I am going to be reviewing a model for a LEED project where there are
multiple buildings (12). I expect there to be many weaknesses in the model
as this is their first attempt at Equest. Each building is small/one story,
and many are duplicates with just different aspects on the site. It seems
the customer has modeled this project with 12 different models. This seems
a pretty cumbersome way to do the model, especially since they share the hot
water service (no heating/cooling). Can anyone speak to if or how it might
be more appropriate/efficient to do this as one structure in Equest?
Secondly, there will be no heating or cooling in this project (central
America). Is there an acceptable way to have mechanical cooling as the
baseline, for acceptance by LEED? I know App G says base and project shall
be the same with none, but since some facilities in the area are built with
mechanical cooling it seems credit may be due. Ideas?
Thanks
Laura
I got the review comment back from LEED that I needed to use the window assembly U-Value and SC Value, not the center of glass. Unfortunately we have the problem, and it sounds like others do too on this forum, that the glass manufacturer gives values for the center of glass values, and then sells their glass to the frame guys to get the frames that the owner and architect want. Neither one is willing to NFRC certify their product. So, my options are to use the values in ASHRAE 90.1-2007 Table A8.2 which are horrible, or model the windows on LBNL Window5.
There are lots of windows and lots of different sizes of windows in the model, so my plan is to find the area (square feet) of each window, and then run Window5 on typical windows in 5 square foot increments (5, 10, 15, 20, etc. square foot windows) so that I can run 10 windows instead of 150, and then put it all in a spreadsheet and solve for the weighted averages.
If I put the weighted average of the window values into Equest, will they accept that? Has anyone ever tried it? I'm in the process of doing another LEED certification that will be using the same technique if it works, but I won't know if it was accepted in the first instance before I submit the second project.
Thanks,
-Jason
Hi Jason,
I really can't comment on the LEED process - but you can input frame conductance separately from a glass package in eQUEST - which allows the software to calculate full-frame values. Although you won't be using NFRC certified numbers (as you point out- for your glass/frame combo they don't exist) - but I would say that inputting frame conductance and glass performance separately and letting the software area-weight them to get full-frame performance gets you pretty close to a hypothetical NFRC number.
Here's what I think the process looks like:
You need to use Window5 to determine what the frame conductance is - I would expect that the frame conductance doesn't vary too much in different sized windows. From an energy modeling standpoint (not sure what LEED/NFRC would say) I would pick a typical size window and model that in Window5 - making the assumption that the calculated frame conductance is valid for the other sizes in your building.
Going back to eQUEST- I would think that you have your baseline (say double pane low-E in an aluminum frame). To set up your "improved windows" case, create a parametric run that first changes the glass to your better glass, and then changes the frame conductance to match what Window5 outputs.
This approach would let eQUEST take care of calculating full-frame performance, and area-weighting the glass and frame. The only problem with this approach is that you ignore the Edge-Of-Glass performance that Window5 calculates, and eQUEST doesn't take into account. Not sure a way around that one yet.
Just an idea- good luck!
Cheers,
Alex Krickx