Designing, enhancing office buildings: Codes and standards
Office buildings might seem like relatively simple structures, but engineers with experience in the field know differently. Codes and standards define minimum design requirements for these buildings.
Christopher Arnold, PE, Vice President, Wick Fisher White, Philadelphia
Saied Nazeri, PE, CPD, LEED BD+C, Senior Vice President, WSP | Parsons Brinckerhoff, San Francisco
Reardon D. Sullivan, PE, LEED AP, Principal, WFT Engineering Inc., Rockville, Md.
Jill Walsh, PE, LEED AP, Principal in Charge of Mechanical Engineering, OLA Consulting Engineers, Hawthorne, N.Y.
Michael Walsh, Project Manager, PEDCO E&A Services Inc., Cincinnati
CSE: Please explain some of the codes, standards, and guidelines you use as a guide when designing office buildings.
Michael Walsh: There are the standard minimum design codes, such as ASHRAE Standard 55: Thermal Environmental Conditions for Human Occupancy and ASHRAE Standard 62.1: Ventilation for Acceptable Indoor Air Quality, NFPA 70: National Electrical Code for electrical systems, and ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings for energy efficiency for MEP systems as well as the building envelope. We also use guidelines such as ASHRAE Advanced Energy Design Guides for Small to Medium Office Buildings. The guide is available as a free download in two versions: achieving 30% and achieving 50% energy savings. Another great publication for renovation projects is the Dept. of Energy/Pacific Northwest National Laboratory's "Advanced Energy Retrofit Guide for Office Buildings."
Sullivan: Typically, we see local jurisdictions requiring compliance with the various versions of the International Building Code (IBC), but most jurisdictions have their own additional code requirements/interpretations. One code that we work with is the DCMR code in the District of Columbia. It is also becoming very common to have jurisdictions mandate some version of "green building" code or standard such as LEED, International Energy Conservation Code (IECC), or ASHRAE.
Nazeri: Some of the codes and standards we use are the IBC, state and/or municipal codes, international building energy codes, state energy codes (most notably in California), CALGreen: California Green Building Standards Code, ASHRAE standards, SMACNA standards, and USGBC LEED.
CSE: How have International Building Code, NFPA, ASHRAE, and other codes affected your work on office building projects? What are some positive/negative aspects of these guides?
Michael Walsh: International codes have provided some consistency and allow the design team to have a level of familiarity; however, each jurisdiction has the ability to amend the code and modify portions as they desire. With the greater emphasis on energy conservation, it is becoming more difficult to perform renovation projects on small budgets.
Nazeri: There are many codes and they change regularly. We must always be on top of the latest changes and advise our clients accordingly. Energy codes, especially in California, have raised performance thresholds routinely. The thermal-performance criteria of building envelopes are becoming more and more stringent. When envelopes do not comply with applicable codes, high-performing HVAC and lighting systems need to compensate and bring the overall energy use into compliance with the applicable codes. Approved energy compliance or simulation software has become more robust, but cannot yet easily model innovative systems. We must often do workarounds or post-processing of data to model these systems.
Sullivan: One of the keys is to understand the differences between a code and a standard. A code is something that a designer is required to do, and a standard is an established professional reference. Whereas the consistency between the model codes has improved, there are often varying interpretations of the local codes that can be challenging to negotiate.
CSE: Meeting codes/standards is often one of the biggest challenges engineers face. What challenges have you recently overcome in a particular jurisdiction or project?
Sullivan: Washington, D.C., has recently adopted a green building code. Like any new code, there is a shakedown period where all the nuances are clarified. This process is taking a longer time to work out because of the understaffing of the permit review office, which is resulting in 12- to 16-wk permit review times for small projects.
Nazeri: Fire life safety codes can the most challenging. In my experience, early engagement with the appropriate authorities and agreement on a preliminary life safety approach, particularly for larger buildings, is an absolute must. The criteria can often be nailed down through a pre-application meeting. Designing these systems late in the project is very risky and expensive. Oftentimes, when working with the fire life safety authorities it is possible to negotiate a less-complicated but equally effective solution to meet a certain design challenge through analysis or equivalencies.
Michael Walsh: Codes inherently lag behind advances in the various building-engineering fields that require early interaction between the design team and local code officials. For example, on the first LEED project we designed, we included waterless urinals as a water-saving technology. At the time, the local code did not recognize this technology, so the design team had to submit for a variance. More recently, with a major office renovation project in the Cincinnati area, we used active chilled beams to not only provide an efficient HVAC system but also due to some physical constraints in a historic building. This required a sit-down meeting with the local code officials to explain how outdoor air was going to be properly delivered to the occupants.
CSE: Are there any specialty projects you've completed for General Services Administration (GSA) that had to meet unusual codes/standards, either in the United States or abroad?
Nazeri: 50 United Nations Plaza was a complete renovation of a historic office building in San Francisco, which included a seismic upgrade and MEP systems upgrade. The design objective was to achieve LEED Gold, but the design team in coordination with GSA was able to achieve LEED Platinum. Federal Center South in Seattle was another successful GSA ground-up office building project. For this LEED Platinum project, a performance bond was put in place to ensure that the energy-use targets were met post-occupancy. Through a comprehensive measurement and verification process during the first year of occupancy, we were able to demonstrate that energy targets were realized prior to final payment to the design team.