Design and experiments of a thermoelectric-powered wireless sensor network platform for smart building envelope

A new thermoelectric-powered wireless sensor network platform is presented for the low-cost environmental sensing in building envelopes through thermoelectric energy harvesting and ultra-low power management. It is designed and prototyped entirely inside a window frame without compromising architectural aesthetics. This self-powered sensing platform is achieved by maximizing the harvested energy from building envelopes and optimizing the wireless sensing unit’s energy consumption. It harvests milli-watt level thermoelectric power from the temperature gradient across building envelopes through thermoelectric generators with an optimized thermal connector. The harvested energy is voltage-boosted and regulated through two integrated circuits that are tailored for ultra-low-power input. A low power system-on-chip is used to supervise the environmental sensing and wireless data communication. The energy consumption is tailored by adjusting the system sleep time to match the harvested energy. The proposed platform is prototyped in a window frame and thoroughly tested, where 1.5 mW of power is harvested from thermoelectric generators under 6 °C of temperature difference, and a 33.4% efficiency to the battery. In the meantime, 0.42 mW power is consumed by the wireless sensing unit under a sampling period of 2 h, which reaches the energy equilibrium state. The energy equilibrium algorithm can project the battery energy based on historical weather conditions, so as to achieve the self-powered condition given a geographic location. This smart building envelope systems include the unique innovations in self-powered system architecture, thermally optimized internal structure, and milli-watt level power management.