Dispersion pattern of contaminants in a displacement ventilated room - implications for demand control.

A passive tracer gas technique has been used in an experimental study of the distribution of contaminants in a room with displacement ventilation. Humans are simulated by heated metallic bodies and the tracer concentration in the breathing zone (exposure) is shown to be greatly influenced by both the position of the tracer source and the air convection current around the bodies. It is shown that pollutants emitted close to a body are completely and directly transported to the upper mixed zone and not mixed into the lower zone.

Demand controlled ventilation - evaluation of commercially available sensors.

A test programme has been designed to evaluate the performance characteristics of sensors for the automatic control of ventilation rates. The test programme consists of two main parts, one being the evaluation of sensor performance in laboratory tests and the other referring to long term characteristics of sensors in actual buildings. Included in thepresent evaluation are eight different types of humidity sensors, two carbon dioxide sensors and five mixed gas sensors.

The use of Hall-Effect sensors to measure the opening position of windows, doors, vents and dampers.

Accurate measurement of the positions of windows, skylights, vents, dampers, etc. has always been a problem for researchers. Often open/closed switches are used which do not indicate the degree of opening which has occurred. The use of Hall-Effect sensors to measure such positions was first proposed for monitoring residential passive air inlets.

Sensor for continuous ventilating rate measurement in livestock buildings.

A new turbinemeter is developed to be used as a ventilating rate sensor in livestock buildings. Starting from a previous sensor, which we introduced in 1983, several improvements were done tobecome a low cost air flow rate sensor with an acceptable accuracy of 60 m3/h in a range from 200 to 5000 m3/h and this for pressure differences from 0 to 120 Pa. This sensor can beintegrated in the climate control equipment of livestock buildings to improve process control.

Demand-controlled ventilation - an alternative to unnecessary air conditioning. Tarpeettoman ilmastoinnin vaihtoehto - tarpeenmukainen ilmanvaihto.

Good indoor air quality and thermal comfort and good energy-efficiency can be achieved simultaneously only if the amount of ventilation can be demand-controlled. Two approaches are discussed in the article: CO2- control and use of so-called air quality sensors. The first experiments have been promising but further development of equipment is still needed, in order to improve the reliability and economy of demand-controlled ventilation.