[Bldg-sim] [EnergyPlus_Support] Food for thought....

Chris Jones cj at enersave.ca
Thu Jun 28 15:44:41 PDT 2012

The discussion has become two discussions - 
weather data and processing. And calibrating to 
TRY (what I call acutal weather data for the same 
billing period) or TMY, tyipcal weather data.

Environment had a number of weather stations with 
hourly data - some with full weather data and 
some with only a few data channels.  Some 
stations were daytime hours only.  One had to 
request a period of data and pay a setup 
fee.  The setup fee was more than the data fee so 
it paid to request a bunch of sites at the same time.
We have an old C-code processor that converts the 
EC data into an old DOE2.1e format text format 
for conversion to a .WTH binary weather 
file.  The processor could use a number of 
different channels depending on the weather 
site.  The input file signalled what channels 
were coming in the text file.  The Hirsh 
processor can convert .WTH files to .bin files.

Environment Canada now has hourly data available 
for much fewer sites.  Cut backs closed dozens of 
sites across the country.  There is a significant 
difference in weather between places like 
Revelstoke and the closest site with TMY 
weather.  With the availability of stations 
smaller places, one could aggregate a weather 
file that captured the differences in temperature and humidity at least.

The good thing to happen with Environment Canada 
is that the WEB site makes hourly data available 
on line for a large number of stations across the 
country.  You can download a month at a time to a 
.csv file.  We now have a spreadsheet with the 
appropriate psychometric functions that converts 
the EC data to TRY data.  We just save the data 
to a text file for the Hirsh weather processor.

We use these TRY files for M&V projects.

At 04:13 PM 28/06/2012, Joe Huang wrote:
>Sorry if I came off as a little smug.  You've 
>actually put in words the main reason why I 
>think building energy modelers have steered away 
>from using historical weather data, which is 
>simply that of  convenience, i.e., there are a 
>lot of "typical year" weather files floating around, but getting hold of
>a usable historical year weather file takes a little more work.
>For the study that I mentioned, Dru and I did 
>not have to do anything because the SANSOM data set,
>available from NCDC, contained 25 years of 
>historical weather files for 239 cities (same as TMY2s).
>That was in 1996, and the availability of 
>historical weather data has only increased exponentially since
>then, although the building energy modeling 
>community seems curiously to not have followed.
>The most notable change, in my view, is NCDC's 
>decision to put the entire ISH (Integrated 
>Surface Hourly) data online in 2005, and then to 
>make it free to all in 2011.  This means that the raw weather reports
>from major stations around the world ( ~ 1,500 
>in the US) are available stretching back to 1980.
>I've been working with the ISH for many years 
>now, and am able to generate complete weather 
>files from any ISH file within seconds, and have 
>been providing that as a service to customers.  Sometime later this
>year, I'll be rolling out something on the Web, 
>but for now, those interested can just send me an e-mail.
>The idea that the ISH is of questionable quality 
>is, in my view, rather backwards.  The ISH is a 
>repository of the weather reports by the 
>"official" weather stations around the world, so 
>if you can't trust that, what can you trust?
>Joe Huang
>White Box Technologies, Inc.
>346 Rheem Blvd., Suite 108D
>Moraga CA 94556
><mailto:yjhuang at whiteboxtechnologies.com>yjhuang at whiteboxtechnologies.com
>(o) (925)388-0265
>(c) (510)928-2683
>"building energy simulations at your fingertips"
>On 6/28/2012 11:48 AM, Jim Dirkes wrote:
>>Dear Joe,
>>No fair! You  and Dru have been at the 
>>forefront energy modeling research for most of 
>>my adult life, and have a big head start.
>>My guess is that you spent a lot of time 
>>preparing the actual weather files for the 
>>research, however.  Unless I’m missing 
>>something, the ready availability of high 
>>quality (e.g., no big hunks of missing data) 
>>actual weather data has been pretty limited 
>>until recently.  With folk like Weather 
>>Analytics getting on board and making it pretty 
>>easy to get and inexpensive, it becomes a lot 
>>faster and lower cost than trying to clean some 
>>of the NOAA / NCDC data, not to mention getting 
>>good data for sites not in or near a major city.
>>Kudos for being way ahead of the industry curve 
>>(at least my own curve)!  It’s getting easier to catch up!
>>p.s., Dru sent me that paper and I’ll be reading it with interest very soon.
>>From: Joe Huang 
>>[<mailto:yjhuang at whiteboxtechnologies.com>mailto:yjhuang at whiteboxtechnologies.com] 
>>Sent: Thursday, June 28, 2012 1:53 PM
>><mailto:EnergyPlus_Support at yahoogroups.com>EnergyPlus_Support at yahoogroups.com
>>Cc: Jim Dirkes; 
>><mailto:bldg-sim at lists.onebuilding.org>bldg-sim at lists.onebuilding.org
>>Subject: Re: [EnergyPlus_Support] Food for thought....
>>I've always thought it was a "no-brainer" to 
>>use actual weather data whenever you're 
>>comparing simulation results to actual 
>>consumption data.  Even with the earliest degree-day software such as
>>PRISM (Princeton Scorekeeping Method) in the 
>>1980's, it was stressed to use the degree days
>>from the period of record, and not the 
>>long-term average, so I'm not sure why this (using actual
>>year weather data) is such a revelation.
>>The variation in total energy consumption of 
>>course depends a lot on the building characteristics.
>>Back in 1996, Dru Crawley and I wrote a paper 
>>on "Does it matter which weather data you use 
>>in energy simulations?", for the ACEEE Summer 
>>Study on Energy Efficiency in Buildings (it also appeared as two
>>separate ASHRAE papers at around the same time) 
>>where we took some prototypical building models 
>>(Dru did commercial, I did residential) and ran 
>>them with various "typical year" weather files 
>>and also 25 years of historical data in 10-12 US locations.
>>Joe Huang
>>White Box Technologies, Inc.
>>346 Rheem Blvd., Suite 108D
>>Moraga CA 94556
>><mailto:yjhuang at whiteboxtechnologies.com>yjhuang at whiteboxtechnologies.com
>>(o) (925)388-0265
>>(c) (510)928-2683
>>"building energy simulations at your fingertips"
>>On 6/28/2012 8:49 AM, Jim Dirkes wrote:
>>Dear Forums,
>>I am busy preparing a short talk for the Fall 
>>ASHRAE Energy Modeling Conference.  The topic 
>>is “An Approach for Calibrating Existing 
>>Building Energy Models to their Utility Consumption”.
>>As part of the preparation, I will address the 
>>issue of how muc h difference might result in 
>>energy conservation measure savings predictions 
>>if you use actual weather data for the billing period versus TMY data.
>>To get a rough idea  how much variation there 
>>might be, I looked at Degree Days for a span of 
>>years.  What a variation! (for the city I’m studying at least)
>>I am not yet sure how that affects total energy 
>>consumption – you’ll have to attend my presentation in Atlanta to find out J.
>>In the meantime, I am starting to think that 
>>existing building energy models should use 
>>actual weather, not TMY data.  Have any of you 
>>run similar comparisons for existing building models?
>><mailto:jim at buildingperformanceteam.com?subject=RE%3A%20%5BEnergyPlus_Support%5D%20Food%20for%20thought%2E%2E%2E%2E>Reply 
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Christopher Jones, P.Eng.
Suite 1801, 1 Yonge Street
Toronto, ON M5E1W7
Tel. 416-203-7465
Fax. 416-946-1005
email cj at enersave.ca
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