window question

krisman
krisman Solar Expert Posts: 57 ✭✭✭✭
in Energy Use & Conservation #1
i have the enery star windows. the ones that can be opened and flipped out, or the top half or bottom half opened. anyway i was noticing that right in the middle, where the window latches are and the two halves meet, you can feel some air all the way across the center and center corners. it is that way with about all the windows in the house. what should i do to insulate this better while assuring that they will still work properly?
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  • Slappy
    Slappy Solar Expert Posts: 251 ✭✭✭✭✭✭
    #2
    Re: window question

    check the "felt/vinyl strip between the 2 window sashes and see if they are still good, some times they look good but they are not? Not only that, check 2 see if their is a minor adjustment can be made at the latches. (but highly unlikely). but sometimes you can loosen the latch screws and put put a little pressure against the latch ( the direction needed ) and re-snug the screws. ????????
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  • krisman
    krisman Solar Expert Posts: 57 ✭✭✭✭
    #3
    Re: window question

    thats kind of where it felt like it was coming from, the felt in behind the window frame. would i need to get some kind of special insulation from the hardware store to replace the felt with or what?
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #4
    Re: window question

    A decent window will have a "meeting rail" that has a fuzzy of felt or rubber gasket to seal. The seal come from the latch squeezing the two halves together, compressing the weather stripping.

    If you can't adjust the latch, contact the manufacturer and complain. "Energy star" rated windows should have a infiltration rating, and if you are feeling the draft they aren't meeting it I would guess! In the real world, over the winter, a strip of clear package sealing tape will cut down on a lot of window leaks without looking like hell!.

    Tony
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  • Slappy
    Slappy Solar Expert Posts: 251 ✭✭✭✭✭✭
    #5
    Re: window question

    thats really hard to say....the mileage will vary from window type and/or manufacture. but a lot of time you can get replacments from your local DIY store. How old are the windows????? are they still under warranty????, if so have the installer/manufacture repair them????
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
    Re: window question

    i'm not speaking from experience, but i was told long ago by someone that pella windows are notorious for leaking seals. of course the older a window gets the more that can go wrong too.
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  • russ
    russ Solar Expert Posts: 593 ✭✭
    #7
    Re: window question

    My new home has large sliding glass windows (would not qualify for energy star) and İ was worried about air infiltration this first winter. Wanted these windows for the view of the bay.

    İ was quite pleased that there really are no drafts coming in around them - the 'fuzzy' strips are working well.
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  • newenergy
    newenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    #8
    Re: window question

    Ok, this is a dumb question, and I live near the beach in California, so almost never heat and never air condition, but...

    What are you supposed to do to get some fresh air? You don't really want your house absolutely perfectly sealed up do you?
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #9
    Re: window question
    newenergy wrote: »
    Ok, this is a dumb question, and I live near the beach in California, so almost never heat and never air condition, but...

    What are you supposed to do to get some fresh air? You don't really want your house absolutely perfectly sealed up do you?

    solution- don't have any windows.

    people don't buy them to have built-in leaks. when you want fresh air you can open the windows.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #10
    Re: window question

    The typical solution is a Heat Recovery Ventilator... Designed for when there is a large temperature difference between the inside and outside air. Works well for both Heated and Air Conditioned spaces.

    Not sure that it does anything useful when inside temp ~ outside temp... Then you have the issue of salt air and humidity and an active dehumidifier (i.e., heat pump) / filter is probably needed.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • russ
    russ Solar Expert Posts: 593 ✭✭
    #11
    Re: window question

    As İ understand it you want approximately 0.35 air changes per hour to control mold, mildew and other contaminant build up. A properly sealed home that passes a blower test will not meet that requirement.

    The HRV is an excellent choice - especially in a new home - can be rather difficult to retrofit. They do use power - mine takes about 4 kWh per day.

    A typical HRV is designed to control humidity as well as act as a heat exchanger.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #12
    Re: window question
    russ wrote: »
    The HRV is an excellent choice - especially in a new home - can be rather difficult to retrofit. They do use power - mine takes about 4 kWh per day.

    Wow! -- That would increase my average power usage for my home by 50%.

