Discusses use of a gas sensor developed on the Taguchi principle to measure air quality and control the volume of outside air introduced. Presents case studies of a concert hall and a lecture room, and calculates energy saving.
A mathematical model, CLIM, is used to compare constant air flow ventilation with adjustable ventilation controlled by indoor relative humidity. Exhaust air flow varies in a ratio of 1 to 4 between 40 and 75% of relative humidity and the mean annual air flow is divided by 2 in comparison with a classical mechanical ventilation system.
Introduces a new HVAC system which adapts the actual needed quantity of outside air and at the same time maintains the demanded thermal conditions. Apart from the temperature, the CO2-level in the controlled zones is used tocontrol the system. The new HVAC system is compared with a conventional one by computer simulation for annual energy consumption.
A gas sensor was used which measures the partial pressure caused by gases polluting the air. The sensor signal was measured in different rooms and compared with the pollution and CO2 rate in the air. The sensor can measure the air quality under various conditions and be used to control the fresh air volume, thus reducing ventilation heat losses.
Reviews the possible indicators for monitoring the indoor air quality and controlling the outdoor air intake. The technical feasibility of the system is also discussed. At present CO2 seems to be the best and most reliable indicator for indoor air quality when occupancy load varies. In future, however, it is likely that measuring devices based on semiconductor technology and measuring devices for particles will be more reliable and inexpensive and so very suitable for controlling the air quality, because they can take into account both occupancy load and tobacco smoke.
Reviews some of the results of the project "The requirement-adapted ventilation system", which is part of an extensive research project "Indoor air quality and ventilation requirements" begun in Finland in 1983. Deals with the results of field measurements in which the relationship between CO2, particles and combustible gases in various buildings were measured and analysed. Also presents results of tests with an air quality-controlled ventilation system in one building.
A control program for a natural ventilation system for agricultural buildings is described which calculates a required ventilation rate, then adjusts vent openings to achieve this ventilation rate with equally distributed flows.
Presents a control system for mechanical ventilation of large rooms such as meeting rooms, cinemas, department stores, etc, based on air quality. Gas sensors are used to measure the pollutant levels and regulate the air flow in the room in relation to the number of people, level of tobacco smoke and other pollutants. The CO2 levels are also recorded. The resulting energy saved is given for three Norwegian buildings.
A passive ventilation system has been installed in four new houses: it comprises simple ducts which lead up from the kitchen and bathroom to outside near the house ridge and utilise the wind and the temperature difference between inside and outside (the stack effect) as driving forces. During occupation the system provided a consistent background ventilation rate: the flows dropped only when it was warm and calm outside (when other ventilation measures might be taken by the occupier); when it was very cold and windy outside the system did not over extract but appeared to self-throttle.
In newly built well insulated houses, a wind of 4 m/s will produce an air change rate of almost 0.3 h-1. However it is considered necessary to obtain air change rates of 0.7 h-1.
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