Green Building Blog

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.

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.

Our Question of the Week focuses on a query from “DC,” a Texas reader who wants to know which residential ventilation system will provide the “most bang for the buck.”

DC knows that a tight home requires a mechanical ventilation system to provide fresh air. But how does one choose among the bewildering array of options? And are there any performance advantages to expensive ventilation systems?

Ever since the premier of USGBC’s two-day REGREEN workshop in Phoenix, AZ at Greenbuild last November, Annette, Rob, and I have been gearing up for a slew of green remodeling workshops across the country — the REGREEN Roadshow. The REGREEN workshops are a lot of fun to teach (and take) for two reasons: one, the blend of builder/remodeler with interior design perspectives is completely refreshing; and two, the substantial and substantive group work woven into the workshop makes for an energetic and invigorating approach.

In a recent discussion from our Q&A forum, Dan Fette asks about fumes off-gassing from spray foam. He is building a house for a chemically sensitive family and wants to make sure he does the right thing. Beyond providing a comfortable and energy-efficient home, Dan rightfully wants to deliver a healthy one.

Martin Holladay tells Dan that while most of the information on off-gassing comes from the spray-foam industry, some good information can be found online.

After trying a variety of ventilation approaches, I've settled on exhaust-only ventilation systems with ventilation rates that are on the low side of most recommendations.

Photovoltaic panels and are one of the design cornerstones of zero-energy homes, which produce as much electricity over the course of a year as they consume.

Installing enough 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. to accomplish this costs tens of thousands of dollars, but as 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. modules continues to fall and efficiencies go up, net-zero performance will be available to many more U.S. homeowners.

A shorter version of this article appeared in Fine Homebuilding.

As much as 60% of all household water consumption can go to outdoor uses. Irrigation systems should be designed not to waste potable water. A good system delivers water efficiently at the right time. Systems that distribute water indiscriminately, like lawn sprinklers, are inherently wasteful.

While lawn and garden work are tempting DIY projects, a certified pro can help you accomplish your water conservation goals more efficiently. At least they can help you make better choices when designing the system.

By Peter Powell, AIA

I have designed over 60 passive solar homes over the last 35 years and have lived in seven of them. Based on that experience, I have come to a few conclusions which, although contrary to conventional passive wisdom, I have found to be valid. I must qualify these comments by saying that most of my experience has been in the Northeast, primarily in Maryland and Pennsylvania, in areas with 4,000 heating degree days and up. The following comments mostly apply to new construction in similar or colder climates.