In the NE, is triple glazing needed only on the south side of the building, cost consideration in mind?
Top. Triple glazing is very effective on the east west and north side of the building, where there isn’t as much solar heat gain during the winter to make up for heat loss. On the south side, solar heat gain can offset a substantial portion of heat loss, so that the need for highly-insulating glazing isn’t as big as on the other sides. Because of this and because double glazing can allow higher solar heat gain than triple glazing, some buildings are designed with triples on all sides except the south. This can of course reduce cost, especially if there is a lot of south-facing glazing. Keep in mind though that the effectiveness of the sun to make up for heat loss depends on whether there is good solar access and whether there is enough thermal mass to store the heat for after sundown. And a design for maximizing solar heat gain should also include shading against unwanted heat gain. For an example of a NE house with triple-pane windows except on the south side, view pages 25 & 26 in th
