One major design tactic to reduce the flow of heat through windows is to make windows with two separated but parallel panes that sandwich an insulating layer of air between them. That sounds simple, but to know just how good any particular design is, window makers need a standardized way to measure how much heat can flow through the windows. That is where the National Institute of Standards and Technology (NIST) comes through the window.

The heat flow measurements require the placement of a standard insulating material, a slab of polystyrene to be exact, between the panes of a window. At NIST, researchers carefully measure and certify the slabs' so-called R value, which is a measure of how good the material is at preventing heat from flowing from one side to the other. The higher a material's R value, the more insulation power it packs for any given thickness.

With this NIST-characterized and certified polystyrene, window makers now can carry out standardized measurement protocols that let them confidently determine how good or bad different window designs are at keeping the heat of summer or the cold of winter on the appropriate side of the window.

Introduce yourself to NIST's Building and Fire Research Laboratory, which works on insulating materials and other building related projects.