UtilityCost Tariff Demand Charges based on max demand in interval

asked 2016-10-04 16:11:06 -0500

rkbest
1392 ●1 ●4 ●13

updated 2016-10-04 18:05:43 -0500

I have to implement a demand charge block that is based on the maximum demand in a 30-minute interval and then applies the rate 1. x per kW for billing period, plus (highest measured 30-minute interval kW demand billing period) 2. y per kW of peak billing demand (highest measured 30-minute interval kW demand peak billing period)

How can this be done using EMS? Any other approach?

( This is part of the https://unmethours.com/question/20352... but I think it needs a separate thread.)

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Complex Tariff Modeling section is also not suitable for finding the demand charges as its dependent on finding the max demand for a 30-minute interval for billing and peak billing times.

rkbest ( 2016-10-04 18:45:41 -0500 )edit

To get a 30-minute interval for kW demand, use the UtilityCost:Tariff field called Demand Window Length and set it to HalfHour. Why are you saying that is not suitable?

JasonGlazer ( 2016-10-05 06:42:16 -0500 )edit

I want to use these http://tampaelectric.com/files/tariff... Time of day rates (GSDT rate). And demand windows will be applicable for all the demand. The demand is to part one for base billing and PLUS demand for peak billing demand (which i think would need to be calculated for peak windows only). Any suggestions of implementing this?

rkbest ( 2016-10-05 11:52:46 -0500 )edit

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answered 2016-10-05 15:18:59 -0500

JasonGlazer

6540 ●20 ●12 http://www.gard.com/

First of all, in order to get the 30-minute interval KW demand, use the UtilityCost:Tariff field called Demand Window Length and set it to HalfHour.

The rate you provided has demand charges both for the demand set during the month and also demand set during the peak time of use period. It is similar to ExampleF that appears in the InputOutputReference as well as in the 5ZoneEconomicsTariffAndLifeCycleCosts.idf example file that comes with EnergyPlus.

In that example only energy rates are associated with the different time periods but it is also possible to use demand rates. For the demand that is set for the peak time of use period in the summer month, you would do something like the following that uses the peakDemand source variable:

UtilityCost:Charge:Simple,
    SummerPeakBillingDemand,                ! Charge Variable Name
    GSDT,                         ! Tariff Name
    peakDemand,                ! Source Variable
    Summer,                       ! Season
    DemandCharges,                ! Category Variable Name
    6.13;                      ! Cost per Unit Value or Variable Name

And for the component of the demand charges for the entire month use the "totalDemand" source variable

UtilityCost:Charge:Simple,
    SummerBillingDemand,                ! Charge Variable Name
    GSDT,                         ! Tariff Name
    totalDemand,                ! Source Variable
    Summer,                       ! Season
    DemandCharges,                ! Category Variable Name
    3.12;                      ! Cost per Unit Value or Variable Name

Of course you need to complete the UtilityCost:Tariff object and reference appropriate schedules for that rate as well as add the energy charges and service charges. Reading through the documentation and examples for the UtilityCost:Tariff object can really help.

For reference here is the tariff:

image description

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Thanks for explaining in depth. I still have one question about the estimation of billing demand and peak demand. I assume from above that the billing windows is same for both. When this simple block calculates the billing demand, does it excludes the peak demand intervals (most likely not)? How does the peak demand variable6.13 calculate for those intervals? Say we have max demand during peak interval of 100 kW, would that mean the total demand charges be $(3.12100+6.13100) or (3.12100+(6.13-3.12)*100)? This is like penalty of using any same demand during peak demand.

rkbest ( 2016-10-05 18:40:10 -0500 )edit

Additionally, where can i find the definition for peak-off-peak, seasonal representation of 1,2,3 that's required for schedule numbers. In I/O ref :- Example F On-Peak is defined for Monday to Friday, while both the schedules (Schedule:Compact, TwoSeasonSchedule, and Schedule:Compact, TimeOfDaySchedule) used are defined For:AllDays? How is the weekends and holidays excluded? Should the TimeOfDaySchedule be defined for weekdays only?

rkbest ( 2016-10-05 18:50:27 -0500 )edit

As the rates for peak and off-peak are same for summer and winter, I think the season would be annual instead of summer of winter. Like UtilityCost:Charge:Simple, PeakBillingDemand, !- Name Tampa_GSDT_ToD, !- Tariff Name peakDemand, !- Source Variable Annual, !- Season DemandCharges, !- Category Variable Name 6.13; !- Cost per Unit Value or Variable Name

rkbest ( 2016-10-05 20:00:28 -0500 )edit

If the 100 kW demand is set during the peak hours it would be (100 x 3.12) + (100 x 6.13). From the utility perspective the portion of the combined cost of the generation and distribution equipment which is trying to be recovered is $9.25/kW but for a building that sets the demand during other times of day there is still equipment cost that they need to recover and that is why the demand charge is separated into two pieces. Not very many utilities use this approach but some do.

JasonGlazer ( 2016-10-06 06:58:10 -0500 )edit

To find the explanation for the schedules look at the documentation for the UtilityCost:Tariff object. Please also review the introduction and framework to get a full understanding of tariffs.

