The most recent blogs at Green Building Advisor

Capillary Breaks Above Footings

Posted on August 5, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Builders routinely install several types of barriers to avoid damp basements. Examples of these features include a layer of crushed stone and polyethylene under a basement slab; asphaltic dampproofing on the exterior side of basement walls; and sill seal made of thin closed-cell foam between the top of a foundation wall and the mudsill. All of these materials are used to reduce the transfer of moisture from the damp soil surrounding a foundation to the interior of the building or vulnerable framing lumber.

Blue Heron EcoHaus: Blower Door Testing

Posted on August 4, 2016 by Kent Earle in Guest Blogs

Editor's note: Kent Earle and his wife, Darcie, write a blog called Blue Heron EcoHaus, documenting their journey “from urbanites to ruralites” and the construction of a superinsulated house on the Canadian prairies. Their previous blog on was called Insulation, Air-Sealing, and a Solar Array. The blog below was originally published in January. (A complete list of Kent Earle's GBA blogs is provided in the “Related articles” sidebar below.)

Why North America Needs Its Own Passive House Standard

Posted on August 3, 2016 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

There's this thing called 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.. It's a terrible name. Almost everyone agrees on that. Look at how its adherents are driven to a frenzy and you'll see that the name doesn't really fit. The houses themselves aren't passive either, but let's leave that aside for now.

When Spray Foam Goes Bad

Posted on August 2, 2016 by Greg Labbe in Guest Blogs

When spray foam goes bad, it’s hard not to feel a bit sick. Sick because this high-performance insulation has a big carbon footprintAmount of carbon dioxide and other greenhouse gases that a person, community, industry, or other entity contributes to the atmosphere through energy use, transportation, and other means. and proper installation is key to its performance. When it’s not installed correctly, it can get expensive for the client, the contractor, and the planet.

How to Vent a Dryer

Posted on August 1, 2016 by Scott Gibson in Q&A Spotlight

The exhaust from a conventional clothes dryer is full of moisture and lint, and the best place to vent it is directly outside. Matt Culik knows this, but his particular situation makes him wonder whether there are circumstances when this rule might be broken.

Culik will soon be moving into a new house, and the intended laundry room does not have a vent connection for a clothes dryer. Coincidentally, he is planning to replace an old electric hot water heater with a heat-pump water heaterAn appliance that uses an air-source heat pump to heat domestic hot water. Most heat-pump water heaters include an insulated tank equipped with an electric resistance element to provide backup heat whenever hot water demand exceeds the capacity of the heat pump. Since heat-pump water heaters extract heat from the air, they lower the temperature and humidity of the room in which they are installed. , and this has given him an idea.

Batteries for Off-Grid Homes

Posted on July 29, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Is solar electricity cheap or expensive? There are two parallel stories circulating these days. One version of the story — the older of the two — is that electricity from 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. (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.) array is more expensive than grid power, and that adding batteries makes PV even more expensive.

The newer tale, oft-repeated on, is that PV is cheap and getting cheaper, and that any utility that tries to limit PV installations is doomed to failure — because homeowners who are disgruntled by a PV-hostile utility will choose to install batteries, cutting the cord to the grid.

Green and Cool Roofs Provide Relief for Hot Cities

Posted on July 28, 2016 by Ashish Sharma in Guest Blogs

More than half of the world’s population lives in cities, and the United Nations projects that this share will rise to 70% by 2050. During the daytime, these expanding urban areas absorb more solar energy than the surrounding countryside. At night they radiate the heat back to the atmosphere. Higher temperatures in cities compared to the areas around them create what are known as urban heat islands (UHIs).

The RESNET Standard Becomes the New Ventilation Battleground

Posted on July 27, 2016 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Just because I haven't written about the jockeying over ventilation rates and strategies with the 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. committee doesn't mean nothing's going on. If you've been following the battle over this issue, you know that Joe Lstiburek, PhD, PE, got fed up with 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. and introduced his own ventilation "standard" in 2013. Then the "Great Ventilation Debate" happened in Detroit, and he got back on the ASHRAE 62.2 committee.

Stuff happened and now RESNET just put an interesting amendment out for public comment. Follow that?

How More Transparent Electricity Pricing Can Help Increase Clean Energy

Posted on July 26, 2016 by Beia Spiller and Kristina Mohlin in Guest Blogs

The price of most goods we purchase is generally based on the costs associated with the goods' production, including the raw materials used to generate them, the labor associated with their manufacturing, and so on. However, when it comes to pricing residential electricity, many regulators choose to use a flat price per unit of electricity (kilowatt-hours, or kWh) that unfortunately fails to adequately reflect the underlying costs of generating and delivering energy to our homes.

Off-Grid in Canada: What We Did for Heat

Posted on July 25, 2016 by Craig Anderson in Guest Blogs

This is the third in a series of posts by Craig Anderson describing the off-the-grid house he built with his wife France-Pascale Ménard near Low, Québec. Craig writes about the "Seven Hills Project" in a blog called Sunshine Saved. For a list of Craig's previous posts, see the list of "Blogs by Craig Anderson" in the sidebar below. This post originally appeared in November 2015.

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