[Equest-users] Proposed building - Safety factors

Bobby Sy rsg4999 at gmail.com
Mon Sep 3 18:21:10 PDT 2012

Hi Yazan,

If it's a LEED project all sizes, volume airflow, efficiencies of all the
equipment in the proposed model should be according to the actual design.
If the project is on schematic design phase, you should coordinate with the
designers about it. That is why I also incorporate their assumed LPD,
occupancy, and plugloads to be fair with the proposed model with size of
equipment the designer calculated.

It's like a battle of two building performances so all neutral inputs like,
occupancy, assumed temperature setpoints, plug / process loads, throttling
range should be close or the same with the HVAC designer's assumptions.

In the end, during the construction submission, LEED reviewer will require
you to use the actual sizes, capacities and efficiencies of the actual

Good luck!


On Mon, Sep 3, 2012 at 3:29 PM, Yazan Abukhait <yazan142us at gmail.com> wrote:

> Good day,
> I used to do modeling using different softwares, lately HAP, and due to
> some limitations on these softwares I converted to eQuest. So I'm a new
> eQuest user and would like to share some thoughts and get some opinions if
> possible.
> When referring to ASHRAE 90.1-2007, appendix G, and as everyone knows, the
> standard requires you to oversize cooing equipments by 15% and the heating
> equipments by 25%, the cause and effect of these values were discussed many
> times before and I think you know the idea behind it, so no problem with
> this. Now, when you move to your proposed building the standard doesn't
> advice on the safety factors to be used, shall they be 15 & 25% as that for
> the baseline, or shall you start from another point using different (i.e.
> lower) safety factors? My standpoint from that was and still: " You can
> start with a 10% safety factor for both cooling and heating loads- for the
> proposed building- then have a look at the simulation results, if the unmet
> load hours for both models are less than 300 and the difference between
> them is no more than 50, then this is a fully compliant modeling, on the
> other hand if one of the two mentioned conditions was violated then you'll
> have -normally - to look for the source of the problem then down size your
> baseline equipment or probably oversize your proposed building equipment(s)
> capacity.
> What do you think of that? would you start with a 10% for the proposed
> building and start from their, or would you not apply and safety factors at
> all to the proposed building and then start from that point?
> Looking for your thought...
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