Walgreens Opens First Net-Zero Energy Retail Store

The Walgreens Company, a global retail pharmacy brand with over 8,000 stores, set out with a vision to create a showcase for innovative, sustainable, high-performance design at a retail location without altering the operational characteristics of the building in order to make it as highly-scalable as possible, and to share this information with the sustainability, architecture, and retail communities in a completely transparent fashion as a means of encouraging the adoption of green building practices wherever reasonably feasible.

The store is expected to achieve net-zero energy use by the U.S. Department of Energy’s most stringent standard (building footprint) at 200,000 kWh consumed and 220,000 kWh produced.  The store has already received the Illinois Chapter of ASHRAE Excellence in Engineering Award, and U.S. EPA Green Chill Platinum Certification.  Additionally the project is on track to earn USGBC LEED PlatinumGreen Globes and Living Building Challenge certifications.

The building is a showcase of innovation and technology not typically found in this format of store.  Getting to the point where the store operates at net-zero energy has been and will continue to be a long path that requires strong communication and collaboration between the Walgreens, designers, engineers, consultants and builders.

The number one Owner’s Project Requirement for the project was to achieve net-zero energy, the secondary requirement was to use an all natural refrigerant in major store systems.  Cyclone Energy Group’s role in the project as the Commissioning Authority provided Walgreens with an energy-focused owner’s advocate from concept through net-zero operations to ensure those two objectives would be met.   To accomplish these goals, Cyclone created a simulation model of the building using the Integrated Environmental Systems Virtual Environment (IES<VE>) software platform and updated that model at every decision making phase of the project, including in-operation.

“We knew going in that net-zero would not be easy to achieve,” Benjamin Skelton, President and Chief Executive Officer of  Cyclone Energy Group, said in a statement. “Chicago is not a typical net-zero climate as it offers relatively few annual hours where outside conditions allow for natural ventilation and free conditioning, and the climate is not a high return-on-investment for renewable energy.”

Skelton added: “we used energy modeling as a commissioning tool throughout the design/construction progress to validate and inform the team about the anticipated performance of the building.  Many options were rejected during value engineering because it would have compromised the buildings net-zero goal.  Using the IES<VE> tool during the start-up of the building allowed us to determine if systems were setup and configured for optimal operation.”

The store opened on November 21, 2013 and is in the final stages of tuning systems for optimal operation.  Walgreens is transparent about the performance of the store and created a live kiosk in the entry that displays realtime performance data on the buildings energy consumption, renewable energy production and how it’s tracking towards the net-zero goal.

About the Store

Gross Square Footage:  14,460
Opened:  11.21.13
Architect:  Camburas + Theodore
Engineer of Record:  WMA Consulting Engineers, Ltd.
Geo-exchange Engineer:  GI Energy
Sustainability Consultant:  WMA Sustainability Services
Commissioning Authority / Energy Consultant:  Cyclone Energy Group
Envelope / Refrigeration Energy Consultant:  Energy Center of Wisconsin

Walgreens Net-Zero Energy Facebook Community

Energy Efficiency

Minimized Plug Loads

Special efforts were made to discourage plug-in parasitic loads to allow for smaller HVAC equipment and minimized off-hour energy consumption. Walgreens incorporated over a dozen specialty time-of-day schedules into the power and lighting systems to de-energize when not needed.

All LED Lighting & Daylighting

Specialty LED fixtures were designed that provided a perfect light distribution across shelving allowing merchandising to eliminate the under-shelf LED lights found in typical stores.  The final designed building has an installed wattage of 0.89 W/SF compared to a typical store of 1.40 W/SF.  Daylight sensing zones were laid out in the general sales area allowing lighting to fluctuate between 100% and 20% power.  Final settings set the maximum closer to 65% on the dimming system provided by Schneider Electric.  Lighting systems consume 40% less energy annually than a typical store.

Automatic Shade Controls

Curtainwall on the West façade creates an open feel and a more transparent experience for customers.  The Lutronautomated shade controls were incorporated into the lower 16’ of fenestration which react automatically to solar flux.  The shades reduce HVAC peak loads and eliminate glare while allowing for a comfortable, diffuse lighting level.

Enhanced Envelope & Light Redirecting Glass

The prototypical store façade design was used to maintain brand but was provided with additional insulation levels.  Walls are R-20 and the roof is R-30.  High-performance curtainwall systems by Oldcastle with a center-of-glass performance of U-0.29 and SHGC-0.26 was incorporated.  Curtainwall glazing above 16’ has specialty light redirecting film by 3M applied.  The film redirects 80% of direct visible light up towards the ceiling and 20% towards the floor.  The film eliminates glare as well as redirects direct radiation to the stratified plenum zone.

