[Equest-users] Low-E Window Film

[Daniel Knapp]

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

Arborus Consulting
Energy Strategies for the Built Environment
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
>  
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