The use of technology abstraction means that our contextual smart home can model 'virtual sensors'. These are sensors that do not physically exist in our smart home but, they are useful sensors that add significant value and context to it. In a contextual smart home virtual sensors come for free!
The 'Hot Water Tank' is a virtual sensor and it maps to the percentage of hot water available in our hot water tank. It is derived by using temperature sensors attached to the hot water tank and an algorithm to calculate its value. It allows us to ask our contextual smart home if there is enough hot water for a bath or shower.
The 'Average House Temperature' is a temperature sensor that our smart home models but it doesn't physically exist. Each time it is queried, our smart home automatically calculates its value in real-time, based upon the configuration of our home and the latest values of all the real temperature sensors that the configuration files define as being inside our home. This is used for Heating, Ventilation & Air Conditioning (HVAC) and other applications and it can be used (like to all the other sensors in our home) to perform intelligent, contextual automation.
Similarly, we also have 'Average Upstairs Temperature' and 'Average Downstairs Temperature' virtual temperature sensors, which are also calculated based on the smart home configuration.
