[Bldg-sim] Energy model calibration - normalizing the utility bills to month start-end

[Jeff Haberl]

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<mailto:........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
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________________________________
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<mailto: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.


[cid:image003.png at 01D09C46.E75BA0D0]
Christopher Jones,P.Eng.
Senior Engineer

WSP Canada Inc.
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Toronto, ON M4P 1E4
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