[Equest-users] URGENT: Window U-values: Total window assembly v/s Glass only

[Brad Robinson]

Is the u-value listed for a manufacturer and specific model on the NRCAN website centre of glass or overall assembly?  Many windows are custom made to suit so I am unclear if each individual custom window would need to be tested.



In eQuest, when entering the window, if the u-value represents the whole window, including frame, do you need to enter a frame width, conductance etc as well under the Window Frame section under Window Properties?  Thanks.


Brad Robinson



________________________________
From: Robby Oylear <robbyoylear at gmail.com>
To: Omar Katanani <omar at ecoconsulting.net>
Cc: equest-users at lists.onebuilding.org
Sent: Wednesday, July 27, 2011 12:32:08 PM
Subject: Re: [Equest-users] URGENT: Window U-values: Total window assembly v/s Glass only


Omar,

The answer depends on the purpose of your study.  If you're trying to get results for a client on the impact of the glazing on their energy performance, this may be adequate.  Make sure you've entered in the framing information properly (metal vs. non-metal).

I'd recommend opening up your simulation output results file (xxxx.SIM) and going to the either the last page of the LV-D report or sort through your LV-E report to see what value eQUEST has calculated.  Compare these values to the ASHRAE Fundamentals results for overall assembly values including frame to see how close you've come.  I would not blindly trust that eQUEST will give you an appropriate overall assembly value based on entering only the center of glass number.

However, if this is for a LEED study, this is not adequate.  This an excerpt from an e-mail I sent out recently regarding LEED and NFRC requirements.

In order to meet LEED EAp2 Minimum Energy Performance, the project must comply with all mandatory provisions of ASHRAE 90.1-2007.  Section 5.4.2 Fenestration and Doors requires that fenestration performance be determined per section 5.8.2.  Section 5.8.2.4 U-factor requires that the U-factor for the overall fenestration area (including framing) be determined in accordance with NFRC 100. If you do not have NFRC data available, values from section A8.2 are the only acceptable alternative.

Robby Oylear, LEED®AP BD+C
Mechanical Project Engineer
Energy Analyst
 
D206-788-4571 |C206-354-2721
www.rushingco.com





On Wed, Jul 27, 2011 at 8:14 AM, Omar Katanani <omar at ecoconsulting.net> wrote:

Dear all,
> 
>I have a small question regarding entering
window properties to eQUEST:
> 
>I have read a lot of emails in the forum
discussing NFRC testing, LBNL Window 5 import, and other topics that I haven’t
paid attention to before. 
> 
>The way I modelled my windows is the
following:
> 
>	1. I have manufacturer’s specifications listing the glass U-values, not the total assembly.
>	2. In the “Glass Types” (eQUEST Detailed Mode), I created glass types, and entered the glass conductance, visible transmittance, SC, and emissivity from the manufacturer’s details I have.
>	3. When creating windows, I specify which glass type (from the ones I created in step 2), in addition to the frame width and conductance.
> 
>I’m assuming that, given that I
entered the u-values for the glass only, and then I entered information about
the frame, then I need not worry about any conversions in U-values, since
eQUEST has all the necessary information to calculate the equivalent u-value of
the whole pane + frame assembly, right?
> 
>I appreciate your feedback / comments
today if possible, as this has become really urgent!
> 
>Many thanks,
>Omar
>___________________________
>Omar Katanani
>Sustainable Design Engineer
>Email: omar at ecoconsulting.net
> 
>EcoConsulting (Lebanon)
>NahasBuilding, 4th floor
>4 St-Maron Street/ Georges Haddad Avenue
>Postal Code: 2028 5806
SAIFI
>Beirut, Lebanon
>Tel:          +961 (0) 1 971 266
>Mobile:    +961 (0) 3 045 045
> 
>EcoConsulting (UK) Ltd
>28 Marshalsea Road
>London, SE1 1HF
>Tel:  +44 (0) 207 939 0989
>Fax:  +44 (0) 207 939 0981
>Website: www.ecoconsulting.net
> 
> 
> 
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