Re: [EnergyPlus_Support] Zone Component Load SUmmary_OutputReport Investigations

["Javed Iqbal eee.javed@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>]

Thank you Jim for sharing your thoughts.

I am convinced with your answers on the radiant fraction load contribution and calculation methodology as per heat balance method. Bit of which is also explained in Engineering and I/O Reference guide, so its clear.

However, I don't get clearity on the sign convention part. I agree that heating sensed load/energy is reported as (-ve sign) and could validate this by looking at zone peak heating load summery in html report. However, the -ve sign in peak cooling gain summary table is confusing. I could think of interpreting this as some qualitative meaning but not the pure mathematical addition and subtraction function to arrive at the peak sensed load for the zone during design day. but what is that??

Looking forward to get some insight on this.

Thanks again for your help!!

On Sat, May 6, 2017 at 10:30 PM, Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

Javed,

The standard cooling load calculations assume that the radiant component of energy emitted into a zone (from lights and other equipment) is absorbed into the walls, floor, and other internal mass. It's then re-radiated to the space over a time period that varies with the surface area and mass properties.

Solar radiation is treated the same way.

I don't know the details of how E+ calculates these delayed components, but I think they use some of the standard ASHRAE calculations.

Generally E+ reports heating energy (energy lost from the zone) as a positive value and cooling energy (energy gained in the zone) as a negative value.

On Sat, May 6, 2017 at 2:12 PM, Javed Iqbal eee.javed@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@yahoogroups.com> wrote:

 

Dear All,

We are investigating zone cooling load peak component summary for analyzing load contribution from all the internal and external sources (refer following table). We are struggling to answer few questions which are as follows:

• We referred engineering manual and I/O guide to understand the sensible delayed column. We found delayed effect contribution is significant, sometime its higher than sensible instant. We are unable to clearly understand how this delayed effect could contribute so high compared to instant gain? what is the basis of this delayed calculations?
• The reported value of sensible delayed could be minimize to zero if Radiative heat fraction defined for people, lights and equipment are reduced to zero in IDF. Hence, Radiative heat fraction effects sensible delayed effect significantly. Are there any industry standard to use optimum Radiative heat fraction for the people, lights and equipment? 
• If the building is highly insulated, the sensible delayed for people, lights and equipment are reported with (-ve sign convention). In the following table the external and interzone wall showing gains with -ve sign. What does -ve sign indicates in sensible delayed column? How to interpret this correctly?

Estimated Cooling Peak Load Components

	Sensible - Instant [W]	Sensible - Delayed [W]	Sensible - Return Air [W]	Latent [W]	Total [W]	%Grand Total
People	4396.35	6572.28	Â	4711.68	15680.31	37.55
Lights	869.22	3686.38	0.00	Â	4555.59	10.91
Equipment	13153.03	11493.52	Â	0.00	24646.55	59.01
Refrigeration	0.00	Â	0.00	0.00	0.00	0.00
Water Use Equipment	0.00	Â	Â	0.00	0.00	0.00
HVAC Equipment Losses	0.00	0.00	Â	Â	0.00	0.00
Power Generation Equipment	0.00	0.00	Â	Â	0.00	0.00
Infiltration	863.78	Â	Â	974.58	1838.37	4.40
Zone Ventilation	0.00	Â	Â	0.00	0.00	0.00
Interzone Mixing	0.00	Â	Â	0.00	0.00	0.00
Roof	Â	25.86	Â	Â	25.86	0.06
Interzone Ceiling	Â	0.00	Â	Â	0.00	0.00
Other Roof	Â	0.00	Â	Â	0.00	0.00
Exterior Wall	Â	-4824.8	Â	Â	-4824.8	-11.6
Interzone Wall	Â	-2594.2	Â	Â	-2594.2	-6.2
Ground Contact Wall	Â	0.00	Â	Â	0.00	0.00
Other Wall	Â	0.00	Â	Â	0.00	0.00
Exterior Floor	Â	-580.3	Â	Â	-580.3	-1.4
Interzone Floor	Â	0.00	Â	Â	0.00	0.00
Ground Contact Floor	Â	0.00	Â	Â	0.00	0.00
Other Floor	Â	0.00	Â	Â	0.00	0.00
Fenestration Conduction	1790.84	Â	Â	Â	1790.84	4.29
Fenestration Solar	Â	1225.17	Â	Â	1225.17	2.93
Opaque Door	Â	0.00	Â	Â	0.00	0.00
Grand Total	21073.22	15003.94	0.00	5686.27	41763.43

â??We would appreciate any help on this.

Thanks, â??

--

Javed Iqbal, LEED AP, CEA

Sr. Energy Analyst 

--

James V Dirkes II, PE, BEMP, LEED AP
CEO/President
The Building Performance Team Inc.
1631 Acacia Dr, GR, Mi 49504

Direct / Mobile: 616.450.8653
jim@buildingperformanceteam.com

Website l  LinkedIn

Coffee cup conversation:
Ideas have consequences. Bad ideas have victims. 


.

--

Javed Iqbal, LEED AP, CEA

Sr. Energy Analyst 

__._,_.___

---

Posted by: Javed Iqbal <eee.javed@xxxxxxxxx>

---

EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx

The EnergyPlus web site is found at:
http://www.energyplus.net/

The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/

Attachments are currently allowed but be mindful that not everyone has a high speed connection.  Limit attachments to small files.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.

Visit Your Group

• New Members 9

• Privacy • Unsubscribe • Terms of Use

__,_._,___