Insulating glass units with low-E and antireflective coatings, and/or methods of making the same
Certain example embodiments of this invention relate to insulating glass (IG) units including three substantially parallel spaced apart glass substrates, wherein at least two of the surfaces include low-emissivity (low-E) coatings and at least some of the non-low E coated surfaces have antireflective (AR) coatings disposed thereon. In certain example embodiments, low-E coatings are provided on the second and fifth surfaces of the IG unit, and each internal surface of the IG unit that does not support a low-E coating does support an AR coating. Additional AR coatings may be provided on one or both of the outermost surfaces in certain example embodiments. In some cases, the center substrate need not be heat treated because of the reduced absorption enabled by providing the low-E coatings on the two outermost substrates, as well as the reduced heat accumulation in the center lite itself and in the two adjacent spacers.
1. A method of making an insulating glass (IG) unit, the method comprising:
providing first, second, and third glass substrates, the second substrate supporting first and second antireflective (AR) coatings on opposing major surfaces thereof, the first substrate supporting a first low-emissivity (low-E) coating on one major surface thereof and the third substrate supporting a second low-E coating on one major surface thereof;
orienting the first, second, and third substrates in substantially parallel spaced apart relation to one another using first and second spacer systems, the first spacer system being located proximate peripheral edges of and spacing apart the first and second substrates and the second spacer system being located proximate peripheral edges of and spacing apart the second and third substrates,
wherein the first substrate is an outermost substrate and the third substrate is an innermost substrate,
wherein the first and second low-E coatings are disposed on interior surfaces of the first and third substrates respectively such that the first and second low-E coatings face one another, and
wherein each said low-E coating comprises, in order moving away from the substrate on which is disposed:
a layer comprising a metal oxide,
a layer comprising zinc oxide,
an infrared reflecting layer comprising silver,
a layer comprising a metal, oxide, or sub-oxide of Ni and/or Cr,
a layer comprising tin oxide, and
a layer comprising silicon nitride;
wherein the IG unit has a visible transmission of at least 70%, a U-value of less than or equal to 0.80, and a g-value of at least 60.
2. The method of claim 1 , further comprising providing Ar gas to a first cavity defined between the first and second substrates, and/or to a second cavity defined between the second and third substrates.
3. The method of claim 1 , wherein the first substrate supports a third AR coating disposed on an outermost surface thereof.
4. The method of claim 3 , wherein the third substrate supports a fourth AR coating disposed on an outermost surface thereof.
5. The method of claim 1 , wherein the second substrate is not heat treated.
6. The method of claim 5 , wherein the first and third substrates are heat treated.
7. The method of claim 1 , wherein the normal emissivity of the IG unit is about 8.0.
8. The method of claim 1 , wherein each said AR coating is a PE-CVD deposited coating.
9. The method of claim 8 , wherein each said low-E coating is a sputter-deposited coating.
10. The method of claim 1 , wherein the AR and low-E coatings are formed using different coating techniques.