Thank you for your reply.
Let's say I have 5 elements (E1,E2,E3,E4,E5) in a model and their respective volumes and element temperatures are V1,V2,V3,V4,V5 and T1,T2,T3,T4,T5. This plugin calculates the volume-weighted average temperature as (V1*T1+V2*T2+V3*T3+V4*T4+V5*T5)/(V1+V2+V3+V4+V5). Right?