Automatic Ventilation Control of Trickle Ventilators

The possible benefits of automatic ventilation control of trickle ventilators in dwellings are investigated. Such ventilators could offer an improvement in performance over fixed ventilators, due to their ability to adjust to environmental conditions without occupant interaction, thus improving energy efficiency and providing adequate indoor air quality. The theoretical performance of both pressure and humidity controlled ventilators are examined and simple equations are presented, calculating the opening area of a ventilator required to maintain a given air change rate as a function of pressure or moisture generation rate. Field tests in a highly instrumented test house were carried out on 3 types of trickle ventilator: fixed, pressure controlled and relative humidity controlled. A computer model of the performance of these types of trickle ventilators was developed, tested and then used to assess the performance of theoretical automatic ventilators, in terms of energy efficiency, moisture control and thermal comfort. The results of the simulations set out the potential for pressure ventilators to reduce the occurrence of over ventilation in dwellings, and for humidity controlled ventilators to reduce the incidence of excess humidity without significantly increasing ventilation heat loss.