Interior storm window benefit?
dfloyd5646
| Posted in Energy Efficiency and Durability on
Hello all,
I am respectfully calling upon the collective wisdom of Martin, Dana (et all)
regarding any potential benefit of an “interior storm window insert”.
Climate zone 3, new construction, Energy Star rated clad dual pane window, low SHGC, (brand/model presently undecided).
My layman’s hunch, (and marketing hype) leads me to believe a possible thermal barrier benefit is available through inserting a form-fitting, plexiglass panel equipped with a gasket, into the interior side of the window frame. (cheaper alternative to triple pane?)
Is there any merit to this, …or am I ripe for “Sham-Wow!” infomerical rip-off?
Thanks,
Dave
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Replies
David,
1. There is a thermal benefit.
2. If this is an operable window, you won't be able to open it anymore.
3. If this is an emergency egress window, you have created a life safety hazard.
4. You have increased the chance that condensation may form on the primary window, and that this condensation may cause discoloration on the sash and stool.
In some instances you'll run the risk of blowing the seals on the insulated glass if you put a third pane up (either interior or exterior). If you're going to do this, do it on shaded or north facing windows, where direct heating by the sun is limited, mitigating the risk of seal damage.
You could remove them in the summer months that should drastically reduce the risk of blowing out the seal.
Dana,
I have heard of the problem you are talking about with exterior storms (especially low-e storms). It is a phenomenon caused by solar heat gain. I have never heard of this problem happening with interior storms.
I checked into adding interior storms (for sound mitigation) to my existing windows. They were pretty expensive at around $300 per opening. A DIY approach probably would be cheaper but still entail the issues listed in Martin's first response.
Sound reducing storm windows would probably be made of laminated glass. Laminated glass is probably about the most expensive glazing option, but it’s best when you’re trying to block sound. Any plastic (acrylic, polycarbonate, etc) will likely have less benefits in terms of reducing sound transmission, but will do as well or better than glass for thermal insulating.
Bill