Musings of an Energy Nerd

How Much Fresh Air Does Your Home Need?

Posted on June 28, 2013 by Martin Holladay, GBA Advisor

The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAEAmerican Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). International organization dedicated to the advancement of heating, ventilation, air conditioning, and refrigeration through research, standards writing, publishing, and continuing education. Membership is open to anyone in the HVAC&R field; the organization has about 50,000 members. ) has had a residential ventilation standard since 2003, when ASHRAE 62.2A standard for residential mechanical ventilation systems established by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers. Among other requirements, the standard requires a home to have a mechanical ventilation system capable of ventilating at a rate of 1 cfm for every 100 square feet of occupiable space plus 7.5 cfm per occupant. (“Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings”) was first approved for publication. (For more information on providing fresh air for homes, see Designing a Good Ventilation System.)

New Green Building Products — June 2013

Posted on June 21, 2013 by Martin Holladay, GBA Advisor

My file of interesting new green building products is bulging again, so it’s time to highlight a few items that have caught my attention.

All About Dishwashers

Posted on June 14, 2013 by Martin Holladay, GBA Advisor

An automatic dishwasher uses hot water and electricity, so it makes sense to choose an efficient model. But before discussing the question of which dishwasher you should buy, we need to address two questions:

Zen and the Art of Grading

Posted on June 7, 2013 by Martin Holladay, GBA Advisor

Green builders have an uneasy relationship with chainsaws and bulldozers. To some environmentalists, these noisy inventions conjure up images of ecosystem destruction and irresponsible land development.

However, just like a hammer or a level, a bulldozer is just a tool. It can be used for good or ill.

Bulldozers are extremely handy when you need to change the grade of a site. Grading matters, and novice builders who ignore grading will eventually be forced to pay attention to the topic.

Is Your Pool an Energy Hog?

Posted on May 31, 2013 by Martin Holladay, GBA Advisor

If your home has a swimming pool, your pool pump may use more electricity than any other appliance in your home — as much as three times the electricity used by your refrigerator. Many residential pools in the U.S. have 1.5-horsepower or 2-horsepower pumps that draw 2,000 watts or more. If you’re not paying attention, you may be running your pool pump for 24 hours a day — even though your pool might be perfectly clean with only 6 hours of pump operation per day.

Climate-Specific Air Conditioners

Posted on May 24, 2013 by Martin Holladay, GBA Advisor

If you live in a humid climate (for example, in Florida), you need an air conditioner that does a good job of dehumidification. But if you live in a dry climate (for example, in Nevada), dehumidification is almost irrelevant, because the outdoor air is so dry. In Nevada, all you need is an air conditioner that lowers the temperature of the air in an energy-efficient way.

Energy Upgrades for Beginners

Posted on May 17, 2013 by Martin Holladay, GBA Advisor

Owners of older homes often contact GBAGreenBuildingAdvisor.com and ask, “What can I do to make my home more energy-efficient?” My standard answer goes something like this: “The first step is to hire a certified rater to perform an energy auditEnergy audit that also includes inspections and tests to assess moisture flow, combustion safety, thermal comfort, indoor air quality, and durability. of your home. The audit report will include a tailor-made list of retrofit measures to address your home’s specific problems.”

Passivhaus Buildings Don’t Heat Themselves

Posted on May 10, 2013 by Martin Holladay, GBA Advisor

For years, the English-language website of the Passivhaus Institut in Germany provided this definition: “A 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. is a building in which a comfortable interior climate can be maintained without active heating and cooling systems. The house heats and cools itself, hence ‘passive.’”

All About Thermal Mass

Posted on May 3, 2013 by Martin Holladay, GBA Advisor

UPDATED on December 4, 2013 with a citation of recent research findings.

What’s the deal with thermal mass? Since manufacturers of materials that incorporate concrete often exaggerate the benefits of thermal mass, it’s easy to get cynical and conclude that the buzz around thermal mass is all hype. But in many climates, it’s actually useful to have a lot of thermal mass inside your house. Just keep in mind that thermal mass may not be as beneficial as its boosters pretend.

Choosing HVAC Equipment for an Energy-Efficient Home

Posted on April 26, 2013 by Martin Holladay, GBA Advisor

Why are the smallest available American furnaces rated at about 40,000 Btuh? Back in the 1960s, a house in a cold climate may have needed such a powerful furnace — or even one rated at 60,000 or 80,000 Btuh. But these days, many new homes have design heating loads that are much smaller — as low as 10,000 to 20,000 Btuh. Over the past 30 years, building envelopes have become tighter and better insulated, but U.S. furnace manufacturers haven’t kept up with the times. For mysterious reasons, they don’t offer furnaces that are small enough for today’s energy-conscious builders.

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