Musings of an Energy Nerd

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.

Using Interior Poly As an Air Barrier

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

Back in the 1980s, Canadian energy experts urged builders to use interior polyethylene 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. material. If the poly was installed conscientiously, and all seams were sealed with Tremco acoustical sealant, the approach worked well — at least in cold climates.

Two New Exterior Insulation Products for Walls

Posted on January 31, 2014 by Martin Holladay, GBA Advisor

Exterior wall insulation? That usually means rigid foam and furring strips — although occasionally, it means mineral wool insulation and furring strips.

But there are other options. Two new products offer builders new ways to keep their wall sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. warm.

All About Furnaces and Duct Systems

Posted on January 24, 2014 by Martin Holladay, GBA Advisor

UPDATED on October 2, 2014 with more information on duct system design.

Many different appliances can be used to heat a house, including boilers, water heaters, heat pumps, and wood stoves. However, most homes in the U.S. are heated by a forced-air furnace.

These devices are connected to ducts that deliver heated air to registers throughout the house. Different types of furnaces are manufactured to burn a variety of fuels, including natural gas, propane, oil, and firewood. The most common furnace fuel in the U.S. is natural gas.

Justin Fink’s Canned Spray Foam Tip

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

I've been paying attention to energy-efficiency and air-sealing tips for many years, but I still learn something new every week. This week, I learned a very useful tip from my fellow Fine Homebuilding editor, Justin Fink.

Justin wrote a great article on canned spray foam, “You Don't Know Foam,” that appeared in the current issue of Fine Homebuilding.

Twenty Below and Off the Grid

Posted on January 10, 2014 by Martin Holladay, GBA Advisor

In a recent blog, Allison Bailes did a great job defining heat and explaining heat flow. It’s important to remember, though, that Allison Bailes lives in Atlanta. When the temperature drops to 6°F in Atlanta, the story makes national news. But when the temperature hits -20°F in Vermont, we just tell our kids to remember to wear a hat when they walk to school.

Open-Cell Spray Foam and Damp Roof Sheathing

Posted on January 3, 2014 by Martin Holladay, GBA Advisor

Now that insulation contractors have been installing spray foam insulation on the underside of roof sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. for several years, we’re beginning to accumulate anecdotes and data on successful installations and failed installations. The anecdotes and data are enough to provide a few rules of thumb for designers and builders who want to install spray foam on the underside of roof sheathing.

Stupid Energy-Saving Tips

Posted on December 27, 2013 by Martin Holladay, GBA Advisor

Just for fun, I recently Googled the phrase “energy-saving tips.” I dove deep — all the way to page 7 of the Google results. My research was profoundly discouraging.

Back in 2011, I wrote two articles about bad energy-savings tips. (See More Energy Myths and A Plague of Bad Energy-Saving Tips.)

Since then, is there any possibility that the quality of online advice improved? Not a chance.

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