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When Weatherizing Increases Radon

Posted February 24, 2014 10:50 AM by Peter Yost
Related Categories: BuildingGreen's Top Stories

Air sealing and other energy retrofits in our homes can raise or lower radon levels. The only way to know is to test.

This blog post first appeared on GreenBuildingAdvisor.com.

Will this be on the test? With radon, the correct answer is always Yes. Photo: National Institutes of Health. Image is in the public domain.We are always trying to avoid unintended consequences of our best efforts to improve home performance. A good example of this is radon gas and air tightness levels in homes during energy retrofits. How are the two levels related, and what can we do about it?

Airtightness and radon levels

There are five main factors that drive radon levels in homes:

Insulated Vinyl Siding: Worth the Extra Cost?

Posted February 20, 2014 1:50 PM by Peter Yost
Related Categories: BuildingGreen's Top Stories, GreenSpec Insights

Two studies indicate some benefits to using insulated vinyl siding, but more data is needed to win over this skeptic.

A weather-resistive barrier combined with insulated vinyl siding had some visible, qualititative results on thermal performance in a new industry study. Image: Vinyl Siding Institute.Setting aside the overall environmental profile of the oft-demonized PVC (check our coverage in this month’s EBN feature “The PVC Debate: A Fresh Look”), I’ve been getting a lot of questions about insulated vinyl siding—the vinyl siding with form-fitted expanded polystyrene (EPS) insulation permanently built into the back side of the double-four courses of vinyl siding.

Thanks to claims being made by the Vinyl Siding Institute and specific manufacturers, I’ve been hearing questions like these:

Commissioning Our Home's Heat-Recovery Ventilator

Posted February 18, 2014 7:08 PM by Alex Wilson
Related Categories: Energy Solutions, GreenSpec Insights

To function properly, any ducted HRV has to be balanced after installation

Barry Stephens measuring the airflow through a ceiling register of our HRV.
Photo Credit: Alex Wilson

After choosing and installing our state-of-the-art heat-recovery ventilator (HRV), we completed a critical step in the installation of any HRV: commissioning, including the critical step of balancing the air flow.

This is absolutely necessary to ensure proper operation and full satisfaction.

4 Resources Help Draw the Shades on Poor Window Performance

Posted February 15, 2014 1:53 PM by Peter Yost
Related Categories: BuildingGreen's Top Stories, GreenSpec Insights

Predicting performance and rationally selecting window coverings—from awnings to films to cellular shades—is incredibly challenging, but real help is on the way.

Photo: Paul Sable. License: CC BY 2.0.Photo: Paul Sable. License: CC BY 2.0.There is a lot of interest in just how much (and at how low a price point) window coverings can improve building thermal performance.

Both the U.S. Department of Energy (DOE) and the U.S. Environmental Protection Agency (EPA) have been working on this issue; electric utilities would like to know how window coverings can fit into their efficiency programs; and both building professionals and consumers need objective guidance on how to compare window coverings—to each other and to window replacement.

Where does our industry stand on assessing thermal performance of window attachments, or coverings? There are four new or emerging resources that paint a more complete picture.

How We Chose Our Heat-Recovery Ventilator

Posted February 12, 2014 11:06 PM by Alex Wilson
Related Categories: Energy Solutions, GreenSpec Insights

Zehnder’s state-of-the-art HRV will provide years of service in providing fresh air with very low energy consumption.

Barry Stephens installing the condensate drain on our Zehnder ComfoAir 350 Luxe HRV. Click to enlarge.
Photo Credit: Alex Wilson

Balanced ventilation requires two fans: one bringing fresh air into the house and one exhausting indoor air (see 6 Ways to Ventilate Your Home). By balancing these two fans and the airflow through their respective ducts, the house is maintained at a neutral pressure—which is important for avoiding moisture problems or pulling in radon and other soil gases.

6 Ways to Ventilate Your Home (and Which is Best)

Posted February 5, 2014 2:46 PM by Alex Wilson
Related Categories: Energy Solutions, GreenSpec Insights

How a green home really "breathes"

Should a green home require a piece of ventilation equipment like our Zehnder HRV?
Photo Credit: Alex Wilson

One of the features in our new house that I’m most excited about barely raises an eyebrow with some of our visitors: the ventilation system. I believe we have the highest-efficiency heat-recovery ventilator (HRV) on the market—or at least it’s right up there near the top.

But first, a lot of people may be wondering, should a "green" home require mechanical ventilation? A lot of people might think that this is just the kind of energy-consuming system that homes should be getting away from—while cracking windows for fresh air.

