The most recent blogs at Green Building Advisor

Really, the argument about whether you should vent a crawl space in a humid climate is over. Advanced Energy's research project from 2002 proved that closed crawl spaces outperform vented crawl spaces.

A quick look at the psychrometric chart below shows that the argument should never have existed in the first place. (Click the image to see an enlarged version.)

[Editor’s note: Liz Johndrow is a natural builder who specializes in the use of cob, strawbale, adobe, earthbag, and earthen plasters. During the winter months, she volunteers in Nicaragua, where she works with villagers, especially women, on construction projects in Sabana Grande, Totgalpa. What follows is a sample of Johndrow’s blog entries written from Nicaragua. You can learn more about her work at her website, Earthen Endeavors.]

Posted April 1, 2013

With the arrival of spring and new plant growth springing up all around, I’ve begun to reflect on my several years of writing this blog post, and I have come to the conclusion that far too often I have been overly critical and close-minded about many things. In addition, I have championed some theories and causes that contradicted many long-standing traditions in design, construction, and renovation. And it’s time to say I’m sorry.

Stuffy homes are unhealthy homes, while homes with plenty of fresh air are healthy. That’s been a commonly held belief for at least 200 years. In the mid-19th century, the connection between ventilation and human health was championed by sanitarians, a group of health experts who blamed the spread of bubonic plague and cholera on “miasma.”

What do you do if you’re a builder and your client (that would be me) hands you a material that no one’s ever heard of, let alone installed in this country, and asks you to insulate his house with it? A lot of smart builders would run the other way. Eli Gould, our partner in the Dummerston, Vermont farmhouse we’re renovating (really re-building), took it on as a challenge.

I was a kid a long, long time ago. Seems like it was another century ... another millennium even. Wait a minute — it was another millennium!

That was back in the day when we used to ride bicycles without helmets, apply mercury to our wounds, move seat belts out of the way (if the car even had them), and put our tongue on steel poles in the middle of winter. Of course, in Texas and Louisiana we just ended up with a bad taste in our mouth from those steel poles and wondered why people made such a big deal about it.

Each month in Portland, Maine, a group of building professionals gathers for an evening of serious Building Science banter. The topic is either focused on a specific aspect of building science or opens up a lively discussion of what a Pretty Good House (PGH) would do in our cold climate of Maine. (For more information on the Building Science Discussion Group in Maine, check out the links in the "Related Articles" box, below.)

Kevin Dickson has come across an article about a high-performance house in Massachusetts that has got him wondering whether big 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. systems are overtaking 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. to become the next big trend in high-efficiency building.

The house is the work of R. Carter Scott and a design team that included Betsy Pettit and Joe Lstiburek of Building Science Corp., among a number of other experts. It was one of eight in Devens, Mass., that Scott’s company, Transformations Inc., was chosen to build for MassDevelopment, the state’s finance and development authority.

In the past, I have been critical of the NAHB’s National Green Building Standard (NGBSNational Green Building Standard Based on the NAHB Model Green Home Building Guidelines and passed through ANSI. This standard can be applied to both new homes, remodeling projects, and additions. ), just as I have been of most other green building programs. While I don’t expect to lose my critical eye, I do believe I have mellowed a bit and developed new opinions about the certification process and each program's role in the industry.

Last week, I drove to Boston for Building Energy 13, the annual conference and trade show of the Northeast Sustainable Energy Association (NESEANorth East Sustainable Energy Association. A regional membership organization promoting sustainable energy solutions. NESEA is committed to advancing three core elements: sustainable solutions, proven results and cutting-edge development in the field. States included in this region stretch from Maine to Maryland. www.nesea.org). There were nine full-day workshops, 12 half-day workshops, and 60 hour-and-a-half sessions, with 10 going on at any one time. I can't possibly do justice to the quality of this event, but I can urge you to go next year and to look for more information about this year's conference on the NESEA website in the coming weeks.