[Equest-users] Cooling hours unmet

[Matthew Higgins]

Patrick - Because it's a VAV system you have to input a value for the 
reheat temperature, which is usually a killer for that system type.

If you have that specified you might look at the HVAC summary tab for 
the project which summarizes each unit and associated zone. There you 
might be able to determine which zone is troubling your hours.

I've also found that an inappropriate control zone can skew the hours 
for an associated system and project. Your zone air volumes may also be 
the issue depending on whether they were modified or not by the original 
user.

Hope that helps!

Matthew Higgins, LEED AP + ASHRAE-HBDP
Environmental Dynamics, Inc.
Architecture and Sustainability Consulting Services
505.242.2851 x.103

Any data provided by the Consultant, verbal or written, are to be considered opinions of building energy and/or daylight performance. The Client understands that the Consultant has no control of occupant habits, equipment or material performance or characteristics, site or climate conditions or the Contractor's method of assembly, and that the Consultant's opinions regarding building energy/daylight performance are made on the basis of the Consultant's professional judgment and experience. The Consultant makes no warranty, express or implied, that the energy/daylight performance of the building will not vary from the Consultant's opinion of building energy/daylight performance.

Furey, Patrick wrote:

> I’m having a problem with unmet throttling hours, and I can’t find any 
> way to remedy it. I’d appreciate any help anyone can offer.
>
>  
>
> Building Description: A school with an air cooled chiller, boilers, 5 
> ahu’s with hot and cold coils, and hw reheat at the VAV boxes. The 
> model also has baseboards in a few spots and a run around energy 
> recovery on each AHU.
>
>  
>
> I am working on an energy model put together by someone who no longer 
> works here. When I run the simulation on his model, I get about 76% of 
> the hours outside of throttling range, all cooling. Following advice 
> I’ve found in the archives, I increase my throttling range from 2 to 6 
> degrees. That brings the hours out of throttling range down to 34%, 
> again all cooling. Night fan control is set to cycle on any. 
> Increasing the sizing factor from 1.25 only help very minimally (1-2 % 
> points). I’ve been messing around with the model, trying different 
> strategies for days and can’t get it in an acceptable range. I’ve 
> attached the project files if anyone could take a look at it.
>
>  
>
> My biggest problem is when the system is sized per the calculated 
> loads, how am I getting so many hours where the system is not meeting 
> the loads.
>
>  
>
> Anyway, thanks.
>
>  
>
> Pat Furey
>
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