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[EnergyPlus_Support] Re: Heating Seasonal Performance Factor

Thank you, Bereket Nigusse. Your answer was useful.
About the field "Outdoor Dry-Bulb Temperature to Turn On Compressor" of the object Coil:Heating:DX:SingleSpeed the explanation is:

The outdoor temperature when the compressor is automatically turned back on following an automatic shut off because of low outdoor dry-bulb temperature. This field is only used for the calculation of HSPF. If this field is not provided, then outdoor bin temperature used in the HSPF calculation is always considered to be greater than this temperature and 'Minimum Outdoor Dry-Bulb Temperature for Compressor Operation' field described above. This assumption is based on AHRI standard 210/240 (2008) and can introduce significant error in the final value of HSPF.

I wonder what value of "Outdoor Dry-Bulb Temperature to Turn On Compressor" should be used for the baseline model according to annex G of ASHRAE 90.1. In fact, ASHRAE requires particular values of HPSF (e.g. in tab. 6.8.1B). Does the fact that in EnergyPlus the HSPF is influenced by a field that is not used in other parts of the simulation make sense?
Regards
Francesco


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Bereket Nigusse <nigusse_ba@...> wrote:
>
> Francesco,
> 
> HSPF is not weather file dependent. There is a set of standard test conditions used to evaluate the HSPF. The standard test condition is representative of the heating season.   
> 
> HSPF is weighted performance of a representative heating season; the heating season being represented by predefined outdoor air temperature bins. The standard defines a fixed weighting factor for each outdoor air temperature bins.
> 
> There are six regions for which the HSPF can be calculated for.  Region IV is the most commonly used for reporting HSPF.  The standard provides the different weighting factors for each region. EnergyPlus calculates HSPF based on this standard test procedure and reports to EIO file.
> 
> You may refer to ANSI/AHRI Standard 210/240 for further details.  
> 
> Hope this helps,
> Bereket Nigusse
> 
> --- On Fri, 3/1/13, FrancescoP <direzionecontraria@...> wrote:
> 
> From: FrancescoP <direzionecontraria@...>
> Subject: [EnergyPlus_Support] Heating Seasonal Performance Factor
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Date: Friday, March 1, 2013, 9:41 AM
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>       On page 640 of "EnergyPlus - Engineering Reference":
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> Heating Seasonal Performance Factor (HSPF) is defined as the total space heating required during the space heating season, divided by the total electrical energy consumed by the heat pump system during the same season.
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> It seems that the HSPF of a heat pump depends on the weather data. In fact I tried to simulate the same model with two different weather files and the Heating Seasonal Performance Factors have changed. Sometimes ASHRAE 90-1:2007 expresses limits as HSPF values (e.g. in table 6.8.1B). Does it mean that the same heat pump could respect the ASHRAE's limit in a climatic context and it could not respect it in another context? It sounds strange.
> 
> Regards
>



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