Walgreens CO2 showcase at 2013 FMI Energy Store Development Conference

At the FMI Energy & Store Development Conference 2013 Walgreens presented its net zero energy retail store in Evanston Illinois, a showcase of innovative, sustainable and high-performance design that features carbon dioxide refrigeration for heating, cooling and refrigeration equipment. The project represents a number of firsts.

Walgreen’s first R744 refrigeration, heating and cooling system, is combined with geothermal, solar and wind energy systems in a building design that claims to be the first US retail application that will produce equal or greater energy than it uses. According to the FMI presentation ‘Executing a Net Zero Energy Design for Retail’, delivered by Rob Olden, CEM, Director of Engineering, North America, GI Energy, Walgreen’s mission statement for this project was to: “Create a showcase for innovative, sustainable, high-performance design at a retail location without altering the operational characteristics of the buildings in order to make it as highly-scalable as possible.”

Walgreens builds first US net zero energy retail store

Thanks to the 219,479 kWh generated by solar and wind power, the Evanston store, which it is estimated will require 200,571 kWh, will generate more electricity than it consumes, making it a net zero energy retail store.

Multifaceted modelling was used to design the pioneering building. This allowed envelop and load minimisation efforts to be identified, together with the most efficient systems for HVAC, refrigeration and lighting. Load reduction efforts include using a revolving door at entry, daylight harvesting and shading controls.

CO₂ refrigeration and geothermal energy yield 2.5 times cooling efficiency

For HVAC and refrigeration the analysis showed that a central CO₂ plant would be the best system to install. The system selected, features uses a CO₂ compressor pack sourced from Sweden and exceeds standard R410 capacity output temperatures so coils can be smaller. It also operates at high delta T, which means low flow rates and lower pumping energy. Moreover, it enables “hybrid” geothermal design by displacing heat to the gas cooler.

Coupled with geothermal energy, which provides a stable and moderate heat source and sink, the vapour compression technology yields 2.5 times efficiency in cooling and 5 times efficiency in heating.

The integration of transcritical CO₂ with geothermal expands the applicability of transcritical systems to warmer climates. The earth is much cooler than the outside air thereby producing a higher efficiency for CO₂ systems. It also enables the application of significant geothermal based tax credits and incentives, thereby reducing the overall premium," said Rob Olden, Director of Engineering, GI Energy.

The CO₂ plant supplies the following:

Heat load
Cooling load high temperature (HT)
Cooler load medium temperature (MT)
Freezer load low temperature (LT)
Domestic hot water (DHW) load
Heat reclaim to building loop and geothermal field

Solar photo voltaic and wind turbine design

Over 800 265W solar panels and two 2000W wind turbines supply the store’s energy. The store is designed to maximise roof space for the solar panels, whilst the micro wind turbines are situated in the car park.

It is estimated that the 30 feet tall (9.1m) turbines, will benefit from Chicago’s reputation as the “windy city” and generate around 7,200 kWh, and, despite the city’s partly cloudy skies, the solar panels will generate 212,260 kWh.

Background

The new store, which is scheduled to open in November, will replace an existing Walgreens at 365 Chicago Avenue.

In order to make the project a reality, Walgreens engineers worked with the city of Evanston and vendors, including Trane, CREE Lighting, Acuity Lighting, Cooper Lighting, CalStar Products, GE Lighting, Geothermal International, SoCore Energy (Photo voltaic design), CTA group (refrigeration) Wing Power (wind turbines) and Camburas and Theodore Architects.