The Building Re-tuning Simulator (BRS) is a free, easy to use, online tool that helps identify low-cost and no-cost re-tuning measures. The BRS allows users to create a simplified building model that estimates energy and cost savings from selected measures using the available heating, ventilation, and air conditioning control measures, operations and maintenance measures, and capital project measures.

Overview

Facility managers often find themselves in the position of addressing occupant comfort demands while also meeting energy efficiency goals. Re-tuning is applicable for facilities with building automation systems (BAS) and minimal existing building commissioning needs (recommissioning or retro-commissioning).

Re-tuning is a data-driven process of improving control of existing building energy systems, centered on the BAS, through the application of four key 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

These four key principles are embodied in a few dozen best-practice re-tuning measures that aim to minimize building energy consumption by identifying and correcting operational problems that plague buildings. 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 with a simple payback of less than 3.5 years
• Identification and correction of operations and maintenance (O&M) issues
• 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:

1. Screen the building to determine if it is a good candidate for re-tuning. 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 that users are provided a way to estimate the energy and cost impacts of various re-tuning control measures via simulation. This allows users to test control settings and prioritize solutions for implementation.

Using the BRS

The recommended steps for using the BRS are as follows:

1. Select a building for re-tuning
2. Collect assessment-level information, such as utility data, building and system details, etc.
3. Create a baseline BRS model
4. Calibrate the baseline model
5. Use the re-tuning dashboard to identify measures and simulate the models individually or as part of a package to estimate savings impact
6. Review the savings table to compare results to the baseline model and evaluate savings by measure and fuel type

Uses and Limitations

The BRS has been developed for application in buildings with a BAS (with trending capability at a minimum). In addition, the building controls and controlled components must be operating properly. The BRS is not an add-on to the BAS and does not implement re-tuning measures. Instead, the BRS is a standalone tool that allows users to simulate re-tuning measures for their modeled building and provides estimates of energy use and savings based on the simulations. Selection and actual in-field implementation of the re-tuning measures must be done separately by the site personnel, and the savings outcomes are not guaranteed.