Net Zero Design Offers Example for Sustainable Living

It’s been two years since the November 2013 completion of Walgreens Net Zero energy store in Evanston just north of Chicago and the building has achieved many accolades including platinum LEED certification in addition to designation as a net zero building and as of December 2015 has the distinction of being the only net zero retail store in the nation.
Net zero status is reserved for buildings not dependent on energy from the grid and in the case of the Evanston Walgreens create more energy than it uses the excess of which which is fed back into the grid. The building notable for it’s two vertical wind turbines in front of the store and also boasts an electric car chargers and a air pump and bicycle station.
Less noticeable than the 35 foot wind turbines are 850 solar panels on the rooftop and a geothermal system which required drilling 550 feet into the ground which provides both heating and cooing to the building. A look inside the building reveals the effective use of daylight harvesting and LED lighting and in addition makes use of carbon dioxide for heating, cooling and refrigeration equipment. A flat screen near the front entrance reveals energy generation and usage along with real time weather information from the micro weather station installed in the building.
Unique to the store is the use of the carbon dioxide heat pump system that sends waste heat that would typically be expelled from the building into storage below ground in the geothermal system. This stored heat can in turn be utilized for heating when needed. The refrigeration system also dispenses with commonly used halocarbon system and instead uses Carbon Dioxide system and represents one of the first large scale deployments of this approach nationally. This means that the system is completely free of hydroflorocarbons that have the effect of depleting the ozone layer. The system itself also provided both chilled and heated water in addition to maintaining both the freezer and cooler. Also integral to the system are an air cooled gas cooler and a variable air volume air handling unit which provides the store with ventilation.
It should be noted that the store did not always achieve net zero energy levels and having been completed in November of 2013 just before the record breaking cold of the 2014 winter required grid energy for the first several months in operation. As a greater understanding of the HVAC and energy systems has led to improved performance throughout 2015 as the system has been tweaked and adjusted and over the past two years, greater levels of efficiency have been reached by examining the system in operation and upgrading the system when necessary.
While it’s clear that this type of store had a huge upfront cost that would limit the accessibility of deploying all if these technologies on this scale, all of what has been actualized can be applied to a certain degree on new constructions and retrofitted into buildings everywhere. We give credit to Walgreens for showing us the possible and putting into application the promise of the best of all possible worlds. While this currently stands as the nations only net zero retail store we hope to soon see other examples like this in coming years as this store serves as a showcase of 21st century building technology at it’s best.