James Dulley

Q: Dear Jim: I would like to add a bright, efficient sunroom to my house for an "outdoors" feeling during the winter and to help heat my home. What reasonably priced sunroom options do I have, and can I expect one to provide solar heat for my house? - Peg N.

A:Dear Peg: There is a vast array of sunroom options that would probably fit your needs even if you're on a fairly tight budget. These designs range from low-cost kits using aluminum frames and acrylic glazing to elaborate decorative ones using curved wood frames and super-efficient glass. Some models are designed to be do-it-yourself kits while others are delivered to your home already completely assembled, or built only by authorized contractors.

It is possible to use your new sunroom to capture solar heat and reduce your overall heating bills, but this will affect the basic design, materials and usable interior floor space. For the typical, reasonably priced sunroom kit used primarily as additional living space, a reasonable efficiency goal is to just make it energy self-sufficient during the winter.

To use a sunroom to assist with the heating of your house, it needs the proper orientation to the sun, much thermal mass and a method to move the solar heat into your house. The orientation should be within 15 degrees of true solar south. This is different than the compass south and varies depending on your location in the country. Your local weather service should be able to tell you how many degrees true solar south varies from compass south in your area.

When attempting to provide heat for your house, you want the sunroom to capture as much solar heat as possible. Without heavy thermal mass to absorb this heat, the sunroom can overheat and much of the heat is lost back outdoors. Typical thermal mass materials are masonry (bricks, concrete, stone) and water in drums. The masonry thermal mass can be built into a wall or floor and can actually be an attractive addition to the sunroom. Warm air ducts are a common way to move the solar-heated air into your house.

The newer do-it-yourself sun-room kits, thanks to computer-aided design and manufacturing procedures, have a professionally built look when completed. I built a sunroom kit on the concrete patio of my house and although it took me a month to do it, it looks very nice. Even the few manufacturers that sell only through authorized contractors who build it for you often allow you to assist in building it to lower the overall cost.

Sunrooms are classified as three-season (not winter usage) or year-round models. You probably want a year-round model since you want to try to help heat your home with it. A year-round model will have double-pane thermal windows and a wood or thermally broken aluminum frame for efficiency. The thermal breaks are more important in colder climates, especially to control

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condensation since people often have many plants in sunrooms. Three-season sunrooms typically have just single-pane windows and screens to be opened like a porch during the non-heating seasons.

The simplest design to build yourself uses an aluminum frame with double-pane clear acrylic windows. During the summer, its specially designed windows can be removed to create an open screened porch. The windows are self-storing beneath the screens. The clear roof is made of tough double-pane polycarbonate (bulletproof glass).

Most sunroom kits, whether contractor-built or do-it-yourself, bolt together like a huge erector set. All of the color-coded components, hardware and fasteners are included for easy assembly. If you order one of the completely assembled sunrooms that bolts down over a foundation or patio, you can be using it within three hours after delivery. Large models are delivered in several preassembled sections.

Models using frames with a curved transition from the front to top are the most attractive, but more difficult to build. These often use wood frames instead of no-maintenance aluminum. If you want curved eaves and an attractive interior with no maintenance, choose a kit with composite framing (wood interior and aluminum exterior).

During the summer, sunrooms often overheat in the afternoon sun. Adding some type of shading device and ventilation is imperative. Exterior shading systems, such as solar screening, are most effective and attractive from the indoors. Most sunroom kits have optional shading systems specifically designed for them.

Another option for more openness is to install just a large, screened folding window wall. Its efficient hinged thermal-glass panels open accordion-style on tracks to expose the screening and entrance door.

Write for (instantly download - www.dulley.com) Utility Bills Update No. 640 - buyer's guide of 12 efficient sunroom/kit manufacturers listing styles, frame/glazing materials, ventilation/shading options, features and passive solar heat producing tips. Please include $3.00 and a business-size SASE. James Dulley, Illinois Country Living, 6906 Royalgreen Dr., Cincinnati, OH 45244.

James Dulley is a mechanical engineer who writes on a wide variety of energy and utility topics. His column appears in a large number of daily newspapers.

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