Effectiveness of various means of extract ventilation at removing moisture from a kitchen.

A kitchen is one of the major moisture producing areas in a dwelling. In order to prevent condensation and mould growth the relative humidity should not be too high. This paper describes a set of experiments comparing methods of kitchen ventilation and their effectiveness at moisture removal. The three methods of extract ventilation were: 1. A mechanical extract fan of extract rate 60 l/s 2. A passive stack ventilation system 3. An open-flued gas boiler The extract fan was only activated during moisture production, whereas the other (passive) methods of extract ventilation were permanently operational. Parameters were varied to assess their influence on both the ventilation rate of the kitchen and on the distribution of moisture about the dwelling. The effect of the kitchen door being either open or closed was investigated as well as the effect of an air-brick and trickle vent. The three types of extract ventilation operated at differing rates throughout the test cycle. High ventilation rate for a short period, slow continuous ventilation, or an intermittent heat driven cycle all gave similar average kitchen ventilation rates. All three methods of extract ventilation can provide a satisfactory solution to moisture control in kitchens in a temperate climate. Closing the door while cooking is as important as providing extract ventilation because it prevents a large proportion of the moisture from migrating upstairs.