A couple of years ago, I added a skylight while remodeling a bathroom. The major reason for the skylight was to keep the room daylit, since I was removing the only window in the room. (The window was in the tiled tub enclosure—you know, the type of window that grows slime mold but makes the tub a bright place to take a shower.) Since skylights have a bad reputation as energy losers, I figured the best I could do energywise was damage control, even though the unit faced south at about a 30-degree slope. I purchased a 4x4-foot Velux doubleglazed unit with low-e glass and a 1/2- inch air gap. At that time, this was about the highest