When assessing apartments, do I have to run the simulation engine each time I generate a new certificate? Helen Reich June 17, 2019 10:29 Follow If the design is thermally the same (e.g. units of identical design, height and orientation), you will not need to run the simulation engine for each unit number, just once. However you will still need to obtain certificates for each unit. Have more questions? Submit a request 0 Comments Please sign in to leave a comment.