Photo Credit: Bonded LogicThere are many, many different options available for insulating a building. Whether for new construction or for an addition, there are many manufacturers and different products which all are meant to accomplish essentially the same thing: controlling the temperature inside the building. Without getting into alternate construction methods, consider some options for insulation in standard frame construction.
Insulation is generally material inserted in the spaces between framing (wall studs). It's purpose is to slow down the process of heat transfer. Creating a lot of little airspaces between the fibers of the insulating material, and using a material that is, itself, a poor conductor of heat makes a wall that retains heat, rather than allowing it to be lost to the outside.
Fiberglas insulation has been the standard in construction. It is sized to fit between framing members spaced 16" or 24" apart (the two most common industry standards). Fiberglas is inert, but stray fibers can be an skin irritant and installers need to wear dust masks to avoid breathing in the fibers. For a do-it-yourselfer, fiberglas is readily available at big box stores and is moderately priced. Forcing the insulation into a space compresses the material and makes it less efficient. Properly installed insulation spreads out to fully fill the space, but without being compressed on itself unnecessarily. Supplemental attic insulation can be as easy as buying unfaced (no kraft paper attached) rolls and unrolling them in the attic.
UltraTouch is manufactured from 85% post-industrial fiber – much of it being blue jean material, giving the insulation its distinctive color. Unlike fiberglas, it does not itch, does not contain any chemical irritants. The fibers are treated with fire retardants to make it safe for use in construction. Like standard fiberglas, it comes in construction standard sizes. For the do-it-yourselfer, the added cost of a cotton insulation may be worth it because of the ease with which it can be installed.
Spray-applied cellulose insulation is another good product. It is made from shredded newspaper and, like UltraTouch, has fire-retardants added to prevent it from being a hazard in construction. In application, the material is simply sprayed onto the walls before the interior gyp board is installed. Any excess material can simply be scraped off and put right back into the spraying machine. Spray applied insulation also fills the wall cavity more completely than batts do, making it better able to fill all the corners and crevices more effectively. Because of the machinery involved in its application, spray applied insulation generally makes sense for larger projects, and may not be cost effective for small additions and renovations.
In any case, having the proper amount of insulation is an important part of a project. Local information is important to consider, as well. And this is far from an exhaustive list of what is available. But, these are probably the top three options that many people will consider.