For purposes of explanation, in various examples discussed herein internal and external capture indices may not be explicitly distinguished, and an overall capture index may instead be determined. In other examples, however, either or both of an external or internal capture index may be determined. For example, some CFD simulations may not provide any airflow information inside of the rack and only the external capture index is possible. In other cases, the internal capture indices may be easier to compute (for example, because rack internals may be idealized in some examples, whereas the external data-center environment may be variable and assumptions about definitions of “l(fā)ocal cooling” may be included). Further, internal capture indices may be sufficient in cases where performance is limited by internal-rack airflow patterns (for example, when containment results in pressure variations which may drive internal airflows and re-circulations).