Replies

1. GBA Editor
   Martin Holladay | Feb 12, 2016 09:13am | #1

   Chris,
   There is no agreed-upon definition to the term "green building," which is why I do my best to avoid using the term.

2. Expert Member
   Dana Dorsett | Feb 12, 2016 04:20pm | #2

   Codes are moving targets, and IRC 2015 has been released, but with few changes to prescriptive R-values/U-factors.

   A prescriptive based approach doesn't really get to the heart of the matter, which is why under IRC 2015 there are performance based exceptions. For instance, the shape of the house can make a bigger difference to the ultimate energy use than whether the attic is R49 instead of R38.

   But even at IRC 2015 code-min (performance or prescriptive-R) it's impossible to get to Net Zero Energy with a solar array that actually fits on the house. How green is that?

   In California Net Zero Energy will become a code requirement for new residential construction beginning in 2020. While that may seem ambitious, over the lifecycle of a house it's cost effective at typical US energy costs if achieved in an aggressively cost-sensitve manner. (Don't just put 10" of closed cell foam over everything and call it "good"- it may never pay back financially.) Home builders iin CA are already upping their game in anticipation, but finding the most cost-effective path for Net Zero tract housing should be an interesting contest (especially in the higher elevation colder parts of the state!).

   A code-min IRC 2012 house doesn't have to be an energy pig, depending on the design it still can be, and it isn't even close to what's financially rational on a full lifecycle basis.

   The importance of Net Zero Energy for new houses is debatable- most houses that will still be around in 2050 are already built. But if a new house is still a net energy importer there is a case to be made that it's not yet green enough. From that perspective IRC 2012 or 2015 are still well behind the curve. It's conceivable that by IRC 2030 there will be requirements for smart home energy management systems and/or rooftop PV.

   No matter how low-energy you make the house, occupant behavior still makes a huge difference. A friend of mine did a deep energy retrofit on a 3-family apartment a few years ago, with R40-ish (whole wall-R) walls, and R70-ish roof, U0.18 windows throughout, etc, and includes the utilities in the rent. Among the current tenants there is a visiting professor from Korea whose average monthly utilities run $25-30. The tenant below him is a grad student, who is running nearly unbelievable $165-170/month (in a unit with lower calculated heating & cooling loads.) On a scheduled annual maintenance visit to check up on the mini-split heat pump last summer the high energy use tenant wasn't home, but most of the lights were on as was the large screen TV & game machine, with the AC set to 65F and there was at least one partially open window. OK, maybe $165 /month isn't so unbelievable... Most people would fall between those extremes, but sometimes it's not the building that needs greening-up. (My friend is starting to re-think the whole notion of including the utilities in the rental rate.)

   Martin: Sure there is no agreed-upon definition, but calling the site "GreenBuildingAdvisor" doesn't seem like a sincere attempt to avoid using the term, eh? ;-)

3. GBA Editor
   Martin Holladay | Feb 12, 2016 04:32pm | #3

   Dana,
   I was hired as an editor for GBA after the site was already named. Now, it's too late to re-name the site.

4. 
   Reid Baldwin | Feb 12, 2016 04:49pm | #4

   The grad student must have had time to move his grow lights for his marijuana plants before the scheduled annual maintenance visit.

5. 
   RD3Sunworks | Feb 12, 2016 05:42pm | #5

   People have tried too hard to specifically define "green building," and so there can be no agreed-upon definition. I think history will just generally show it to mean a building that integrates with nature as best as possible, like a tree. It just stands there collecting and storing the energy and nutrients it needs, and doesn't negatively affect its environment. That's the prettiest shade of green, I think.

   Achieving the prettiest shade of green building is currently just a goal of mankind--the best we can do is not even close. Chris, the building codes are even farther away from the prettiest shade--they aren't even close to the best we can do. They move toward the best we can do and ultimately, perhaps, toward the prettiest shade slowly, due to the massive inertia of society.

   I don't typically use the term green, either, just because everyone wants to right away define it specifically.Therein lies the mistake. Nature doesn't do that---there are infinite shades of green. I think the name of this website is just fine, as long as we recognize that we are trying but still
   have a way to go to achieve the prettiest shade of "green building."