Musings of an Energy Nerd

Thermal Barriers and Ignition Barriers for Spray Foam

Posted on April 11, 2014 by Martin Holladay, GBA Advisor

Do building codes require spray foam insulation to be protected with a layer of drywall or a comparable barrier for fire safety? The answer is yes, usually — but not always.

There is no simple answer to the question, for several reasons. The first reason is that the code is complicated.

The second reason is that the code is poorly written.

The third reason is that the code is subject to interpretation by local code officials.

Residential Commissioning

Posted on April 4, 2014 by Martin Holladay, GBA Advisor

Building a new home usually requires work by several subcontractors, including electricians, plumbers, and HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. installers. At the end of the job, someone — usually the general contractor — has to verify that all of the specified work has been completed.

Has the water heater been installed? Check.

Air conditioner? Check.

Ducts? Check.

Ventilation system? Check.

Deep Energy Retrofits Are Often Misguided

Posted on March 28, 2014 by Martin Holladay, GBA Advisor

All through the 1980s and 1990s, a small band of North American believers worked to maintain and expand our understanding of residential energy efficiency. These were the pioneers of the home performance field: blower-door experts, weatherization contractors, and “house as a system” trainers. At conferences like Affordable Comfort, they gathered to share their knowledge and lick their wounds.

These pioneers understood what was wrong with American houses: They leaked air; they were inadequately insulated; they had bad windows; and their duct systems were a disaster.

Stay Away from Foil-Faced Bubble Wrap

Posted on March 21, 2014 by Martin Holladay, GBA Advisor

Most brands of foil-faced bubble wrap are only 3/8 inch thick or less, and have an R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. of only 1.0 or 1.1. Since the product often costs more per square foot than 1-inch thick rigid foam rated at R-5, why would anyone use bubble wrap as insulation?

When the Gas Pipeline Shuts Down

Posted on March 14, 2014 by Martin Holladay, GBA Advisor

In the wake of the recent military crisis in Crimea, energy experts have been discussing whether Vladimir Putin will be tempted to gain political advantage by shutting the valves on the Russian natural gas pipelines that supply Ukraine and Western Europe. Regardless of whether this scenario is likely, such speculation raises the question: How would urban residents in a cold climate cope if the supply of natural gas were suddenly turned off?

All About Washing Machines

Posted on March 7, 2014 by Martin Holladay, GBA Advisor

About 82% of U.S. homes have a clothes washer. Each of these appliances is used, on average, to wash about 300 loads of laundry per year. On an annual basis, residential clothes washers use more energy than dishwashers but less than refrigerators.

Exhaust-Only Ventilation Systems and Radon

Posted on February 28, 2014 by Martin Holladay, GBA Advisor

Articles on mechanical ventilation commonly warn builders that exhaust-only ventilationMechanical ventilation system in which one or more fans are used to exhaust air from a house and make-up air is supplied passively. Exhaust-only ventilation creates slight depressurization of the home; its impact on vented gas appliances should be considered. systems can pull 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. into a house through foundation cracks. The warning makes intuitive sense: after all, an exhaust-only ventilation system works by depressurizing a house with respect to the outdoors, and it seems obvious that 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. could pull soil gases into a basement.

One thing I’ve learned over the years, however, is that just because an idea is intuitively obvious, doesn’t mean it’s true. Throughout history, many observers have speculated; far fewer have actually made measurements.

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

Posted on February 21, 2014 by Martin Holladay, GBA Advisor

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.”

EMFs and Human Health

Posted on February 14, 2014 by Martin Holladay, GBA Advisor

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.

Do Homeowners Need to Understand Home Performance?

Posted on February 7, 2014 by Martin Holladay, GBA Advisor

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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