UVA is scheduled to switch some operations to generators Tuesday in an effort to reduce  demand by 6 megawatts, or 11 percent of its electric use.  The school is asking employees to cut their electrical use at work as much as possible between 2 and 3 p.m.  The exercise is part of UVA's participation in the department of Mines, Minerals and Energy's demand response program.  In a similar exercise last year, UVA reduced its consumption from the electric grid by nearly three megawatts.