Replies

1. 
   Clewless1 | Jan 25, 2009 09:54pm | #1

   Generally speaking ... you already have insulated walls and double glass. The improvements on either will likely be RELATIVELY expensive ... i.e. have a long payback (although there may be other benefits that may affect this).

   Adding insulation to an uninsulated wall will cut heat loss by say 95%. Doubling that level of insulation will only reduce heat loss of the first layer of insulation by a relatively small percent (maybe 1-5%). This is called the law of diminishing returns.

   Lesson? Install all you can possibly afford the first time ... it may be economical then. To add it later, may not be economical.

   Wall insulation may be expensive to install for your situation. If you reside your house, though ... opportunity knocks ... add some rigid insulation to the outside for a pretty small cost.

   Not sure if I'm getting the point across right. If your window frames are good, you might consider low-e glass replacements in existing frames. That will save roughly 36% over double glass. Since glass is a big part of heat loss in the house, it might be worth it.      Food for thought.

1. 
   billybob21 | Jan 26, 2009 03:06am | #6

   Are there any rules of thumb I can apply here? I have this handy infrared gun with a type K thermocouple attachment and I am taking readings all over the house. I can find wall and windows that are colder than others (4-10 deg F lower) , but I am really hoping for what range of expected measurements should be for a 60 to 70 deg F delta T should be.. If I have standard glass and go to Low E (~30 % improvement). Would this represent a 10 deg F increase in the window temp (for a 6 deg F day and the inner pain is reading ~ 50 deg F) )? The house has radiant heat int he floor and I am just really amazed at how cold the walls and windows are......

1. 
   Clewless1 | Jan 26, 2009 01:20pm | #9

   You can calculate the theoretical temp at any point in the construction given a steady state situation. That will require some digging up of some old references. Are you measuring exterior surface temps or interior? Your device ... it actually measures the surface temp? Good devices that do this accurately are very expensive. Cheap ones may not give you accuracy or consistency. Is this the point and shoot laser type device?

   Whatever you do ... take care in wall temp measurements as the temp (theoretical) at any framing point will be different than the center of the insulated stud bay. I'm not familiar with whether you can get accurate surface temps of windows, either.

   I'll try to grab a reference to do some calcs Monday night and see if I can shead some light on this a bit. (maybe DanH will add to his post as well). FYI I think a lot of things can affect the surface temp at any point in time including wind exposure and orientation of windows/proximity to other things that might affect them (including maybe a neighbors window, but there we are getting into an area I know less about ... i.e. the affect of other elements on the thermal stratification through a window (wrong term, I think, it's late).

   For steady state you would need to ensure your house has been heated evenly throughout (say for a couple days) to get accurate readings, I think. With radiant floors, interior surface temps may be affected greatly by varying exposure of the surface to the floor. For example, furniture that blocks the 'view'/exposure of the window or wall to the floor. A floor that sees a wall will give you a different value if it can see the floor (at least nearby). Same for a window. A window with a sofa or table in front of it will be different than a window w/ a clear line of sight to the adjacent heated floor.

   In other words you may not be able to pull your infrared pistol out and 'willy nilly' point and shoot at anything and expect accuracy. You got a license for that thing partner?  Just kidding. But ... heads up ... maybe time to do some reality checking on your end. Can you be more specific about the device you are using and exactly what you are doing w/ it?

   Till 'tomorrow' night. ...

2. 
   Piffin | Jan 25, 2009 10:15pm | #2

   "I bought the house with cheap double pain vinyl windows already installed "

   I like your spelling of double-pane when describing cheap vinyl windows, LOL

    

    

   Welcome to the
   Taunton University of Knowledge FHB Campus at Breaktime.
    where ...
   Excellence is its own reward!

1. 
   EricPaulson | Jan 25, 2009 10:26pm | #3

   .........beat me to it! 

1. 
   Piffin | Jan 26, 2009 12:15am | #5

   Hey, no more cynical responses from the choir, LOL 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

2. 
   Clewless1 | Jan 25, 2009 11:34pm | #4

   well when all you got is double glazing ... maybe they are a 'pain' (in your wallet)  

   : )   LOL

3. 
   DanH | Jan 26, 2009 03:25am | #7

   6.8F outside. 52-54 at center of vanilla Andersen double pane windows. 67.5 on exterior walls. 64.5-67.5 on exterior walls. Thermostat set at 69. Standard 70s 2x4 fiberglass walls with hardboard siding, brownboard sheathing, & drywall.

   The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
1. 
   Clewless1 | Jan 26, 2009 12:57pm | #8

   6.8 degF outside?? Are you also referring to outside surface temps in your reference  or inside? .... uh looks like inside, but I didn't want to assume, either. You gave one temp for exterior walls AND a range? Am I reading you right?

1. 
   DanH | Jan 26, 2009 02:30pm | #10

   That's the reading on our outside thermometer. The other readings are taken from the inside of exterior walls, using an IR thermometer.
   The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith