Our solution reduced greenhouse gasses by 957 metric tons annually, equivalent to 201 cars.
Asset Facts
Date Built 1975
Square Feet 216,500
Asset Type Warehouse
Project Facts
Annual Energy Savings 1,387,718 kWh
Annual Cost Savings $142,963
Gross Investment $462,134
Rebates $109,837
Rebates as % of Total Project Cost 48.6
Net Investment $237,547
Net Payback 1.66 years
ROI: 60.2%
Energy Savings 70%
70% reduction total building electricity use
Aisle occupancy lighting controls reduced fixture runtimes by 50%
RTU conversion resulted in 44% reduction in unit electricity use
Overall fixture wattage reduced by over 60%
kWh Annually
Challenge
The Library of Congress Annex is a 216,500 ft² warehouse and storage facility located in Landover, Maryland, just outside of Washington, DC. GreenGen assessed the facility and identified areas to improve the overall energy efficiency of the building, targeting interior and exterior lighting, mechanical, and controls systems.
The existing rooftop units (RTUs) were operated on a binary on/off system, resulting in excessive use at times when building demand is less than full output
The primary source of lighting throughout the interior and exterior spaces in the facility were high-pressure sodium (HPS) high-bay and area fixtures
The interior fixtures are not controlled for space usage, but rather are often on in the frequently vacant storage aisles
Our Solution
This solutions package was awarded an MEA EmPOWER MD grant of $135,000 from the state of Maryland for energy savings projects resulting in total building electricity reduction of 20% or more. GreenGen coordinated all rebate capture activities with the local utility and the state of Maryland to secure funding for nearly 50% of the total project cost.
Installed controllers on the 14 RTUs, enabling power and output modulation with building demand
Replaced interior 100 W HPS high-bay fixtures with 53 W LED fixtures
Installed occupancy-based controls on the aisle and high-bay fixtures to limit runtimes to periods when the storage aisles are actually in use
Retrofitted exterior HPS fixtures with LED fixtures to reduce wattage by about 70%
