The most recent blogs at Green Building Advisor

Can Cellulose be Used in an Unvented Roof?

Posted on October 31, 2011 by Scott Gibson in Q&A Spotlight

Dean Manoogian has a Cape Cod style house in Portland, Maine, and is puzzling over the best way to retrofit the roof with rigid foam insulation.

Working with both an insulation company and a roofing contractor, Manoogian has come up with a plan: apply 2-in. rigid foam on the interior of the dormered roof and then fill the rafter bays with dense-packed cellulose.

Scary Stories for Halloween

Posted on October 28, 2011 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

What’s scary for a green builder? Mold in the crawl space?

Naw — mold is a routine problem. What’s really scary is the end of the world as we know it.

A decade or two ago, the end of the world as we know it was a matter of concern for a few nutty survivalists in Idaho. Now it is a matter of discussion at academic conferences.

Several mechanisms have been proposed for the coming economic collapse. Some are based on New Age nonsense, while others are based on hard science.

From Designed to Built: Delivering Your Green Home

Posted on October 27, 2011 by Christopher Briley in Green Architects' Lounge

It's one thing to design a house, and it's another thing entirely to turn that design into a physical reality. In this episode, we kick back with an autumn cocktail (the Northern Spy) and talk about the process of bringing on a builder and the challenges of keeping relationships, quality, cost, and expectations managed along the way.

Hey, do you want to talk about wall sections? Too bad. Jesse joins us for our “What's Bothering Jesse?” segment, and he lets us know that he's a little tired of all the attention that walls command from the green community. So, we'll talk about that instead.

A Heating Fuel Cost Comparison Calculator

Posted on October 26, 2011 by Tristan Roberts in Energy Solutions

I recently caught up with where the rest of the world was in 2005 by watching the hit documentary “March of the Penguins.” It’s been on my list for a while but when evening arrives I’m much more prone to watching films about people — people like James Bond, for example. But my wife and I had a baby two weeks ago, and suddenly movies narrated by Morgan Freeman seem like more appropriate family fare.

Video: Installing Rigid Foam Under Footings

Posted on October 25, 2011 by Skylar Swinford in Guest Blogs

This construction site video of the Karuna House in Yamhill County, Oregon, demonstrates installation of a geofoam foundation that will superinsulate the bottom of the 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. and help the project achieve 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. and Minergie-P-ECO certifications.

Lead Carpenter Scott Gunter narrates the process of:

  • screeding out gravel,
  • back dragging with rake as needed,
  • compacting gravel,
  • marking outside foundation wall line on foam,
  • setting and aligning geofoam, and
  • drilling and pinning geofoam into place.

PV Systems Have Gotten Dirt Cheap

Posted on October 25, 2011 by Jesse Thompson in Guest Blogs

Something strange has happened to the price of 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.) systems in the last year. PV has gotten dirt cheap.

Honestly, it's gotten cheaper faster than our office has realized, and we try to stay up on these things. Worse, we've realized we haven't been making proper recommendations to our clients because of it.

It's also shifting some of the underpinnings of our typical design analysis in strange ways, and it looks like there are some unexpected consequences we haven't yet figured out.

Book Review: Retooling the U.S. Housing Industry

Posted on October 25, 2011 by Carl Seville, GBA Advisor in Green Building Curmudgeon

Sam Rashkin, until very recently the head of Energy Star for Homes, recently published Retooling The US Housing industry, a book of his opinions on, and suggestions of how to improve, the new home industry. The book is a fairly quick read with a great history of housing, and a good analysis of how the U.S. home building industry evolved to its current state.

Can Polyethylene Be Used as an Air Barrier?

Posted on October 24, 2011 by Scott Gibson in Q&A Spotlight

Polyethylene sheeting has had its ups and downs as a preferred building material over the last 20 years.

At one time, it was routinely used in wall assemblies as a vapor barrier. As building scientists learned more about air and moisture movement through walls and ceilings, however, they began to advise builders that an interior vapor retarder is better than an interior vapor barrier, and the perceived usefulness of poly plummeted.

Martin’s 10 Rules of Lighting

Posted on October 21, 2011 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Most homes use too much energy for lighting. According to the U.S. Energy Information Administration, the average American household uses 1,667 kWh per year for lighting, which amounts to 15.3% of residential electricity use. Ironically, this energy devoted to lighting is used inefficiently, so the usual result is a dim house with dark, depressing corners.

Membranes réfléchissantes: une solution en quête d'un problème

Posted on October 20, 2011 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

ENGLISH VERSION
Une membrane réfléchissante est un panneau brillant ou une membrane souple qui est utilisé dans la construction. Bien que la résistance thermique (valeur R) de ces membranes est à peu près de zéro, elles peuvent être utilisées comme partie d'un assemblage en construction — par exemple, un ensemble constitué d'une pellicule radiante et d’un espace d'air — pour ralentir le flux de chaleur.

Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!