Development of an Outdoor Temperature-Based Control Algorithm for Residential Mechanical Ventilation Control

Smart ventilation systems use controls to ventilate more during those periods that provide either an energy or IAQ advantage (or both) and less during periods that provide a disadvantage. Using detailed building simulations, this study addresses one of the simplest and lowest cost types of smart controllers—outdoor temperature-based control. If the outdoor temperature falls below a certain cut-off, the fan is simply turned off. The main principle of smart ventilation used in this study is to shift ventilation from time periods with large indoor-outdoor temperature differences, to periods where these differences are smaller, and their energy impacts are expected to be less. Energy and IAQ performance are assessed relative to a base case of a continuously operated ventilation fan sized to comply with ASHRAE 62.2-2013 whole house ventilation requirements. In order to satisfy 62.2-2013, annual pollutant exposure must be equivalent between the temperature controlled and continuous fan cases. This requires ventilation to be greater than 62.2 requirements when the ventilation system operates. This is achieved by increasing the mechanical ventilation system airflow rates.