Comparing Passive & Mechanical Ventilation of a Room for Hybrid Ventilation

Session 10 Paper 1, CIBSE ASHRAE Technical Symposium, Imperial College, London, UK
18th and 19th April 2012

This study compares solely passive ventilation of a typical small office with mechanical ventilation at a fixed volume flow rate. The office is heated from a floor area heat source (e.g. underfloor heating) and, consequently, the distribution of temperature within the room is approximately uniform. We consider a work-day usage cycle and develop predictions for the change in temperature with time during three phases: warming, steady-state and cooling, representing morning, daytime and evening, respectively. We present the results of simplified mathematical models, whose predictions have been validated against measurements made in small-scale physical experiments. Finally we consider implications to the design of a hybrid or mixed-mode ventilation strategy.