# [Equest-users] Queries

Piyush Varma varpiyush at gmail.com
Tue May 4 08:51:13 PDT 2010

```Hi,
thank you all...again the alternating solar gain factor is thorn in my
flesh...i was actually looking for  hourly data for New Delhi for eight
orientations (N,S,E,W,NW,NE,SW,SE)...
just in case anybody is familiar with the Admittance Procedure here is the
formula

Qs(swing)-Swing in Fluctuating gains for Transparent surfaces.
A-Area of the glazing
I-Intensity
S-Solar Gain Factor

Formula
*Qs(swing)=A X I(swing) X S(swing)*
where, I(swing)=Intensity(at time t) - Average Intensity
& S(swing)=S(at time t)-Average S

here is what Nick had suggested...but having tried that i didnt quite get
the right results...maybe i am doing some thing wrong.....I would get S=.86
for all sunshine hours(mult factor=1) & S=0 for the night(& early morning)
hours when there is no sunshine (mult factor=0) but here is a gist of the
previous brainstorming session..

Hi Piyush,

Apologies, I wasn’t sure whether you meant SHGF.

I did some googling to check my vocabulary and found this reference:
http://www.levolux.com/L_PDF_Files/Lev.
Comp Analysis Table.pdf<http://www.levolux.com/L_PDF_Files/Lev.%20Comp%20Analysis%20Table.pdf>

It looks like:  Solar Gain Factor (S Factor) = Shading Coefficient (SC) *
0.87

I can add that:  Shading Coefficient (SC) = (Center of Glass SHGF) / 0.87

So to answer your first question, while this is the first time I’ve
personally run into S Factors, it would appear they’re analogous to a
center-of-glass SHGF, but can vary based on external shading devices
(including trees, curtains and shades) per the above.  I’m copying
eQuest-users to share the following procedure and to allow others to correct
any misunderstandings we may have regarding what S Factor really means – I
hope you don’t mind!

So per your second inquiry to determine the hourly S Factors, and because I
was curious, here’s a procedure:

-          Create an hourly report/block for the window(s) in question
selecting the items shown in the  screengrab below – SC and “Value by
which…” SC multiplier for those of you in the archives.

-          Run the simulation and open the hourly results up in excel (hit
the ‘hourly results’ button in the sim viewer).

-          Multiply those values across to get your hourly effective SC, and
again by 0.87 to get an hourly S Factor.

On Tue, May 4, 2010 at 8:02 PM, Nick Caton <ncaton at smithboucher.com> wrote:

>  Piyush,
>
>
>
> Off the list here, please do not (on my account) hesitate to copy any of
> our previous off-list discussion regarding alternating solar gain factors –
> not everyone maintains an archive to look up your previous query easily.
>
>
>
> I’m do not think I have understood exactly what you’re looking for, but
> weren’t you essentially trying to extract an hourly output for solar
> admittance to a space to check against a separate simulation’s?   As a
> humble suggestion, framing your question to the list with some additional
> context regarding your purpose might help others to guide you to what you’re
> looking for ;).
>
>
>
> Best wishes as always,
>
>
>
> ~Nick
>
>
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, E.I.T.***
>
> PROJECT ENGINEER
>
> 25501 west valley parkway
>
> olathe ks 66061
>
> direct 913 344.0036
>
> fax 913 345.0617
>
> *Check out our new web-site @ *www.smithboucher.com* *
>
>
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Demba Ndiaye
> *Sent:* Tuesday, May 04, 2010 9:02 AM
> *To:* Pasha Korber-Gonzalez; Piyush Varma
>
> *Cc:* equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Queries
>
>
>
> It make think of the sign convention used in Thermodynamics. You have the
> System and its Surroundings. Let’s say that the System is the building.
>
>
>
> In Thermo, heat received by the system from its surroundings (cooling load)
> is “positive”. The heat lost by the system to its surroundings (heating
>
>
>
> It is the inverse for work.
>
>
>
> _____________
>
> Demba NDIAYE
>
>
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Pasha
> Korber-Gonzalez
> *Sent:* Tuesday, May 04, 2010 5:25 AM
> *To:* Piyush Varma
> *Cc:* equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Queries
>
>
>
> Piyush,
>
>
>
> I can help with 01., but I do not understand the concept of alternating
> solar gain factor that you are referring too, or maybe I just don't
> understand the question exactly.
>
>
>
> For 01. I have always known the symbols of heating energy to be referenced
> as (+) for cooling and (-) for heating although I can't give you the exact
> reference this nomenclature comes from.  In terms of the positive for
> cooling energy it is a description for heat energy being present in the
> conditioned space(s)/building in terms of heat energy being gained (or
> generated.)  Where the negative symbol is used to represent heating energy
> this is describing that heat energy from the space/zone is being
> lost via....whatever the mechanism (i.e. ext. wall or window conduction
> losses, to exhaust air heat energy loss from the building, to infiltration
> effects, etc.)
>
>
>
> As long as you can keep your symbols managed with in your own simulation
> work don't let this little quirk stop you from reporting your numbers in
> your preferred format.  It is good that you are asking these types of detail
> questions so that you can ensure your own foundation of understanding for
> the tools you use.  This is what makes a good energy simulator.   Keep
> asking questions, this list is a HUGE benefit from my experience.
>
>
>
> pasha
>
> On Tue, May 4, 2010 at 2:55 AM, Piyush Varma <varpiyush at gmail.com> wrote:
>
> Hi all,
>
>
>
> I am an eQuest newbie and had 2 small queries which hopefully would be
>
>
>
> 01. What's the logic behind eQuest giving positive (+ve) Cooling Loads &
> gives me the opposite values, eQuest i.e. negative cooling loads & +ve
> heating loads, have checked all sign convention...can't figure out why? My
> algorithm simulates for Delhi's (India) climate predominantly, cooling
>
>
>
> 02. I have asked this before...is there any library for data of alternating
> solar gain factors, especially for Delhi, India. (As far as i believe
> it does'nt take into account the alternating solar gain factor...)
>
>
>
> hope these get resolved soon, thanks in advance.
>
>
>
> Regards,
>
> Piyush
>
>
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