VRF system electricity consumption increases when system gross rated cooling capacity increases

asked 2021-03-30 23:10:24 -0500

Prasanth M's avatar

updated 2021-04-01 11:03:01 -0500

Hi group,

I am new to energy plus. I am working on a two story office building. Initially it is connected with VRF system of gross rated cooling capacity 38776.4 W. Total calculated design zone sensible cooling capacity is 16511.59 W and total user designed zone sensible cooling capacity is 9425.4 W. For this configuration, the electricity consumption is 154 kWhr/m2 building area. Again I increase the gross rated cooling capacity of VRF system to 117500 W. Then the electricity consumption has increased to 244 kWhr/m2 building area. So why the electricity consumption increases when VRF system capacity increases?

Your help is highly appreciated,

Thanks in advance.

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As per my understanding zone sensible cooling load is constant then the electricity consumption also should have come constant after increased my vrf gross rated cooling capacity but the electricity consumption increased after increased my vrf gross rated cooling capacity. why?

Prasanth M's avatar Prasanth M  ( 2021-03-31 02:04:19 -0500 )edit

When you increase the VRF capacity, the system will have lower part-load ratios and thus higher cycling losses. I suggest looking at all inputs related to part load (for example this and this).

shorowit's avatar shorowit  ( 2021-03-31 09:56:50 -0500 )edit