Re: [EnergyPlus_Support] Why different electricity consumption?

the 2nd and 3rd senario both have a setpoint at 5am of 27 that changes in one step to 24. I bet you used the same schedule for the winterdesignday and summerdesignday because your schedule probably used the alldays keyword which therefor included these day types. This deturmines the size of these two equipments as being almost if not identical.

the first scenario uses (also for the designday) a constant 24 deturmining a different equipment size. So you should expect senario 2 and 3 to be very similar and 1 to be different. And that is indeed the case.

Tip: be specific on the setpoint schedule used during the design days to size you equipment. the common way to avoid oversizing is to keep a constant temperature with no steps for sizing days. the other option is to specify an acceptable "pull down" time which deturmines the amount of time the equipment is allowed to take to meet the setpoint after the step change is imposed...typically 0.5 hours for an air system. Otherwize, the equipment is oversized to meet the instantanious peak averaged over the timestep and oversized equipment is inefficient when operating at part load.

2015-02-12 16:13 GMT+01:00 Fakeha Sehar fakeha_s@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>:

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the three scenarios are as follows

Set point 24 hr = 24C

Set point (5am-9pm) = 24C; set point (9pm-5am) = 27

Set point (5am-2pm; 5pm-9pm) = 24C; set point (2pm-5pm, 9pm-5am) = 27C;Â

On Thursday, February 12, 2015 6:48 AM, "'jeannieboef@xxxxxxxxx' jeannieboef@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

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What are your setback temperatures for the 24 and 27 senarios...perhaps the step from setback to setpoint has the same amplitude?Â

Mit freundlichen GrÃ¼Ã?en- Sent from my iPhoneÂ (excuse the brevity)

i. A.
Jean Marais
b.i.g. bechtold
Tel. Â +49 30 6706662-23

On 11.02.2015, at 21:45, "Fakeha Sehar fakeha_s@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

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But then why are red and blue values same during the highlighted time if it has to do with autosizing? The green line indicates the scenario when cooling set point is kept at 24C all day, while red and blue lines indicate scenarios when cooling set points are either 24C or 27C.

On Wednesday, February 11, 2015 12:00 PM, "'jeannieboef@xxxxxxxxx' jeannieboef@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

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If you autosized the system, then your equipments are not the same size and will perform marginally different (part-load performance).

Mit freundlichen GrÃ¼Ã?en- Sent from my iPhoneÂ (excuse the brevity)

i. A.
Jean Marais
b.i.g. bechtold
Tel. Â +49 30 6706662-23

On 11.02.2015, at 14:31, "Fakeha Sehar fakeha_s@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

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its the same system simulated with different cooling set points, but during the highlighted time in the three sets of simulations the cooling set point is 24C.

On Tuesday, February 10, 2015 11:28 PM, "Rajeev rajeevkamal@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

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What are these profiles of? Every system behaves differently and can be within the error range of measurement and operations.

Sent from my iPhone

On Feb 10, 2015, at 10:32 PM, Fakeha Sehar fakeha_s@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

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In the attached figure, three electricity consumption profiles are shown.Â All profiles during the highlighted time have same set point of 24 deg C, so why the green colored line has slightly lower electricity consumption?

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