five plans to import air-sealing products and ventilation fans from Germany, as well as HVAC equipment from Denmark.

Top 10 Air Leaks in Existing Homes — Part 1

Posted on March 03,2015 by Tristan Roberts in air leak

Whenever we’re working on the outside of a home—the roofing, siding, or site—my uncle Chris will remind me to think like a drop of water. Mentally tracing how a raindrop is likely to travel down a building, and including details to move it off and away, is a simple exercise that is too often ignored. Today, though, we’re going to talk not about water but about air. I have a new exercise to propose to Chris: think like a wisp of air.

Air Sealing With Sprayable Caulk

Posted on March 03,2015 by user-756436 in air leakage

Homes insulated with fiberglass batts are leakier than homes insulated with cellulose or spray polyurethane foam. Until recently, fiberglass batt manufacturers shrugged off the damning air-leakage data, insisting that their batts could deliver the R-value promised on the packaging — and then changed the subject.

Joe Lstiburek’s Airtightness Goals

Posted on March 03,2015 by Fretboard in air leaks

In commentary recently posted to the Building Science Corporation website, building scientist Joe Lstiburek takes a stroll down memory lane and reflects on his attempts in the early 1980s to help develop an airtightness standard for residential construction in Canada.

Georgia Pulls the Attic-Ventilator Plug (Sort of)

Posted on March 03,2015 by Fretboard in air sealing

Attic ventilator fans have taken a whupping in the court of building science, played starring roles on useless-products lists, and gotten roughed up in the comments sections of blogs. Now they’re gadget non grata in Georgia’s supplement to the 2009 International Energy Conservation Code.

New Air Sealing Requirements in the 2009 International Residential Code

Posted on March 03,2015 by user-756436 in air barrier

One of the most cost-effective ways of lowering residential energy costs is to reduce a home’s air leakage rate, so it makes sense for energy codes to ratchet up air-sealing requirements. The latest (2009) version of the International Residential Code does exactly that.

Questions and Answers About Air Barriers

Posted on March 03,2015 by user-756436 in air barrier

UPDATED on December 12, 2014 Builders of a certain age — say, those older than about 55 or 60 — started their careers at a time when no one talked about air leakage or air barriers. Back in the early 1970s, even engineers were ignorant about air leakage in buildings, because the basic research hadn’t been done yet. Times have changed, and most residential building codes now require builders to include details designed to reduce air leakage. Today’s young carpenters are working on job sites where air barriers matter.

Air Leaks or Thermal Loss: What’s Worse?

Posted on March 03,2015 by ScottG in air leakage

Beefing up R-values and reducing air leaks are the twin rallying cries of builders focusing on energy efficiency. Regardless of the particulars of the house design, more insulation and fewer air leaks make houses more comfortable, more durable, and less expensive to heat and cool. No one seems to argue that point. But Al Cobb wonders which is more significant.

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