March 8, 2016 zacherlaw 0 Comments

   ASHRAE 12-2000

    Most occupations adhere to standards of safety or quality that are developed over many years, and designing interior building systems is no exception. The American Society of Heating, Refrigeration, and Air-Conditioning Engineers, Inc. (ASHRAE) is an organization that produces updated standards and guidelines for jobs involving central systems in buildings. The guidelines are not guaranteed to prevent accidents or eradicate risks, but are generally considered the best ways to prevent undesirable occurrences.

The ASHRAE 12-2000 Guideline, entitled Minimizing the Risk of Legionellosis Associated with Building Water Systems, focuses on what architects, construction companies, and maintenance employees should do to maintain a safe environment for their patrons and ensure that their water is free of Legionella bacteria. Guidelines like these are very important because they set a standard of accountability that might otherwise be unknown or disregarded. For example, if these guidelines didn’t exist and a group of people contracted Legionnaires’ disease at a Shopping Mall, the owners of the Shopping Mall could say that it wasn’t their fault because they were unaware of how to prevent such an occurrence.  Standards not only help to maintain a safe environment, they also hold those in charge responsible for making sure that the standards are met.

In the 15 page report, the authors cover a group of topics ranging from the ecology of Legionella to the proper design and maintenance of potable and emergency water systems, heated spas, decorative fountains, cooling towers, and humidifiers. Below are some excerpts that demonstrate the wealth of valuable knowledge that can be found in the Guideline:

  • Ecology of Legionella – The risk of transmission of infection to humans depends on the presence of several factors: conditions favorable for amplification of the organism, a mechanism of dissemination (e.g., aerosolization of colonized air), inoculation of the organism at a site where it is capable of causing infection, bacterial strain-specific virulence factors, and the susceptibility of the host.
  • Transmission of Legionnaires’ Disease – The first event [needed to occur for Legionella to infect is], survival in nature, is generally outside the scope of building engineering and management practices. The next three events – amplification, dissemination, and transmission – can be influenced by engineering design and maintenance practices.
  • Recommended Treatment/Design – New shower systems in large buildings, hospitals, and nursing homes should be designed to permit mixing of hot and cold water near the showerhead. The warm water section of pipe between the control valve and showerhead should be self-draining.


These are just some small segments of this document, and the rest is just as informative. If you have the chance, read the guidelines and see if they can apply to your own situations.

Download link: ASHRAE 12-2000 Download

ASHRAE 12-2000 and Its Significance in Preventing Legionella Propagation was last modified: March 8th, 2016 by zacherlaw

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