One can expect a clean, algae-free uncovered pool to use anywhere form 2-4ppm FC per day. Any time you add something on top of the water, e.g., enclosure, cover, etc., you're going to change that loss rate because the biggest driver of FC loss is UV photolysis. For example, I covered my pool in the spring with a simple translucent blue bubble cover. The reduction in UV light getting to my pool was enough to make my FC spike up to double the normal levels I keep it at. Therefore I have to dial back my SWG quite a bit to compensate (my pH also stabilized with barely any acid demand at all). An enclosure probably lets in more UV than a bubble cover, but the reduced exposure is probably enough to make the FC demand noticeably lower.