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Saving Energy

Wal-Mart Stores’ ongoing quest to reduce its energy consumption and enhance its sustainability will take another leap forward with the installation of new, high-efficiency packaged rooftop units. The chain expects to start installing the equipment during the third quarter of this year.

“Reducing energy usage is an essential part of our sustainability initiatives, and these new, cutting-edge, high-efficiency units will help us meet those goals,” said Jim McClendon, chief engineer, prototype and new format development, Wal-Mart Stores, Bentonville, Ark.

The new units, which are built to maximize efficiency and reduce energy usage, were developed by Lennox Industries, Dallas, in cooperation with Wal-Mart. The equipment is specifically designed to achieve a high level of energy efficiency during part-load operation, which typically accounts for a majority of the operating hours of HVAC units in a retail store.

“In addition to maximizing efficiency at the high end when the units run full capacity, we also maximized efficiency at reduced capacity, which is something that most HVAC manufacturers have not focused on,” said Mike Walker, Lennox Commercial product manager.

Energy Expenditures


Energy expenditures are expected to…over the next year Source: Chain Store Age/Leo J. Shapiro & Associates
  All stores 2007 Drug store 2007 Supermarket 2007 Department store 2007 Home Center 2007 Specialty apparel 2007 Big-box store 2007 Hard lines specialty 2007
  Increase 57.3% 37.5% 68.2% 55.6% 66.7% 52.2% 56.3% 50.0%
  Decrease 8.3 0.0 9.1 33.3 0.0 8.7 6.3 0.0
  The same 28.1 62.5 18.2 0.0 25.0 30.4 37.5 33.3
  Not reporting 6.3 0.0 4.5 11.1 8.3 8.7 0.0 16.7
Average energy cost per square foot (mean dollars) $1.73 $1.33 $2.72 $1.75 $1.05 $1.97 $1.30 $1.50
Average percent of total sales spent on energy costs 0.8% 0.4% 1.0% 0.9% 0.6% 1.1% 0.8% 0.2%

The energy-efficiency performance of the rooftop unit surpasses current efficiency requirements as set by the United States and Canada. It also is above the stricter energy-efficiency standards set to take effect in the two countries during the next few years.

“In payback-analysis simulations, we are in excess of 30% efficiency when we run these units against standard efficient equipment,” Walker said.

The new units are intended for both new construction and retrofits, and it is expected that Wal-Mart (as well as other retailers) will use them in both scenarios.

“There is a lot of old equipment out there,” Walker said, “and the difference in efficiency from replacing those older units with this unit will be significant.”

The new units feature an intelligent unit control system that reduces the total cost of ownership by speeding up and simplifying maintenance and installation activities. The control system aids in reliability by monitoring and controlling unit performance.

© 2014