Sensing the indoor environment is a complicated task accomplished through the use of multiple expensive sensors. In order to reduce costs, the Autonomous Robotic Environmental Sensor (ARES) is developed. ARES is a custom-designed omniwheel robot with high modularity, allowing many environmental sensors to be mounted to it. For navigation of an indoor environment, feedback linearization and sliding mode controllers are developed using a kinematic model, modified to include wheel slip. Testing shows the sliding mode controller provides the best performance for indoor environmental sensing. ARES is used to measure environmental variables in a large laboratory. Measurements are collected at multiple positions periodically over a diurnal cycle. Environmental statistics and predictions of thermal comfort derived from collected data are presented, showing that ARES is capable of taking meaningful measurements of the environment at a fraction of the cost of stationary sensors.