Results System Fans energy

koen.govers · Posts: 80

Hi Andy,

I have completed a simulation of an office building and get strange results for the fans energy consumption.
If I compare the DB results with manual calulation I get a 4-5 error factor.
- DB result: System Fans: 521.710 kWh/year
- Manual calculation (see used values below): 118.261 kWh/year.

the (by hour simulation) results of total fresh air (ach) seem right(schedule and flow) but the fan power isn't.

I'm working with:
Compact HVAC,
unitary single zone,
System Availability: Scheduled with occupancy,
Min AHU Outside Air RequirementScheduled with occupancy,
Fan operation Mode: Continuous,
Pressure rise: 1900 Pa,
Total efficiency: 68.
Outside aid definition method: By zone

The total ventilation flow should be around 19.000 m³/h (manual calculation).
Schedule: 15 h/day, 260 days/year.

Do you have an idea of what the problem could be?

Thanks,

Koen

koen.govers · Posts: 80

Andy,

I've just sent you the files by e-mail.

Koen

Andy Tindale · Posts: 1162 Location: Stroud

Remember that fan airflow is the supply flow rate which may include recirculated air in addition to the outside air flow rate.

If this does not explain it, could you send details of your calculation for fan energy so we can compare it with the E+ results? I saw the data on the spreadsheet you sent but didn't understand the steps. It would help if you could translate the headings.

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