[Equest-users] Low-E Window Film

Alex Krickx akrickx at seriousmaterials.com
Fri May 27 10:16:30 PDT 2011


Does adding a Low-E film improve the U-factor, or just reduce the emissivity? Maybe posting some of the Window5 information up here will help us understand the performance increase/troubleshoot what’s happened.

Cheers,
Alex

Alex Krickx, LEED AP
Building Energy Specialist
[cid:image001.jpg at 01CC1C57.25B2D070]
1250 Elko Dr, Sunnyvale, CA 94089
(t) 408.541.8124

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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of MattDubrovich at Eaton.com
Sent: Friday, May 27, 2011 10:14 AM
To: danielk at arborus.ca; Mike.McAardle at state.vt.us
Cc: equest-users at lists.onebuilding.org; draphael at IDS-TROY.COM
Subject: Re: [Equest-users] Low-E Window Film

Low-e films reflect heat back into the space based on their emissivity so you can expect heating savings even with a lower SHGC.

I’d expect Window5 to include the correct emissivity and for that to be passed through the glass definition to eQuest.  Is the film on the correct surface in Window5?  If you were entering your glass in eQuest using the simplified method you would have to change the emissivity manually.

Though this is from the manufacture, it’s still an interesting read: http://www.enerlogicfilm.com/pdf/EnerLogic-White-Paper.pdf


Matt Dubrovich

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Daniel Knapp
Sent: Friday, May 27, 2011 9:23 AM
To: McArdle, Mike
Cc: equest-users at lists.onebuilding.org; Dan Raphael
Subject: Re: [Equest-users] Low-E Window Film

On 2011-05-27, at 11:05 AM, McArdle, Mike wrote:

Dan, Do You mean  decreasing the heat  load  ( not increasing )

If the solar heat gain is reduced in winter, less heat from the sun will enter the windows and the heating load will be increased.



Thank you,  Sincerely,

Michael J. McArdle , P.E.
Buildings Engineer II, Project Manager
State of Vermont,
Buildings and General Services (BGS)
2 Governor Aiken Avenue
Montpelier, Vt. 05633

Office: 802-828-5650;  cell: 802-272-4828

From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Daniel Knapp
Sent: Friday, May 27, 2011 11:01 AM
To: Raphael, Dan
Cc: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: Re: [Equest-users] Low-E Window Film

How does the film affect the U-value and the SHGC for the window?  It sounds like the film is reducing the solar heat gain coefficient, and increasing the heating load.  You should also keep in mind that outdoor air loads can dominate the heating load in winter and that envelope effects can be minimal depending on the climate and type of building.  You may want to look into the loads reports in the SIM file to see what effects the film has on the building cooling and heating loads.

Cheers,
Dan

—
Daniel Knapp, PhD, LEED® AP O+M
danielk at arborus.ca<mailto:danielk at arborus.ca>

Arborus Consulting
Energy Strategies for the Built Environment
www.arborus.ca<http://www.arborus.ca/>
76 Chamberlain Avenue
Ottawa, ON, K1S 1V9
Phone: (613) 234-7178 ext. 113
Fax: (613) 234-0740




On 2011-05-27, at 10:42 AM, Raphael, Dan wrote:


Has anybody successfully modeled window film installation using eQuest?  Specifically, I am trying to model the Vista EnerLogic low-e film (since it is eligible for tax incentives).  I’ve used Optics5/Window5 to construct the glass type using the EnerLogic applied film (NFRC ID# 2545) and imported that into eQuest.  When I test this retrofit in a sample building, the savings are not what I expect (~65 yr. payback, assuming $7 installed cost).  I would expect to see a payback somewhere around 10-15 years.  What bothers me is that in the model, the heating load increases, which would be expected for a typical window film, but this film claims to have savings in all seasons due to the ability to trap heat in the building.  If anybody has had any success in modeling these window films and could provide me with step-by-step instructions or any guidance, it’d be greatly appreciated.

Thanks!

Dan Raphael
Building Performance Analyst
Integrated Design Solutions
Architecture, Engineering, Interiors & Technology
1441 W. Long Lake, Suite 200
Troy, Michigan 48098
tel:   248.823.2171
fax: 248.823.2200
www.ids-troy.com<http://www.ids-troy.com/>

<image001.png><http://www.energystar.gov/>

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