Space-settlement conceptual designs have previously been accomplished using "Earth-normal" physiological conditions. The purpose of this paper is to quantify the habitat weight and cost penalties associated with this conservative design approach. These penalties are identified by comparison of conservative Earth-normal designs with habitats designed to less than Earth-normal conditions. Physiological research areas are also recommended as a necessary prerequisite to realizing these potential weight and cost savings. Major habitat structural elements, that is, pressure shell and radiation shielding, for populations of 102, 104, and 106 , are evaluated for effects of atmospheric pressure, pseudo-gravity level, radiation shielding thickness, and habitat configuration. Results show that broader habitable g-ranges, reduced atmospheric pressure, and detached radiation shielding all have a significant effect in reducing habitat costs. Also, a minimum cost per person is discovered for a habitat with a population of about 105, and this cost is independent of habitat configuration.
