ASHRAE Headquarters - Net-Zero Energy Building Design


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From a simulation-aided design perspective, there are many innovative categories worth highlighting for the new ASHRAE Headquarters building in Atlanta, GA.

Key Facts

  • An All-Electric Design and Net-Zero Energy Building
  • Exceptional Daylight Performance (Spatial Daylight Autonomy sDA)
  • Load Calculations using the ASHRAE Heat Balance Method
  • Adaptive Thermal Comfort for Occupants using ASHRAE Standard 55
  • Common Dedicated Outside Air System for Dehumidification and Zonal Radiant Systems
  • Demand Controlled Ventilation and Displacement Ventilation

ASHRAE are one of the foremost industry pioneers in the decarbonization of the built environment and their new global Headquarters building in Atlanta, renovated to operate as a net-zero-energy (NZE) building, is testament to this. The project design team, which includes IESVE users, Integral Group, employed a range of innovative design strategies to achieve this net-zero energy ready building.

Subsequent building performance analysis from a group of ASHRAE Technical Committee 4.1 Members, including IES’ Liam Buckley, highlighted some of the simulation-aided design analysis on this ASHRAE Headquarters building. The following overview summarizes the many innovative categories worth highlighting from the project, in which an IESVE building performance model was able to support.

(1)   Net-Zero Energy Building

ASHRAE’s new headquarters is designed to operate as an all-electric at Net-Zero Energy (NZE) building, thanks to the installation of a 332-kW photovoltaic (PV) system. The PV system is a combination of three sub-arrays, which are sub-metered in the Building Energy Model shown below:

  • 187 kW ballasted rooftop array on east & west wings
  • 65 kW ground mount on a south-facing hill adjacent to the building
  • 81 kW ground mount situated in an unused section of a car parking area

(2)   Simulation throughout Design Phases

Thanks to the PV installation, a limiting Energy Use Intensity (EUI) of 21 kBtu/ft2 was targeted for this existing building refurbishment.  Iterative design options throughout the design phases resulted in a range of low-energy solutions. These include:  

  • A reconfigured window-to-wall ratio (WWR) and 18 new skylights.
  • Common Dedicated Outdoor Air Systems (DOAS) for outdoor air ventilation, coupled with enthalpy heat recovery.
  • Radiant panels and Ceiling Fans.
  • Demand Control Ventilation (DCV) in high occupancy spaces and Displacement Ventilation (DV).

Six water source-heat pumps (WSHPs)

(3)   Optimized Load Calculations using the ASHRAE Heat Balance Method

For over 20 years, ASHRAE has recommended the Heat Balance (HB) Method as the preferred method for calculating heating & cooling loads. With such a low-energy target in mind, a considerate zoning strategy and accurate load calculations are very important.  Included in the load’s analysis:

  • Horizontal and vertical solar shading on most windows.
  • Sensible Loads analysis at the zone and Latent Loads Analysis at the AHU.
  • Heat gains from the reversible ceiling fans.
  • Analysis of Adaptive Thermal Comfort for Occupants and Operative Temperature.

(4)   Exceptional Daylight Performance (Spatial Daylight Autonomy, sDA)

Of the many daylighting metrics available, Spatial Daylight Autonomy (sDA) likely best considers the annual sufficiency of indoor daylight levels. In the in regularly occupied spaces of the ASHRAE HQ, the working plane analysis areas are considered for sDA, for the percentage that meets a minimum illuminance level of 300 lux, for 50% of the operational hours per year. The 18 new skylights provide an exceptional daylight performance, which is especially impressive considering the simultaneous requirements from a thermal/energy perspective


Founded in 1894, ASHRAE is a global professional society committed to serve humanity by advancing the arts and sciences of heating ventilation, air conditioning, refrigeration and their allied fields.  ASHRAE recently launched a Task Force for Building Decarbonization (TFBD), so they continue to demonstrate leadership and promote the organization’s mission.

To learn more about ASHRAE’s state-of-the-art, high-performing net-zero-energy efficient global headquarters building, go to and

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