Indoor environmental quality

Indoor environmental quality:
From the occupant point of view, the ideal situation is an indoor environment
that satisfies all occupants (i.e. they have no complaints) and does not
unnecessarily increase the risk or severity of illness or injury. Both the satisfaction
of people (comfort) and health status are influenced by numerous
factors: general well-being, mental drive, job satisfaction, technical competence,
career achievements, home/work interface, relationship with others,
personal circumstances, organizational matters, etc. and last but not least
environmental factors, such as
• IAQ: comprising odour, indoor air pollution, fresh air supply, etc.;
• thermal comfort: moisture, air velocity, temperature;
• acoustical quality: noise from outside, indoors, vibrations;
• visual or lighting quality: view, illuminance, luminance ratios, reflection;
• aesthetic quality.
Although there is rich scientific literature and the reports of several
national experiences on this subject, a uniform set of criteria for the countries
of Europe has not yet been defined.
Currently, in several standards and guidelines, human indoor environmental
requirements for spaces are expressed by physical and chemical
indicators (temperature, Decibel, Lux, CO concentration, etc.) (CEN, 1998;
ASHRAE, 2004a; ISO, 2005). Although required levels in those standards
and guidelines are met, it can be concluded from several studies that the
IEQ as experienced by occupants is not always acceptable and sometimes
is even unhealthy, causing health and comfort problems (Bluyssen et al.,
1995). This mismatch is due to several reasons:
• the relationship between objective measurement and human assessment
is not known for all physical/chemical parameters. No consensus model
is available for air quality. For light, recent findings show that brightness
of the surroundings is the key element and not only the illuminance
(Light & Health Research Foundation, 2002).
• even if established models for separate subjective issues exist [e.g. thermal
comfort (Fanger, 1972) and noise], the holistic effects of all separate
physical/chemical factors are still largely unknown.
Besides the physical/chemical indicators, other indicators are being
used such as the percentage of dissatisfied occupants, productivity numbers
(Clements-Croome, 2002), sick leave, estimated life expectations
(Carrothers et al., 1999) and even the number of deaths related to a BRI.
However, the determination and use of these indicators has not been documented
in guidelines or standards.
In several spaces (cars, space industry and buildings), health complaints
and comfort problems are strongly related to the available methods of ventilation.
This relation has been shown, for example, by the increased risk of
infectious disease transmission (recirculated air), sources in heating, ventilating
and air-conditioning (HVAC) systems causing an overall distribution
of unwanted pollutants (Bluyssen et al., 2003), and stagnant zones and
draught (insufficient ventilation effectiveness). Complaints are in general
related to air quality, thermal comfort and noise parameters.