Re-posted (Not sure if the original got on the list?)

Dear all,

I'm hoping to find a method that can be implemented in Excel for extracting
a glazing transmittance from two or more sets of temperature results.

*Our problem:*
We assess simulated comfort criteria where operative temperatures in a zone
above 27degC must be in the 1%-ile or less. We extract a *glazing
transmission* that will 'only just' meet this criterion from two or more
sets of results. We have limited access to parametric runs, hence only two
or more sets of thermal modelling results.

*What we've used up to now:*
In order to 'roughly' evaluate the solar transmissivity that helps achieve
this criterion we have used TREND and other functions for curve fitting in
excel to interpolate a transmissivity from two or more sets of results.

We have two problems with this approach:
1. such a narrow band of results are being focused on so the calc is
subject to inaccuracies
2. our modelling software is limited to one hour timesteps and can only
report temperatures in 1 degree intervals

*Possible solution?*
My gut fee is that we can extract the information more reliably from a
broader band of data. Is there an approach that looks at the spread of
temperature distribution from, say, 25 to 28 degC for two or more result
sets and extracts the transmissivity that matches the 1%-ile.

*Is there such a method?*

Minor note: We limit changes to glazing absorptance between our parametric
runs, aiming for only changes in transmissivity and reflectance. We have
found operative temperatures to increase with higher glazing absorptance.

Best regards

Chris