Houses are Dumb without Smart Ventilation
As we move to high performance housing and especially toward zero-energy homes, ventilation represents a larger and larger fraction of the space conditioning energy requirements. Ventilation standards, such as ASHRAE Standard 62.2 (or codes that use it, such as California Title 24), are typically met by continuous ventilation for their whole-house requirements, but met intermittently for their local exhaust requirements. Higher indoor air quality (IAQ) performance, as well as lower HVAC power and energy consumption, can be achieved by being smarter about how and when ventilation occurs. Numerous smart ventilation strategies are possible in high performance homes, such as increasing ventilation when the outdoor temperature is less extreme, scheduling ventilation during off-peak hours, avoiding ventilation during periods of poor outdoor air quality, and reducing whole house ventilation operation in response to incidental ventilation (e.g., bathroom or kitchen fan operation) and occupancy. Smart ventilation, in the form of a ventilation controller, can be used to implement all of these strategies and more. In this paper, we outline the theoretical requirements of a smart controller, discuss the real-world practicalities of control input options, and provide some actual examples of smart ventilation controls for residences. Ventilation controllers are flexible, and they can be used to fulfill the varied needs of building occupants, designers, policy makers, and program managers. Furthermore, as web-connected devices, the operation of a smart ventilation controller could be changed at will, in response to changes in policy, climate conditions, or grid dynamics.