Commercial Buildings

BCBC Part 3

Commercial Building Energy Audits - ASHRAE Levels 1, 2, & 3


Auditing your building’s energy usage is the first step to building a solid plan for improving energy efficiency.
Without an energy audit, you may be spending money on projects you think are improving your building’s energy efficiency but that, in reality, aren’t really moving the needle that much.
The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) outlines three different levels of energy audits. The audit levels differ based on how intensive they are and what type of outcome you can expect.

A commercial building energy analysis can generally be classified into the following three levels of effort:

Take some time to learn about each audit level before deciding whether you need an ASHRAE Level 1, Level 2, or Level 3 energy audit for your building.

Level 1—Walk-Through Survey

The ASHRAE Level 1 audit is also called a simple audit, a screening audit, or a walk-through audit. This is a basic audit of a building. It includes brief interviews with the facility staff, a review of utility bills and other relevant operating data, and a limited walkthrough of the building surveying its systems and operations. The ASHRAE Level 1 audit identifies high-level opportunities for energy and cost savings. A report provides potential no-cost and low-cost energy conservation measures, a summary of utility data, and potential capital improvements that warrant further consideration. The report is a tool that building owners can use to determine how well the building is performing and serves as a baseline for measuring future improvements. It can also guide building owners on how best to prioritize energy-efficient projects or if further evaluation is needed.

Level 2—Energy Survey Analysis

The ASHRAE Level 2 audit can include the findings of a previous ASHRAE Level 1 audit, and it is a more detailed analysis of the building and its energy use. A Level 2 energy audit will identify and provide savings and cost analysis of all practical measures that meet the owner’s constraints and economic criteria.  Key facility staff is interviewed in-depth to gain a better understanding of the operational strategies and any existing problem areas in the building systems. Architectural, mechanical, electrical, and control drawings are reviewed. A detailed energy report is provided that includes energy usage patterns, recommended energy efficiency measures and corresponding economics, and implementation guidelines. Research is also done to determine available utility rebates and incentives that are applicable for the suggested efficiency measures and an economic analysis is performed based on simple payback. This level of detail and financial analysis in an ASHRAE Level 2 audit provides sufficient information for facility staff to justify energy-efficient project implementation.

Level 3—Detailed Analysis of Capital Intensive Modifications

An ASHRAE Leve 3 audit is also known as an Investment Grade Audit. This is the most detailed and rigorous of the audits and the engineering analysis of this audit focuses on the capital-intensive projects identified in an ASHRAE Level 2 audit. Utility data is supplemented with monitoring data. Data from the building automation system or from data loggers may be used to collect detailed information from major energy-consuming systems during an expanded time of weeks or months. This data is used to create a whole building model simulation, where a computer simulation models the way a building would operate before and after the energy efficiency measures or major capital projects were implemented. Building owners can use this expanded level of detail to feel confident in determining where to make major capital improvements.

Preliminary Energy-Use Analysis (PEA)

The PEA precedes an audit of the building. During the PEA the analyst analyzes the historic utility use, peak demand, and cost; develops the Energy Cost Index (ECI) of the building (expressed in dollars per floor area per year), and develops the Energy Utilization Index (EUI) of the building (expressed in kBtu/ft2 [MJ/m2] per year).

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