[Bldg-sim] What do people do about Leap Years? was Re: Energy model calibration - normalizing the utility bills to month start-end

Tue Jun 23 13:21:57 PDT 2015

I think the cleanest is you just pretend every day is off by one. Ignore
all of the month garbage (yes you'll be off by a day at times). Just think
about it as days 1-365, with the right day of the week assigned. You can
reassign your holidays if you want. You wind up dropping the real 12/31.

But I like the "just use EnergyPlus" option.

On Tue, Jun 23, 2015 at 12:57 PM, Jim Dirkes <
jim at buildingperformanceteam.com> wrote:

>
>    1. Use EnergyPlus :), which allows >365 days.  This is also helpful
>    when the combined two-fuel billing cycle is 13-14 months.
>    2. Ignore the 1/365 difference.  Do you really think it will matter
>    much?
>
>
> On Tue, Jun 23, 2015 at 2:48 PM, Joe Huang <
> yjhuang at whiteboxtechnologies.com> wrote:
>
>>  This is a little off-topic, but something I've pondered for some time...
>>
>> The question is when people are using eQUEST/DOE-2 with historical year
>> weather, what do you do when it's a leap year?  Since DOE-2
>> always simulates a 365-day year,  do you just ignore the missing leap
>> day, but then don't the Days of Week also get screwed up starting in March?
>>
>> Since a quarter of the years are leap years, I've never understood why
>> accounting for them has been considered an insignificant detail.
>> I mean, if I told you that a quarter of the time your simulation results
>> would be a little wrong, isn't that a pretty high frequency?
>>
>> Many eQUEST/DOE-2 users also have the mistaken impression that the fault
>> lies in the DOE-2 weather files, which is not true.
>> Believe it or not, but the packed DOE-2 weather file format actually
>> contains 384 days (32 days per month), and all the DOE-2 weather files I
>> produce always contains Feb. 29 for the leap years (as well as other
>> enhancements like greater precision in the data).
>>
>> So, where does the problem lie?  It's in the clock within DOE-2 that
>> always sets February to be 28 days.  In other words, DOE-2 will read the
>> weather file and do the simulation only through February 28th, even though
>> the weather file contains data through February 32nd (:-)), although
>> everything beyond the 28th would be blank on non-leap years, and beyond the
>> 29th on leap years.
>>
>> When I've looked through the DOE-2.1E code, there are even flags setting
>> the leap years but these are never used. I've thought many times of toying
>> around with the code to see how difficult it would be to implement leap
>> years, but just haven't gotten around to it.  As far as I can see, the
>> biggest difficulty might might have to do not with the simulation itself,
>> but with the reporting.
>>
>> I'd like to know if others think this is something of sufficient
>> importance to merit further investigation.
>>
>> Joe
>>
>> Joe Huang
>> White Box Technologies, Inc.
>> 346 Rheem Blvd., Suite 205A
>> Moraga CA 94556yjhuang at whiteboxtechnologies.comhttp://weather.whiteboxtechnologies.com for simulation-ready weather data
>> (o) (925)388-0265
>> (c) (510)928-2683
>> "building energy simulations at your fingertips"
>>
>> On 6/23/2015 10:27 AM, Collinge, William Overton wrote:
>>
>>  All,
>>
>>
>>
>> This is a fantastic thread, and I am wondering if it could be taken one
>> step further to query if anyone has experience with methods to attempt
>> calibrating models of energy savings attributable to retrofits of multiple
>> systems simultaneously (plant, envelope, HVAC etc. – as most real-world
>> retrofits likely are), going past the 4- or 5-parameter breakpoint
>> regression models to incorporate inverse modeling of specific load types
>> and their space- or time-variable characteristics. This would fit under
>> multivariate methods in the last line of Table 2 in the older version of
>> ASHRAE Guideline 14 that Jeff Haberl has posted on his website, and would
>> attempt to standardize Maria’s Step 5 below without (possibly) the need to
>> conduct as much in-depth field verification as might otherwise be required.
>> I’ve dabbled in this a little bit…without extensive discussions with others…
>>
>>
>>
>> Example: changing the OA ventilation rate is going to have a specific
>> load profile versus some retrofit that affects the solar gain rate. Of
>> course, much easier in theory to do calibrations of this sort with hourly
>> meter data versus monthly utility bills…
>>
>>
>>
>> Bill Collinge
>>
>> Postdoctoral Scholar
>>
