The most recent blogs at Green Building Advisor

Looking at the Costs of LEED Version 4

Posted on February 3, 2016 by Stuart Kaplow in Guest Blogs

With the November 1, 2016, deadline approaching when new LEEDLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. projects must register under the new LEED version 4, the real estate industry has been raising questions about the costs and benefits of LEED v4 compliance.

Foundation and Nailbase Details for a Minnesota House

Posted on February 2, 2016 by Elden Lindamood in Guest Blogs

This is the second part of a blog series by architect Elden Lindamood about the design and construction of his own home. The first installment was called A Low-Energy House for Northern Minnesota.

Why Is It So Cold In Here?

Posted on February 1, 2016 by Scott Gibson in Guest Blogs

J Pritzen's single-story Illinois house was built in the 1950s. It's heated with a gas furnace fully capable of meeting the heating loadRate at which heat must be added to a space to maintain a desired temperature. See cooling load., but somehow it isn't getting the job done.

The single-story brick house has a mostly insulated, but unheated, basement. Warm air is distributed on the main floor by a series of floor registers set near exterior walls, and an energy auditEnergy audit that also includes inspections and tests to assess moisture flow, combustion safety, thermal comfort, indoor air quality, and durability. tells Pritzen the furnace is cranking out 10,000 BtuBritish thermal unit, the amount of heat required to raise one pound of water (about a pint) one degree Fahrenheit in temperature—about the heat content of one wooden kitchen match. One Btu is equivalent to 0.293 watt-hours or 1,055 joules. more per hour than is lost through the walls and roof.

Smart Vapor Retarders for Walls and Roofs

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

During the winter, when indoor air is usually warm and humid, most wall 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. is cold. Under these conditions, we really don’t want water vapor to move from the interior of our homes toward the exterior. That’s why builders in the 1980s installed polyethylene on the interior side of walls.

The Effect of Low Oil Prices on Climate Emissions

Posted on January 28, 2016 by David Goldstein in Guest Blogs

Editor's note: The first blog in this two-part blog series was titled How Low Oil Prices Can Be Good for the Environment.

Don’t Let Your Garage Make You Sick

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

The odds are high that the indoor air quality is worse in a home with an attached garage than in a home without one. Just take a look at the photo here to see some of the potential sources of pollutants that can get into your home's air. How many do you see?

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.

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