The loft as an air escape route.

Describes technique for measuring the volume of air leaving a house through the loft. Two tracer gases are used; nitrous oxide is released in the house and carbon dioxide in the loft. The mean concentration of N2O in the loft gives the volume of house air infiltrating the loft: and the mean concentration of CO2 gives the ventilation rate of the loft itself.< Gives two examples of the use of this technique and gives loft ventilation rate as a function of wind speed for one house.