The last couple weeks I’ve written about two of the common myths of green building: that it has to cost more to build green and that green building is mostly about materials. This week I’ll cover another myth: that green building products don’t perform as well as conventional products.

Following up on my recent post about LEED and other green programs, it occurs to me that the people responsible for creating and managing most green home certification programs have completely missed the big picture. I hope and believe that one day, through a combination of more stringent codes, legislation, and marketplace demands, we will reach a point where green building becomes the minimum acceptable standard.

Although building science has evolved rapidly over the last 40 years, one theme has remained constant: builders are still confused about vapor barriers.

Any energy expert who fields questions from builders will tell you that, year after year, the same questions keep coming up: Does this wall need a vapor barrier? Will foam sheathing trap moisture in my wall? How do I convince my local building inspector that my walls don’t need interior poly?

This podcast series is excerpted from a two-day class called "Building Science Fundamentals" taught by Dr. Joe Lstiburek and Dr. John Straube, of Building Science Corporation.

Until recently, I hadn’t really given much thought to the builders in my town with the green leaves on their signs and the logos — “We were green before it was a color” or “Green since 1978” — who never show up at the green council meetings and won’t even certify to 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. because “it’s too expensive.” I was there once, belligerently misinformed, so I figure I can afford to turn the other cheek when I drive past a greenwasher's sign on the street.

Last week I wrote about one of the common myths of green building: that it has to cost more to build green. This week, I’ll tackle another myth: that green building is mostly about materials.

The 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. standard is probably the most stringent available standard for energy-efficient buildings. Passivhaus buildings have to meet a strict airtightness standard (0.6 air changes per hour at 50 Pascals), so they tend to be much tighter than homes that meet 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. or LEED for HomesLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. A brief overview of the points structure: - Certified: 45 – 59 points - Silver: 60 – 74 points - Gold: 75 – 89 points - Platinum: 90 – 136 points Total available points: 136 Total prerequisite points: 25 requirements.

We’re all familiar with the food pyramid — the triangle with grains and cereals at the bottom and fats and sugars at the top. Inspired by the food pyramid, a Midwestern electric utility, Minnesota Power, has created a useful graphic called the energy conservation pyramid. (According to a Minnesota Power spokesperson, the originator of the conservation pyramid was Bob McLean, the chief operating officer at Hunt Utilities Group.)

Energy audits can be a single slice evaluation of home performance, just looking at energy, albeit in a comprehensive analysis of energy performance. Whole-house assessments are green because they take a systems integration approach to evaluating home performance, looking at the individual and combined effects of energy, water, indoor air quality, and durability performance.

Having written about green building for more than twenty years now, I’ve encountered lots of misperceptions. One of those is that green building always has to cost a lot more than conventional building. There are plenty of examples where it does cost more (sometimes significantly more), but it doesn’t have to, and green choices can even reduce costs in some cases. Let me explain.