The Federal Energy Management Program’s Building Re-tuning Simulator (BRS) is a no-cost, web-based tool that provides users a simulated approach to estimate energy, cost, and CO₂ emissions savings from implementing various Re-tuning™ measures. Users create a simplified building model that estimates energy savings, cost savings and CO₂ reduction from selected simulations using the available heating, ventilation, and air conditioning (HVAC) control measures, operations and maintenance (O&M) measures, and capital project measures.

Overview

Facility managers often find themselves in the position of addressing occupant comfort demands while also meeting energy efficiency and carbon reduction goals. Re-tuning is applicable for facilities with building automation systems and minimal existing building commissioning needs (recommissioning or retro-commissioning). Re-tuning is a systematic process aimed at minimizing building energy consumption by identifying and correcting operational problems that plague buildings. Because federal buildings account for nearly 60% of the energy used in the United States, Re-tuning presents a significant opportunity to optimize buildings to save energy and reduce CO₂ emissions. Re-tuning measures are based on the following four basic principles:

• If you don’t need it, turn it off
• If you don’t need it at full power, turn it down
• Mitigate simultaneous heating and cooling
• Reduce infiltration and unnecessary outdoor air supply

This re-tuning approach has been successfully implemented at federal sites with the following outcomes:

• Building energy savings ranging from 5 to 25%
• Energy cost savings on the order of $0.185/square foot-year with a corresponding simple payback of 0.3–3.5 years
• Improved thermal comfort through correction of faults and making airside systems responsive to specific zone demands.

The re-tuning results above were achieved by teams of re-tuning technicians visiting sites. The BRS gives on-site staff the ability to simulate their buildings and determine which measure(s) merit consideration for implementation.

BRS Framework

The BRS breaks down the re-tuning process into broad sections called modules. Each module has several action steps that lead users through planning and preparation, data collection, building and equipment modeling, and simulation of re-tuning measures.

There are three steps that should be taken before using the BRS, as follows:

1. Screen the building to determine if it is a good re-tuning candidate. This can be done by completing the Re-tuning Candidate Checklist.
2. Identify staff that will be able to provide building-specific knowledge support for the HVAC systems, controls, and building operating requirements. Staff supporting the BRS and re-tuning processes may include the building manager, energy manager, O&M contractor, and controls technicians/contractor.
3. Review the BRS databook before entering into the BRS tool to determine availability of the building, equipment, and operations data needed to complete the BRS modeling.

While the BRS modules are focused on the specific steps and documentation required to move through the re-tuning process, a list of associated resources is provided to allow users the opportunity to explore topics of interest in greater depth, including methodology and FAQs.

The primary benefit of using the BRS is users are provided a way to estimate the energy, cost, and CO₂ impacts of various re-tuning control measures via simulation. This allows users to test control settings and prioritize solutions for implementation.

Uses and Limitations

The BRS has been developed for application in buildings with a building automation system (with trending capability at a minimum). In addition, the building controls and controlled components must be operating properly. It is important to remember that the BRS is not:

• An add-on to the building automation system. The BRS is a stand-alone tool that allows users to simulate responses to user-selected re-tuning measures for their modeled building
• An automated decision system that provides users re-tuning recommendations.

Instead, the BRS is a tool that develops estimates of energy use and savings for the user-selected re-tuning measures based on simulations. Selection and actual in-field implementation of the re-tuning measures is done separately by the site, and the savings outcomes are not guaranteed.