The hidden role of heating distribution in hybrid-supply displacement ventilation

Prior to the current study, the role played by the distribution of room heating on hybrid ventilation was not known. Here, we establish this role across a spectrum of heating distributions. By increasing the number n of localised heat sources, we quantify and compare hybrid–ventilation behaviour ranging from a single heat input ( n = 1 ) through to the heating of the entire floor plan ( n → ∞ ) . For a given heat load, our analysis reveals that the choice of heating distribution n has a pronounced effect on airflow rates. Indeed, increasing n can even reverse the direction of airflow. This sensitivity highlights the central role of heating distribution in hybrid ventilation. Contrary to common perception, the natural ventilation component of the hybrid system is reduced to zero as the strength of the mechanical component is increased from zero, revealing that hybrid ventilation provides only weak mechanical leverage; modest increases in hybrid-ventilation flow rate requiring large increases in mechanical supply. Key implications for design of this interaction between the mechanical component and the natural component (the latter indelibly linked to the heating distribution n ) are highlighted and discussed.