Patent ID: 8377524

Claim:
A vacuum window unit comprising: first, second and third spaced apart glass substrates, wherein a first low pressure space having pressure less than atmospheric pressure is located between the first and second glass substrates, and a second space is located between the second and third glass substrates, the second glass substrate being located between the first and third glass substrates, a plurality of spacers disposed in the first low pressure space; and wherein the second glass substrate has a greater thickness than thickness(es) of the first and third glass substrates; wherein first and second low-emissivity coatings are provided respectively on surfaces of the first and third glass substrates that face the second substrate; wherein the first and second glass substrates are the same size, and wherein the first and second glass substrates are larger in size than is the third glass substrate, and wherein a sash comprising foam is located between the second and third glass substrates, but is not located between the first and second glass substrates.