Cold Weather Tests the Limits of Our Mini-Split Heat Pump

Posted January 29, 2014 11:30 AM by Alex Wilson
Related Categories: Energy Solutions, GreenSpec Insights

Testing the limits of the air-source heat pump in our new house with this cold weather

The interior unit of our Mitubishi air-source heat pump. Click photos to enlarge.
Photo Credit: Alex Wilson

It’s been pretty chilly outside. A number of people have asked me how our air-source heat pump is making out in the cold weather. I wrote about ths system last fall, well before we had moved in to our new home. Is it keeping us warm?

First, if you want to get up to speed on the surprising and counterintuitive nature of how an air-source heat pump works, check out our primer on the topic—which includes a great diagram.

We’ve only been living in the house for a few weeks, but so far, so good. Our 18,000 Btu/hour Mitsubishi mini-split heat pump (MSZ FE18NA indoor unit and MUZ FE18 outdoor unit) is doing remarkably well in keeping us comfortable. We don’t have any oil or gas heating in the house, only the electric heat pump and a small wood stove that we’ve fired up twice so far.

The indoor heat pump unit is mounted on a wall next to our kitchen, and it’s been operating pretty steadily in this cold weather. (Even though we’ve heated with wood for decades and have all the wood we could ever use, I’ve been curious how the house will do just on electricity, so have refrained from using the wood stove.)

On the Benefits of Online Learning

Posted January 21, 2014 12:27 PM by Alex Wilson
Related Categories: Energy Solutions

With a new group of online BAC courses starting this week, I’m reminded of the benefits of learning—and teaching—from home.

San Francisco Bay Area traffic. Click to enlarge.
Photo Credit: Getty Images

Truth be told, I was slow warming up to online instruction. Ten years ago, in early 2004, BuildingGreen was approached by Boston Architectural College (then Boston Architectural Center—but with the same acronym BAC) about collaborating on sustainable design curriculum. There is so much value in face-to-face instruction and student interaction, I thought, how could online instruction take its place?

But we did collaborate, helping BAC develop it’s Sustainable Design curriculum. And I created and for a number of years taught one of the foundation online courses for the program: “Sustainable Design as a Way of Thinking,” which is now being taught by my friend David Foley.

This assemblage of courses, now housed in BAC’s Sustainable Design Institute, offers the most comprehensive, accredited online instruction in sustainable design anywhere. There are nearly three dozen courses offered that can be taken as continuing education courses by anyone, taken as part of graduate degree programs, or taken as electives as part of a relatively new MDS (Masters in Design Studies) program in Sustainable Design that is now in its third year.

Look Under the Sea for Safe Nuclear Waste Storage

Posted January 15, 2014 4:35 PM by Alex Wilson
Related Categories: Energy Solutions
Workers entering the Yucca Mountain nuclear waste storage facility in 2006.
Photo Credit: Isaac Breekken, AP

With nowhere on land to turn, we should look under the seabed for places to bury high-level nuclear waste

For more than 30 years the nuclear industry in the U.S. and nuclear regulators have been going down the wrong path with waste storage—seeking a repository where waste could be buried deep in a mountain. Nevada’s Yucca Mountain was the place of choice until…it wasn’t.

Any time we choose to put highly dangerous waste in someone’s backyard, it’s bound to cause a lot of NIMBY opposition, even in a sparsely populated, pro-resource-extraction place like Nevada, and in the case of Yucca Mountain, powerful Nevada senator Harry Reid has hardened that opposition politically.

Aside from NIMBYism, the problem with burying nuclear waste in a maintain (like Yucca Mountain) or salt caverns (like New Mexico’s Carlsbad Caverns—an earlier option that was pursued for a while in the 1970s) is that the maximum safety is provided at day one, and the margin of safety drops continually from there. The safety of such storage sites could be compromised over time, due to seismic activity (Nevada ranks fourth among the most seismically active states), volcanism (the Yucca Mountain ridge is comprised mostly of volcanic tuff, emitted from past volcanic activity), erosion, migrating aquifers, and other natural geologic actions.

A better storage option

I believe a much better solution for long-term storage of high-level radioactive waste is to bury it deep under the seabed in a region free of seismic activity where sediment is being deposited and the seafloor getting thicker. In such a site, the level of protection would increase, rather than decrease, over time.

Stay Safe When Using Space Heaters and Wood Stoves

Posted January 8, 2014 7:43 PM by Alex Wilson
Related Categories: Energy Solutions

Cold weather, when wood stoves are cranked up and portable electric space heaters are brought out of the basement and plugged in, is when most house fires occur

Enjoying a wood stove on a cold winter day.
Photo Credit: Alex Wilson

The morning paper had yet another story about a destructive house fire—fortunately no fatalities (this time*), but the total loss of another home and another family’s belongings. And like many others, the culprit appears to have been the wood stove.

So many of the home fires we experience in Vermont result from trying to keep warm. Some have to do with faulty installation of wood heating equipment; many others result from improper operation of that equipment or management of the ash.

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