If, on one hand, energy conservation systems such as air-tight buildings can provide a dramatic reduction in energy losses, on the other hand, air circulation is substantially lower.
Other than buildings becoming increasingly enclosed, their automation level has increased as well. This development has created a dependency on computerized controls to operate automated air conditioning systems which have become all but mandatory in buildings, in particular service buildings.
Temperature and humidity, being the only criteria currently used to evaluate air quality, are unable to provide the necessary information other parameters may bring to properly make this assessment. Despite the increasing concern for energy savings, inner air quality (IAQ) has been often disregarded and put aside.
If, on the one hand, energy conservation systems such as air-tight buildings can provide a dramatic reduction in energy losses, on the other hand, air circulation is substantially lower. As a consequence the average concentration of airborne pollutants in interior spaces substantially increases.
Nowadays we are aware that a number of pollutants – such as carbon monoxide, carbon dioxide, ammonia, sulphur dioxide and nitrogen – are produced inside buildings by organic-solvent based construction materials, cleaning detergents, mould, must and human metabolism and activities (such as washing and cleaning). These pollutants compromise building users’ health and productivity.
Some of these buildings are even classified as being ill due to their poor inner air quality. From those situations stemmed the expression Sick Building Syndrome (SBS), characterized by the transitory ill state of its users which is reversed as soon as they leave the building in question.
The sickening of buildings is mostly related to inadequate maintenance of air conditioning systems and ventilations. These can become incubators of micro-organisms which easily spread along the ventilation shafts throughout the building.
The expression Sick Building emerged in the United States and Scandinavia in the 1970s and is used to describe situations in which a significant number of users (about 20% according to Robertson:2005) present the following symptoms:
- Eyes: irritation, dryness and itching;
- Nose: irritation, dryness and congestions;
- Throat: dryness, hoarseness, itching and cough;
- Skin: irritation, dryness, itching and erythema;
- Head: aches, nausea and dizziness;
Air quality plays an important role in this process. However, comfort conditions should also be taken into account since excessive cold or heat, air drafts, inadequate humidity, vibrations, noise and lighting may interact with each other and cause user complaints to increase.
Measures could and should be undertaken to prevent interior air pollution from affecting its users. In time that will reduce sick leaves, expenses with medical treatments and increase overall productivity. These measures are part of a monitoring programme specifically designed to inspect, process and evaluate the maintenance or air systems in building.
Inadequate maintenance of air conditioning systems may cause microorganisms to develop and spread across buildings.
The first stage of the process consists of an inspection of the project and of the operation of the air conditioning systems. External air admission rates must be checked and adjusted to meet needs. Cooling, heating and humidification systems must also be examined.
On the second stage an analysis of noxious gas concentrations will be performed on key points of the building. The last stage consists on the continuous monitorization of the building by placing gas sensors and performing regular surveys. Regular reports should be produced to provide actions and recommendations to ensure inner air quality.
Having a healthy building implies having good inner air quality. That, in turn, implies adequate ventilation rates and continuous monitoring of the facilities.
Some estimates tell us people in urban contexts spend up to 80 or 90% of their time indoors. This means that for most of our time we are subjected to some form of artificial environment in an enclosed space or building. What’s worse is that the altered environment is mostly changed for the worst as the problem of inner air quality is real and continues to grow.
This is a problem, however, that is very difficult to appraise since there are many chemical compounds involved and many of them are imperceptible such as radon (Rn), for instance.
The legal, economic and public health issues associated to air quality are fated to become a dominant concern over this century. Inner air quality problems will inevitably make the work of engineers, architects and other industry professionals far more complex.
Research into these matters has had a great development since the 1990’s, in particular in the USA and some European countries. Several public and private agencies are involved in the study of air quality.
In 2008 the European commission put into action the New Air Quality Directive for countries to compile their existing legislations to control air renovation in buildings and promote its quality.
In this directive the air quality objectives were defined as well as the compliance criteria to be applied by 2010.
Certifications of inner air quality have since demanded construction pathologies to be minimized, in particular internal or superficial condensations that might compromise the longevity of construction materials and the inner air quality.