The Battery-Free Building — How Indoor Harvesting Reshaped Sensor Design

Buildings get smarter every year — HVAC, occupancy, air quality, energy tracking. Every one of those sensors used to need a battery, a technician visit, and a replacement schedule that quietly ate into deployment ROI. That model is breaking. Indoor light harvesting has moved from research demo to shipping technology, and a generation of European sensor makers has built product lines around it. This panel unpacks what battery-free indoor IoT actually looks like today — the product design decisions, the BOM math, the installation and maintenance realities, and the honest limits of where harvesting still can't compete. Three vantage points: the harvesting source vendor, a commercial building sensor maker with a decade of battery-free deployments, and an indoor air quality specialist shipping harvested-power sensors at scale.