The IBC/IMC, the AIA, and Chapter 7 of the ASHRAE Handbook—HVAC Applications all reference ANSI / ASHRAE Standard 62 for determining ventilation. ANSI / ASHRAE Standard 62 provides two methods for engineers to follow to determine the required minimum ventilation rate to achieve acceptable indoor air quality.
To obtain compliance for ventilation design, there are two procedures in the ASHRAE standard. The ventilation rate procedure states that acceptable IAQ is achieved by providing ventilation air of the specified quality and quantity to the space. The indoor air quality procedure identifies a method for achieving acceptable IAQ within the space by controlling known and specifiable contaminants.
Ventilation Rate Procedure
The ventilation rate procedure provides a more definitive, prescriptive procedure based on physiological needs and subjective evaluations. The indoor air quality procedure uses guidelines for the specification of acceptable concentrations of certain contaminants in indoor air —with no prescriptive formula for ventilation rates.
The Indoor Air Quality (IAQ) Procedure
The indoor air quality procedure typically does not result in lower outside air in healing environment applications since the various potential sources of contamination require ventilation rates to be equal to that of the ventilation rate procedure. Additionally, the indoor air quality procedure requires the designer to specifically identify how each of the known contaminants is to be dealt with. The problem facing system designers with this procedure is in determining the possible contaminants that may result from the eventual use/occupancy of the healing environment. For example, controlling formaldehydes, aldehydes, nitrogen dioxides, organics, etc., all need to be understood and accomplished with “engineering reason” when tackling this method. As a result, most designers opt for the more common ventilation rate procedure (VRP ) to determine outdoor airflow needs at the space and system levels. This method prescribes the outdoor air quality acceptable for ventilation, outdoor air treatment where necessary, ventilation rates, and the criteria for reductions of outside air where recirculation treatments occur.
ASHRAE also addressed maintenance of outside ventilation systems. ANSI /ASHRAE Standard 62-2001 identifies minimum ongoing operation and maintenance criteria. The requirements of this section apply to buildings and their ventilation systems and their components constructed or renovated. In section 8.4 of ASHRAE 62, it states:
At a minimum of once every three months or as specified in the Operations and Maintenance Manual, the outdoor air dampers and actuators shall be visually inspected or remotely monitored and determined to verify that they are functioning in accordance with the Operations and Maintenance Manual.
ANSI /ASHRAE Standard 62’s definition of a maintenance manual is as follows:
An operations and maintenance manual either written or electronic shall be developed and maintained on site or in a centrally accessible location for the working life of the applicable ventilation system equipment or components.
This manual shall be updated as necessary. The manual shall consist, at a minimum, of the operation and maintenance procedures, final design drawings, operation and maintenance schedules, and any changes made thereto and the maintenance requirements.
Measuring Air Quality
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