41.   Much of the heat loss in houses occurs through the windows.

42.   Most of the windows have low-e double glazing, two layers of glass with an interior film that increases resistance to heat loss and gain.

43.   Obviously it is a big source of heat loss.

44.   One of those things is windows, which can be a major heat loss.

45.   Paul Siple and Charles Passel set out to measure how much the wind accelerated heat loss.

46.   Plus, he adds, there is no heat loss up a chimney because gas inserts and fireplaces are sealed.

47.   Sea ice can reflect solar energy to reduce surface warming or insulate water against heat loss.

48.   Some small birds enter a nightly torpor, reducing their body temperature to limit heat loss to the cold night air.

49.   Skylights may have to be shaded in winter to reduce heat loss, and in summer to prevent excessive heat gain.

50.   Such heat loss poses a serious risk of death from hypothermia for people drinking outside in cold weather, he said.