[Bldg-sim] Cooling Load in EnergyPlus

Hussein Abaza ahussein at spsu.edu
Fri Mar 4 10:35:41 PST 2011


Thank you; 
I am running the example file Supermarket_Detailed which has a 50m x 50m supermarket but the Electricity:HVAC [J](Monthly) for July in Tampa weather is 1.3 × 10 9 . 
	
To convert this into Kwh I multiplied it by 2.7778 × 10 −7 which gives 363Kwh only . I think it should be around 100 times this amount. Am I doing something wrong? 
Thank you for any help 

----- Original Message ----- 
From: "Ery Djunaedy" <ery.mailinglist at gmail.com> 
To: bldg-sim at lists.onebuilding.org 
Sent: Friday, March 4, 2011 12:26:08 PM GMT -05:00 US/Canada Eastern 
Subject: Re: [Bldg-sim] Cooling Load in EnergyPlus 

Sandeep, 

This is what I call a legacy topic from the DOE2 era. You better search the posts in EnergyPlus support mailing list. Search for "cooling load component", and you will find an interesting discussion. 

In summary, you will not find a cooling load component report in EnergyPlus nicely formatted a-la LS-C report in eQuest/DOE2. 

If you try to match the total gains v.s. the cooling load for every time step, then you will be in for a long ride. Take the solar radiation gain, for example. The GAIN for a particular time step is not necessarily converted into cooling LOAD at the next time step. If your building is thermally massive, then the delay plays an important role and it could be hours before the solar radiation GAIN becomes an actual LOAD as seen by the thermostat. Do not forget about this, if you try to match the cooling load report with the total gains. 

If you are talking about peak cooling load, then you will need to focus on the zone sizing report. Calculating the gains component is easy because the schedule is always 100% on. You just need to quantify the ventilation load. 

Please note that the report suggested by Paul below is the convection report. I imagine that you would expect a conduction report? EnergyPlus zones technically cannot see conduction through opaque surfaces, in the sense of A*U*DeltaT. They can only see convection and radiation. In fact, if you try to match A*U*DeltaT for external wall with this report (Surface Int Convection Heat Rate) then you will have a hard time explaining. If you keep this in mind, the differences can be easily explained. 

Cheeers, 

Ery 

On 03/04/2011 07:07 AM, Paul Raftery wrote: 


Hi Sandeep, 


A full list of the available output variables are given in the .rdd file (it is one of the files output from the simulation). Simply copy the relevant line from that file into your .idf (or .imf) file, rerun the simulation, and the new variable(s) will be output to the .csv and .eso files. 


e.g. Adding this line to the input file will give you the convective heat gain from all interior surfaces in your model. 
Output:Variable,*,Surface Int Convection Heat Rate,hourly; !- Zone Average [W] 


Regards, 
Paul 

On 4 March 2011 13:50, Sandeep Kachhawa < sandeep.kachhawa at gmail.com > wrote: 



Dear All 

Can we get the individual break-up of cooling load in EnergyPlus ? Internal loads (People, Equipment & Lighting), Infiltration loads and Window gains are available but the gians from Walls and Roof is missing. Surely EnergyPlus does calculate all the above loads to size the Cooling Equipment but there is no such specific output. 

Regards 
Sandeep Kachhawa 


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Dr. Hussein Abaza, Assistant Professor 

Construction Management Department 

SCHOOL OF ARCHITECTURE ’ 

CIVIL ENGINEERING TECHNOLOGY 

And CONSTRUCTION 

1100 South Marietta Parkway , Marietta , GA 30060-2896 

Website: www.spsu.edu/cost Tel: 678-915-3719 Fax: 678-915-4966 

E-mail: ahussein at spsu.edu 



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