Office building insights:

• HVAC systems are being designed with sustainability and energy efficiency in mind.
• Challenges in office building design often come from a disconnect between building owners and tenants.

Respondents: 

• Jarron Gass, PE, CFPS, Fire Protection Discipline Leader, CDM Smith, Pittsburgh
• Danielle Passaglia, PE, LEED GA, Mechanical engineer, SmithGroup, Chicago
• John Yoon, PE, LEED AP, Principal, McGuire Engineers, Inc., Chicago

What unique heating and cooling systems have you specified into such projects? Describe a difficult climate in which you designed a heating, ventilation and air conditioning (HVAC) system.

Jarron Gass: Recently, I’ve observed the use of variable refrigerant flow (VRF) systems, which provide energy-efficient and precise temperature control by using refrigerants for both heating and cooling. These systems are especially ideal for multi-zone buildings. I’ve also seen methods like displacement ventilation, which delivers cool air near the floor to improve air quality and reduce overall energy usage by minimizing the air handling capacity. Additionally, geothermal systems, which leverage the earth’s stable temperatures for more efficient heating and cooling, have gained popularity and are now considered more mainstream than unique.

Danielle Passaglia: SmithGroup’s DC Water Headquarters project utilized waste heat recovery by tapping into the city’s sewage system and using it as a heat exchanger utilizing SHARC technologies. This project also utilized rain harvesting, modular heat recovery chillers and dedicated outdoor air system units with chilled boxes. West Coast projects have the continual risk of forest fires and poor air quality, which adds considerations when looking at ventilation, filtration and air quality.

Have you specified a radiant heating or cooling system into an office building? Describe the project.

Danielle Passaglia: Radiant floor heating paired with variable air valves with reheat has been used in some of my previous new construction projects in lieu of separate perimeter heaters. This allows energy savings because the hydronic radiant keeps the building to setback temperatures during unoccupied hours with no need to run the air handling units. The radiant floor also provides additional thermal comfort for the occupants and works well with areas with double-height ceilings.

How have changes in codes or standards impacted the design of HVAC systems for office buildings?

Danielle Passaglia: The refrigerant phase-out plan from the Environmental Protection Agency trickled down into codes, standards, and equipment selections and availability. The phase-out of refrigerants like R-134A and R-410 has required new accommodations to account for A2L refrigerants with different design criteria. This includes ventilated shafts, increased ventilation criteria, and additional alarm and leak detection. Codes are consistently becoming more stringent in terms of efficiency, making owners and tenants consider the level of metering and tracking required for their systems.

Describe an HVAC ventilation system you’ve worked on or encountered in an office building that included hoods, fire suppression systems or other specialized ventilation systems.

Danielle Passaglia: I have worked on tenant interior projects with large commercial kitchen designs in high-rise construction. This design required kitchen grease exhaust fans, hoods and dedicated makeup air units. The biggest piece of coordination was determining how the operation of the tenant’s kitchen equipment, mechanical equipment, base building systems and building automation systems communicated to one another during normal operation, fire/smoke emergency conditions and under other floor emergency conditions.

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

Danielle Passaglia: New construction office buildings allow for early studies and recommendations at the schematic design phase, which includes advocating for a well-sealed, strong-performing envelope and considering higher first-cost systems (like geothermal) paired with tax grants and state incentive programs. In existing buildings, especially with an entire building retrofit, providing comparisons between standard systems and more sustainable solutions with energy and cost comparisons or payback periods helps convince clients to go with more efficient solutions. Consultants also study and provide recommendations on ways to improve efficiency by updates to the sequence of operations and controls when total equipment replacement is not possible.

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

Danielle Passaglia: When tenants are occupying floors of a landlord building, the challenge comes with bridging the tenants’ requirements and wants with what is feasible within the base building design and the landlord’s requirements. Tenants are often more selective with where they choose to build out offices and are conducting site due diligence investigations before signing leases. New construction limitations and the motivation levels of the client are going to be the first cost. Consultants can recommend solutions that satisfy the client and design for future well-being. 80% of buildings today will still be around in 2050, so the challenge will be how to retrofit existing buildings for decarbonization, especially in heating-driven climates where existing equipment is not adaptable to lower water temperatures that newer technology provides and the added power demands of new electrified equipment.

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