FUEL BREAKDOWN - comparison with Energy+ reports

e.nabo · Posts: 39

Gents,
I am running a simulation of a building comparing what consumptions advantages could give having an opaque ventilated facade. I have been the simulation of the building without vent facade in Design Builder.
Then I have been exporting the IDF to Energy+, I have applyied the vent facade. The thermal loads seems reasenable but I have a problem to compare fuel breakdown. My question is: Boiler 2-gas(Kwh) and Chiller (Electricity) (Kwh) from with Energy+ reports (from eplusout.rdd) are determined? There is any tip for easy comparison? Thanks a lot and compliments for your efficient support.
Emanuele

Andy Tindale · Posts: 1149 Location: Stroud

Emanuele,

Thank you for your comments about our support service.

When comparing output from DesignBuilder with that from stand-alone EnergyPlus simulations, I would recommend comparing loads instead of fuel consumption. For example compare DesignBuilder 'Cooling delivered' with E+ 'Zone/Sys Sensible Cooling Rate'. I think you will probably run into problems trying to compare fuel breakdown because DesignBuilder calculates fuel consumption from loads internally using simple equations. For Simple HVAC, fuel consumption is calculated as:

FuelUse = (Load * DistribLossFactor) / Eff

Where DistribLoss = 1 + % distribution loss/100

And

Eff is the seasonal COP

Also:

Distribution energy = 0.001 * DistrEnergyWm2 * Area

During the periods when the heating/cooling system is in operation.

I don't think there is a corresponding simple fuel consumption in EnergyPlus.

Regards
Andy

e.nabo · Posts: 39

Guys,

I tried to obtain cooling delivered Kwh(Montly)from the E+ Sys Sensible Cooling Rate[W](Monthly) to compare same results with the DesignBuilder's

I am doing:
Cooling rate *24 hours *30 or 31 days / 1000

probably is wrong, do we need to know exactly how many hours the cooling is delivered or am I wronging the formula?

Thanks a lot.
Cheers

Emanuele

Andy Tindale · Posts: 1149 Location: Stroud

Emanuele,

Your formula looks correct, so I'm not sure what to suggest next. Perhaps you should look at a very simple IDF file generated by DesignBuilder and try to reproduce the output displayed in the program from that in the .eso file.

Regards
Andy

e.nabo · Posts: 39

Thanks Andy,

I found the corrispondence using Zone, Sensyble Heating/Cooling (J) and convert it to KWh.

Another question DesignBuilder it is using Airflow Network model.

Unfortunately the Airflow Network model can’t handle the nonstandard external boundary conditions and I am working with externalnaturalventilatedfacade.

What part of DesignBuilder generate the airflow network do I have an alternative to have a asimulaztion without using it?

Thanks a lot!
Thanking

Emanuele

Also for your knoledge I got this answer from the guy that made the AIRFLOWNETWORK looking at the DB file:

“There are two input mistakes in the AIRFLOWNETWORK:MULTIZONE:REFERENCE CRACK CONDITIONS object in the input file

The correct pressure value should be 101320 {Pa}, instead of 10132.

The correct value of humidity ratio is 0.005 {kg/kg}, instead of 5.”

Andy Tindale · Posts: 1149 Location: Stroud

Emanuele,

You can switch off the Airflow Network 'Calculated' option by switching the Ventilation model option to 'Scheduled' on the Model options dialog. In this case ventilation rates are predefined and scheduled prior to the simulation without regard to internal temperatures, external temperatures etc. More details on this are available in the online help.

Thanks for the input about the AIRFLOWNETWORK:MULTIZONE:REFERENCE CRACK CONDITIONS data. This has already been fixed in the current beta release 1.2.

Regards,

Andy

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