The most recent blogs at Green Building Advisor

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 GBAGreenBuildingAdvisor.com, 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.

A Researcher Looks at Insulated Roof Assemblies

Posted on July 22, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Kohta Ueno knows a lot about insulated roofs. As a researcher and engineer at Building Science Corporation in Westford, Massachusetts, Ueno has seen plenty of well-designed roofs, as well as plenty of rotten 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 a building science researcher like Ueno, rotten sheathing isn’t a disaster; it’s data.

Fannie Mae’s Financing for Solar is a Game Changer

Posted on July 21, 2016 by Anonymous in Guest Blogs

By LAURIE GUEVARA-STONE and JAMIE JOHNSON

Mortgage giant Fannie Mae just unlocked the lowest cost of capital for new 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.) installations to date. This follows the recent decision of the Department of Housing and Urban Development (HUD) to finance new solar installations within a first mortgage transaction. HUD's decision is a potential game-changer for the solar industry, with the ability to bring about the next order-of-magnitude increase in solar installations.

The Third Time’s the Charm

Posted on July 19, 2016 by Carl Seville, GBA Advisor in Green Building Curmudgeon

After two failed attempts at building a new house, I’m finally ready to get started. My first plan, started in 2009, was shot down by the historic commission.

Mounting Baseboard Heaters Unconventionally

Posted on July 18, 2016 by Scott Gibson in Q&A Spotlight

Writing from Detroit, a Climate Zone 6 locale, Marlena Crows poses this question: Must electric baseboard heaters necessarily be installed at floor level, or can they be mounted higher on the wall and get an assist for heat distribution from a ceiling fan?

Comparing the Properties of Insulation Materials

Posted on July 15, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

We’ve all seen tables that list the R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. per inch for a variety of insulation types. These tables are handy, of course, but because old information is endlessly republished, in some cases long after the old information becomes obsolete, the tables are often flawed. Most authors make little effort to update these tables in light of the latest information from researchers.

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