By far the most important, least expensive option when it comes to saving heat energy in the winter is insulation. Obviously, the most prudent thing one can do is to find ways to hold on to the heat one has. Insulation is a one-time expense and saves you money whenever you move into the heating (or cooling) season. Insulation can be done progressively so the outlay of funds doesn't have to happen all at once. Insulation is something that can be done relatively easily by most homeowners. For all these reasons (and more), this is the most sensible place to start.
There are a few fundamental principles to consider when it comes to thinking about how to insulate (here comes the science teacher part). Heat energy always moves from an area of high concentration to low concentration. So, in the winter, if the temperature in your home is 70 and the temperature outside is 20, the heat in your home wants to escape to heat the outdoors. Insulation doesn't prevent the heat energy from doing this, it only slows it down. A second, less thought of consideration, is that the same principle holds for moisture. Moisture will also move from an area of high concentration to an area of low concentration. Water molecules are dissolved in the air and, as you know, water as a gas will turn into water as a liquid when it gets cold. This is something you obviously don't want to happen inside your walls. This is why vapor barriers are included as part of most fiberglass insulation.
The second principle is simply that heat rises. So, if your heat source is downstairs, the heat will rise gradually to the upstairs. Subsequently, cool air is more "dense" and will sink to the lowest part of your home. The combination of these two processes is called convection. There's many good images out there to convey the idea. Click here for one.
So, to best way to figure out how to approach adding insulation to your home is to think of these two concepts together and decide how the heat energy is escaping your home during the heating season.
One of the most obvious places heat energy leaves your home is through the windows. If your walls are 6 inches thick and your windows are 3/4 of an inch thick, this is a no-brainer. As much as 30% of a homes heat in winter may leave through the windows. Nice Fine Homebuilding article on windows here. Windows are rated in U-values. Insulation is rated in R-value. R-value = 1/U-value. So, even the most energy efficient windows with a U-value of 0.25 means that the R-value is 4. No matter how well they insulate, they are still holes in your wall that lose heat because they have less insulating value than standard wall insulation.
Consider that heat rises. So, even if you are conscientious, turn your upstairs thermostat down during the day (if you have one), the heat from the downstairs is going to migrate upstairs and leave through the windows. One of the most prudent things to do to your windows is, when it gets cold, add a layer of clothing to keep more of the heat in. For me, light is a necessity, especially in winter. So, while using a rigid insulation insert might work well for filling this "hole in the wall", it blocks out light. Not an option for us but may be for you.
Visit your local hardware or bigbox store in the fall and you'll see kits for seasonal window sealing. Frost King is the one I see most often. This stuff is nothing more than shrink wrap attached to inside window frames with double-sided tape. This is fine if you don't plan on using your window, accessing blinds, etc. and it is designed to be seasonal. I have found that the double-sided tape degrades and the plastic comes unstuck by the next heating season. A 3-pack can be found for as little as $4.00. So, if you have 12 windows to cover, it might cost you $16.00 to experiment next winter. Not a bad investment to investigate this option.
One of the things I've decided to do this summer is build light frames that will friction fit into many of our windows. These will be covered with shrink film on both sides. The idea is that they will act as an additional double layer of insulation. They will create a layer of dead air space between the two layers of plastic within the frame and a thicker layer of dead air space between the window and this inside "storm window". I'm not sure how long the film will last, how well they will store over the summer months and what mischief our cats might make but I feel it's an inexpensive solution and worth the experiment. I plan to use rough-cut lumber as we have a local sawmill in our area and buy a roll of industrial shrink with a heavier weight. I haven't found a low-priced source for this yet. Visit this post for an update!
The second thing I am doing is adding to and modifying the insulation in the ceiling above our second floor. R-30 insulation was used but wasn't installed correctly and was just loosely stuffed in to the spaces between joists.
We also have recessed light cans in the ceiling. Once in the attic, I discovered that these cans each acted as little chimneys that sucked the heat out of our upstairs into the unheated attic space. I have just completed building "boxes" out of 1.5 inch thick blue foam board. These surround and cover each light in the attic space. I caulked each joint with 30 yr caulk and "pinned" the boxes together with nails.
[On high density insulation board. Now, I'm not an advocate for using more fossil fuel products but, if their one-time use saves regular fossil fuel use in the long run, it makes sense to me in terms of cost-benefit.]
There are areas of the ceiling I am unable to get to without ripping something apart. But, I think that if you are approaching this kind of project, a certain type of philosophy has to prevail. "It's not about what you can't do, it's about what you can do that makes a difference".
More later as I complete this project and investigate interesting options for heating our home.
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