[Bldg-sim] RTUs with HW coils

[David S Eldridge]

How many zones are there, and are there the same number of single-zone
AHUs in your base case?  How are the baseboards controlled?

 

5,229 btu/sf/yr is pretty low for heating, depending on your climate.
The other figure may be high for an office (again depending on climate)
but looks to be the right order of magnitude if there is significant
cold weather.

 

I would start with the SS-O reports, and also compare the total number
of unmet hours for both cases, to verify that you are providing the same
conditions for each alternative.

 

That level of difference between the alternatives sounds more like the
first case has cooler than expected zones rather than the result of a
system type change (even to a multizone).

 

David

 

 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of W. Peter
Anderson
Sent: Wednesday, January 30, 2008 12:09 PM
To: Building Model
Subject: [Bldg-sim] RTUs with HW coils

 

Greetings-

I am preplxed by a dramtic increase in heating load for my building-
35000 sq ft two story office.

 

Base case equipment is Packaged Single Zone DX, fixed outside air (15%).
Base board perimeter radiators to heat.

 

The Propsed Case is Packaged Multizone with HW heat.  I added
economizers, and kept the same baseboard.


The base case condtion used 183 MMBTU/year.

The revised model consumes 3338 MMBTU/year.

 

Space temperatures looked slightly different, but with in 2F-5F

 

Any thoughts?  All things are identical expect the RTUs.  I have checked
everything I could think off.

 

Regards,

W. Peter Anderson, P.E
JP Engineering
41 Mechanic Street
Windsor, CT 06095
Ph: 860/688-5223
Fax: 860/688-5269

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