The Virtual Habitat project (V-HAB) at the Technical University of Munich (TUM) aims to develop a dynamic simulation environment for life support systems (LSS). Within V-HAB a dynamic human model interacts with the LSS by relevant metabolic inputs and outputs based on internal, environmental and operational factors. The human model is separated into five sub-models (called layers) representing metabolism, respiration, thermoregulation, water balance and digestion. The Wissler Thermal Model was converted in 2015/16 from Fortran to C#, introducing a more modularized structure and standalone graphical user interface (GUI). While previous effort was conducted in order to make the model in its current accepted version available in V-HAB, present work is focusing on the rework of the passive system. As part of this rework an extensive assessment of human body measurements and their dependency on a low number of influencing parameters was performed using the body measurements of 3982 humans (1774 men and 2208 women) in order to create a set of easy-to-use predictive formulas for the calculation of length and circumference measurements of various body parts.