The most recent blogs at Green Building Advisor

The Potwine Passivhaus Gets Insulation and Drywall

Posted on December 30, 2014 by Alexi Arango in Guest Blogs

As they set out to build a single-family PassivhausA 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. on Potwine Lane in Amherst, Massachusetts, Alexi Arango and LeeAnn Kim asked themselves, “Is it possible to live without burning fossil fuels?” One measure of success would be meeting their goal of net-zero energyProducing as much energy on an annual basis as one consumes on site, usually with renewable energy sources such as photovoltaics or small-scale wind turbines. performance. This is the eleventh blog in a series.

Passive House is Looking for a Few Good Men (and Women)

Posted on December 29, 2014 by Carl Seville, GBA Advisor in Green Building Curmudgeon

I make no claim to being an expert on 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., but ignorance has never stopped me from expressing my opinion before. Among the major complaints about the Passive House standard is that it has inflexible energy use requirements, and the European-designed program does not effectively address the wide range of U.S. climate zones. This inflexibility often leads those who pursue this certification to install enormous quantities of insulation, particularly under slabs, which raises a variety of questions and concerns about the usefulness of this practice.

Solar Thermal Is Really, Really Dead

Posted on December 26, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

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..

Placing a Concrete Foundation on Rigid Foam Insulation

Posted on December 23, 2014 by Mike Steffen in Guest Blogs

It should go without saying that any high-performance building should be built on a solid foundation. So why would we set our building on a layer of foam insulation?

The answer, of course, is to limit thermal bridgingHeat flow that occurs across more conductive components in an otherwise well-insulated material, resulting in disproportionately significant heat loss. For example, steel studs in an insulated wall dramatically reduce the overall energy performance of the wall, because of thermal bridging through the steel. . Those bridging effects can cause a significant amount of heat loss through the mass structure at the base of the building. By thermally isolating the building foundation from the ground, building performance is improved, not only from an energy performance standpoint but also in terms of comfort and moisture management.

How to Heat a Garage

Posted on December 22, 2014 by Scott Gibson in Q&A Spotlight

If you're lucky enough to have a garage, you already know it can be used for more than keeping your car out of the snow. As Kent Jeffery explains in a Q&A post at GreenBuildingAdvisor, garages also are useful for car and equipment repairs, and for storing garden vegetables, cans of paint and anything else a spouse may not want in the house.

But in order for a garage to serve those purposes, the temperature has to be above freezing — and for much of the country that means a source of heat.

Martin’s 2014 Christmas Poem

Posted on December 19, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

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.”

Choosing a Base Temperature for Degree Days

Posted on December 17, 2014 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Degree days are a combination of time and temperature. We looked at their uses and where they come from in Part 1 of this series, and now it's time to go a little deeper.

The temperature enters as a temperature difference, ΔT (delta T), but it's not the ΔT between inside and outside of the building. It's the difference between the outdoor temperature and the base temperature. But what is this thing called base temperature?

Tilt/Turn Windows Are Fabulous

Posted on December 15, 2014 by Alexi Arango in Guest Blogs

As they set out to build a single-family PassivhausA 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. on Potwine Lane in Amherst, Massachusetts, Alexi Arango and LeeAnn Kim asked themselves, “Is it possible to live without burning fossil fuels?” One measure of success would be meeting their goal of net-zero energyProducing as much energy on an annual basis as one consumes on site, usually with renewable energy sources such as photovoltaics or small-scale wind turbines. performance. This is the tenth blog in a series.

Is OSB Airtight?

Posted on December 12, 2014 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

UPDATED on December 16, 2014

Most builders assume — and GBAGreenBuildingAdvisor.com 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.

Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!