4 posts / 0 new
Last post

Hi Deepak

I think you can specify destratification fans so that would essentially be the same. Other than that you could try splitting the zone in 2 and letting internal air transfer between the zones work out the exchange but that's not really the ideal way to do it.

Otherwise you probably need to think CFD and you'd be in the realms of moving mesh transient CFD then and I wouldn't recommend that.

Not an easy one to solve really.

Dr Paul Carey

Paul Carey's picture
Joined: 2011-10-02
Reputation: 0

I would take a different approach - concentrate on comfort reporting. Not sure
if E+ reports Fanger PPD or PMV but you could do this in ESP-r by cranking up the air
velocity used for comfort calculations. And impose high heat transfer for convection
either via fixed heat transfer coefficients or a fan hc regime. This might allow you
to avoid CFD.

Regards, Jon Hand

Jon Hand's picture
Joined: 2011-10-02
Reputation: 0

Deepak ,

If your focus is indeed thermal comfort, within IES VE you can, if
desired, adjust heat transfer coefficients for surfaces, which will
influence radiant comfort, and in the results viewer adjust the air
velocity for thermal comfort analysis.

If you wish to look at any one simulation time step in more detail, you
can then export the boundary conditions, etc. to the CFD module in the
VE and look at local air velocities and thermal comfort in a space with
the ceiling fan, or at least a reasonable approximation of such a fan.

If you wish to look at the energy saving potential for ceiling fans, you
may first want to study the thermal comfort implications with respect to
room temperature set points (i.e., can you use a higher cooling set
point to achieve the desired level of thermal comfort with the ceiling
fan). Having done so, you can then run the energy model with adjusted
set points to determine energy savings and re-check the thermal comfort
analysis to ensure that the design requirements throughout the simulated
time period will be met with the adjusted set points plus ceiling fans.


Timothy Moore

Timothy Moore2's picture
Joined: 2011-10-02
Reputation: 200

I think this level of detail in modeling is unnecessary. In fact, I don't think there's
need for any enhancements to the thermal modeling
of the building to assess the comfort benefits of ceiling fans. Ceiling fans do not
change the thermal conditions of the space (except for
a little added heat generated by the fan motor). It provides comfort through air motion
experienced by the occupants. The improved
comfort can be quantified explicitly using Fanger's equation, or implicitly if you
calculate an equivalent temperature to that with still air.

Joe Huang

Joe Huang's picture
Joined: 2011-09-30
Reputation: 406