Value Roll Ups to Area Objects

What will be the best way to roll up values ( for some specific attributes) from child objects to Area Objects in System Platform. The way must be dynamic (static scripting with + is not suitable) as the child objects could be added or deleted in the area or could be reassigned to a different area. As an eg, my Data Hall is an Area Object, which has Cabinets having kW attribute in it. It is required to have sum of all kW at Data Hall level. This is very easily done in PI with simple steps of configuration but couldn't find anything much simpler in System Platform