    One more thing to strike off the system (temperate climate).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • russ
    russ Solar Expert Posts: 593 ✭✭
    #13
    Re: window question

    Depends on the amount of air flow - this is a 6000 sq ft home

    There are many different sizes but the 0.35 air changes per hour is important.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #14
    Re: window question

    Our home is 1/4 that size--so that make it a bit better... I have sealed up several homes now (mostly double pane vinyl windows and doors--although added fiberglass insulation in this last home)--and my wife always complains about not enough fresh air afterwords.

    Sealing up the windows is a big help to reduce infiltration. The other help was to seal up the central heat inlet ducts--the 70 year old home was not that weather tight and the ducts pulled in most/stale air from the crawl space.

    Adding drain pipe to roof drains, perf pipe and drain rock around the perimeter of the property plus a sump pump got rid of the wet crawl space once and for all.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #15
    Re: window question

    The important aspect of this is "controlled" ventilation. One other solution, if you don'e use a heat exchanger is a whole house exhaust fan, couple with an damper controlled intake, usually on the cold air return of the HVAC. A timer can control the amount of time these two run, regulating air changes. At the very least you can cut off the vent ait if it is very cold for part of the day.

    Like I say, the key is being able to control the intake air.

    Tony
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #16
    Re: window question

    Hmmm... How much heat is lost in a 6,000 sq.ft. building with 0.35 air changes per hour and 20F (11C) temprature difference:
    • 6,000 sq.ft.
    • 8 foot ceilings
    • Say 20F (11F) change between inside/outside air temp
    • 0.35 change per hour
    • 0.018 BTU per cu.ft.
    • 1 watt = 3.41214 BTU/h
    Using above:
    • 6,000 cuft * 8 ft * 0.35 per hour * 0.018 btu/cft * 20F change = 6,048 BTU/Hr
    • 6,048 BTU/H / 3.41214 BTH/H = 1,772 watts
    • 1.772 kW * 24 hours = 42.5 kWhrs per day (assuming heating 20F differential air)
    That is a fair amount of heat/cooling load... Vs 4kW for a heat recovery ventilator...

    An "average" home may have:
    [FONT=Arial, Helvetica, sans-serif]A measure of how quickly the air in an interior space is replace by outside (or conditioned) air by ventilation and infiltration. Air change rate is measured in appropriate units such as cubic meters per hour divided by the volume of air in the room, or by the number of times the home's air changes over with outside air. For example, if the amount of air that enters and exits in one hour equals the total volume of the heated part of the house, the house is said to undergo one air change per hour.

    Air change rate is an indication of the air-tightness of a home, but it is difficult to pin down because it depends significantly on how the house is used, as well as the wind and temperature differentials it experiences during the year. Even if the rate were determined with some precision, which is established with a blower-door test, there is no assurance that value would apply under other conditions. For this reason, rough estimates are generally used when referring to a home's air tightness.

    The US national average of air change rates, for existing homes, is between one and two per hour, and is dropping with tighter building practices and more stringent building codes. Standard homes built today usually have air change rates from 0.5 to 1.0. Extremely tight new construction can achieve air change rates of 0.35 or less. Most homes with such low air change rates have some form of mechanical ventilation to bring in fresh outside air and exchange heat between the two air streams.

    To get an idea of what your home's air change rate might be, consider that a tight, well sealed newly constructed home usually achieves 0.6 air changes per hour or less. A reasonably tight, well constructed older home typically has an air change rate of about 1 per hour. A somewhat loose older home with no storm windows and caulk missing in spots has an air change rate of about 2. A fairly loose, drafty house with no caulk or weatherstripping and entrances used might have an air change rate as high as 4, and a very drafty, dilapidated house might have an air change rate of as high as 8.     [/FONT]

    Sort of makes heating/cooling the "average home" an energy impossibility.

    My old 1,000 sqft home with the old windows probably "leaked" more air than a 6,000 sq.ft. modern home...

    Now I don't feel nearly as bad about the Federal Weather stripping program:

    Obama's federal government can weatherize your home for only $57,362 each

    In must be a job done really well (yea--those are 5 month old numbers--but what the heck--its just statistics).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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