Mia-

This really depends on the type of collections you will have in the museum as well as in a collections storage area. If the architects are not familiar with museum requirements it would be an excellent idea to hire a conservator to consult on the project, especially during the program stage. There are other essential things to consider in the architecture and engineering of a museum beyond HVAC. Having been very heavily involved in the planning and review of a collections and conservation facility at a major museum as well as well over a decade of dealing with issues in everything from historic houses to museums I cannot stress how important it is to get expert advice and get it right when you can, before drawings and engineering requirements are final.