There are specific circumstances where spot heating could win out, though. Consider big open areas like church naves, gym halls, concert halls, large open-plan workshops and so on. Even if it's cost-efficient to heat these when they're near their intended or maximum occupancy, it's often too expensive to heat them for say 1-3 people. (And it just takes too long to heat them if the small group of people enters at short notice.) These buildings also tend to have high ceilings, so from any point on the ceiling you're fairly likely to have a mostly unobstructed line of sight to any person in the hall. So use ceiling-mounted narrow-throw IR spot lights trained on the small number of people inside to warm them. By hitting each person from decently-widely-separated directions with two to four different heat lamps at the same time it should be possible to overcome the problem of radiant asymmetry without having to resort to local insulation. Apparently some work is being done on this at MIT: http://www.economist.com/news/technology-quarterly/21615065-... http://senseable.mit.edu/local-warming/ .