Accuracy and development of tracer-gas measurement equipment.

1979 a project was launched at Technological Institute, Copenhagen with the purpose of developing a method for continuous measurement of air change rates in occupied dwellings. Today - 10 years later - we can introduce the first generation of mass-produced measuring equipment performing measurements of air change rates employing the method of constant concentration of tracer gas. The principles used in the first model, which was introduced 1981, are largely identical to those used in the latest model. However, components and programmes have been changed several times, Furthermore, through the years new programmes that expand the capability of the measuring equipment have been developed. The paper will discuss the development that has taken place over the 10 years, which problems have caused the biggest trouble and how they were solved. Also, the types of measurement performed with the equipment will be touched upon, and we shall take a closer look at a couple of special measurements. Finally, the accuracy of the equipment as well as the cost of reaching today's level of development will be discussed.