What about windows?

Dan Peel

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Dan Peel

Window coverings

Do any of you apply the window coverings for design heat loss?
In a few exercises with great rooms and sun spaces it seems to make a huge difference.
Are there practical reasons to ignore the window coverings?
Just taking a break from reviewing for the RPA exams Saturday...... Dan

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Dave Palmer

Martha Stewart

Hi Dan, You can't figure window covering in heatloss because if they are like my wife she changes drapes,curtains ALOT!If the people move and covering goes too it would change things. I remember my Mom would put up the "winter drapes" in the fall they were a woolen nylon blend with a poly liner. Looked good but were heavy,with them closed you could develop film in the living room.Dave

Mike T., Swampeast MO

Window Coverings

Like said window covering taste, fashion and practice all change considerably with time so in almost all cases you consider windows "bare" when conducting a heat loss. About the only exceptions might be a greenhouse with automatic, movable "window blankets" or when an architect/engineer has specified that window coverings be considered.

Sun spaces can get really strange but just as winter-time solar heat GAIN is rarely factored in, neither is heat loss through uncovered windows. Summer solar gain is another matter. A sun space (particularly with lots of west glass) is nearly impossible to balance with the rest of the structure unless some "shade factor" is included in the heat gain. If you size A/C for bare windows in such a circumstance your unit will be HUGE and the sun space will be MUCH too cool at night or when the sun is not shinging in.