PRL Insulating Glass Units improve thermal performance by providing a thermal break between the glass and the sealed air spacer. The IG units are a high quality, total energy performance product that translate into reduced energy cost and increased comfort. The IG units will keep the heat in during the cold weather and will retain the heat out during the hot weather. The IG units can give a greater value when conjunction with Low-E and reflective coated glass. Low-E glass should always be insulated with the coating to the inside (surface #2). Our IG unit’s have been tested and certified by IGCC.