Designing flexible, complex office buildings: HVAC/plumbing

Respondents

Jason Gerke, PE, CxA, LEED AP BD+C, Mechanical & Plumbing Group Leader |, Principal, Graef, Milwaukee

Jason Majerus, PE, CEM, LEED AP, Senior Engineering Leader | Principal, DLR Group, Cleveland

Pui-Yee So, PE, LEED Green Associate, Electrical Engineer, Design Team Lead, Page, Austin, Texas

John Yoon, Lead Electrical Engineer, McGuire Engineers Inc. (MEPC), Chicago

CSE: What unique heating and cooling systems have you specified into such projects? Describe a difficult climate in which you’ve designed an HVAC system.

Gerke: We have used a variety of systems for office building projects, whether new or renovation projects. The most unique system we have used is variable refrigerant flow (VRF). This type of system has proven to be both reliable and flexible for our design needs, and it is able to meet owner’s project requirements for temperature and sound. We have used this type of system specifically in Milwaukee. A standard application of VRF would not provide adequate heat for a Wisconsin winter, so we have used unique, nonstandard solutions, such as indoor air-cooled condensers.

CSE: How have you worked with HVAC system or equipment design to increase a building’s energy efficiency? 

Majerus: Many office projects still lend themselves to a packaged rooftop-unit approach. There are many reasons for this including budget and schedule. But because there have been significant improvements in the technology, and resulting efficiency of this type of equipment, this approach can be part of a holistic strategy to reduce building energy use. Many rooftop units now have optional variable-speed compressors that contribute to a dramatic improvement in part-load efficiency, and because buildings tend to operate at part load 90% of the time, this can result in significant energy savings.

CSE: What is the most challenging thing when designing HVAC systems in office buildings?

Gerke: Sound is the primary challenge when designing HVAC systems in an office environment. An office is used to conduct business. An occupant cannot be required to go to a different room to carry on a conversation or find a quiet space to work. All spaces must be both controlled to an appropriate temperature and an acceptable sound level. Designing for proper sound levels may require using general guidelines for duct sizing, selection of grilles, and soundproofing of equipment enclosures. However, the most conclusive method for ensuring a positive outcome is to work with an acoustician who is able to model spaces based on parametric values determined by the design team.

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