Northrop Grumman – Energy Audit, RCx

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Project Overview

The client is a leading global aerospace and defense company that provides services to government and commercial customers. This audit evaluated seven buildings and a central chiller plant encompassing over 1,586,000 square feet at the Northrop Grumman Space Park in California. Northrop Grumman desired to identify energy conservation measures (ECMs) in an effort to reduce greenhouse gas (GHG) emissions. Most of the easily identifiable or achievable GHG reduction projects were previously identified and implemented. The client sought further expertise to aggressively identify additional GHG reduction projects.

The Solution

Abraxas Energy Consulting performed an energy audit and retro-commissioning (RCx) feasibility assessment at the Northrop Grumman Space Park. Initially, a utility analysis was conducted on monthly submeter data to establish a baseline for energy usage at each facility. Twelve months of submeter data for electricity and natural gas were used to conduct the analysis. The generated baseline and utility costs were used to calculate potential energy savings. GHG emission reduction was calculated based on the energy savings in units of metric tons of CO2.
While on-site, engineers investigated each facility’s lighting and mechanical systems including HVAC, building controls, and process loads. During the investigation, relevant information on each facility’s existing condition was collected. The assessment included reviewing drawings, schedules, and nameplate data in addition to interviewing site personnel and observing energy-related equipment operation. A complete inventory of major energy-using HVAC equipment was collected and presented in the report.
A list of ECMs was generated that, when implemented, could reduce energy usage and cost, and GHG emissions. These energy saving measures were explained in a detailed report which included a description of the existing condition and measure description, in addition to associated installation costs, savings, simple paybacks, and GHG emission reduction. Utility rebates and incentives for ECMs were also investigated and included where applicable.


Abraxas identified 105 ECMs resulting in overall energy savings and reductions of GHG gas emissions. An estimated $1,617,379 in total incentive and rebate value was also found. Many capital measures were identified including replacing chillers and boilers with new higher efficiency units, upgrading clean room vacuums, and converting constant volume dual duct AHUs to VAV systems.
The RCx feasibility assessment also identified many easy to implement measures that should be included in a proper RCx study. These measures included repairing AHU economizers, revising control setpoints, installing VFDs on pumps and fan drives, and instituting new control strategies such as static pressure rests, supply air temperature resets, and demand control ventilation.
Additionally, several low-cost or no-cost related operation and maintenance (O&M) measures were also identified and included in the report. O&M measures included weatherizing entrance and exit doors, fixing control air leaks, replacing broken or loose exhaust fan drive belts, replacing dirty air filters, and cleaning a facility’s cool roof.


Abraxas identified 105 potential ECMs, although only 85 were prioritized for immediate implementation. Prioritized ECM savings totaled $2,606,098 and 11,541 metric tons of CO2 (GHG emission reduction). Implementation of the selected measures yields a 2.4 year simple payback before incentives. The list of ECMs was prioritized based on which measures could be implemented immediately, during the following year, or beyond. Some interactive effects were accounted for in the calculation of energy savings such that if a different implementation sequence is followed the savings realized will vary to a degree.

Total savings amounts to 22,866,649kWh per year in electricity, 872,251 Therms per year in natural gas, and 11,541 metric tons of CO2 per year. Total energy savings results in an 18% reduction in GHG emissions and a 16% reduction in energy cost. All values were evaluated using spreadsheet calculations and bin simulations based upon standard energy saving estimating methods and known and assumed operating conditions.