Greystone Energy Systems is Canada's leading ISO 9001-2000 registered manufacturer of Building Automation Systems sensors and transducers. Greystone manufactures peripheral devices for the sensing and monitoring of temperature, relative humidity, wet and dry pressure, carbon monoxide, carbon dioxide, IAQ, current, IO devices and more. We also supply SCR's, power monitors, duct smoke detectors and more providing customers with a single source for all their BMS peripheral devices.