carbon dioxide

The first part of this article insists on the importance of a good ventilation system (polluted air exhaust, humidity, filtration, VOCs exhaust). The second part deals with a test house, equipped with either decentralized or centralized ventilation system. CO2 and ventilation rate measurements being compared, the validation of a model for the determination of the indoor CO2 concentration levels in one room of the house has been made.

The goal of the present study was to examine the influence of CO2 concentration in the air ofindoor spaces on human well-being and intensity of mental work. Ten experimental subjectswere used in four experimental conditions with different CO2 concentrations (600, 1500,3000, 4000 ppm). Microclimatic parameters (CO2 concentration, temperature and relativehumidity of the air, surface temperature of walls) were measured.

The paper presents part of the outcomes from the project set up by the Polish Committee forScientific Research and devoted to development of the recommended control strategies forDemand Controlled Ventilation (DCV) systems in Poland. The performance of both differentCO2-based occupancy detection algorithms for online demand controlled ventilation systemsand different methods of digital filtration of signals have been studied.

Mixing ventilation and displacement ventilation were compared in an intervention study inclassrooms. Particles, cat allergen and CO2, were measured in classroom air at different levelsabove the floor, during regular lessons. With mixing ventilation, the particle concentrationtended to decrease with height, with a stronger gradient occurring for larger particles. Withdisplacement ventilation, the particle concentration increased with height, except for particles>25 m. The displacement system thus tended to have a slight upward displacement effect onmost of the particles.

One of the most common measures of IAQ (indoor air quality) is carbon dioxide, CO2, generated by human respiration, in particular, where the main source of pollutions are occupants. In this report, the occupancy-related pollutants are considered as the main pollutant source. However, other type of sources may also be removed satisfactory when governing the ventilation system for removal of

Carbon-dioxide (CO2) based demand controlled ventilation (DCV) offers the potential for moreenergy efficient building ventilation compared with constant ventilation rates based on designoccupancy. A number of questions related to CO2 DCV exist regarding energy benefits, optimalcontrol strategies, and indoor air quality impacts for contaminants with source strengths that areindependent of the number of occupants. In order to obtain insight into these issues, a simulationstudy was performed in six commercial and institutional building spaces.

In France, in non residential buildings, these systems are generally controlled by either a CO2 sensor or optical movement detection (infrared).The part of the study we present here was to determine :- laboratory tests methods to assess the performances of CO2 sensors for ventilation application.- the working performances of these sensors, and particularly the long term stability in a meeting room.- a methodology to assess the performances of CO2 DCV system in French technical agreementThe main results of this study are :- it is easy to characterize (to calibrate) the sensors- the long term

The aim of this study was to test the following hypthesis : in schools, bacterial markers may be increased in indoor air because of the presence of children.Dust samples were collected from the school rooms when occupied but also when unoccupied during the week-end. Results have been analysed and the conclusion is that in unoccupied rooms the airborne dust is of environmental origin, whereas the increase level of dust in occupied rooms is due to the children presence.

This paper proposes a space zone model for the calculation of all the airflow parameters based on tracer gas measurements, including flow rates of outdoor air, VAV supply. This approach gives a practical protocol for buildings managers to evaluate the performance of airside systems and determine air-conditioning and ventilation system performance parameters within acceptable errors.

Accurate mathematical models of airborne infection are needed to estimate the risk from secondary transmission of biological warfare agents. An equation has been derived by the authors : they determined the fraction of inhaled air that has been exhaled previously by someone in the building by using a CO2 concentration as a marker for exhaled-breath exposure.
There is a critical rebreathed fraction of indoor air below which airborne propagation of common respiratory infections and influenza will not occur.