how to evaluate energy consumption in single zone simulation

koen.govers · Posts: 80

I want to evaluate different insulation options for a single zone in an office. I used the single zone simulation tool.

When I look at the simulation results of the zone, i see four interesting data. But I can't make up which one is responsible for the total energy concumption of the zone.

1)annual reheat energy versus annual heating delivered
Do I need to add them? Or is one of them the total energy concumption?

2) annual cooling energy versus annual cooling delivered.
Sometimes there is a difference of 2.5 between them. I suppose the COP. Sometimes this is less...?

Koen

Andy Tindale · Posts: 1198 Location: Stroud

Koen,

Normally, you need to be at building level to view energy consumption, but with single zone models this is not possible... so you have two options:

a. Calculate energy consumption from the zone data you have
b. Switch back to whole building mode, delete any unnecessary blocks etc and set the adjacency of surfaces in the zone of interest to adiabatic. In this case you can view data at the building level.

1. It sounds like you are using compact HVAC, in which case, the annual heating delivered represents the warming effect of air on the zone and not heating energy consumption. Annual reheat energy is the heating energy going into the heating coils and is much closer to the energy consumption you are looking for. However depending on the system type in your using, there may be additional energy in central heating coils which is displayed at building level (and not accessible using single zone mode). If you do not have any preheat or central heating coils (VAV system) then annual reheat energy is the data you need. You should multiply this by the system efficiency to calculate fuel used.

2. Likewise for cooling, you need the annual cooling energy, not annual cooling delivered. The difference between the two will depend on the temperature of the outside air - if the outside air is already cool then less cooling energy is required from the fans to achieve a given 'cooling delivered'.

I hope this explains it,

Andy

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