mechanical ventilation

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Ventilating a Home in Cold Weather

You need fresh air, but bringing in cold outdoor air can cause problems

Posted on Jan 10 2018 by Allison A. Bailes III, PhD
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When I woke up Saturday morning, the temperature outdoors was -40 degrees. The wind chill was -100 degrees! It was just unbelievably, impossibly, inhumanly cold outside. Fortunately, that was on a mountaintop in New Hampshire and not where I was. I happened to have woken up on a mountaintop in North Carolina, where the temperature was a much warmer -3°F.


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Image Credits:

  1. Energy Vanguard

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Revisiting Ventilation

An updated overview of residential ventilation systems

Posted on Nov 17 2017 by Martin Holladay
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My comprehensive article on residential ventilation systems, “Designing a Good Ventilation System,” was published back in 2009. A few things have changed in the last eight years, so it’s time to revisit the topic.


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Image Credits:

  1. Lunos and Soler & Palau

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Ventilation Failures and Vocabulary Lessons

A report from the recent EEBA conference in Texas

Posted on Oct 21 2016 by Martin Holladay
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During the last week of September, I attended the annual conference sponsored by the Energy and Environmental Building Alliance (EEBA). This year’s conference was held in Frisco, Texas.

EEBA was founded in Minnesota in 1982; the original name of the organization was the Energy Efficient Building Association. Thirty-four years later, EEBA is still going strong.


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Image Credits:

  1. All photos: Randy Martin

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Is Your Ventilation System Working?

There’s no way to know whether your fans are working properly unless someone has measured the airflow rates

Posted on Apr 15 2016 by Martin Holladay
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What’s a “faith-based ventilation system”? It’s a ventilation system installed by a contractor who never verifies the air flow rates after the equipment is installed.

So, will this type of ventilation system work? It’s hard to say — because no one measured anything.


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Image Credits:

  1. Image #1: Martin Holladay

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All About Indoor Air Quality

Which materials, substances, and practices are important to keep your indoor air fresh and healthy?

Posted on Mar 11 2016 by Martin Holladay
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Many owners of green homes are concerned about indoor air quality. GBAGreenBuildingAdvisor.com often receives questions from homeowners who worry that some building materials emit dangerous chemicals. For example:

  • Will the glue in my plywood or OSB subfloor emit dangerous fumes?
  • Will borateBoron-containing chemical that provides fire resistance to materials such as cellulose insulation and provides decay and termite resistance to wood products. Borate is derived from the mineral borax and is benign, compared with most other wood treatments.-treated cellulose insulationThermal insulation made from recycled newspaper or other wastepaper; often treated with borates for fire and insect protection. off-gas enough to affect the health of my children?
  • What type of clothes dryer is best from the perspective of indoor air quality?

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Image Credits:

  1. Eugene Kim / Flickr

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Ventilation for Your Tight House — Part 2

Our guest, Sonia Barrantes, continues the conversation about the best options for a healthy, comfortable ventilation system

Posted on Sep 17 2015 by Christopher Briley

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Our conversation with Sonia Barrantes continues. (If you missed it, here is a link to Ventilation for Your Tight House — Part 1.)

We've come to realize that we all want simple rules of thumb to guide our design process. Unfortunately, there isn't a rule of thumb for everything and we're going to have to rely on some common sense, good advice, and good old-fashioned engineering to get this balanced ventilationMechanical ventilation system in which separate, balanced fans exhaust stale indoor air and bring in fresh outdoor air in equal amounts; often includes heat recovery or heat and moisture recovery (see heat-recovery ventilator and energy-recovery ventilator). system right.

Our cocktails are refreshed and we're ready to go.


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Image Credits:

  1. Photos #1 and #3: Air Pohoda
  2. Photo #2: Alex Willson
  3. Photo #4: 475 High Performance Building Products

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Misconceptions About HRVs and ERVs

A heat-recovery ventilator isn’t a space heating appliance, makeup air unit, dehumidifier, or energy-saving device

Posted on Jul 24 2015 by Martin Holladay
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Since refrigerators have been around for almost a hundred years, most Americans know what a refrigerator is used for. But heat-recovery ventilators (HRVs) and energy-recovery ventilators (ERVs) have only been around for about 30 years, and many Americans still don’t know much about these appliances.

GBAGreenBuildingAdvisor.com regularly receives questions that show that some homeowners are confused about the purpose of these appliances, so it’s worth examining and debunking common misconceptions about HRVs and ERVs.


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Image Credits:

  1. PNNL

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Using a Glycol Ground Loop to Condition Ventilation Air

How much energy can one of these $2,000 systems collect?

Posted on Apr 10 2015 by Martin Holladay
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Most energy-efficient homes include a mechanical ventilation system — often an HRV(HRV). Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger; a similar device, an energy-recovery ventilator, also transfers water vapor. HRVs recover 50% to 80% of the heat in exhausted air. In hot climates, the function is reversed so that the cooler inside air reduces the temperature of the incoming hot air. or ERV(ERV). The part of a balanced ventilation system that captures water vapor and heat from one airstream to condition another. In cold climates, water vapor captured from the outgoing airstream by ERVs can humidify incoming air. In hot-humid climates, ERVs can help maintain (but not reduce) the interior relative humidity as outside air is conditioned by the ERV. that brings in fresh outdoor air while simultaneously exhausting an equal volume of stale indoor air. The main problem with introducing outdoor air into a house is that the air is at the wrong temperature — too cold during the winter and too hot (and often too humid) during the summer.


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Image Credits:

  1. Image #1: Charles Bado
  2. Image #2: Peter Schneider
  3. Image #3: Isover Multi-Comfort House
  4. Image #4: Zehnder

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Spray Foam Insulated Homes Need Ventilation

Contractors who don't ensure adequate ventilation put themselves — and their customers — at risk

Posted on Oct 22 2014 by Allison A. Bailes III, PhD

Most installations of spray foam insulation, when properly installed, act as an air barrierBuilding assembly components that work as a system to restrict air flow through the building envelope. Air barriers may or may not act as a vapor barrier. The air barrier can be on the exterior, the interior of the assembly, or both.. When you use it instead of the fluffy stuff (fiberglass, cellulose, cotton), a house will be more airtight. That's good.

When a house is airtight, the nasties in the indoor air tend to stick around. Volatile organic compounds (VOCsVolatile organic compound. An organic compound that evaporates readily into the atmosphere; as defined by the U.S. Environmental Protection Agency, VOCs are organic compounds that volatize and then become involved in photochemical smog production.), water vapor, odors, radonColorless, odorless, short-lived radioactive gas that can seep into homes and result in lung cancer risk. Radon and its decay products emit cancer-causing alpha, beta, and gamma particles., and other stuff you don't want to immerse yourself in make the home's indoor air quality worse.


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Image Credits:

  1. Energy Vanguard

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Another Report on the Great Ventilation Rate Debate

A clear winner emerged at the ventilation debate held at the recent Affordable Comfort conference in Detroit

Posted on May 26 2014 by Nate Adams

Here is my rundown of the recent Affordable Comfort (ACI) conference in Detroit.

It was great to catch up with — or at least brush by — longtime industry friends, in the case of Allison Bailes of Energy Vanguard and Andy Frank of Sealed. It’s really cool that the industry is small enough you can become friends with even the big names.


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