>> University of Pittsburgh
>>
>> Department of Civil and Environmental Engineering
>>
>>
>>
>>
>>
>>
>>
>> *From:* Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org
>> <bldg-sim-bounces at lists.onebuilding.org>] *On Behalf Of *Maria Karpman
>> *Sent:* Tuesday, June 23, 2015 12:02 PM
>> *To:* 'Jeff Haberl'; 'Joe Huang'; bldg-sim at lists.onebuilding.org
>> *Subject:* Re: [Bldg-sim] Energy model calibration - normalizing the
>> utility bills to month start-end
>>
>>
>>
>> Hello all,
>>
>>
>>
>> We usually do the following to calibrate model to monthly utility bills:
>>
>> 1)      Create or purchase weather file corresponding to pre-retrofit
>> period for which we have billing data. Lately we’ve been using
>> WeatherAnalytics files, which we found to be more cost effective than
>> creating our own (they charge $40 for an annual file).
>>
>> 2)      Run simulation using this weather file instead of TMY.
>>
>> 3)      Standard simulation reports (we typically use eQUEST) show usage
>> by calendar month (e.g. January, February, etc.) which is usually not
>> aligned with dates of utility bills, as noted in the question that started
>> this thread. As Brian mentioned in one of the earlier posts, this may be
>> circumvented by entering the actual meter read dates into eQUEST as shown
>> in the screenshot below. This will align usages shown in eQUEST’s “E*”
>> reports such as ES-E with the actual utility bills.  The approach does not
>> allow entering more than one read date per month (e.g. we can’t capture
>> April 3 – 28 bill). For projects where this limitation is an issue we
>> generate hourly reports that show consumption by end use for each meter in
>> the project, and aggregate it into periods that are aligned with utility
>> bills.
>>
>>
>>
>> 4)      We then copy simulation outputs (either from ES-E or hourly
>> reports, depending on the method used) into a standard spreadsheet with
>> utility data. The spreadsheet is set up to plot side by side monthly
>> utility bills and simulated usage, and also calculates normalized mean bias
>> error (NMBE) and variance CV(RMSE).
>>
>> 5)      If we did not to where we want to be with NMBE and CV(RMSE) we
>> adjust and re-run the model, and re-paste results into the same
>> spreadsheet.
>>
>>
>>
>> In my experience regression analysis using weather as independent
>> variable (i.e. running model with TMY file and normalizing for difference
>> in weather) or relying on HDD to allocate usage to billing periods can be
>> very misleading, mainly because on many projects weather is not the main
>> driver of consumption. For example energy usage of a school during a given
>> time period depends much more on vacation schedule than outdoor dry bulb
>> temperatures.
>>
>>
>>
>> Thanks,
>>
>>
>>
>> --
>>
>> *Maria Karpman *LEED AP, BEMP, CEM
>>
>> ________________
>>
>> Karpman Consulting
>>
>> www.karpmanconsulting.net
>>
>> Phone 860.430.1909
>>
>> 41C New London Turnpike
>>
>> Glastonbury, CT 06033
>>
>>
>>
>> *From:* Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org
>> <bldg-sim-bounces at lists.onebuilding.org>] *On Behalf Of *Jeff Haberl
>> *Sent:* Tuesday, June 23, 2015 10:16 AM
>> *To:* Joe Huang; bldg-sim at lists.onebuilding.org
>> *Subject:* Re: [Bldg-sim] Energy model calibration - normalizing the
>> utility bills to month start-end
>>
>>
>>
>> Hello Joe,
>>
>>
>>
>> Yes, you can count the degree days and regress against that to show a
>> correlation. However, one will get a better "fit" to the weather data if
>> you regress to the degree day that is calculated for the balance point
>> temperature of the building -- hence the inverse model toolkit or the
>> variable based degree day method.
>>
>>
>>
>> PRISM actually calculates the degree days to a variety of change points
>> and actually provides a table for each location that you use as a look up.
>> The IMT will actually perform a variable based degree day calculation that
>> agrees well with PRISM. IMT will also provide you with the average daily
>> temperature for the billing period.
>>
>>
>>
>> When using DOE-2 for actual billing periods, one will have to extract the
>> appropriate hourly variable, sum it to daily and then regroup to align with
>> the billing periods. Here's a chunk of code that will create a dummy plant,
>> display PV-A, PS-A, PS-E and BEPS, and extract the relevant hourly
>> variables to normalize the BEPS to the utility bills:
>>
>>
>>
>> INPUT PLANT ..
>>
>>
>>
>> PLANT-REPORT VERIFICATION = (PV-A)
>>
>> $ PV-A, EQUIPMENT SIZES
>>
