Anyone who pays much attention to the weather knows that winter sun rides lower in the sky than the hot, high sun of summer. That's one reason the weather turns cold in winter.

That simple fact lets you take advantage of the low winter sun, using it to help heat your home, and beat the heat of the summer sun, keeping your home cooler without fans or air conditioning.

How? A plain overhanging shade for the windows on the south side of your home that lets the low winter sun slip under it and into your windows but blocks the high summer sun. This type of shade, one of the basic elements of passive solar architecture, is simple in concept; but to work properly, it must be properly designed.

The critical factor is the distance the shade hangs out from your house. If the overhang is too great, you'll lose some free solar heat during the winter. Too little overhang will cause overheating in the summer.

Computing the overhang is tricky. It depends on the height of your windows and the geographical location of your home. Houses in the north require more overhang than those in the south.

For a large window, running almost from floor to ceiling and ideal for collecting solar heat, a 4' overhang is about right if you live at around 40* north latitude. In southern Canada you might need 4 1/2', while in the southern states, 3 1/2' would be about right. These figures are all approximate. Before you go to the bother and expense of erecting such a shade, it would probably pay to have a local architect compute the proper overhang for your particular situation. He can do the job by consulting tables of sun angles.

Note that this type of shade is effective only on windows that face fairly close to due south; it's just about useless on windows that face east or west because the sun is always fairly low in the eastern and western skies. Thus it will shine under the shades all year round. That's fine during the winter, but during the summer, a low-lying afternoon sun shining in through a west window can heat up a house in a hurry.

For this reason, it's best to use other means to keep the sun off windows on a west wall. Trees or shrubs are one good solution, especially those that drop their leaves in the winter and let you collect a bit of free heat when you need it. Q -- Since I installed my woodburning stove, I have cut my heating bills just about in half. My neighbors think I'm nuts, but I even enjoy cutting and spliting my own firewood. There's one problem, though. Every year I break the wooden handle on my splitting maul at least once. Isn't there something stronger than wood for tool handles? A -- you have a couple of alternatives: Steel orfiberglass. Stotz Corp. (13603 Station Road, Columbia Station, Ohio 44028) sells splitting mauls with steel handles. They come in two weights, 20 and 12 pounds, and are guaranteed for 10 years, Brookstone Co. (127 Vose Farm Road, Peterborough, NewHampshire 03458) sells fiberglass replacement handles for sledges, mauls and axes. The handles fasten into your existing tool head with an epoxy mounting kit included with the handle. Brookstone also sells mauls and sledges with the glass handles already mounted. Q -- Two years ago I had insulation blown into the walls of my home. This past summer the paint on the outside of the walls started to blister. Did the insulation cause the problem? What do I do now? A -- The insulation may be a contributing factor, but the real problem is that you have no vapor barrier in your walls. The easiest way to add one to an existing home is to coat the interior surface of the walls with a vapor-resistant paint.

In the past I've always recommended a glossy oil base paint for this purpose. Then over that you put a coat or two of an ordinary flat wall paint of your choice. Now there's a better product -- a latex primer-sealer designed just for this purpose. It dries faster than oil paints, and can be overcoated without the sanding or deglossing required to assure good adhesion over glossy oil paints. It's called Insul-Aid and it's made by Glidden. Q -- I've been trying to decorate the walls of my son's bedroom by painting on a large supergraphic. I use maksing tape to get clean lines between the various colors, but every time I pull the tape off, it peels some paint away with it. I've tried not pressing the tape too firmly in place, but then paint seeps under it. What's wrong? A -- There are a few tricks to using masking tape. First, be sure any paint you apply the tape to is completely dry. If it isn't, it may peel off with the tape. Second, be sure to press the tape down firmly to prevent the seepage problem you mentioned. Third, remove the tape as soon as the paint you have applied is dry to the touch. Fourth, peel the tape back against itself at a sharp angle: do not pull it straight out from the wall, for that will increase you chances of peeling away paint.