ABSTRACT
Water heating in Pakistan and its neighboring countries predominantly relies on inefficient, natural gas-wasting water heaters whose mechanical design has remained largely unmodified since their inception in the 1960s. The inefficiency of these water heaters has added much to the woes of depleting gas reserves of the region, leading to a widening demand-supply gap. Pakistan is facing its worst ever natural gas crisis due to a COVID-19 hit economy that cannot carry the burden of expensive imports, especially during the Russo-Ukrainian conflict that has sent the gas prices soaring in the international market. We respond to this challenge with a sense of urgency by proposing a solution that minimizes the wastage of natural gas in water heating, which consumes about half the gas supplied to residential consumers in the country. Our solution replaces the mechanical control of the water heater with an IoT-inspired, electrical retrofit design combining hardware and software for smart control through user-defined schedules or machine learning, while solving several challenges that arise from replacing a mechanical control system with an electrical one. Empirical results demonstrate 70% reduction in consumption. © 2022 ACM.
ABSTRACT
We present the design and evaluation of a 3.5-year embedded sensing deployment at the Mithræum of Circus Maximus, a UNESCO-protected underground archaeological site in Rome (Italy). Unique to our work is the use of energy harvesting through thermal and kinetic energy sources. The extreme scarcity and erratic availability of energy, however, pose great challenges in system software, embedded hardware, and energy management. We tackle them by testing, for the first time in a multi-year deployment, existing solutions in intermittent computing, low-power hardware, and energy harvesting. Through three major design iterations, we find that these solutions operate as isolated silos and lack integration into a complete system, performing suboptimally. In contrast, we demonstrate the efficient performance of a hardware/software co-design featuring accurate energy management and capturing the coupling between energy sources and sensed quantities. Installing a battery-operated system alongside also allows us to perform a comparative study of energy harvesting in a demanding setting. Albeit the latter reduces energy availability and thus lowers the data yield to about 22% of that provided by batteries, our system provides a comparable level of insight into environmental conditions and structural health of the site. Further, unlike existing energy-harvesting deployments that are limited to a few months of operation in the best cases, our system runs with zero maintenance since almost 2 years, including 3 months of site inaccessibility due to a COVID19 lockdown. © 2020 ACM.