Musings of an Energy Nerd

Simple Methods for Measuring Air Flow

Posted on January 23, 2015 by Martin Holladay, GBA Advisor

UPDATED on April 15, 2016.

What is Comfort?

Posted on January 16, 2015 by Martin Holladay, GBA Advisor

Buildings have had central heating for only about 140 years, and they have had air conditioning for only about 80 years. For most of human history, people took comfort in winter from a stone fireplace — somewhere to heat up a kettle or warm one’s hands.

Once heating and cooling systems were developed, almost everyone wanted them. Why? Because people want to be comfortable.

Building a Foam-Free House

Posted on January 9, 2015 by Martin Holladay, GBA Advisor

UPDATED on May 22, 2015

Redefining Passivhaus

Posted on January 2, 2015 by Martin Holladay, GBA Advisor

In January 2012, Katrin Klingenberg, the founder of the 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. Institute U.S. (PHIUS), announced that her organization would develop a new passive house standard for North America — a standard that differed from the Passivhaus standard developed in Darmstadt, Germany.

Solar Thermal Is Really, Really Dead

Posted on December 26, 2014 by Martin Holladay, GBA Advisor

Back in early 2012, in an article called “Solar Thermal Is Dead,” I announced that “it’s now cheaper to heat water with a 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. array than solar thermal collectors.”

Now that almost three years have passed, it’s worth revisiting the topic. In the years since that article was written, the cost to install a photovoltaic (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.) system has dropped significantly. Moreover, I’ve come across monitoring data that allow for a more accurate estimate of the amount of electricity needed to heat water with electric resistance elements or a heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump..

Martin’s 2014 Christmas Poem

Posted on December 19, 2014 by Martin Holladay, GBA Advisor

With apologies to Edgar Allan Poe

Once upon a midnight dreary,
    while I pondered, weak and weary,
Many unpaid bills and letters
    from my local big-box store —
While I nodded, nearly napping,
    suddenly there came a tapping,
As of someone gently rapping,
    rapping at my office door.
“’Tis some visitor,” I muttered,
    “tapping at my office door —
        Only this and nothing more.”

Is OSB Airtight?

Posted on December 12, 2014 by Martin Holladay, GBA Advisor

UPDATED on August 13, 2015

Most builders assume — and has long reported — that oriented strand board (OSB) is a good 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.. If a builder uses a high quality tape like Siga Wigluv, Zip System tape, or 3M All Weather flashing tape to seal 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. seams, OSB wall and roof sheathing can act as a building’s primary air barrier.

How to Use the Psychrometric Chart

Posted on December 5, 2014 by Martin Holladay, GBA Advisor

When you drive a borrowed car, it takes a few moments to figure out how to operate the windshield wipers and the headlights. But in your own car, your hand reaches for these switches without thinking.

Using the psychrometric chart is a little like driving a car. If you use the psychrometric chart every day, you don’t have to orient yourself. But if you are like me, and you only consult the psychrometric chart two or three times a year, it’s useful to refer to a cheat sheet every time you use it.

Revisiting an Energy Saving Handbook from 1979

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

Rummaging through the shelves of a used book store, my son Noah came across an old paperback called Energy Saving Handbook. Written by James W. Morrison, the book was published by Harper & Row in 1979.

A brief web search failed to reveal any biographical information about the author. However, I discovered that the book was published under several different titles, and was distributed by at least four state energy offices. Morrison’s book may have been funded by the U.S. Department of Energy; some of its chapters seem to have been repurposed from government brochures.

Heat Transfer When Roasting a Turkey

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

Recently I decided to research heat transfer during turkey roasting. It turns out that this issue has been extensively studied by physicists and engineers.

As with houses, there are two basic camps: those who use computer modeling and those who make measurements. Some researchers feel more comfortable at a desk with a laptop; others feel more comfortable in a kitchen with a thermometer.

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