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Making Fiberglass Work

With proper air-sealing and attention to installation details, batt insulation works great

Posted on Apr 13 2015 by Lee Kurtas
prime

When building science and home efficiency really took off in the mid-1990s, insulation contractors started hearing regularly about how the type of insulation used affects a building’s energy efficiency. Blower-door testing and thermal imaging of existing homes proved that fiberglass—as it’s typically installed—didn’t perform as well as other types of insulation, especially spray foam. As a result, builders and architects doing projects with energy-performance benchmarks started specifying spray foam as a way to ensure better airtightness and thermal resistance.


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Image Credits:

  1. All photos by Patrick McCombe

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Batt Insulation is Still Making Me Batty

The installation quality of fiberglass batt jobs just isn’t getting any better around here — even in homes seeking LEED certification

Posted on Feb 7 2013 by Carl Seville

I recently performed the pre-drywall inspection on a small home seeking LEEDLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. certification. The local building inspector had visited and approved the batts for covering up.


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Image Credits:

  1. All photos by Carl Seville

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Grading the Installation Quality of Insulation

How to tell the difference between perfectly installed insulation and a lousy insulation job

Posted on Aug 27 2012 by Allison A. Bailes III, PhD

Six years ago, RESNET published a major revision of the HERSIndex or scoring system for energy efficiency established by the Residential Energy Services Network (RESNET) that compares a given home to a Home Energy Rating System (HERS) Reference Home based on the 2006 International Energy Conservation Code. A home matching the reference home has a HERS Index of 100. The lower a home’s HERS Index, the more energy efficient it is. A typical existing home has a HERS Index of 130; a net zero energy home has a HERS Index of 0. Older versions of the HERS index were based on a scale that was largely just the opposite in structure--a HERS rating of 100 represented a net zero energy home, while the reference home had a score of 80. There are issues that complicate converting old to new or new to old scores, but the basic formula is: New HERS index = (100 - Old HERS score) * 5. Standards, officially named the 2006 Mortgage Industry National Home Energy Rating Systems Standards. One important new feature in the standards was the grading of insulation installation quality. Before this change, R-13 insulation installed poorly (as shown in the second photo, below) was equivalent to any other R-13 insulation, including insulation with impeccable installation quality (as shown at the top of this article).


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Image Credits:

  1. Energy Vanguard
  2. RESNET

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Fiberglass versus Cellulose

Fiberglass batts are inexpensive and widely available, but dense-packed cellulose does a better job of reducing air leakage

Posted on Mar 5 2012 by Erik North

The two least expensive and most commonly used residential insulation are fiberglass and cellulose. Granted, fiberglass is about 50 times more common — but a distant second is still second.

Unless the homeowner opts for spray foam, the insulation choice usually comes down to fiberglass vs. cellulose. So what are the advantages and disadvantages of each one? How are they similar and how are they different?


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Image Credits:

  1. Erik North

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(At Least) Four Things Are Wrong With This Picture

The answers to last week’s ‘What’s Wrong With This Picture?’ game

Posted on Feb 14 2012 by Rob Hammon

Last week we published this photo as part of our “What’s Wrong With This Picture?” series. The photo shows a substandard fiberglass insulation job that was representative of an entire residential subdivision that hoped to qualify for Energy StarLabeling system sponsored by the Environmental Protection Agency and the US Department of Energy for labeling the most energy-efficient products on the market; applies to a wide range of products, from computers and office equipment to refrigerators and air conditioners.. Examples like this show that quality control by HERSIndex or scoring system for energy efficiency established by the Residential Energy Services Network (RESNET) that compares a given home to a Home Energy Rating System (HERS) Reference Home based on the 2006 International Energy Conservation Code. A home matching the reference home has a HERS Index of 100. The lower a home’s HERS Index, the more energy efficient it is. A typical existing home has a HERS Index of 130; a net zero energy home has a HERS Index of 0. Older versions of the HERS index were based on a scale that was largely just the opposite in structure--a HERS rating of 100 represented a net zero energy home, while the reference home had a score of 80. There are issues that complicate converting old to new or new to old scores, but the basic formula is: New HERS index = (100 - Old HERS score) * 5. raters is a weak link in the Energy Star program.


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Image Credits:

  1. BIRA
  2. US DOE

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What’s Wrong With This Insulation Job?

Readers are invited to spot all of the problems shown in a photo of recently installed fiberglass batts

Posted on Feb 7 2012 by Rob Hammon

In many areas of the country, homes are receiving Energy Star labels they don’t deserve. Major errors like the ones shown in this photo are supposed to be caught by the HERS rater who performs third-party verification services. This home slipped through the cracks.

The photo shows at least four errors serious enough to have prevented the home from receiving an Energy Star label. Can you spot them?

Next week, we will post the answers that a Building America team, BIRA, came up with.


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Image Credits:

  1. ConSol
  2. Building America

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Installing Fiberglass Right

It’s hard to do a perfect job

Posted on Jul 10 2009 by Martin Holladay

Of all of the commonly used types of insulation — including cellulose, rigid foam, and spray polyurethane foam — fiberglass batts perform the worst. As typically installed, fiberglass batts do little to reduce airflow through a wall or ceiling assembly; rarely fill the entire cavity in which they are installed; and sometimes permit the development of convective loops that degrade insulation performance.

Knowing this, why would any builder choose to install fiberglass batts? The answer is simple: because fiberglass batts cost less than any other type of insulation.


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Image Credits:

  1. Fine Homebuilding

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