[Bldg-sim] climate zone Rome

Joe Huang yjhuang at whiteboxtechnologies.com
Wed Feb 3 07:42:38 PST 2016


I beg to differ on this.  ASHRAE Climate Zones are very simply defined based of degree 
days, plus what I consider a  faulty use of precipitation to differentiate "wet" from 
"dry" climates.  When a EPW stat file gives the ASHRAE Climate Zone as 3, it's simply 
reporting the number of degree days in the file, and in that sense, absolutely correct.  
The reason for the discrepancy is that ASHRAE 90.1, or actually ASHRAE Standard 169 
(Climate Data for Building Design Standards), did their climate zone mapping, they came up 
with a degree day value that put Rome in Climate Zone 4. The problem in this case is that 
all 3 weather files for Rome that I've looked into (IWEC, IWEC2, IGDG - the one  used by 
Francesco) show HDD from 1440 to 1514, much below the 2000 HDD to fall into  Climate Zone 
4. I have a good idea how Standard 169 derived its degree days, but am waiting for 
confirmation lest I misspeak.

In the meanwhile, I would also recommend using the climate zone shown in 90.1 to set the 
reference building, but only because that's what listed, not because it's technically better.

Joe

Joe Huang
White Box Technologies, Inc.
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Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
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On 2/3/2016 6:43 AM, Jim Dirkes wrote:
> Francesco,
> As I recall, the E+ weather files derive the climate zone based on various attributes of 
> the weather data.  In fact, I think there is a qualifying statement within the .EPW 
> files which says the climate zone may not be "perfect"
> For that reason, I would use the climate zone referenced in 90.1
>
> On Wed, Feb 3, 2016 at 9:15 AM, Francesco Passerini <fpasserini.tn at gmail.com 
> <mailto:fpasserini.tn at gmail.com>> wrote:
>
>     In order to understand what thermal transmittances I shall impose in a baseline
>     model for LEED, I have to understand in what climate zone I shall consider Rome.
>     In TABLE B-3 "International Climate Zones" of ASHRAE 90.1-2010, "Roma/Fiumicion" is
>     zone 4, while in the weather file zone 3C is indicated.
>     The weather file for Fiumicino is available here:
>     https://energyplus.net/weather-location/europe_wmo_region_6/ITA//ITA_Roma-Fiumicino.162420_IGDG
>     If you see the .stat file, HDD18°C = 1514, which respects the thermal criteria for
>     zone 3C (see Table B-4).
>     Is TABLE B-3 based on other weather data?
>     Best Regards
>     Francesco
>
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>
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