Office building codes, standards may change
COVID, employee well-being and indoor air quality issues have all changed the way office building codes and standards are considered
- Daniel Donahoe, PE, Senior Mechanical Engineer, LEO A DALY, Omaha, NE
- Tyler Jensen, PE, LEED AP, Studio Leader, ESD, Chicago, IL
- Brad McNiff, PE, LEED AP, WELL AP, Principal, GHT Limited, Arlington, VA
- Gerald Williams, PE, LEED AP, Senior Mechanical Engineer, CRB, St. Louis, MO
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?
Daniel Donahoe: For office buildings, typically we see the International Building Code used for mechanical, plumbing and energy conservation. Government office spaces will typically include ASHRAE 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings and use a LEED rating system or Green Globes. IECC 2018 is becoming the norm. Post-COVID, the WELL standard is becoming more popular.
Tyler Jensen: The International Code Council model codes are adopted most frequently in jurisdictions across the U.S. This includes IBC, IECC, International Mechanical Code, International Plumbing Code and International Fire Code. However, almost all jurisdictions include specific local amendments that are critical to understand and follow. Some municipalities such as Chicago forego model codes completely and have their own dedicated codes, although Chicago is thankfully in the process of modernizing building codes to align with ICC. ASHRAE standards for energy (90.1), ventilation (62.1) and thermal comfort (ASHRAE 55: Thermal Environmental Conditions for Human Occupancy) are also frequently referenced in LEED requirements and are important to be aware of.
How are codes, standards or guidelines for energy efficiency impacting the design of such buildings?
Daniel Donahoe: HVAC systems are becoming more complex to achieve greater energy efficiency. The complexities include heat recovery, economizer control and fault detection, chilled water temperature and pressure reset, supply air temperature reset and ventilation controls. Lighting systems have switched over almost entirely to addressable controls. The building envelope has also become more complex, with continuous insulation requirements and more stringent linkage requirements driving increases in energy performance.
Tyler Jensen: Energy codes are becoming increasingly stringent and driving design teams to evaluate energy performance early in the design. Core and shell office buildings are leasing market driven and typically include highly glazed facades to attract tenants with the access to views and daylight. For energy code compliance and to achieve LEED and other sustainability goals, we are working with the design team from early stages in order to optimize the building envelope and to apply efficient MEP systems. Prescriptive energy codes require a maximum 40% window-to-wall ratio, which is rarely achieved, which then requires a performance-based approach. Detailed, iterative energy modeling is then used to confirm compliance.
What new or updated code or standard do you anticipate will come about due to COVID-19? What changes do you anticipate?
Daniel Donahoe: In future code cycles, I would look out for higher ventilation standards, which will dictate higher outdoor air and minimum filtration levels.
Tyler Jensen: Energy codes and ventilation codes have always been in conflict to some extent. COVID-19 ventilation best practices and WELL and other standards that highlight the benefit of increased ventilation have only increased the conflict. Energy codes want to drive down energy use, but heating and cooling of fresh ventilation air is a large percentage of total office building energy use. In response to COVID-19, energy codes may provide exceptions or relax criteria related to ventilation, especially for temporary circumstances when there is increased risk of airborne disease transmission. Ventilation codes may also expand to include sections about pre- and post-occupancy purge cycles, which are recommended by ASHRAE as industry best practice for office buildings.
What are some of the biggest challenges when considering code compliance and designing or working with existing office facilities?
Daniel Donahoe: HVAC controls are playing a greater role in the energy code. Many older buildings do not have the control capacity or capability and, therefore, more extensive HVAC control work is required in a renovation. Often a full lighting system upgrade to LEDs and addressable controls is required. Depending on what kind of building envelope you have in an existing building, you might consider upgrades to improve energy performance. The building envelope limits how aggressively you can design HVAC systems to reduce energy use. If it’s an inefficient envelope, you can’t really downsize the HVAC to be more efficient because you’re fighting against the envelope performance. Sometimes the envelope is so poor and upgrading it so costly that it doesn’t make sense to upgrade the HVAC.
What are some of the challenges that exist between what the building owner wants, how the building needs to accommodate occupants and complying with particular codes and standards?
Daniel Donahoe: Lighting controls can be a point of contention for clients, who don’t want to see lighting that turns off when people are in their spaces. However, newer energy codes require it, so it becomes a challenge to find a solution that will impact them the least.