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Re: [EnergyPlus_Support] Natural vs. mechanical ventilation - difference in heating loads



Hi Farhang,

I think in model B, the energy that the system needs to provide air is added to air stream, therefore you need less energy to warm the air.

Regards,
Kamran


On Tue, Jan 14, 2014 at 5:29 PM, <farhang.tahmasebi@xxxxxxxxx> wrote:
 

Hi,


Using HVACTemplate:Zone:IdealLoadsAirSystem object in EnergyPlus 8.1.0, I compared the Zone Ideal Loads Supply Air Sensible Heating Energy in 2 models:

A) With an ideal load system, with no outdoor air provided by system, and an infiltration of 0.01 m3/s

B) With an ideal load system with 0.01 m3/s outdoor air provided by system, no heat recovery, no economizer and no infiltration.

However, despite the equal amount of outdoor air provided, the Zone Ideal Loads Supply Air Sensible Heating Energy in model B is 27% lower that model A. Does it make sense?

I found out that the average amount of outdoor air that comes actually to the zone (based on the outputs) is 0.0104 m3/s in model A and 0.0102 m3/s in model B. But this difference can not explain that 27% relative deviation. 

Can somebody explain this? Does it make a difference that we bring the outdoor air via windows or a mechanical system without heat recovery?

Regards,
Farhang

Univ. Ass. M.Sc. Farhang Tahmasebi
Department of Building Physics and Building Ecology
Vienna University of Technology
Karlsplatz 13, 1040 Vienna, Austria
e-mail: farhang.tahmasebi@xxxxxxxxxxxx




--
Kamran Naeiji

PhD. Student
Technische Universität Berlin
Faculty VI Planning Building Environment
Chair Design and Structure
Secretariat A 16
Straße des 17. Juni 152,
D-10623 Berlin

Tel.: +49 (0)30 314-21483
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