The most recent blogs at Green Building Advisor

Calculating the Embodied Energy Payback for Passivhaus Buildings

Posted on July 19, 2012 by mike eliason in Guest Blogs

A common 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. topic that rears its head every now and again is the embodied energy of construction. While this can be an important issue, we generally feel it’s a moot point for Passivhaus projects – especially the ones we design (owing to better optimized assemblies and less insulation!).

The Magic of Cold

Posted on July 16, 2012 by Allison A. Bailes III, PhD in Building Science

With the recent heat wave that set all kinds of records across the US, including an all-time high of 106° F here in Atlanta, air conditioning has become quite the topic of conversation. Why, just yesterday I overheard two little old ladies* on a park bench debating thermostatic expansion valves versus capillaryForces that lift water or pull it through porous materials, such as concrete. The tendency of a material to wick water due to the surface tension of the water molecules. tube metering devices — and almost coming to blows over it!

The Connection Between Obesity and Climate Change

Posted on July 13, 2012 by Martin Holladay in Musings of an Energy Nerd

Positive feedback loops that reinforce global warming are scary. Here’s an example of such a feedback loop: warmer temperatures melt Arctic sea ice earlier in the spring and reduce the size of the summer ice pack. Since the dark ocean has less reflectance than ice, a smaller ice pack means that more solar radiation is absorbed by the ocean every summer, further warming the planet.

Trade Contractor Management — Part 2

Posted on July 12, 2012 by Carl Seville in Business Advisor

Before you commit to the time and energy required to put together a complete management system for your trade contractors, you may want to know what you will ultimately get out of it. A good system will help you get more consistent, high quality work, reduce confusion and problems, help new trade contractors get up to speed quickly, improve your back office operations, and avoid confusion throughout the company. Sound interesting?

Energy Star Homes Must Comply with Version 3 Guidelines Now

Posted on July 11, 2012 by Allison A. Bailes III, PhD in Building Science

On the 1st of this month, the Energy StarLabeling system sponsored by the Environmental Protection Agency and the US Department of Energy for labeling the most energy-efficient products on the market; applies to a wide range of products, from computers and office equipment to refrigerators and air conditioners. new homes program moved fully (well, almost) into the much more rigorous set of guidelines called Version 3. There's been a lot of discussion on the the transition for the past three years, when the Energy Star team at the U.S. EPA first started vetting the update with HERSIndex or scoring system for energy efficiency established by the Residential Energy Services Network (RESNET) that compares a given home to a Home Energy Rating System (HERS) Reference Home based on the 2006 International Energy Conservation Code. A home matching the reference home has a HERS Index of 100. The lower a home’s HERS Index, the more energy efficient it is. A typical existing home has a HERS Index of 130; a net zero energy home has a HERS Index of 0. Older versions of the HERS index were based on a scale that was largely just the opposite in structure--a HERS rating of 100 represented a net zero energy home, while the reference home had a score of 80. There are issues that complicate converting old to new or new to old scores, but the basic formula is: New HERS index = (100 - Old HERS score) * 5. raters and home builders. In case you've ignored or haven't heard much about it yet, here's a quick overview of what's new:

Choosing an Air Conditioner

Posted on July 11, 2012 by Alex Wilson in Energy Solutions

[Author's note: Some modifications have been made since this blog was originally posted.]

I have never owned an air conditioner, and I don’t have any immediate plans to change that. But if I did, what would I look for?

For only occasional use and when you don’t want to spend more than $1,000, the options are limited to room air conditioners, which are most commonly installed in windows. These cool the rooms in which they are installed, though in a small house or one that’s very-well-insulated and tight, a single window unit may be able to cool much of the house.

Air-Source or Ground-Source Heat Pump?

Posted on July 9, 2012 by Scott Gibson in Q&A Spotlight

Dana is building a tight, well-insulated house in climate zone 6 and now faces a choice between a ground-source heat pumpHome heating and cooling system that relies on the mass of the earth as the heat source and heat sink. Temperatures underground are relatively constant. Using a ground-source heat pump, heat from fluid circulated through an underground loop is transferred to and/or from the home through a heat exchanger. The energy performance of ground-source heat pumps is usually better than that of air-source heat pumps; ground-source heat pumps also perform better over a wider range of above-ground temperatures. and an air-source heat pumpHeat pump that relies on outside air as the heat source and heat sink; not as effective in cold climates as ground-source heat pumps. for heating and cooling.

“After the 30% tax incentive, there is not much increase in cost for the geo system,” Dana writes in a Q&A post at GreenBuildingAdvisor. “I am being told different stories in regard to system performance and longevity of equipment (depending on what side of the fence you’re on).”

New Green Building Products — July 2012

Posted on July 6, 2012 by Martin Holladay in Musings of an Energy Nerd

Once again, the “in” box on my desk is beginning to fill up with a stack of brochures describing interesting new products.

I've selected four products to review in this latest roundup: an insert panel to improve the thermal performance of insulated concrete forms (ICFs); a new wall system for manufactured stone veneer; and two new water-resistive barriers (WRBs).

Chilling Out With Air Conditioners

Posted on July 5, 2012 by Alex Wilson in Energy Solutions

[This reflects a few corrections from the original posting]

My wife and I did our outside work early, while the weather was still bearable. Since mid-day we’ve been holed up in the house. It’s not exactly cool indoors, but we’ve had the house closed up and it’s about 15 degrees cooler than outdoors. If it gets much warmer, though, I admit that I’ll at least be thinking about getting an air conditioner—as I do every year for a few days during the hottest weather.

Essential Energy-Audit Equipment

Posted on July 3, 2012 by Erik North in Guest Blogs

I thought I’d put together a list of all of the tools and equipment I use during an energy audit. Not all of these tools are used during every audit, and some aren’t essential to investigating the house. I’ve separated the lists into two categories: essential items and useful items.

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