Specifying for sustainability: Reference standards
Every engineer needs a benchmark. In specifying, that's a reference standard.
One of the foundations of specifying is performance specifying, which was covered in a previous blog post. To specify performance, the engineer needs to provide clear, measurable, and quantitative goals in order to determine that the desired performance has been achieved.
If an existing industry standard already covers the necessary performance criteria, rather than writing this information in the specification, it may be simpler for the engineer to reference that standard, which would also include manufacturing guidelines, quality control, and interoperability among assemblies. The specification becomes one that uses or is created around a reference standard.
A reference standard is useful when an industry standard exists and has been adopted by most manufacturers and end-users of the product. An example is the connector that interfaces with the car in a vehicle charging assembly, which is governed by the SAE J1772 standard. ASHRAE Standard 189.1 and the International Green Construction Code (IgCC) are also reference standards, but electric vehicle chargers are a little more specific and a little more exciting, so we'll use that as an example.
SAE J1772 is an industry standard connector that allows for intelligent Level 1 and Level 2 charging at up to 240 Vac and 80 amps. The standardized connector includes phase conductors for electricity, communications, and shock protection that are compatible with commercially available electric vehicles. The standard also specifies materials, quality control measures, and manufacturing processes, which may include references to other industry standards. Including all of these items would result in a fairly long specification, and if the engineer writing the specification wasn't familiar with the standards, processes, and quality control measures, he or she would likely miss something.
This is where the reference standard becomes helpful. A simple reference to the SAE J1772 standard, or incorporating the standard by reference, alleviates a significant amount of work for the engineer and allows for instant compatibility with the owner's electric vehicles.
Of course, referencing SAE J1772 is just a part of an electric vehicle charger specification. A vehicle charger includes many other components, such as cable, a cable retention device, a NEMA 3R cabinet, and the electronics that regulate the charging. Some of these items may be able to be specified by their respective standards while others may require nonstandard options, or have no standards associated with them. Nonstandard options may run the gamut from dc fast charging, which may require modification of components built to and then changed beyond a referenced standard, to simply an abnormally long cord to accommodate certain types of electric vehicles. In either case, the reference standard provides a means for the engineer to build off an existing standard.
If a lot of this sounds like incorporation by reference, which was covered in an earlier blog post, that's because it is very closely related. Incorporation by reference is the blanket term for incorporating a document into another document by mention of the document. Citing a reference standard does this. If you're a little hazy on incorporation by reference, it may be worth reviewing that article, as there are a couple caveats to incorporating by reference.
After all is said and done, it’s important to note that it is rare, however, that a specification is built around one or more reference standards. The reference standard is just one method used to specify products or assemblies, with the other methods being performance, descriptive, and proprietary. In fact, most specifications typically use a combination of these different types of specifying.
One last thing—it's easy to include references to industry standards on engineering drawings, but the fact that the products must meet the specification has to be defined somewhere on the drawings or in the specifications that products must meet the specification. And if the final design includes modification to the standard, it is best to write a specification “from scratch” without incorporating the standard by reference in order to avoid confusion.
What references do you often use in specifications? Do you find it easier than tailoring your own specification? Share your comments below.
Michael Heinsdorf, PE, LEED AP, CDT is an Engineering Specification Writer at ARCOMMasterSpec. He has more than 10 years' experience in consulting engineering, and is the lead author of MasterSpec Electrical, Communications, and Electronic Safety and Security guide specifications. He holds a BSEE from Drexel University and is currently pursuing a Masters in Engineering Management, also at Drexel University.