Interest in green homes, exemplified by net zero energy homes, may be growing but there is an issue: because there is a lack of comparable homes, appraisals for green homes are more difficult to do:

Last year, single-family green home construction represented 17 percent of the homebuilding market, in effect doubling since 2008, according to a report by McGraw-Hill Construction. Researchers predict that by 2016, green home construction could comprise 29 percent to 38 percent of the market, as builders devote more time to green projects. The share of remodeling projects labeled as green is expected to rise as well…

Appraisers are slowly getting up to speed. Since 2008, almost 4,900 appraisers nationally have participated in 275 courses on green and energy-efficient valuation conducted by the Appraisal Institute trade group. Still, green home appraisals continue to be difficult, in part because there are few comparable sales but also because the building technology is changing. That makes it hard for appraisers to value — and for lenders to accept those higher values — home features that can run the gamut from rain barrels to a tankless water heater to a whole-house geothermal heating system…

In the Chicago area, Midwest Real Estate Data LLC added “green” fields to its multiple listing service so sellers can highlight environmentally friendly features of their homes to potential buyers. The Appraisal Institute created an addendum to appraiser forms to help analyze the value of green features. And lenders are starting to track so-called green mortgages to see if defaults are lower than on traditional home…

To increase the chances that improvements that go above and beyond what’s required by local building codes is correctly valued, experts recommend documenting green features added to a home.

They also urge builders and consumers to consider obtaining third-party certification about the home’s energy efficiency.

Put another way, there is more cultural and economic interest in green homes. People want to both reduce their energy costs but also want homes that are “responsible” and not seen as energy-hogging McMansions. However, it takes some time for the whole market to catch up to the perceived higher values of these new homes. This is the real issue here: while extra money and time may be spent on green features, appraisers aren’t yet “rewarding” builders and homeowners with the increase in housing value they think a more efficient and green-conscious home deserves.

Thinking more broadly about this, I wonder about the motivations of builders who are constructing more green homes. Are they motivated more by wanting to be green or by the knowledge there is a growing market for such homes? Of course, being green and making money can go together and perhaps this is how it should work in a perfect world. But, this might matter for some who are more concerned about being green and who wonder if being green is currently about being trendy which could endanger such causes down the road when the cultural and economic winds change.