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Efficiency Bid® - General Calculation Guidelines

To facilitate a quick and efficient program process, it is necessary to have the bid properly completed with justified savings calculations attached for each project measure.

Preparation Basics

When preparing a bid summary, assume that the individual reviewing your application, while having a technical background in energy efficiency, will not have direct knowledge of your specific application. The description(s) you provide should contain sufficient detail to enable the reviewer to understand the processes involved, the proposed savings measure and how the measure will achieve the stated savings. To facilitate the review process:

• Break up calculations and associated descriptions into smaller steps, which will make the thought process easier to follow
• Fully describe simulations/software used
• Attach (and be able to electronically submit) printouts/reports summarizing the inputs and results of simulations or other software used in preparing the calculation(s)
• Attach any manufacturer's data, production data and/or other documentation that supports the inputs and assumptions used in calculations or descriptions. Spot measurements of load, whether in kW or amps, under realistic operating conditions are preferred over assumed loads and/or use of manufacturer's design values

Preparing and documenting your savings estimate can be further divided into four steps:

Step 1. Process / Measure Description

The importance of providing a detailed description of the process and associated energy-saving measure cannot be overstated since it provides the reviewer with the necessary background information to understand the calculations that follow. The measure description should be divided into three sections:

1. Existing process/equipment
2. Proposed new equipment retrofit or enhancement
3. Resultant equipment and/or process (post installation)

In each section, include sufficient information on the process and equipment involved so that it will be clear to the reviewer how the proposed measure will be implemented and how it will achieve the stated savings. For instance, if energy savings will be achieved using an energy management system that implements a new control strategy, provide a complete description of the energy management system, the existing and proposed control strategies, and the controlled equipment.

Step 2. Establish Baseline Annual Energy Use

The Efficiency Bid program provides incentives to Sponsors who install equipment/improvements that go beyond standard efficiency or baseline equipment. Standard efficiency refers to equipment that meets either state/federal efficiency requirements or current industry practice. Baseline energy use is established using accepted standards for currently available equipment. For instance, the Energy Policy Act of 1992 established federal guidelines for electric motor efficiency.

The equation used for baseline energy use calculation is:

It may be necessary to develop a table of equipment loads and the annual operating hours at each load to arrive at an annual energy use estimate. The table should accompany the sponsor's bid.

Baseline energy use calculation is critical to the savings calculation; therefore, the calculation and associated description must provide sufficient information on the process, equipment and applicable standards to justify the proposed baseline energy use. In many instances, the baseline energy use will coincide with the energy use of the existing equipment/process prior to implementation of the savings measure. However, this will not always be the case since existing equipment may not comply with currently accepted efficiency standards.

To obtain the baseline value, it may be necessary to adjust the energy use estimate for the existing equipment to account for standard equipment efficiency. For example, a sponsor who proposes to replace an existing 50-horsepower motor with a nominal full-load efficiency of 90.2 percent, with a premium efficiency motor having an efficiency of 94.1 percent, must establish the baseline energy using the accepted standard motor efficiency. In this case, the previously mentioned Energy Policy Act of 1992 guideline for a 50-horsepower motor is 93 percent; therefore, the baseline energy use of the existing motor must be calculated based on the higher 93 percent efficiency value, which reduces the baseline (and associated savings) value.

Step 3. Establish Post-Installation Annual Energy Use

The equation used for the post-installation energy use calculation is essentially the same as for the baseline calculation.

It may be necessary to develop a table of equipment loads and the annual operating hours at each load to arrive at an annual energy use estimate. The table should accompany the sponsor's bid.

Post-installation calculation is based on projected performance of the new equipment or process. Use of simulation software such as eQUEST or another DOE2-based software package is acceptable as long as the inputs and associated assumptions (if any) are clearly stated and can be verified. Use of a manufacturer-specific simulation product may be acceptable but will require additional information on the underlying principles used by the software. The description submitted must provide sufficient detail so that the application reviewer will understand the basis for the projection. If deemed necessary, the reviewer may substitute an alternative method of estimating the post-installation energy use.

Step 4. Calculate Energy Savings

Once the baseline and post-installation annual energy use estimates are completed, the savings estimate is the difference between the annual baseline and post-installation estimates.