Principle 4 - Vigilance

A considerable amount of energy produced and consumed in homes is wasted - i.e. it fails to deliver occupant value. This has many causes, including grossly energy-inefficient systems, poor usability or operator controls, etc. But one salient cause is the lack of home systems ability to monitor or measure the environment in which they are operating, and act upon those measurements. In commercial buildings, it is now common to see 'responsive' systems in lighting and A/C: there are occupancy sensors that turn off lights/lower setbacks when no one is around. But despite the fact that the technology underpinning these (networked sensors, and computer-controlled actuators) have become very inexpensive, they have not been adapted for residential use extensively.

The reactive house - since it relies solely on locally sourced, limited carbon-free energy - must aggressively manage energy use, and will thus be vigilant - alert and responsive to its environment and occupants. It will embrace tools and related systems and techniques such as are found in commercial operations. In fact, responsive systems can go even further, using predictive data to optimize energy use. Here's a possible scenario: suppose a short range weather forecast indicates a severe storm (and temperature drop). The reactive house could calculate the additional expected heating load, and the loss of PV generation during the storm, and make proactive adjustments (lower set-point by a few degrees) to ensure sufficient power throughout the storm, or ask the occupants for guidance.

An alert house can not only manage energy usage better than an 'unconscious' one, it can improve occupant comfort, ease, and safety: a helpful light on a dark staircase, a timely warning when critical supplies are running low, etc.