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
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
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.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"
Thanks, Joe. I appreciate the additional insights. I suspect that LEED
reviewers don't know as much background as you do and are inclined to
follow the 90.1 table.
Francesco, if it's beneficial for your client to use Climate Zone #3, I
think you could make a case for that based on Joe's insights and
information. If your project is registered with USGBC, you can ask
questions in advance of a formal submission of the modeling results - that
might be worth doing to settle the question before defining the model.
Joe,
Just wanted to add to Jim?s note of appreciation. You are a constant source of insight on a wide ranging set of topics the modeling field. The historical perspective (and not saying you?re old!) is fantastic, even for many of us that have been at this for a while. Thanks.
Paul
PAUL ERICKSON LEED? AP
PRINCIPAL
SUSTAINABLE PRACTICE
AEI | AFFILIATED ENGINEERS, INC.
5802 Research Park Boulevard | Madison, WI 53719
P: 608.236.1112 | C: 303.859.7523 | www.aeieng.com
perickson at aeieng.com
From: Bldg-sim> on behalf of Jim Dirkes >>" >
Date: Wednesday, February 3, 2016 at 9:53 AM
To: Joe Huang
Cc: "bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] climate zone Rome
Thanks, Joe. I appreciate the additional insights. I suspect that LEED reviewers don't know as much background as you do and are inclined to follow the 90.1 table.
Francesco, if it's beneficial for your client to use Climate Zone #3, I think you could make a case for that based on Joe's insights and information. If your project is registered with USGBC, you can ask questions in advance of a formal submission of the modeling results - that might be worth doing to settle the question before defining the model.
Joe is correct. What's reported is what's in the weather file... degree
days. And what Standard 90.1 (and now Standard 169) reports is based on
climate (period of record).
When using actual weather data, I have seen a location change climate zones
from year to year. Which makes sense, some years are warmer and some are
cooler. One example I found, Beijing China, for the years 1982-1999, the
climate zone varies from 3C to 5A, while the IWEC file is 5A. And Standard
169-2013 has it at 4A (same data as 2009 Handbook).
FYI, Rome is CZ 3A in 169-2013.
In all cases, what is in Standard 90.1-2010 is what should be used, based
on climatic conditions not a single year of weather. Standard 90.1 (and
189.1) has recently adopted the 169-2013 data, which will be incorporated
into 90.1-2016.
Following up on this question ("Why is Rome in ASHRAE Climate Zone 4 when the weather
files say it has less 1514 HDD ?),
I checked through various versions of ASHRAE 90.1 and Standard 169. Rome was so listed as
CZ 4 in Version 2004 (which I have) down through Version 2010 (which I don't have but
trusting what Francesco said :-)), but as CZ 3A in Version 2013.
However, when I looked in the Table D-3 of Version 2004, it gives Rome as having 2684
HDD65 (Fahrenheit), which converts to 1491 HDD10 (Celsius), which is consistent with the
1541 HDD10 of the weather file that Francesco is using (there are always a few percentage
point differences between the long-term HDD and that from a typical year file).
Therefore, my conclusion is that there's a mistake in ASHRAE 90.1-2010, and my suggestion
to Francesco is to base the reference building thermal properties on Climate Zone 3A for
ASHRAE 90.1-2013, or if you don't have a copy, use Climate Zone 3A for ASHRAE 90.1-2010
and point out the error to whoever judges your LEED application. It should be a "no-brainer".
Joe
Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"
Francesco,
I just checked my SI version of 90.1 and in fact the Climate Zone for Rome
listed in Table B1-3 should be climate zone 3 not 4 based on the HDD and CDD
data listed in Table D-3 and the Climate Zone criteria listed in Table B
1-4.
One suggestion would be to submit an informal request to ASHRAE 90.1
clarifying whether this is a mistake. The committee can usually turn around
an informal interpretation very quickly and then you would be able to submit
to LEED with greater confidence using the correct Climate Zone.
My gut says that GBCI would be reasonable in accepting the use of Climate
Zone 3 given that it is pretty clear this is an error in Table B1-3.
Cheers,
Mike
Michael Tillou, PE, LEED AP BD+C, ASHRAE BEMP
Atelier Ten
T +1 (212) 254 4500 x208