i have been interested in vacuum insulation for a long time now. A full vacuum would allow absolutely no heat transfer through conduction (or convection, a special case of conduction). Completely full vacuums cannot be created, but a near vacuum can be achieved economically even in mass produced items such as vacuum thermoses, and provide a very high level of insulation in a very thin layer. A reflective foil layer, even thinner than the vacuum insulation, then prevents most radiation leakage, creating a very effective level of insulation.
Vacuum insulation of housing appears to have only been recently moving into a commercial existance. VIPs (vacuum insulated panels) are mass produced panels that are vacuum insulated for use in housing, with exterior materials to prevent damage (damage to a VIP to the point of allowing air leakage would result in complete insulation failure). They claim an R-Value of about 30 per inch (compared to up to 8 for foam or 4 for fiberglass). They have been used in a few select applications, but have not made mass progress yet. Mass sales are planned for use in floors, ceilings, and walls, especially in manufactured homes, in metal roofing, and in exterior doors.
There doesn’t appear to be vacuum insulated windows. Such an item would turn what is normally the largest point of heat loss in a house to a not-so-significant insulation problem. This would allow more window to be installed to provide a much more powerful passive solar heating system without the normal night heat loss problems. Glass, though weak against pressure at a point, is strong against the uniform pressure of holding gases or vacuums. With a proper thickness of glass and well sealed housing, a normal looking window could have an insulation value potentially much greater than a well insulated houses walls or ceiling.
I plan to attempt to make some vacuum based insulation, both wall/ceiling/floor panels and windows, for my home (which is very poorly insulated currently) until I succeed or until commercial alternatives become available and affordable. I only have to wait until I have the money and know-how to do it. For me, this insulation would be extremely benificial. I plan to move into a truely mobile home (mine is one of those more stationary types) which would greatly benifit from thin but highly effective insulation. I also like passive solar heating, and this would help immensely with it.