Office buildings focus on air quality, energy efficiency, sustainability

Designing office buildings in a post-COVID world is a challenging task with engineering variables and energy efficiency goals

By Consulting-Specifying Engineer February 12, 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

What unusual systems or features are owners requesting to make their office facilities more efficient?

Elena Bollas: We’re seeing creative exteriors, such as electro-chromatic glass, smart facades and sustainable shading features.

Timothy J. Hedrick: We are seeing an increase in owners wanting more information on how to make their buildings more efficient, which is great for the industry and environment. As far as unusual systems requests, I wouldn’t consider this system as unusual as it was five years ago, but we are seeing an increase in photovoltaics and working with local utilities to capture some of their power usage back through roof mounted solar panels. We run into this request when an owner is having a new facility constructed and they own the building.

What types of sustainable features or concerns might you encounter for office buildings that you wouldn’t on other projects?

Jon Silhol: Natural ventilation can be used in office buildings that cannot be used in all building types. This was a key feature in designing Arizona’s first net zero building. Exterior shading is a key feature in reducing heat gains from the building envelope. A project that was completed about 10 years ago had a large glass facade that faced south. The building used an operable louver system that tracked the position of the sun. This system is able to balance maximizing daylighting and minimizing heat gain through the glass facade. This shading device helped contribute to the building obtaining LEED Gold certification.

Elena Bollas: The possibility of multiple tenants with varying floor plans and desired energy-efficient requirements is common in office building projects.

To offset the IAQ needs of more frequent air changes, what energy efficiency features are you adding?

Elena Bollas: Dedicated outside air systems.

What are some of the challenges or issues when designing for water use in such facilities?

Elena Bollas: The varying tenant demands for water usage can be a challenge. A combination of commercial and residential requirements typically leads to split system designs. Not knowing what features will be used by future tenants requires more conservative sizing of piping systems for instance, often leading to oversized piping, pumps and water heating equipment resulting in higher first cost. It is also necessary to design piping systems that eliminate dead-end pipe runs and to allow for effective control of water recirculation to maintain proper temperature and prevent the risk of waterborne pathogens (Legionella).

What level of performance are you being asked to achieve, such as WELL Building Standards, LEED certification, net zero energy, Passive House or other guidelines?

Jon Silhol: We still see buildings pursuing LEED certification. The most recent building I have been involved with is the new concourse expansion at Sky Harbor International Airport in Phoenix. Energy reduction is always a key in achieving the desired certification level. The new mechanical systems connected to an existing central plant, which limited the energy savings associated with the mechanical system. Improvements were done to the mechanical system such as adding ionization systems and ductwork sizing reduce static pressure requirements.

These items along with other items were done to maximize the energy reduction directly associated with the mechanical systems. A holistic approach was used as well with significant energy savings from the lighting system and using electro-chromatic glass to reduce the exterior envelope heat gains.

Elena Bollas: We’re generally pursuing the following: LEED and Austin Energy Green Building, and we are seeing more interest in net zero designs as well as WELL certification.

What types of renewable or alternative energy systems have you recently specified to provide power?

Jon Silhol: We have designed photovoltaic systems for several projects. There are a lot of hours in the year these systems can operate being the southwest desert. There is a local municipality that requires 3% of the building’s energy usage to come from renewable resources. This helps get PV systems incorporated into the building design and reduce the energy consumption of the building.

High-performance design strategies have been shown to have an impact on the performance of the building and its occupants. What value-add items are you adding these kinds of facilities to make the buildings perform at a higher and more efficient level?

Jon Silhol: We have been incorporating increased ventilation, filtration and thermal control into buildings. We have been increasing ventilation and filtration for some time to help create a better indoor environment. These are in line with ASHRAE’s COVID-19 guidelines that were issued in early 2020. We have also been able to provide additional thermal comfort control on the projects that have underfloor air distribution systems. These systems are great for allowing more individuals to control their own space. High-performing building components are incorporated into all the buildings we work on. Over the last few years building envelopes have been commissioned to ensure performance just like how mechanical and electrical systems have been commissioned for years.