The most recent blogs at Green Building Advisor

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.

A Review of Siga Wigluv Air-Sealing Tape

Posted on February 11, 2014 by Matt Risinger in Guest Blogs

Every house needs four control layers. In order of importance, these layers need to provide:

  1. 1. Water control
  2. 2. Air control
  3. 3. Vapor control
  4. 4. Thermal control

The building codes have dictated the levels of thermal control and vapor control that builders must adhere to, and nearly every builder in the U.S. knows off the top of their head the R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. of the insulation in their walls and attics.

The Big Allure of Cheap PV

Posted on February 10, 2014 by Scott Gibson in Q&A Spotlight

Until now, Patrick McCombe has believed that improvements to the envelope of his home should come before an investment in photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow. panels. Now he's weighing a deal that seems too good to pass up.

McCombe lives in Connecticut (he's an associate editor at Fine Homebuilding magazine) and he recently attended an informational meeting sponsored by an organization working to lower the cost of PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow.. Panels could be purchased or leased, but the bottom line was that with federal and state incentives, McCombe could buy a 10-kilowatt array for $15,000.

Do Homeowners Need to Understand Home Performance?

Posted on February 7, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

My father was a college professor who was respected for his scholarship. Yet Dad doesn’t pay much attention to the physical world. If he were asked to define the stack effectAlso referred to as the chimney effect, this is one of three primary forces that drives air leakage in buildings. When warm air is in a column (such as a building), its buoyancy pulls colder air in low in buildings as the buoyant air exerts pressure to escape out the top. The pressure of stack effect is proportional to the height of the column of air and the temperature difference between the air in the column and ambient air. Stack effect is much stronger in cold climates during the heating season than in hot climates during the cooling season., he’d probably guess that it was a type of exhaustion caused by walking past miles of library bookshelves. According to a family legend, the engine of our family’s Volkswagen van had to be rebuilt in 1963 because my father drove thousands of miles without checking the dipstick or changing the engine oil.

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