[Bldg-sim] sizing for baseline case acc to App. G

[Jackson, Alan]

No. This is a function of the flow, not the capacity.

 

Alan Jackson, LEED AP
KlingStubbins

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Chris Yates
Sent: Thursday, June 24, 2010 7:39 AM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] sizing for baseline case acc to App. G

 

So does that mean, for an all air system, off-coil temperature is
actually lower in cooling and higher in heating for the startup period?
Chris

On 24/06/2010 12:16, Seth P. Spangler wrote: 

Vinay,

 

You are to increase the cooling/heating coil capacities as required by
ASHRAE Appendix G. However, the over sizing is for coil capacity only -
the airflow rate should be sized at 100% of what your energy modeling
program calculates as being required to meet the space load.

 

Thanks

 

Seth Spangler, LEED(r) AP 

 

RMF Engineering, Inc 

Ph: (843) 971-9639 ext:1497

Fax: (843) 971-9641 

sspangle at rmf.com

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of James V
Dirkes II, PE
Sent: Wednesday, June 23, 2010 7:16 PM
To: 'Vinay Devanathan'; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] sizing for baseline case acc to App. G

 

Dear Vinay,

 

I'm not sure of the rationale for the ASHRAE 90.1 oversizing
requirements, however here are my thoughts:

I think the principal engineering rationale for oversizing is to allow a
building to reach its setpoint temperature quickly after a period of
inactivity.  As an example, if a building is inactive during a holiday
and the temperature is allowed to float several degrees lower (in
winter), the additional 25% heating capacity will enable faster return
to the normal setpoint temperature.  Steam heating systems can need even
more capacity for proper warmup capacity.

Oversizing is also a common practice as a "safety factor".  Most load
calculation software even has a separate input for adding this "safety
factor". 

 

 

 

The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Vinay
Devanathan
Sent: Wednesday, June 23, 2010 10:00 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] sizing for baseline case acc to App. G

 

Hello All,

Just to clarify a point - 

What does the oversizing of capacities by 15% for cooling and 25% for
heating exactly mean? Do we only size the cooling and heating capacity
or also increase the airflow rate corresponding to the oversizing?

Thank you.

 
 
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