The thermal environment (TE) inside swine production systems substantially affects animal performance as well as facility natural resource usage; hence, our measurement, understanding, and assessment of the TE must be advanced to sustainably meet the animal-protein demand of the growing global population. The TE describes the parameters that influence heat exchange between an animal and its surroundings, with maximum animal performance achieved when minimal thermoregulatory effort is required. Instrumentation and analysis techniques connecting the impact of the TE on total heat loss and subsequently, to animal performance in intensive housing systems are limited. Therefore, the goals of this dissertation research were to create a novel measurement system for quantifying the TE, develop a mechanistic model to understand the interaction between pigs and their TE, and lastly, establish the methodology to assess the TE for improved management strategies. This dissertation describes the design, validation, and implementation of an innovative TE sensor array (TESA) featuring dry-bulb and black globe temperature, airspeed, and relative humidity measurements. A low-cost omnidirectional thermal anemometer was engineered and calibrated with documented measurement uncertainty for reliable airspeed measurements. These measured parameters were needed as inputs to estimate the convective, radiative, and evaporative modes of heat loss in the developed model, which simulated the cascade of behavioral and physiological thermoregulatory responses of group-housed, grow-finish pigs as a function of the TE. Model results were used to generate a new thermal index for assessing different combinations of the TE and predicting the subsequent impact on animal performance. This index was applied to spatially and temporally analyze data collected from a network of 44 TESAs deployed symmetrically in two rooms of a commercial swine facility. TESA adds a new level of measurement precision greatly needed in modern facilities and goes beyond solely measuring dry-bulb temperature. The testing and calibration of TESA demonstrates the functional performance capabilities of the instrument and sets the standard for animal production sensor development. The mechanistic model provides reasonable agreement with previously published results and can be used to inexpensively explore different combinations of the TE on swine performance. Overall, this dissertation will help the swine industry by providing new technology and methods to quantify the impact of TE on performance for improved housing system management and control decisions. This dissertation will advance the corpus of knowledge required to provide food security for the growing global population through economically and sustainably housed pigs.