天窗有很多种形式，从廉价的塑料圆顶到可操作的屋顶窗户，可兼作屋顶紧急出口。即使是最基本的天窗也可以让日光进入室内空间，否则就必须用电来照明。可开合的天窗还有一个额外的好处，就是可以把上层房间的闷空气排出。天窗也可以提供很好的户外景观，这取决于它们的摆放方式。天窗玻璃既使用塑料，也使用各种玻璃。塑料，通常是丙烯酸或聚碳酸酯，比玻璃便宜，但它不耐划伤，长时间暴露在阳光下可能会变脆和变色。聚碳酸酯具有更高的抗冲击性，并且比丙烯酸更贵。塑料天窗被制造成各种形状——圆顶、矩形、圆形、椭圆形和三角形——这是很难用玻璃复制的。更昂贵的天窗是用玻璃制成的，制造商现在提供了各种各样的玻璃选择。这在为特定的屋顶位置或特定的气候区选择天窗时是有用的。 Skylights are manufactured by many companies, although there are only a few national players. The residential market for off-the-shelf skylights is dominated by Velux, a Danish company. Maine-based Wasco claims a distant second place. Other manufacturers, such as Tam, Columbia,and Sun-Tek, are stronger regional forces. Fakro, is a major European manufacturer but it hasn’t made serious inroads in the U.S. to date. Three major window manufacturers ( Andersen, Marvin and Pella) have dropped out of the skylight business in recent years as the industry consolidated. In addition to mass-marketed residential skylights, there’s also a booming trade in high-end custom skylights for residential as well as commercial buildings. Wasco considers itself the leader in that field. Matching…