How To "Strutt" Series
Choosing a Mechanical Calculation Method
The majority of the Mechanical userforms allow the user to select a calculation method, e.g. Blue Book, CIBSE, ASHRAE, etc.
Strutt users are often uncertain which method is most suitable for their calculation. The following is a brief summary of each method.
- ASHRAE: American Society of Heating, Refrigeration and Aircon Engineers. Tends to be used in the USA, since it is their local body. The 1991 version can be optimistic in terms of loss but has the largest user base and is probably the most established method. The straight lined duct attenuation methodology in ASHRAE 2019 is based on very comprehensive and recent research.
- AIRAH: Australian Institute of Refrigeration, Aircon and Heating. Seems to be quite a conservative method.
- Blue Book: Produced by Arup. Based on what the authors thought was the most appropriate standard to use for a given calculation. The duct equations are largely based on the AIRAH 1987 manual. The bend equations are from SRL (Sound Research Lab).
- CIBSE: Chartered Institution of Building Services Engineers. A newer method (2005). Tends to give answers in between AIRAH 1987 and ASHRAE 1991.
- VDI2081: From the Association of German Engineers. Provided for German projects so that mechanical calculations are consistent with local practice.
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