infiltration

Air Leaks From Your Home To Your Attic Need To Be Sealed

Posted on April 18,2015 by Tamasin Sterner in air leak

It’s important to keep attic air out of the house and house air out of the attic. That's why the home performance industry and every above-code building program make it a top priority to fully separate attics from the rest of the building. When the attic isn’t fully air sealed from the living space and the combustion appliance zone, three undesirable scenarios can occur:

The Top Two Reasons Powered Attic Ventilators Are a Waste of Money

Posted on April 18,2015 by ab3 in attic

Three years ago I wrote an article titled, Don’t Let Your Attic Suck: Power Attic Ventilators Are a Bad Idea. Nearly a hundred thousand page views and 93 comments later, it's still generating lots of heat. I don't know why so many people are so defensive about powered attic ventilators (PAVs), but here are a few of the things they've said to me in the comments:

Fixing a Leaky Log Home

Posted on April 18,2015 by ScottG in air leak

Early settlers who felled their own trees to build log homes were probably so grateful to be out of the weather they didn't worry about air leaks or cold walls. But when your heating bills are $500 a month, it's a different story altogether. That's the situation facing ADK Homeowner, as he explains in a Q&A post at Green Building Advisor.

The Mixed-Up IAQ and Infiltration Limit Blues

Posted on April 18,2015 by ab3 in indoor air quality

Last week, I caught the second day of Building Science Corporation's Experts' Session. (Click the link to download the presentations from the BSC website.) Joe Lstiburek spoke the whole day about ventilation, and I’ll be writing an article about that soon. At the end of that day, though, we got a little surprise.

An Interview with Dr. Joseph Lstiburek

Posted on April 18,2015 by ab3 in air leakage

Dr. Joe Lstiburek of Building Science Corporation is on a mission. The issue is residential ventilation. He contends that the residential ventilation standard, ASHRAE 62.2, ventilates at too high a rate, causing problems with humidity in hot or mixed humid climates, comfort and dryness in cold climates, and too much energy use everywhere. The 2013 version makes it worse.

Blower Doors Have Become Essential

Posted on April 18,2015 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.

Heat Loss from Air Is No Big Deal, Right?

Posted on April 18,2015 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 Perform a Heat-Loss Calculation — Part 2

Posted on April 18,2015 by user-756436 in design temperature

To continue last week’s discussion of heat-loss calculation methods, let’s consider a simple rectangular building, 20 feet by 30 feet, with 8-foot ceilings. Let’s assume it has an 8-foot-high basement with uninsulated concrete walls; the below-grade portion of the basement is 7 feet high, with 1 foot above grade. To keep things simple, we’ll assume that the house has a flat roof, and that each side of the house has two windows (each 3 ft. by 4 ft.) and one door (3 ft. by 7 ft.). The house doesn’t have a chimney.

Who Knew the Stack Effect Could Be So Controversial?

Posted on April 18,2015 by ab3 in air leakage

Recently, I wrote a little article about the stack effect to explain that the flow of air and heat is upward in winter but downward in summer. Turns out, the stack effect is a hot topic. That article has gotten 25 comments so far. When I posted it to the RESNET BPI group on LinkedIn, it got another 22 comments.

Top 10 Air Leaks in Existing Homes – Part 2

Posted on April 18,2015 by Tristan Roberts in air barrier

From an energy-efficiency standpoint, the trouble with owning an old home is that you’re stuck with whatever bad decisions the previous owners made, and historical trends also tend to work against you. The trouble with building a new home is that you are the one that is going to make the bad decisions. The best opportunity to make important decisions that will deliver energy efficiency for the life of the home is during design. There is rapid diminution of these opportunities during construction and then during use of the home.

Air Sealing With Sprayable Caulk

Posted on April 18,2015 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.

Air Leaks or Thermal Loss: What’s Worse?

Posted on April 18,2015 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.

Air-Sealing Tapes and Gaskets

Posted on April 18,2015 by user-756436 in air leakage

UPDATED March 8, 2013 After this article was published, Martin Holladay conducted a test of eleven air-sealing tapes on a variety of materials. To read the results of Holladay's testing, see Backyard Tape Test and Return to the Backyard Tape Test.

Blower Door Basics

Posted on April 18,2015 by user-756436 in blower door

Leaky homes are hard to heat and hard to cool. The only way to know whether your home is leaky or tight is to measure its air leakage rate with a blower door. A blower door is a tool that depressurizes a house; this depressurization exaggerates the home’s air leaks, making the leaks easier to measure and locate. An energy-efficient house must be as airtight as possible. Many older U.S. homes are so leaky that a third to a half of the home’s heat loss comes from air leaks.

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