Indoor Air Quality is a major concern to businesses, building managers, tenants, and employees because it can impact the health, comfort, well being, and productivity of building occupants. Individuals spend up to 90% of their time indoors and many spend most of their working hours in an office environment. Air borne bacteria are 2-10 times higher indoor then outdoor.
Indoor air quality is not a simple, It is a constantly changing interaction of complex factors which affects the type, level, and importance of pollutants in indoor environments.
These factors include: sources of pollutants or odors; design, maintenance and operation of building ventilation systems; moisture and humidity; and occupant perceptions and susceptibilities. In addition, there are many other factors that affect comfort or perception of indoor air quality.
Pollutants in our indoor environment can increase the risk of illness. Most buildings do not have severe indoor air quality problems; even well-run buildings can sometimes experience episodes of poor indoor air quality.
Pollutants can be generated by outdoor or indoor sources, including building maintenance activities, pest control, housekeeping, renovation or remodeling, new furnishings or finishes, and building occupant activities.
There are numerous sources of airborne toxic pollutants in these indoor environments where outdoor air ventilation provides the only primary means to dilute pollutant concentrations. Volatile Organic Compounds (VOC's) are one class of indoor pollutants that may cause irritation to building occupants.
HVAC System in an Airports account for upto 60% of electricity consumption. Major cost borne by the Users.
Volatile Organic Compound (VOC)
In Indoor Environment Toxic Gases are emitted from wide variety of sources:
It adversely affect to:
Allergy, Asthma, Eye & Nasal irritation, Affect respiratory tracts, etc.
In an indoor environment human being Exhale Carbon dioxide it cannot be reduced or oxidized. It is not a toxic or carcinogen but a high level of CO2, causes:
Odour is a major Irritants & it is cause from various sources:
This is a residual odor & difficult to dilute from conventional method.
To address Sick Building Syndrome (SBS) the AHU systems take “Outdoor Air” to dilute Volatile Organic Compound (VOC) and reduce Carbon dioxide (CO2) within acceptable limits.
Conventionally Fresh Air is used to improve Indoor Air Quality (IAQ)
Load profile of fresh air
Energy Consumption- 150 CFM of Fresh Air will require 1ton of cooling load. (Approximately)
Position of ASHRAE on reducing fresh air intake: “ASHRAE approves reduction in fresh air, if chemical contaminants in air are removed”.
“Procedure for use of cleaned recirculated air: The amount of outdoor air may be reduced by recirculating air from which offending contaminants have been removed or converted to less objectionable forms. Formaldehyde, for example may be oxidized to water and carbon dioxide. The amount of outdoor air depends on the contaminants generated in the space, etc.