Revision history [back]

I'm a little unclear about what you are asking here. It looks like you have included a table showing the cooling energy for a RHFS and a VRV system. How have you modelled the VRV system in eQUEST? Are you concerned that the energy savings for space cooling are too high? Is there something in particular that makes you think that they are too high? Given that the VRV building is said to have shading and given that the RHFS may have zone reheat (i.e. simultaneous heating and cooling) the results my be accurate. You might want to look at the output reports from eQUEST to try to get a better understanding of where the additional cooling energy in the RHFS system is coming from. For example, the LS-C report shows the peak cooling and heating load. You might want to check here to see if the shading drops the peak cooling load substantially. Also, the SS-E report shows the number of hours of coincident cooling-heating load for the building and the SS-C report shows the number of hours of coincident cooling-heating loads for an individual system. You can open the .SIM file in a text editor (it's in the same directory that the project files are saved in) or by selecting "Tools" -> "View Simulation Output" from the menubar.

From looking at the input files you sent me the following stand out:

EL1 West Perim Spc (G.W1) is modelled as CONDITIONED in Proposed and UNCONDITIONED in Standard; same for "EL2 West Perim Spc (G.W1)”;
LIGHTING-W/AREA = 1 in Standard and 0.5 in Proposed. A lower lighting power density will greatly reduce the cooling load in the Proposed model.
In the Standard Model under the spaces you are using TEMPERATURE = ( 77 ). There is no equivalent setting in the Proposed model. According to the DOE-2 Dictionary, this is the space air temperature used for the LOADS calculation. I’m not sure what affect this setting has, is it just for sizing or does it affect the actual energy calculation?
As you noted, the Proposed model has fins, and the Standard model does not
The fan power is higher in the Standard model with defaults set to 0.000396 kW/cfm in the Proposed and 0.000652 kW/cfm in the Standard; it also appears that different supply air flow rates are used in each model.
the windows in the Proposed have GLASS-CONDUCT = 0.33 and in the Standard have GLASS-CONDUCT = 0.59

If you are trying to figure out the cause of the difference in cooling savings I recommend that you start by looking at each change in the model in isolation.

Try setting the fan power and supply air flow rate to be the same in each model. How does this affect the cooling savings?
Try removing the fins from the Proposed model to match the Standard model. How does this affect the cooling savings?
Remove the TEMPERATURE setting from the Standard model. Does this change the results at all?
Try modelling the lighting identically in both models.
Make sure all spaces are modelled identically as CONDITIONED/UNCONDITIONED in both models.

Once the models are identical in all respects, apart from the system type (VRF vs. RHFS), check the cooling savings and compare them with your expectations. I strongly suspect they will be somewhat less than 50% after you have changed the lighting, matched the fins on the windows, and modelled the windows identically.