Are there “Stock” energy efficent (~R5) windows?

Hi All,I’m currently designing my house and trying to take a simple and budget approach. I have no problem designing my house with a stock window size (all 3’x5′ for… Hi All,I’m currently designing my house and trying to take a simple and budget approach. I have no problem designing my house with a stock window size (all 3’x5′ for…Read MoreGreenBuildingAdvisor