Office buildings focus on air quality, energy efficiency with codes and standards

Designing office buildings in a post-COVID world is a challenging task with engineering variables. Learn about codes and standards

By Consulting-Specifying Engineer February 18, 2021


  • Elena Bollas, PE, Mechanical Engineer, Page, Austin, Texas
  • Timothy J. Hedrick, PE, Principal/Electrical Engineer, RTM Engineering Consultants, Schaumburg, Ill.
  • Dan Luzius, LEED AP, Principal, DLR Group, Seattle
  • Jon Silhol, PE, LEED AP BD+C, Mechanical Engineer, SmithGroup, Phoenix

Please explain some of the codes, standards and guidelines you commonly use during the project’s design process for office facilities. Which codes/standards should engineers be most aware of?

Timothy J. Hedrick: As an electrical engineer, we typically use NFPA 70: National Electrical Code as a guideline for our designs. However, for office buildings I would say the code to be most aware of is the 2018 International Energy Conservation Code. This code will go over all MEP requirements for office buildings to save energy, including lighting control and HVAC requirements.

Jon Silhol: Engineers should be aware of the local codes that are adopted within the city the building is located in. Typically, this is the International Building Code or California’s building codes.

I reference several ASHRAE standards: ASHRAE 15: Safety Standard for Refrigeration Systems and Designation and Classification of Refrigerants; ASHRAE 52: Method of Testing General Ventilation Air-Cleaning Devices; ASHRAE 55: Thermal Environment Conditions for Human Occupancy; ASHRAE 62.1: Ventilation and Acceptable Indoor Air Quality; ASHRAE 90.1: Energy Standard for Building Except for Low-Rise Residential Buildings; ASHRAE 135: BACnet – A Data Communication Protocol for Building Automation and Control Networks and ASHRAE 189: Standard for High-Performance Green Buildings Except Low-Rise Residential Buildings. Other standards and guidelines include NFPA, ARI and SMANCA for duct design requirements.

Elena Bollas: We rely on all of the following codes and standards: ASHRAE 90.1, International Code Council, International Green Construction Code, LEED Building Council Guidelines (Version 4.1 is the most current edition of guidelines) and NFPA. We are increasingly seeing an interest in WELL building certifications and are also using these standards more.

What are some best practices to ensure that such buildings meet and exceed codes and standards?

Elena Bollas: It is important to understand the owners’ expectations for their buildings from the start. On a small scale, knowing the expected use and population for each office space prevents overdesigning and allows for efficient zoning. HVAC engineers can design and specify equipment to meet or exceed code, but that is only one piece of the puzzle. Knowing the building standard we are designing to, while also understanding critical items of the owner, helps guide early conversations internally about building construction materials, U-values and lighting choices. These all play a role in building efficiency.

Timothy J. Hedrick: AT RTM, we use quality control and quality assurance reviews to ensure our MEP designs meet and exceed the proper codes and standards. We make sure the engineer of record and the project manager do internal reviews at certain stages of each project to ensure these guidelines are being met.

Jon Silhol: First is to know what the code requires. It’s hard to design building systems without knowing what the requirements are. A person should read and research the code to understand what is required. The code commentary can be helpful to understand what the code is requiring and deceiver “code language.” Also, use the people around you as a resource. There is a good chance a coworker or someone you know in the industry has come across a similar situation. A project should always be reviewed by another engineer before being issued for quality assurance. A QA/quality control workflow can catch a lot of issues in the design phase before coming larger issues during construction or post-occupancy.

How are codes, standards or guidelines for energy efficiency impacting the design of such buildings?

Jon Silhol: They are pushing buildings to become more energy efficient. This is important otherwise minimal improvements would be made to lower the effect that buildings have on the environment. We still see a lot of the base system requirements being used, but they are being refined to improve energy performance. This can be adding energy recovery to certain mechanical systems, using water-saving plumbing fixtures, managing plug loads or improvement in the lighting controls.

Dan Luzius: We see impact especially in states such as Washington, which has a uniquely stringent energy code which drives the bulk of our MEP designs. A “code minimum” MEP design targeting the prescriptive compliance path typically achieves a LEED Silver status. That said, good environmental design is more than just code minimum and we’ve been fortunate to work with clients who share the same passion. We work closely with our clients and internal teams to push the envelope. We design systems that continually go beyond code requirements in terms of energy efficiency.

Elena Bollas: With many office buildings trying to achieve higher energy performance standards, we use complex energy models on a significant number of projects. The coordination starts early in the design process and the results from the energy performance models at each stage of design help us guide conversation with the rest of the design team on areas of potential energy improvement.

What new or updated code or standard do you anticipate will come about due to COVID-19? What changes do you anticipate?

Jon Silhol: I anticipate we will see the most updates from ASHRAE because COVID-19 spreads so easily in aerosol form. The current recommendations for office buildings include pre- and post-occupancy flush-outs and a minimum MERV 13 filter. These are easy to incorporate into new buildings and most buildings can accomplish this. I will be interested to see what happens with the minimum ventilation requirement. This is been reduced through the years because building envelopes have gotten tighter and the need to conserve energy. I will also be interested to see how humidification is incorporated into non-health care facilities. These buildings typically do not have humidification and building operators are not used to working with them. Also, how the building envelope is constructed will have to be looked at to prevent condensation forming.

What are some of the biggest challenges when considering code compliance and designing or working with existing office facilities?

Jon Silhol: The item that comes up the most is the ventilation requirement. The office planning trend has been to densify, which requires additional outside air than what the building was designed for. Most of the projects that I have been involved with have been able to be grandfathered in to the code that base building was designed to. Usually in this case the base building has enough outside air to meet the new requirements. There have been times when supplemental ventilation and exhaust systems have had to be incorporated to meet the requirements of the new space layout.

The number of toilet fixtures is also an issue due to more dense office space in existing buildings. Often new fixtures have been added and getting the plumbing systems routed to new locations can be difficult.

Dan Luzius: Existing facilities can be extremely challenging when it comes to local energy code compliance. The minimum requirements for office buildings drive our designs toward decoupled HVAC systems which consist of a DOAS and a space conditioning system such as an active chilled beams or VRF. Existing office buildings typically have lower floor-to-floor heights, making it a challenge to fit two separate HVAC systems in a 24-inch ceiling plenum. Our teams have learned to get very creative from a coordination standpoint. We heavily rely on our BIM tools and process to get us there. It’s often more cost-effective to demolish the existing MEP systems and design entirely new systems from both a design and construction perspective.

Elena Bollas: The first major challenge is knowing the boundaries of what is being newly constructed versus being left untouched. “Existing to remain” equipment is not required to be upgraded to new code standards, but only if it is truly left undisturbed. Another challenge encompasses existing building exterior construction. Older construction can have lower U-values, which can make achieving energy efficiency qualifications more difficult.