2 Comments

1. 
   dickrussell | Nov 28, 2011 12:44pm | #1

   Air inlet height above grade - implementation
   A summary of changes to ES for version 3 was presented here on GBA last March, along with some discussion of what they got right and wrong with the changes:

   https://www.greenbuildingadvisor.com/blogs/dept/musings/energy-star-homes-program-raises-bar-version-3

   One thing I noted was that ventilation air inlets had to be four feet above grade, and I wondered both why that was imposed and how the duct to it would be routed in some houses. I still do. Clearly snow depth is at least one factor, as EPA has amended the first release of ESv3 to specify two feet above grade for CZ 1-3 and still four feet for CZ 4-8. There is a special exception specifying 2 and 2.5 foot numbers for CZ 4 and 5 of North Carolina, based on historic snowfall data, and a note says exceptions may be given for other states based also on historic data.

   Intake of contaminants also seems to be of concern, as the air inlet must be covered with a mesh of 0.5" or tighter mesh to keep out rodents and debris. There also is a recommendation (but not a requirement) that there be easy access to the inlet for periodic cleaning.

   It's a puzzle to me as to why EPA has gone past what ought to be required of the building itself for energy efficiency and into the realm of things that are a matter of periodic maintenance and timely snow removal. Even the four foot height requirement above grade is no guarantee that snow won't bury an inlet in some locations, so why try to make it prescriptive at all, but leave it as a recommendation?

   I haven't seen anything in ESv3 that addresses how to route air inlet ducts to comply with the height above grade requirement. For a house with a basement or at least a crawl space with enough headroom for locating HVAC there, and with minimal foundation wall extending above grade, the location of the inlet hood will have to go through the wall above the basement or crawl space. If there is no closet against an outer wall at a suitable location, for hiding an insulated duct coming up from below, where is the duct supposed to go without looking ugly? It would seem that only a double framed wall or one done with I-joist studs offers any possibility for hiding the duct. I can't help but think that EPA didn't think through that height requirement as to implementation.

2. 
   wjrobinson | Nov 28, 2011 03:57pm | #2

   Seriously, Dick, building a
   Seriously, Dick, building a thousand square foot home made of hundred thousand components, dozens of systems, rooms full of furniture and people, no place to hide one thousandth of the entire footage a duct?

   You don't need Walt Disney's imagination but I think a closet for example could "cloak" the evil mandated perturbance....

   Just sayin..... (In fun by the way!)
   Aj funster/cryptician/builder/GBAnamerebel