I just had replacement windows put in my home and got the Resistance Glass System from Tri-State Home Design in Edison, NJ. The glass makes my home feel so much different in temperature. I actually had to turn down the thermostat. They say I will get a 43% savings in my fuel bill this year, so hopefully Ill make some money back with that Resistance Glass. It has no gases inside so I will get the same savings year after year.