Q: I want to make an inexpensive solar cooker to cut my utility bills and cut pollution from power plants. Can I make one myself that gets hot enough to bake cakes and roast meats?
A: It is very easy to build a solar cooker that can bake cakes and breads at temperatures as high as 400 degrees. Vegetables and meats can be slow cooked at lower temperatures under 300 degrees.
There several effective do-it-yourself solar cooker designs, one costing only about $10 for materials. You can also buy collapsible solar cookers with fiberglass frames and hi-tech insulation and seals. These are very convenient to use at home or when camping.
In addition to cutting your utility bills, using a simple solar cooker instead of your oven helps protect the environment -- no pollution, no global warming, no ozone layer destruction, etc.
A simple, yet very effective, do-it-yourself design is made with plywood, aluminum foil, rigid foil-faced fiberglass insulation (from a furnace installer), cardboard or Masonite, and double-strength window glass.
Make a plywood box with an angled front (faces the sun) which is left open. Glue rigid fiberglass insulation to the inside of the box with the foil facing inward and paint it flat black. Mount hooks on the sides to support a horizontal wire tray for the food cooking pot.
Make reflectors from foiled-covered cardboard to direct more of the sun's rays into the front of the box. The proper mounting angles are important to capture enough heat. Place a dark glass or metal cooking pot in the cooker and place the glass cover over the slanted front. With the reflectors adjusted properly, the temperature can reach 400 degrees.
The simplest and least expensive design (about $10) of solar cooker (called a solar box cooker) is made from old cardboard boxes, newspaper, aluminum foil and old window glass. In its simplest form, it can easily reach temperatures of 250 degrees, hot enough to cook most meats and vegetables.
You make two open-top cardboard boxes (one smaller than the other). Line the boxes with aluminum foil. Lay crumpled up newspaper for insulation in the bottom of the larger box and then set the smaller box inside it. Fill in the side gaps between the boxes with more newspaper or several more pieces of foil-covered cardboard.
Paint a flat metal tray black and lay it in the bottom. Put dark metal covered cooking pots on the tray. Cover the top of the box with the glass and put it in the sun. Adding a foil-covered reflector tilted up from the top increases the cooking temperature.
You can write to me for "Utility Bills Update No. 136" showing do-it-yourself instructions and diagrams for making these two simple designs of solar cookers. Please include $1.50 and a self-addressed business-size envelope.
Q: I have added an insulating pad under my carpet and now I have to cut 1 inch off the bottom of my wooden bathroom door. What is the best way to saw it so it doesn't splinter?
A: First, plan to cut enough off to leave at least a 1/2 -inch gap for adequate air inlet area when the bath vent fan is running.
Using a sharp utility knife, score a deep groove along the cut line. Carefully saw along the bottom edge of the groove. Sand the edge.
Q: I had some large super-efficient low-E argon gas-filled windows installed. There is a checkerboard pattern visible at times all over the glass. What is causing it and what can I do about it?
A: You are seeing a stress pattern caused by the tempering process. It is not uncommon in tempered glass and is usually apparent only when the light strikes the glass at a particular angle. It is often more apparent in very large windows because of a pillowing effect, a slight bowing of the glass.
Contact your window contractor to see if it is worse than generally accepted standards.
Q: Would you please explain what a blower door test is? It is used to determine the energy efficiency of my house.
A: A blower door test is a method to determine how much outside air leaks into your house. It is also helpful in locating the leaks so you can seal them. A typical older house can leak out all its air once each hour.
A technician usually fits a fan, which is built into a frame covered with airtight nylon, into a window or door. When this exhaust fan is switched on, gauges measure the air flow rate being sucked out and the pressure. This data is fed into a computer which calculates how leaky your house is.
Questions should be addressed to James Dulley, c/o Baltimore Sun, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.