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.

While energy experts often advise builders to exceed minimum code requirements for insulation, Icynene Incorporated, a manufacturer of open-cell spray polyurethane foam, is swimming against the tide. Surprisingly, Icynene is trying to convince builders to install less insulation than the code requires.

Peter:
Yes, we admit it; the blog title is a play on words from the oft-quoted Kermit the Frog. But it continually amazes me how many building professionals, companies, and organizations don’t have or clearly state a comprehensive and clear definition of building green. Without one, you risk confusing your staff and your clients. With one, you ensure that everyone is on the same page, from the beginning of and throughout the whole construction process.

As part of a new Master Certified Green Professional designation, NAHB worked with GreenBuildingAdvisor to develop a rigorous training course covering green home building, full of building science and quality construction details. This course premiered at the International Builders Show in Las Vegas just last week.

A shorter version of this article appeared in Fine Homebuilding.

Last week, I provided an overview of the 30% federal tax credits that are in place for 2009 and 2010 for residential energy upgrades. Most of the provisions of those tax credits are very good. In the rush to do a lot very quickly, though, some mistakes were made. One such mistake, in my opinion, has to do with the credit provided for window replacement.

I had a discussion several months ago with a designer I know regarding energy efficiency in a project she is working on. She recently took the initiative to become a licensed residential contractor and is now managing entire projects. I applaud her for making this transition and for working hard to maintain her professionalism in an industry where there are a lot of fly-by-night operators. The homeowner is interested in making the house more efficient, and our conversations focused on those aspects of the project.

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.

Our latest Question of the Week comes from a homeowner in New Jersey. Monica is uncertain of the best way to insulate the roof of a new second-story addition on her Cape Cod home. She wonders whether it's wise to insulate directly under the roof sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. — especially since the mounting system for her 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. array requires 54 holes to be drilled in her asphalt shingle roof.

Leaky homes are hard to heat and hard to cool. The only way to know whether your home is leaky or tight is to measure its air leakage rate with a blower door. A blower door is a tool that depressurizes a house; this depressurization exaggerates the home’s air leaks, making the leaks easier to measure and locate.

An energy-efficient house must be as airtight as possible. Many older U.S. homes are so leaky that a third to a half of the home’s heat loss comes from air leaks.