From the wider natural environment, to controlling the environment of a room in a building, Low Power RF communications are commonly used in the sector. Wireless sensors can be used to monitor environmental factors such as river levels and atmospheric pollution. RFs link can be utilised for data loggers and water utility company water treatment works. Other example applications include agriculture (e.g. irrigation control). Indoor environments can use RF communications to provide the feedback and control paths for air conditioning, central heating systems (HVAC) or refrigeration management in supermarkets. Local authorities may use RF remote control in selective lighting to improve security in an urban environment. Home, garden and garage often contain devices that make use of RF communications for convenience or security. Home automation using RF is quite common, even un-noticed, for example as a wireless room thermostat (wireless sensor) in domestic central heating, or as a wireless bell-push for the doorbell. Garage door opening can be conveniently controlled by an encrypted RF control signal. In the garden, sprinkler irrigation systems and greenhouse ventilation / frost guard may also use products containing an RF module.