JasonGlazer ( 2016-10-06 07:02:46 -0500 )edit

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answered 2016-10-05 20:02:13 -0500

rkbest
1392 ●1 ●4 ●13

updated 2016-11-16 13:25:08 -0500

As the rates for peak and off-peak are same for summer and winter, I think the season would be annual instead of summer of winter. The Total tariff structure could be:

!-   ===========  ALL OBJECTS IN CLASS: UTILITYCOST:TARIFF ===========

UtilityCost:Tariff,
    Tampa_GSDT_ToD,          !- Name
    Electricity:Facility,    !- Output Meter Name
    kWh,                     !- Conversion Factor Choice
    ,                        !- Energy Conversion Factor
    ,                        !- Demand Conversion Factor
    TimeOfDaySchedule,       !- Time of Use Period Schedule Name
    TwoSeasonSchedule,       !- Season Schedule Name
    ,                        !- Month Schedule Name
    HalfHour,                !- Demand Window Length
    30,                    !- Monthly Charge or Variable Name
    ,                        !- Minimum Monthly Charge or Variable Name
    ,                        !- Real Time Pricing Charge Schedule Name
    ,                        !- Customer Baseline Load Schedule Name
    ,                        !- Group Name
    BuyFromUtility;          !- Buy Or Sell


!-   ===========  ALL OBJECTS IN CLASS: UTILITYCOST:CHARGE:SIMPLE ===========

    UtilityCost:Charge:Simple,
    Peak_energy,             !- Name
    Tampa_GSDT_ToD,          !- Tariff Name
    peakEnergy,              !- Source Variable
    Annual,                  !- Season
    EnergyCharges,           !- Category Variable Name
    0.02898;                 !- Cost per Unit Value or Variable Name

UtilityCost:Charge:Simple,
    Off-Peak_energy,         !- Name
    Tampa_GSDT_ToD,          !- Tariff Name
    offPeakEnergy,           !- Source Variable
    Annual,                  !- Season
    EnergyCharges,           !- Category Variable Name
    0.01046;                 !- Cost per Unit Value or Variable Name

UtilityCost:Charge:Simple,
    PeakBillingDemand,       !- Name
    Tampa_GSDT_ToD,          !- Tariff Name
    peakDemand,              !- Source Variable
    Annual,                  !- Season
    DemandCharges,           !- Category Variable Name
    6.13;                    !- Cost per Unit Value or Variable Name

UtilityCost:Charge:Simple,
    BillingDemand,           !- Name
    Tampa_GSDT_ToD,          !- Tariff Name
    totalDemand,             !- Source Variable
    Annual,                  !- Season
    DemandCharges,           !- Category Variable Name
    3.12;                    !- Cost per Unit Value or Variable Name

UtilityCost:Charge:Simple,
    FuelCostAdjustEnergyCharge,  !- Name
    Tampa_GSDT_ToD,          !- Tariff Name
    peakEnergy,              !- Source Variable
    Annual,                  !- Season
    EnergyCharges,           !- Category Variable Name
    0.03937;                 !- Cost per Unit Value or Variable Name

UtilityCost:Charge:Simple,
    FuelCostAdjustEnergyCharge,  !- Name
    Tampa_GSDT_ToD,          !- Tariff Name
    offpeakEnergy,           !- Source Variable
    Annual,                  !- Season
    EnergyCharges,           !- Category Variable Name
    0.03564;                 !- Cost per Unit Value or Variable Name

UtilityCost:Charge:Simple,
    EnergyConservCharge,     !- Name
    Tampa_GSDT_ToD,          !- Tariff Name
    totalEnergy,             !- Source Variable
    Annual,                  !- Season
    DemandCharges,           !- Category Variable Name
    0.65;                    !- Cost per Unit Value or Variable Name

UtilityCost:Charge:Simple,
    CapacityCharge,          !- Name
    Tampa_GSDT_ToD,          !- Tariff Name
    totalDemand,             !- Source Variable
    Annual,                  !- Season
    DemandCharges,           !- Category Variable Name
    0.53;                    !- Cost per Unit Value or Variable Name

UtilityCost:Charge:Simple,
    EnvironCharge,           !- Name
    Tampa_GSDT_ToD,          !- Tariff Name
    totalEnergy,             !- Source Variable
    Annual,                  !- Season
    EnergyCharges,           !- Category Variable Name
    0.00429;                 !- Cost per Unit Value or Variable Name

UtilityCost:Charge:Simple,
    TaxofeightPercent,       !- Name
    Tampa_GSDT_ToD,          !- Tariff Name
    SubTotal,                !- Source Variable
    Annual,                  !- Season
    Taxes,                   !- Category Variable Name
    0.025641;                !- Cost per Unit Value or Variable Name

Let me know if I have missed something? The week schedule will be defined for weekdays with peak=1 and offpeak=3 followed by Weekends and Holidays =3.

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I think the monthly charge is one of those costs depending on the voltage being used and not the sum of all three.

JasonGlazer ( 2016-10-06 07:05:15 -0500 )edit

I will check the monthly rates. Do you think the rest of the tariff structure is now set correctly? I did not include the schedules so the complete idf is here http://pastebin.com/CJBjbL1Q

rkbest ( 2016-10-06 11:22:16 -0500 )edit

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