The most recent blogs at Green Building Advisor

Ditch the Tax Credits for Renewables

Posted on January 26, 2016 by Tristan Brown in Guest Blogs

Congress last month extended valuable tax credits to producers of electricity from wind turbines and purchasers of solar equipment, a move that came as a relief to an industry that has experienced rapid growth in recent years.

A tax credit for wind power producers had lapsed almost a year ago, and the credit for solar power was scheduled to decline sharply at the end of 2016. Now, renewable electricity generators have several years of unprecedented stability: the renewed wind and solar power credits don’t expire until 2020 and 2022, respectively.

Getting Spray Foam Right

Posted on January 25, 2016 by Paul Eldrenkamp and Rachel White in Guest Blogs

Spray foam insulation scares homeowners more than it should — although this is hardly surprising given the horror stories that abound on the Internet. While some of these stories are legitimate, more are based on skewed perceptions or flawed science. The truth is that spray foam is an incredibly effective insulation material and that failures are incredibly rare.

Passive Air Inlets Usually Don’t Work

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

If your house has an exhaust-only ventilationMechanical ventilation system in which one or more fans are used to exhaust air from a house and make-up air is supplied passively. Exhaust-only ventilation creates slight depressurization of the home; its impact on vented gas appliances should be considered. system, does it need passive air inlets — that is, holes in the wall to let in outdoor air? In most cases, the answer is no. Unless your house is very, very tight — close to the 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. standard of 0.6 ach50 — your building’s envelope is almost certainly leaky enough to allow for the smooth operation of a bathroom exhaust fan rated at 50 cfm or 100 cfm.

Leak-Free Skylights

Posted on January 21, 2016 by Mike Guertin, GBA Advisor in Green Building Blog

I used to worry every time I installed a skylight. Even with the best installation detailing, I could still expect a storm to hit from just the right direction and drive water behind the flashing.

When I discovered peel-and-stick membranes, my worrying days ended. Now I follow a series of simple steps that hasn’t failed in more than 15 years’ worth of installations. The key to success is integrating the membrane and the flashings with the shingles to direct water back to the surface of the roof. Although the project shown here is a retrofit, I would flash it the same way on a new home.

How Low Oil Prices Can Be Good for the Environment

Posted on January 20, 2016 by David Goldstein in Guest Blogs

Over the past year and a half, oil prices have declined from over $100 a barrel to less than $35 a barrel. Should environmentalists be worried that this will cause people to turn away from clean energy and fail to meet climate pollution goals?

Finishing Touches for a Pretty Good House in New Hampshire

Posted on January 19, 2016 by Brian Post in Guest Blogs

Editor's note: This is the fifth in a series of blogs chronicling the design and construction of a house owned by Brian Post and Kyra Salancy. The first blog in the series was titled Building a Small House in the White Mountains.

Foundation Plan for a Snowy Climate

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

Nathan Scaglione's central New York State building site gets plenty of snow and cold weather during the winter, and that's proving to be a sticking point in his plans for a new house.

He'd prefer a slab-on-grade foundation rather than a basement, even though a full basement would be a more typical choice in this part of the country. The foundation would consist of concrete-block stem walls extending to a footing below frost line. Exterior walls would be framed on top of the block walls, roughly 24 inches above grade. Inside the block walls, Scaglione will pour a concrete slab floor.

Preventing Water Entry Into a Home

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

If it is designed well, the thermal envelope of your home should control the flow of heat, air, and moisture. Unfortunately, the floors, walls, and ceilings of older buildings are often leaky: they leak heat, they leak air, and they leak moisture.

If you are building a new house, you have the opportunity to control the flow of heat, air, and moisture through your home’s building envelopeExterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials.. The result will be a durable, comfortable building that doesn’t cost much to heat and cool.

Settings Matter

Posted on January 14, 2016 by Noah Horowitz in Guest Blogs

Now that the gift-giving holidays are nearly in the rearview mirror and bill-paying season is just ahead, it's a good time to remind you that those electronic devices given or received need not result in higher electric bills.

There are ways to keep your energy use under control without always visiting your brother-in-law's house to borrow a little electricity. In fact, many electronics manufacturers today offer settings that fine-tune the efficiency of their gadgetry — and usually those settings are pretty easy to manipulate.

The Pros and Cons of Skylights

Posted on January 13, 2016 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Everyone loves skylights. Right? They bring so much light into a room they can turn a Seattle kitchen into a bright and sunny Florida room. Especially at this time of year (in the northern hemisphere), having that extra light can brighten even the darkest days of winter.

But skylights have a dark side, too. If you're not aware of that when incorporating these roof windows into a home, you can end up with high energy bills, rooms that are unusable at certain times of the year, or expensive repairs due to moisture problems.

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