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

[Vinay Devanathan]

Mr. Dirkes and Mr. Spangler,

Thank you so much for both of your inputs on this. I am clear with the
concept of oversizing and also what Appendix G says.

Thanks again!

On Thu, Jun 24, 2010 at 7:16 AM, Seth P. Spangler <sspangle at rmf.com> 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® 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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