There is one additional and very influential decision that must be taken
before the preparation of the specification can be started. This is that
between the prescriptive and the performance models. Making a selec-
tion between these depends on a number of factors:
The vocabulary of up-to-date technology held by the design team. The existence of forward thinking research in a particular area of the
industry. The likelihood of suitable construction firms being willing to
assume the responsibility for what are in essence design decisions.
The conventional specification for many years has been one that encap-
sulates the considered decisions of the designers on the best ways of
solving the accommodation problem set by the client.