The wine and whisky industry looses about 2% of their produce to angels' share every year:
Angels' share is a term for the portion (share) of a wine or distilled spirit's volume that is lost to evaporation during aging in oak barrels.
SimplyGuest faces something similar. Our properties may not have 100% occupancy at all times. The accommodation may go empty when we are not able to fill a bed or room for any reason. This can happen for various reasons; the gap between a guest leaving and the next joining; during the initial days when we sign up a new house; when we are about to let go of a house.
We call it Angels' stay. Number of days when no guest is staying in a house. Its represented either as a percentage or as number of days. The whole house could be empty, resulting in 100% angels' stay, or it could be partially empty, one or more rooms or beds are unoccupied while rest of the house is occupied.
In any case, occupied or not, the house will have an active high-speed WiFi, LPG connection, DTH, maid servant, and all other facilities.
Update on Dec 2, 2016: we have a way of measuring angels' stay using occupancy rates. Read the full article.