The most recent blogs at Green Building Advisor

Rainscreen Gaps and Igloos

Posted on August 9, 2013 by Martin Holladay in Musings of an Energy Nerd

For the past 17 years, Joe Lstiburek and Betsy Pettit have hosted an annual conference, the Westford Symposium on Building Science, near their home in Massachusetts. Informally known as “summer camp,” the invitation-only gathering attracts hundreds of builders, engineers, architects, professors, and building science researchers.

The attendees listen to presentations at a conference center during the day and relax in Joe and Betsy’s backyard during the evening.

Getting Power From Solar Equipment When the Grid is Down

Posted on August 8, 2013 by Alex Wilson in Energy Solutions

One of the biggest complaints I hear about most solar-electric (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. or 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.) systems is that when the grid goes down you can’t use any of the power that’s produced. Consumers have spent thousands of dollars on a PV system, and during an extended power outage on a bright, sunny day when the PV modules are certainly generating electricity, they are disappointed that none of that electricity can be used.

ASHRAE 62.2 Committee Chair Defends Ventilation Standard

Posted on August 7, 2013 by Allison A. Bailes III, PhD in Building Science

The great ventilation debate of 2013 roars on. Last month, I wrote about Building Science Corporation's residential ventilation standard for new homes, to be released officially at Building Science Summer Camp this week, and then followed that up with an interview with Dr. Joseph Lstiburek.

Sealed-Combustion Appliances and Hot Tub Parties

Posted on August 5, 2013 by Erik North in Guest Blogs

Sealed-combustion appliances are apt to become more common as the new energy codes introduce residential airtightness standards. This means that you’ll need to pay close attention to heating system safety. Fortunately, the new codes lay out explicit guidelines for combustion appliances.

Building and energy codes often get adopted piecemeal around the country. In Maine, we’ve adopted the 2009 International Energy Conservation Code (IECC International Energy Conservation Code.), but have exempted towns below a certain population level.

If Only Green Homes Could Be Sold Like Breakfast Cereal

Posted on August 2, 2013 by Martin Holladay in Musings of an Energy Nerd

Just the other day, I was looking at a box of breakfast cereal. The largest lettering on the box were the three words naming the cereal: Frosted Shredded Wheat. Next in prominence came the tag line: “Contains 6 g. of fiber per serving.”

You’re probably thinking, “so what?” Manufacturers of processed food make claims like this so frequently that we’ve all gotten used to them.

Smart Vapor Retarders

Posted on July 31, 2013 by Alex Wilson in Energy Solutions

Nowhere in building design has there been more confusion or more dramatic change in recommended practice than with vapor retarders. Thirty years ago, we were told to always install a polyethylene (poly) vapor barrier on the warm side of the wall. Then we were told to forget the poly and go with an airtight layer of drywall (airtight drywall approach). Insulation contractors, meanwhile, often said to skip the vapor barrier; we need to let the wall or ceiling cavity dry out.

It made for a lot of confusion. And I’m not sure we’re totally out of the woods yet.

An Interview with Dr. Joseph Lstiburek

Posted on July 31, 2013 by Allison A. Bailes III, PhD in Building Science

Dr. Joe Lstiburek of Building Science Corporation is on a mission. The issue is residential ventilation. He contends that the residential ventilation standard, 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., ventilates at too high a rate, causing problems with humidity in hot or mixed humid climates, comfort and dryness in cold climates, and too much energy use everywhere. The 2013 version makes it worse.

Finding the Insulation Sweet Spot

Posted on July 29, 2013 by Scott Gibson in Q&A Spotlight

Anders Lewendal, a builder in Bozeman, Montana, is wrestling with a familiar dilemma: What's the right amount of insulation to put in a house?

"Our theory," he writes in Q&A post at GreenBuildingAdvisor, "is that too little insulation wastes energy and equally, too much insulation wastes energy. Where is the sweet spot in each climate zone?"

To that end, Lewendal is proposing more performance testing.

All About Dehumidifiers

Posted on July 26, 2013 by Martin Holladay in Musings of an Energy Nerd

An energy-efficient home in a hot, humid climate should have a tight envelope, thick insulation, energy-efficient appliances, and low-solar-gain windows. If you include these features in a new home, your air conditioner won’t run as often as your neighbor’s. That’s good.

But there is a downside to the fact that your air conditioner runs rarely: during the hours that your house has no active cooling, it also has no active dehumidification. As a result, your indoor relative humidity is going to rise.

Getting to Know Spider Insulation

Posted on July 25, 2013 by Alex Wilson in Energy Solutions

We’ve just completed the installation of a relatively new and (at least in New England) little-known insulation material called Spider. As a reminder, the house we are renovating (really rebuilding) in Dummerston, Vermont, has provided an opportunity to try out dozens of innovative products and materials that I’ve long researched and written about in Environmental Building News.

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