[BLDG-SIM] Heating and Cooling ventilation system

[hamnmegs at ozemail.com.au]

Chris,
I've had the same frustration over the years.  John's suggestion is the best in my experience.

Using the SZRH system (one system per zone) will be a good approximation if your zones (FCUs) have similar mixed air temperature demands.  If you have a situation with significant load diversity or mismatched cooling capacity and zone load (i.e. some zones calling for cooling earlier than others) then this approximation may be unacceptable to you.

There is one other approach, use the OA-FROM-SYSTEM.  In this case set up a dummy zone with no loads (you need a little load but basically zero) and use a reset schedule to control supply air temperature.  You could leave the heating and cooling coils active if your outdoor air system is tempering.  Use this system to pass the return air temperature (effectively supply air due to zero load).  You can set the outdoor air system volume manually if you do want to see the tempering energy, otherwise temperature only (not mass flow) is being passed to your fan coils.

The problem with this approach is getting a reset schedule which approximates your actual supply air temperature demands.  I have found heatign and cooling energy very sensitive to this schedule as you would expect.  You get into recool and reheat situations easily and at other times miss out on economy cycle cooling.

I understand that a robust implementation of minimum outdoor air systems may potentially be added to the DOE-2.2 engine in the near future.  This would get around this problem along with a number of others.

Regards,
Graham
> 
> From: Chris Jones <cj at cr-jay.ca>
> Date: 30/11/2003 13:41:53
> To: <BLDG-SIM at gard.com>
> Subject: [BLDG-SIM] Heating and Cooling ventilation system
> 
> I am looking to simulate a four-pipe fan coil with economiser 
> control.  This is not possible with DOE2.1E and when I scan the DOE2.2 
> documentation it looks like it also lacks the capability to simulate a fan 
> coil system with economiser control.  The system I want to simulate is a 
> unit-ventilator with heating and cooling coils, an outdoor air damper with 
> economiser control.  This type of system is being used in schools - new and 
> retrofit.  An example of a configuration is discussed in "TPFC for Schools 
> (Esource).pdf" an Esource article.  My client is interested in converting 
> from hot water convectors to a two or four pipe unit ventilator.
> 
> Thanks for any insight into simulating this configuration.
> 
> 
> 
> 
> 
> Chris Jones, P. Eng.
> 14 Oneida Avenue
> Toronto, ON M5J 2E3
> Tel. 416 203-7465
> Fax. 416 203-8249
> 
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