>>
>>
>> SUMMARY = (PS-A,PS-E,BEPS)
>>
>>
>>
>> $ PS-A, PLANT ENERGY UTILIZATION SUMMARY
>>
>> $ PS-E, MONTHLY ENERGY END USE SUMMARY
>>
>> $ BEPS, BUILDING ENERGY PERFORMANCE SUMMARY
>>
>>
>>
>> HVAC=PLANT-ASSIGNMENT ..
>>
>>
>>
>> $ EQUIPMENT DESCRIPTION
>>
>> $ ELECTRIC DOMESTIC WATER HEATER
>>
>>
>>
>> BOIL-1 =PLANT-EQUIPMENT TYPE=ELEC-DHW-HEATER SIZE=-999 ..
>>
>>
>>
>> $ ELECTRIC HOT-WATER BOILER
>>
>>
>>
>> BOIL-2 =PLANT-EQUIPMENT TYPE=ELEC-HW-BOILER SIZE=-999 ..
>>
>>
>>
>> $ HERMETICALLY SEALED CENT CHILLER
>>
>>
>>
>> CHIL-1 =PLANT-EQUIPMENT TYPE=HERM-CENT-CHLR SIZE=-999 ..
>>
>>
>>
>> $ Graphics block for Data Processing ***
>>
>>
>>
>> RP-3 = SCHEDULE THRU DEC 31 (ALL) (1,24) (1) ..
>>
>>
>>
>> $ 8 = Total PLANT heating load (Btu/h)
>>
>> $ 9 = Total PLANT cooling load (Btu/h)
>>
>> $ 10 = Total PLANT electric load (Btu/h)
>>
>>
>>
>> BLOCK-3-1 = REPORT-BLOCK
>>
>> VARIABLE-TYPE = PLANT
>>
>> VARIABLE-LIST = (8,9,10) ..
>>
>> BLOCK-3-2 = REPORT-BLOCK
>>
>> VARIABLE-TYPE = GLOBAL
>>
>> VARIABLE-LIST = (1) ..
>>
>> HR-3 = HOURLY-REPORT
>>
>> REPORT-SCHEDULE = RP-3
>>
>> REPORT-BLOCK = (BLOCK-3-1,BLOCK-3-2) ..
>>
>>
>>
>> END ..
>>
>>
>>
>> COMPUTE PLANT ..
>>
>>
>>
>> STOP ..
>>
>>
>>
>> 8=!  8=)  :=)  8=)  ;=)  8=)  8=(  8=)  8=()  8=)  8=|  8=)  :=')  8=) 8=?
>> Jeff S. Haberl, Ph.D.,P.E.inactive,FASHRAE,FIBPSA,......jhaberl at tamu.edu
>> <........jhaberl at tamu.edu>
>> Professor........................................................................Office
>> Ph: 979-845-6507
>> Department of Architecture............................................Lab
>> Ph:979-845-6065
>> Energy Systems Laboratory...........................................FAX:
>> 979-862-2457
>> Texas A&M
>> University...................................................77843-3581
>> College Station, Texas, USA, 77843.............................
>> http://esl.tamu.edu
>> 8=/  8=)  :=)  8=)  ;=)  8=)  8=()  8=)  :=)  8=)  8=!  8=)  8=? 8=) 8=0
>>    ------------------------------
>>
>> *From:* Bldg-sim [bldg-sim-bounces at lists.onebuilding.org] on behalf of
>> Joe Huang [yjhuang at whiteboxtechnologies.com]
>> *Sent:* Monday, June 22, 2015 9:17 PM
>> *To:* bldg-sim at lists.onebuilding.org
>> *Subject:* Re: [Bldg-sim] Energy model calibration - normalizing the
>> utility bills to month start-end
>>
>> Maybe I'm missing something here, but why can't you just count up the
>> degree days for the utility period?
>> I hope you're not working with average or "typical year" degree days, but
>> the degree days from the same time period.
>>
>> I also recall that the old Princeton Scorekeeping Method (PRISM) back in
>> the 1980's allows the user to enter the degree days for that time period,
>> so it's not a new problem.
>>
>> 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"
>>
>>  On 6/22/2015 6:09 AM, Jones, Christopher wrote:
>>
>>  When calibrating an energy model to utility bills the utility bills
>> often don’t align with the month start and end.  I have reviewed a couple
>> methods to calendar normalize the utility bills but find them somewhat
>> unsatisfactory.
>>
>>
>>
>> For example the method I am looking at does the following:
>>
>> The April gas bill runs from March 25 – April 24.  The algorithm takes
>> the average number of m3 per day from that bill, applies it to the days in
>> April.  Then it takes the average number of days from the May bill which
>> runs from April 24 – May 25 and applies that average to the remaining days
>> in April.
>>
>>
>>
>> The issue is that the March-April period has much higher HDD than the
>> April-May period and the “normalized” gas usage is significantly lower than
>> the simulation data for April.
>>
>>
>>
>> I am wondering if there are any papers or other sources of information as
>> to how others approach this problem.
>>
>>
>>
>>
>>
>> [image: cid:image003.png at 01D09C46.E75BA0D0]
>>
>> *Christopher Jones,*P.Eng.
>> Senior Engineer
>>
>>
>>
>> *WSP Canada Inc.*
>>
>> 2300 Yonge Street, Suite 2300
>>
>> Toronto, ON M4P 1E4
>> T +1 416-644-4226
>>
>> F +1 416-487-9766
>>
>> C +1 416-697-0065
>>
>>
>>
>> www.wspgroup.com
>>
>>
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>
>
> --
>
> James V Dirkes II, PE, BEMP, LEED AP
> CEO/President
> The Building Performance Team Inc.
> 1631 Acacia Dr, GR, Mi 49504
>
> Direct: 616.450.8653
> jim at buildingperformanceteam.com
>
> Website <http://buildingperformanceteamcom>l  LinkedIn
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>
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