Single-zone VAV Air Handling Units

A four-pipe Trane VAV dedicated outside air system (DOAS) and seven (7) 4-pipe Trane single-zone VAV air handling units were sized based on the reduced building load.  The DOAS unit provides ventilation to each space and allows for the single-zone VAV systems to module between 100% speed and 0% speed depending on space demand.  The DOAS also modulates ventilation based on CO2 levels in the retail spaces.

Triple-temp CO2 Heat Pump

The design team considered many cooling and heating plant options and ultimately settled on a transcritical, triple-temperature CO2 heat pump system that allowed refrigeration heat to be reclaimed for use by building HVAC and domestic hot water systems.  The single-package heat pump system provided by GI Energy and manufactured by Green and Cool serves the freezer, cooler and provides both heating and chilled water to the store HVAC systems.  Waste heat from the system also feeds a pre-heat tank for domestic hot water.  The system has a refrigeration gas-cooler but also uses eight (8) 500-foot deep geo-exchange wells to store heat for use during heating season.  The project has heating water, chilled water, condenser water and geo-exchange systems.  All systems have pumps with variable speed drives.

Cyclone Energy Group worked with Energy Center of Wisconsin to model this complex and very unique system.  Cyclone provided  Energy Center of Wisconsin with the building load profile from IES<VE> and ECW used the Trnsys simulation tool to model the geo-exchange and refrigeration system.  ECW then sent the profile for that combined system back to CEG and the final energy simulation was established.

Renewable Energy

The roof of the building is angled in optimal orientation for solar production.  SoCore Energy provided 849 micro-inverter photo voltaic panels.  SoCore estimates annual energy production could be 256,000 kWh.  Cyclone Energy Group’s estimates are closer to 220,000 kWh.  With either estimate, it produces more than the store is anticipated to consume in a typical year.

Two eight foot vertical blade wind turbines are located in the parking lot.  They are anticipated to produce in the order of 7,000 kwh annually, enough to offset fan energy in the store.

Indoor Air Quality

Natural Ventilation

The three-tiered roof incorporates operable clearstory glazing at each tier.  All operable glass has motorized actuators to allow for natural ventilation.  The operable windows can also be used during economizing conditions and for heat relief and pre-conditioning.


Triple-temp CO2 Heat Pump

The transcritical triple-temp CO2 heat pump system allows the store to use only natural refrigerants.  The design team had to go to Sweden to find equipment that could support the store loads.   Walgreens and the design team worked with the Swedish manufacture Green and Cool to customize the design of the system to support the store and the manufacture had to perform special UL certification to meet local codes.

Light Redirecting Film

Light redirecting film by 3M allows for 80% of direct daylight and radiation to be redirected to the stratified plenum space, saving HVAC energy, reducing glare and enhancing natural daylight penetration further into the store.  The remaining 20% continues on the original direct path.

Other Innovations

  • 256 kW Solar Photovoltaic Array (entire roof area)
  • Two vertical wind turbines
  • Two electric-vehicle charging stations

Operation & Maintenance

Measurement & Verification

A networked building automation system has been installed with Trane Controls to allow for remote control and monitoring by operations and 
maintenance personnel.  Because of the research oriented nature of the project, a highly detailed measurement & verification plan was designed to collect data once operational.  Electrical sub-metering was installed on all plug, lighting, HVAC and other systems.  Data will be gathered throughout the project and compared to modeled energy performance.  The data will be used to make adjustments necessary to ensure net-zero operation.  Furthermore, the data will serve as a tool when designing future stores.  A kiosk is located at the entrance to the store that shows the general public the real-time performance of the store.

Using IES<VE>, Cyclone Energy Group commissioned building systems using data collected through the automation system.


Commissioning was incorporated early in planning and design of the project.  An Owner’s Project Requirements document served as a tool to keep the design team focused on the primary objective of the project:  Net-Zero Energy Performance.  As a check, energy modeling updates were performed throughout the project, including start-up, functional testing and operation.  The Owner was involved with commissioning and the systems were tuned as needed to put the building on a path towards net-zero.

Cost Effectiveness

The project, being a research project and living laboratory for the retail design and operations community, incorporates innovating and cutting edge technology.  While the budget of the project is confidential, Walgreens has shared that it used a strategy of using marketing funds to offset the some of the additional construction costs.  As far as store operation, being net-zero energy, it is expected to be revenue generating.

Environmental Impact

ENERGY STAR Target Finder reports the store, without on-site generation, will have a site energy use intensity of 52 kBtu/ft2/yr and produces a total of 157 MtCO2e, over 55% better than the median retail store.  The average Chicago Walgreens store uses 450,000 kWh.  At a design of 200,000 kWh, Evanston Net-Zero is nearly 60% better.

With solar photovoltaic and on-site wind generation, the store is expected to surpass net-zero energy performance.  Walgreens is attempting to achieve net-zero energy production without including the wind turbines.

Annual Energy Use:                             200,000 kWh

Onsite Renewable Generation:         220,000 kWh

Total:                                                      – 20,000 kWh