Natural environmental conditions in 16th century Calke Abbey, Devonshire, England, preserved the contents of rooms while they were heated, until sixty years ago. During restoration of the building since 1985, much of its contents have been housed in wooden cases inside a polyethylene tent or draught-proofed room containing dehumidifiers, thus holding 65 percent RH for 35p to 40p per day. Rooms in the restored building are held at 50-65 percent RH by conservation heating to 5 degrees C above outdoor temperature, year-round.