[Greenbuilding] What R-2000 is not (was re: please rant

[Christophor Faust]

Dear All,
   
  While I have taken Eric, Shawna and Peter up on their offers/requests for additional information directly, I did want to respond to our two budding math geeks directly, and beg their forgiveness (W vs. W-hr) but hopefully make a point at the same time.  
   
  Lets say for a home to be considered "sustainable", it needs to durably provide a safe, healthy and comfortable indoor living environment.  (It may also need to supply power to your TV, VCR & portable ARC welder too, but that really isn't a function of the building's design, rather the "end use" that the building is applied towards.)  In order to meet the needs of a sustainable level of performance, the building would need to heat, cool, humidify, make hot water and ventilate an enclosed space as a minimum (for the NOLA Standard of Sustainability we added refrigeration too, but that isn't a universal requirement of passive survivability, thus not included here).  
   
  To accomplish these tasks, the designer can choose either to apply the rejection model strategy of building energy design performance, (R2000 home design), which results in something like:
   
  Sustainable Deficit = 
   
  A 2000 sq,ft, R2000 Home @ 20,000 W-hr/m^2 - yr = ~ 4,500 kW-hr/yr or about $550/yr (US) to heat, cool, humidify, ventilate & make hot water; (a very generous number in most climate zones). => 2.5 kW solar array (~ $18,750 US installed)
   
  Or she/he might choose an interactive model strategy like the one I mentioned in my previous post:
   
  A 2000 sq.ft. PTE Home @ 160 W-hr/m^2 - yr = ~ 36kW-hr/yr or about $5/yr (US) to heat, cool, humidify, ventilate & make hot water; (again a very generous number too).
  => 0.1 kW solar array (~ $1,000 US installed)
   
  But the point is that there isn't anything that the R2000 home can realistically do to change its number number (not R-1,000,000 envelope & EE of 100%), whereas there is literally an infinite number of ways that the interactive model can eliminate its "sustainable deficit".  (Literally the differential pressure that occurs across a dwelling could be used to as the prime mover of the integrated system.)
   
  Which was what I was attempting to convey with my original posts.  Again, I do apologize for leaving off the (hr) in my earlier posts.  Does that still make me a troll?
   
  AOF

David Delaney <ddelaney at sympatico.ca> wrote:
  At 08:05 AM 14/04/2007, Nick Pine wrote:
>David writes:
>>
>> It's hard to make any sense of 160W/m^2-yr.
>
>How about 160 W/m^2?

Which is, as you well know, the same as my 160 W.yr/(m^2.yr). I was just trying to preserve 
all of the symbols of the original. Also, when you write it as 160 W.yr/(m^2.yr) 
it eliminates the need for a separate comment about its being yearly average power. 

David 


_______________________________________________
Greenbuilding email list
List info: http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.org
List email: Greenbuilding at listserv.repp.org
Managed by BuildingGreen, Inc. http://www.buildinggreen.com
publisher of Environmental Building News and GreenSpec(r)
Hosted and archived by REPP / CREST http://www.crest.org


       
---------------------------------
Ahhh...imagining that irresistible "new car" smell?
 Check outnew cars at Yahoo! Autos.