The most recent blogs at Green Building Advisor

Do Combustion Safety Testing Protocols Need Fixing?

Posted on February 26, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Burning fuels inside a house can lead to serious health and safety problems. That's why energy auditors perform a variety of combustion safety tests to find potential hazards and recommend fixes.

A couple of weeks ago at the Dry Climate Forum, I heard Vi Rapp, PhD, from Lawrence Berkeley National Lab (LBNL) make an argument for changing the way we do combustion safety testing. It turns out that one of the tests we do may not be as helpful as many people think it is.

Flash and Batt in the Roof

Posted on February 24, 2014 by Scott Gibson in Q&A Spotlight

"Flash and batt" is an insulation technique that combines the air-sealing superiority of spray foam insulation with the cost benefits of fiberglass batts. An inch or two of polyurethane foam seals the cavity and the batt insulationInsulation, usually of fiberglass or mineral wool and often faced with paper, typically installed between studs in walls and between joists in ceiling cavities. Correct installation is crucial to performance. adds R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. without costing an arm and a leg.

That's roughly the plan Dave Frank is considering for the roof of a house — presumably his own house — in Climate Zone 5. But his plan contains a twist: He wants to spray the underside of the roof deck with foam and install the batts between the joists at ceiling level.

What’s the Definition of an ‘R-20 Wall’?

Posted on February 21, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Builders often talk about the R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. of their walls. But if a builder claims to have an R-20 wall, what does that mean?

Building codes commonly include a table listing the minimum prescriptive R-values for walls and ceilings in different climate zones. For example, Table R402.1.1 in the 2012 International Energy Conservation Code (IECC International Energy Conservation Code.) informs builders that the minimum prescriptive R-value for walls in Climate Zones 3, 4, and 5 is “20 or 13+5.”

Commissioning Our Heat-Recovery Ventilator

Posted on February 20, 2014 by Alex Wilson in Energy Solutions

In last week's blog I described our state-of-the-art Zehnder 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. ), explaining its various features and specifications. This week I’ll review what should be a critical step in the installation of any HRV: commissioningProcess of testing a home after a construction or renovation project to ensure that all of the home's systems are operating correctly and at maximum efficiency. , including the critical step of balancing the air flow.

This is absolutely necessary to ensure proper operation and full satisfaction from a Zehnder HRV and most other HRVs.

Should Home Builders Pay the Energy Bills?

Posted on February 19, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Three questions have been nagging at Rick Chitwood over the past 5 or 6 years. First, why is the HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. industry in California, where he lives and works, so pathetic?

Second, why have California’s strict energy standards, which have been in effect since 1978, not corrected the problem?

Third, how is it that he, who came to the HVAC business through a nontraditional route, has become a leader in the industry?

Visiting a District Heating Plant in Austria

Posted on February 18, 2014 by Andrew Dey in Guest Blogs

Annette, our daughters and I just spent a week in Flachau, Austria, with Annette’s family. Flachau is not far from the Austrian city of Graz, where Annette lived until she was twelve years old. Thirty years ago, Flachau was a sleepy farming village, and today it’s a bustling ski town.

A Post-Passivhaus Paradigm for Energy-Efficient Design

Posted on February 17, 2014 by alan abrams in Guest Blogs

Last night, I enjoyed an intense conversation with my friend Bill Updike. Bill, who has been closely following the developing partnership between PHIUS and Building Science Corporation, is the green building specialist at the Washington, D.C. Department of the Environment.

We were talking about cost-effective energy-efficient design, and Bill tossed off a comment that the key to any design — at least in our mixed-humid climate here in Maryland — should be the latent loadCooling load that results when moisture in the air changes from a vapor to a liquid (condensation). Latent load puts additional demand on cooling systems in hot-humid climates. of the building. When he said that, my mind lit up like a pinball machine showing three cherries.

EMFs and Human Health

Posted on February 14, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Every now and then, green builders are approached by clients who are worried about exposure to electromagnetic fields (EMFs). Such clients have read that EMF exposure can make them sick, and they’re interested in building a house that minimizes EMF exposure.

In the modern world, EMFs are ubiquitous. Most of us are surrounded every day by weak electric and magnetic fields that are generated by electrical wires, home appliances, cell phones, and broadcasting equipment.

Our Top-Efficiency Heat-Recovery Ventilator

Posted on February 13, 2014 by Alex Wilson in Energy Solutions

In last week's blog I reviewed some of the general strategies used for ventilating buildings — or not. This week, I’ll zero in on the types of 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). in which heat is recovered from the outgoing airstream to preheat the incoming fresh air.

Understanding Air Barriers, Vapor Barriers, and Drainage Planes

Posted on February 12, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Is housewrap a vapor barrier? What's the purpose of building paperTypically referring to Grade D building paper, this product is an asphalt-impregnated kraft paper that looks a lot like a lightweight asphalt felt. The Grade D designation has come to mean that the building paper passes ASTM D779 (minimum 10-minute rating with the “boat test”) and different products are called out as “30-minute” or even “60-minute” based on D779 results. At times confused with roofing felt, roofing felts and building paper differ in two ways: felts are made of recycled-content paper, building papers of virgin paper; felts are made of a heavier stock paper; building papers a lighter stock. See also roofing felt.? Who'll stop the rain? I've covered this topic in various forms before, but the confusion about what the different building materials do is so widespread that I have to keep coming back to it.

I'm going to keep it simple here so maybe we can get a few more people to use the proper terms, and especially to know when not to use the term “vapor barrier” ... and when not to use it.

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