• Home
  • About
  • News & Events
  • Products & Services
  • Portfolio
  • Partners
  • Blog
  • FAQ
  • Contact Us
+94 77 308 8013
Call us to get a free consultant
We are hiring!
Twitter Linkedin Instagram
Logo of Airflow Systems Sri Lanka
  • Working Hours 8.00-17.00
  • 011 256 2764
  • airflow@sltnet.lk
  • Home
  • About
  • News & Events
  • Products & Services
  • Portfolio
  • Partners
  • Blog
  • FAQ
  • Contact Us

  • Home
  • About
  • News & Events
  • Products & Services
  • Portfolio
  • Partners
  • Blog
  • FAQ
  • Contact Us

  • Home
  • FAQ

Have a question?

Have a query? Please check this question and answers
What is ventilation?
Definitions covering ventilation and the flow of air into and out of a space include: Purpose provided (intentional) ventilation: Ventilation is the process by which ‘clean’ air (normally outdoor air) is intentionally provided to a space and stale air is removed. This may be accomplished by either natural or mechanical means.
What is infiltration?

This is the uncontrolled flow of air into a space through adventitious or unintentional gaps and cracks in the building envelope. The corresponding loss of air from an enclosed space is termed ‘exfiltration’. The rate of air infiltration is dependent on the porosity of the building shell and the magnitude of the natural driving forces of wind and temperature.

When Is Ventilation Not Appropriate?

Too often it falls upon ventilation to accomplish tasks for which it is not appropriate. The prime role of ventilation is to dilute and remove pollutants from unavoidable sources. In essence these are those generated by occupants themselves and by their essential activities. All other pollutants should be controlled by elimination or source containment. Some pollutants are chemically reactive, adsorbed on to surfaces, or have emission characteristics which are stimulated by the ventilation process itself.

How Much Ventilation Is Needed?

The quantity of ventilation needed depends on the amount and nature of pollutant present in a space. In practice an enclosed space will contain many different pollutants.

Can Ventilation Energy Loss Be Avoided or Recovered?

Ventilation energy demand can be reduced considerably by adopting a variety of energy efficient ventilation techniques. These include:  Minimizing the need for ventilation: Energy demand may be curtailed by ensuring that the need for ventilation is reduced. This means minimizing emissions from avoidable pollutant sources. Any extra ventilation needed to dilute and remove avoidable pollutants can be equated directly against conditioning load.  

Is There a Relationship Between Ventilation and Health?

Poor ventilation can be associated with unhealthy buildings. Miller (1992), for example, highlights the association of increasing bacteriological concentration with decreasing ventilation rates, while Billington (1982) has produced an historical review of the role of ventilation in improving health and reducing the spread of illness. Studies reported by Sundell (1994) and others have shown that symptoms of building sickness can occur at all ventilation ranges.

How Do Ventilation Needs and Strategies Differ According to Building Type?

Ventilation needs and strategies differ according to occupancy patterns and building type. Main considerations are:

  • Type of the building
    • Single Storey or Multiple Storey with basement
    • Either industrial or commercial
  • Number of occupants
Can Ventilation be Used for Cooling?

Frequently, the dominant pollutant is ‘heat’ itself. Particularly in large commercial office buildings, high heat loads are developed through lighting, computing and other electrical sources. Further heat gains are derived from occupants, solar radiation and high outdoor temperatures. These factors make cooling of the indoor air essential. The choice is either to introduce refrigerative cooling or to introduce ventilation cooling. In either case heat gains should be minimized by good building design and reduced power consumption.

What is Ventilation Efficiency?

Indices of ventilation efficiency characterize the mixing behavior of air and the distribution of pollutant within a space. These two aspects may be subdivided into indices of air change efficiency and pollutant removal effectiveness respectively. Ventilation efficiency is based on an evaluation of the ‘age’ of air and on the concentration distribution of pollutant within the air. Some indices are based on room averaged values, while others refer to specific points or locations.

What Calculation Techniques are Available?

Calculation techniques and numerical models are essential for any design process. They provide the means by which the designer can develop and investigate an idea before being committed to the final product. Typical design aspects cover system sizing, performance evaluation, indoor air quality prediction, energy impact assessment, and cost benefit analysis. A calculation technique or model is used to analyze the interaction of design options with fixed constraints.

How Does Ventilation Work?

Ventilation is accomplished by introducing ‘clean’ air into a space. This air is either mixed with the air already present in the enclosure to give ‘mixing’ or ‘dilution’ ventilation, or is used to ‘displace’ air in the space to give ‘displacement’ or ‘piston flow’ ventilation.  These techniques give characteristically different pollutant profiles.  

Why is Ventilation Needed?

Ventilation is needed to provide oxygen for metabolism and to dilute metabolic pollutants (carbon dioxide and odor). It is also used to assist in maintaining good indoor air quality by diluting and removing other pollutants emitted within a space but should not be used as a substitute for proper source control of pollutants. Ventilation is additionally used for cooling and (particularly in dwellings) to provide oxygen to combustion appliances. Good ventilation is a major contributor to the health and comfort of building occupants.

What is the Energy Impact of Ventilation?

Approximately 30% of the energy delivered to buildings is dissipated in the departing ventilation and exfiltration air streams. In buildings constructed to very high Standards of thermal insulation, the proportion of airborne energy loss can be much higher.

What Is the Relationship Between Ventilation Rate and Odour?

Odor can be regarded as a ‘pollutant’ or as an indicator of the presence of pollutant. Sometimes it may alert the occupant to a potential health risk, although this need not always be reliable since some highly toxic pollutants, such as radon and carbon monoxide, are odorless. More generally, odor causes discomfort, especially in sedentary environments such as the office or home. A difficulty with odor analysis is that many odors cannot be measured by instrumentation.

How Is the Choice of Ventilation Influenced By Climate and Local Environment?

The severity of climate influences the degree of heating or cooling that is necessary to condition the incoming air. Greater potential exists for the use of complex ventilation strategies combined with heat recovery when ventilation heating or cooling loads are high. A system that may be cost effective in one climatic zone may not be appropriate in another.

Can Outdoor Air be Cleaned?

Outdoor air may be ‘cleaned’ by filtration. This is a method by which particulates and, sometimes, gaseous pollutants are removed from the air. Pollutants are intercepted by a filter while allowing clean air to pass through. This method of air cleaning is especially necessary when high concentrations of particulates are present or when the source of pollutant is derived from outside the building. Potential benefits can include improved air quality, reduced dependence on ventilation and improved energy efficiency.

What Measurement Techniques are Available?

Measurements are needed to verify the performance of ventilation systems and to test the air-tightness of the building shell. They are essential for commissioning, diagnostic analysis, design evaluation and research.

What Units are Used for Ventilation and Air Infiltration?

Various units are used to describe the rate of ventilation. These include:   Volumetric flow rate: Ventilation and air infiltration is commonly expressed in terms of a volumetric air flow rate e.g. liters/s (l/s) or m³/s.

we will assist you

Request a free Consultation

Logo of Airflow Systems

We help our clients archive

We constantly strive to align our product portfolio to be in tune with the evolving technology of the time thereby ensuring that we are capable of meeting any requirement, irrespective of the size of the project or technology involved.
Facebook

Address

airflow@sltnet.lk
14/2/C, Galpotta Road,
Athurugiriya, Sri Lanka

Contact

+94 77 355 9433
+94 11 256 2764

Quick Links

  • Home
  • About Us
  • News & Events
  • Product & Service
  • Portfolio
  • Partners
  • FAQ
  • Contact Us
Copyright 2020. Design & Developed by SolutionsW3.com