airtight

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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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Most ‘Houses That Breathe’ Aren’t Very Comfortable

Instead of expecting fresh air to come through your leaky walls, give your house a set of lungs

Posted on Oct 22 2013 by Robert Swinburne

Recently I heard another comment from a builder who wants to build a house that breathes. I started to reply in an e-mail, and then decided to write a blog instead.

What we are doing nowadays in the world of high-performance homes is based on studying hundreds of thousands of houses built in the last half century that have failed — including the majority of superinsulated and passive solar homes built in the 1970s and 1980s in the Northeast — and applying those lessons to building a durable house.


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Image Credits:

  1. Shutterstock

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Meet the Tightest House in the World

An Alaska couple sets a world mark with a blower-door test result far below the Passivhaus standard

Posted on May 9 2013 by Scott Gibson

A Dillingham, Alaska, couple has claimed a world record for airtightness in a 600-sq. ft. home with 28-in. thick walls and a ceiling rated at R-140.

According to the World Record Academy, a blower-door testTest used to determine a home’s airtightness: a powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s airtightness can be determined. Operating the blower door also exaggerates air leakage and permits a weatherization contractor to find and seal those leakage areas. measured 0.05 air changes per hour at 50 pascals of pressure (ACH50), less than 10% of the very rigorous PassivhausA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. air-tightness standard of 0.60 ACH50.


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Image Credits:

  1. Tom Marsik

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Joe Lstiburek’s Airtightness Goals

The renowned building engineer explains why the Passivhaus limit of 0.6 ach50 is just fine — except when it isn’t

Posted on Sep 22 2011 by Richard Defendorf

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.


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Image Credits:

  1. Buildingscience.com

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Visiting Passivhaus Job Sites in Washington State

The Energy Nerd flies to the West coast, camera and notebook in hand, to document new energy-efficient homes in Seattle and Olympia

Posted on Apr 8 2011 by Martin Holladay

On March 16, 2011, I flew to Seattle for a three-day visit to Washington state. Although the main purpose of my visit was to attend the spring conference of Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. Northwest, I devoted a day and a half to visiting Passivhaus buildings and construction sites in Seattle and Olympia. With the help of my gracious hosts, Dan Whitmore and Albert Rooks, I was able to see four Passivhaus sites and a large workshop where Passivhaus wall panels were being assembled indoors.


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Image Credits:

  1. Martin Holladay
  2. theolympian.com

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Does Spot Ventilation Work in an Ultra-Tight House?

A homeowner wonders where makeup air comes from

Posted on Nov 22 2010 by Scott Gibson

UPDATED: 12/9/10 with expert opinions from David White and Marc Rosenbaum

Frank O's new house is tight — very tight. Tests by an energy auditor measured 0.13 air changes per hour at 50 pascals of depressurizationSituation that occurs within a house when the indoor air pressure is lower than that outdoors. Exhaust fans, including bath and kitchen fans, or a clothes dryer can cause depressurization, and it may in turn cause back drafting as well as increased levels of radon within the home. (ACH50), meaning the house beats the very stringent airtightness target of the PassivhausA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. standard.

Frank O has installed a heat-recovery ventilator (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. ) to provide fresh air as well as fans for spot ventilation and a range hood fan rated at 189 cubic feet per minute (cfm).

Sounds perfect. So what's the problem?


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Image Credits:

  1. Green Building Advisor

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Makeup Air for Range Hoods

If your kitchen has a powerful exhaust fan, it may be pulling air down your chimney or water-heater flue

Posted on Nov 19 2010 by Martin Holladay

UPDATED on January 8, 2018

Most homes have several exhaust appliances. These typically include a bathroom fan (40-200 cfm), a clothes dryer (100-225 cfm), and perhaps a power-vented water heater (50 cfm), a wood stove (30-50 cfm), or a central vacuum cleaning system (100-200 cfm). But the most powerful exhaust appliance in most homes is the kitchen range-hood fan (100-1,200 cfm).


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Image Credits:

  1. GE
  2. Energy Design Update
  3. Bill Smith, www.buildingdiagnosticsnh.com

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Solar Versus Superinsulation: A 30-Year-Old Debate

A dispute from the late ’70s and early ’80s still sheds light on energy-efficient design

Posted on Oct 8 2010 by Martin Holladay

The oil price shock of 1973 sparked a burst of interest in “solar houses.” During the 1970s, owner-builders all over the U.S. erected homes with extensive south-facing glazingWhen referring to windows or doors, the transparent or translucent layer that transmits light. High-performance glazing may include multiple layers of glass or plastic, low-e coatings, and low-conductivity gas fill. — sometimes sloped, sometimes vertical. Many of these houses included added thermal massHeavy, high-heat-capacity material that can absorb and store a significant amount of heat; used in passive solar heating to keep the house warm at night. — concrete floors, concrete-block walls, or 55-gallon drums filled with water.


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Image Credits:

  1. At Home In the Sun, Garden Way Publishing
  2. Sun/Earth Buffering and Superinsulation, Community Builders

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