Midcoast Green Collaborative Forum

May 18, 2008

Sustainability Post #6 — Window screens.

Filed under: Information — Tags: , , — Topher @ 10:00 pm

Do you leave the screens in you windows and storm windows during the winter. We have been telling clients to remove them, but didn’t have a number for amount of energy saved. Searching the web, I found nothing, so I decided to do a little testing of my own.

First, I got a light meter and one of my screens (black fiberglass, standard spacing). The light meter read 75 foot-candles in my test location (out of direct sunlight), and 50 foot-candles with the screen over it.

Next, I placed three pieces of dark soapstone (12″ x 12″ x 1/2″ tiles) near a window facing south, on a sunny March day around noon. One piece was placed in the shade, one in direct sunlight (through the window), and one with the screen in the window. I came back and measured the temperatures of the three stones with an infrared thermometer from a distance of about 1 foot. The shaded stone measured 76.7ºF, the one in the screened window 88.7ºF, and the one in the unscreened window 96.7ºF.

From this it would appear that leaving screens in windows or storms during the winter block about 30-40% of the heat that would otherwise enter through the windows. Audits have the amount of heat obtained from passive solar through windows ranging from 10-25% of the fuel based heating. So, window screens represent somewhere between 3-10% of total fuel.

If you have screens on the outside of your windows or in your storms, bring them in for the winter.

— Topher

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3 Comments »

  1. OK but probably just on south windows, on others I suspect that the reduced air flow they cause would increase overall efficiency of the window.

    Comment by al heath — June 4, 2008 @ 3:34 pm

  2. Do you have any numbers on how much a screen affects the laminar flow, and what that would do to r-value?

    The numbers for solar gain are pretty impressive even for North windows. And, of course, most triple track storms would have the screen inside a piece of glass where it would help not at all on air flow, but would hurt solar gain.

    Comment by Topher — June 4, 2008 @ 3:43 pm

  3. […] posts — lots of nice, accessible, generally bite-sized, hands-on observational science. One swell example begins, "Do you leave the screens in your windows and storm windows during the winter? We have […]

    Pingback by How Window Screens Affect Winter Fuel Use in Heating Climates | Eco Friendly Mag — January 20, 2009 @ 6:24 pm


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