Specifying for green building: Part 1
How do you structure specifications to properly specify building performance that is compliant with a green building code such as LEED v4?
Designing a project to a green building code, such as U.S. Green Building Council LEED v4, Green Globes, ASHRAE Standard 189.1, or the International Green Construction Code (IgCC), requires a the engineer think outside the normal approach to specifying.
There are four common ways to specify a system or assembly, and it is key to remember that each method has an associated level of risk or liability for the engineer. The rule of thumb is that the more detailed a specification, the more liable the engineer is for the final performance. In the order of least to most potential liability and difficulty to write, these four types of specifications are descriptive, performance, reference standard, and proprietary.
A descriptive specification, the most traditional and comprehensive type of specification, provides a detailed description of the final product or system qualities and workmanship. It has no manufacturer or products restrictions as long as they meet the described level of quality. A performance specification specifies levels of performance that the finished product must meet. A reference standard specification relies on a third-party standard that the engineer should be very familiar with, which may be incorporated by reference.
And on the other end, a proprietary specification provides not much more than the model number and installation standards. (In actuality, there is quite a bit more to a proprietary specification, but it is too much to include in a blog post. See the CSI Construction Specifications Practice Guide for more detailed information.)
You can see the quandary. The more specific the requirements, the more responsible the engineer is for final performance of the system. In a descriptive specification, the specifying information is broad enough that the contractor has a wide range of products to review, choose from, coordinate, and integrate into the finished product. Meanwhile, in a proprietary specification, the contractor is limited to a certain product, which also limits pricing flexibility, and the engineer assumes liability for the choices made while writing the specification.
Ideally, the answer is a holistic approach to the drawings and specifications that clearly communicates minimum levels of performance and available product choices. This requires an understanding of the different types of specifying, and how to use multiple types within one specification document.
Part 2 will be a discussion on performance specifying.
What have your experiences been when specifying for LEED, IGCC, or Green Globes? Does this correlate with your approach and experience? Share your experience via the “comments” section 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.