The Difference Between ASHRAE Level 1, 2 & 3 Energy Audits
(And What to do with that Information … Energy Management for Your Building or Portfolio, Part 1)
Originally I wrote and posted this article in 2010, and this is an update with new information. Next month I will post a prequel to this article, just like Star Wars! That next article will help building owners and portfolio managers plot a course to achieving long-term performance improvements.
It still stands that not all energy audits are the same. Understanding the differences in level of effort and classification will help you get the most from your investment in energy efficiency.
Energy audits vary in depth, depending on the configuration of the building energy systems, the project parameters set by the client, and the scope and capabilities offered by the energy auditor. Because it usually is not possible to know where the audit process will lead and what level of effort will be most cost effective, ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) has defined three progressive levels, or types, of audits.
The Level-1 audit start with a simple assessment of the five main building energy systems: lighting, environmental (ventilation, air conditioning, heating), water heating, the building envelope, and “plug” or “process” loads . Once that is complete and digested, the intent of the “levels” is to move to more detailed audits if there are systems that need deeper analysis.
Following this approach allows the building owner to take an informed approach to capital investing based on that information. That will be the subject of the next post, the sequel, where we learn about the real identity of Darth Vader!
ASHRAE Level 1 – walk-through analysis/preliminary audit
The Level 1 audit alternatively is called a “simple audit”, “screening audit” or “walk-through audit” and is the basic starting point for building energy optimization. It involves brief interviews with site operating personnel, a review of the facility’s utility bills and other operating data, and an abbreviated walk-through of the building. The ASHRAE Level-1 audit is geared toward understanding the general building configuration, and defining the type and nature of energy systems, and then identification of potential for energy improvements.
The audit should result in a preliminary, high-level, energy-use analysis for the entire facility, and a short report detailing the findings, which may include identifying a variety of efficiency opportunities, or energy efficiency measures (EEM’s). This report can provide detailed recommendations for straightforward measures, like a lighting upgrade, and also may identify some very visible projects or operational faults (like turning off the lights during the day).
The ASHRAE Level-1 audit is intended to help the energy team understand where the building performs relative to its peers; establish a baseline for measuring improvements; deciding whether further evaluation is warranted; and if so, where and how to focus that effort. The Level-1 also will outline the range of potential financial incentives available from Federal, State, Local, and Utility sources.
We include an ASHRAE Level-1 Assessment as part of all of our solar-energy projects.
ASHRAE Level 2 – Energy Survey and Analysis
The next step for most facilities is the ASHRAE Level-2 audit. The Level-2 project starts with the findings of the Level-1 audit, and evaluates the building energy systems in detail to define a variety of potential energy-efficiency improvements. This should include the Building Envelope, Lighting, Heating, Ventilation, and Air Conditioning (HVAC), Domestic Hot Water (DHW), Plug Loads, and Compressed Air and Process Uses (for manufacturing, service, or processing facilities). This study starts with a detailed analysis of energy consumption to quantify base loads, seasonal variation, and effective energy costs. From there, the study should include an evaluation of lighting, air quality, temperature, ventilation, humidity, and other conditions that may affect energy performance and occupant comfort. The process also includes detailed discussions with the building Ownership, Management, and Occupants to explore potential problem areas, and clarify financial and non-financial goals of the program.
The Level-2 audit should result in a clear and concise report and briefing with the Owner and Management Team describing a variety of EEMs including no- and low-cost measures, modifications to system controls and building automation, operational changes, and potential capital upgrades. The findings should include general costs and performance metrics, as well as a means for the Owner to evaluate the EEMs and decide how to proceed with implementation.
Many of the EEMs revealed during the ASHRAE Level-2 audit can be implemented quickly with fast financial payback for the Owner. Other EEMs will require more detailed analysis of benefit and cost and the other goals that are important to the Owner. The audit should define next steps to accomplish this analysis and decision making. Sometimes it is through discussion with manufacturers or suppliers or other relatively simple means. For other EEMs, involving complex interaction among building systems and potentially large financial investments, it may be necessary to dig deeper into the building operation and also the human factors influencing performance. This is where the ASHRAE Level-3 audit becomes essential.
ASHRAE Level 3 – detailed analysis of capital intensive modifications
Some of the system upgrades or retrofits revealed by the Level-2 audit may require significant investments of capital, personnel, and other limited resources. Before making this level of investment, the Owner will want to have a much more thorough and detailed understanding of the benefits, costs, and performance expectations. This is the purpose of the “investment-grade” Level-3 ASHRAE audit. There may be only a few capital-intensive EEMs exposed by the Level-2 audit, or there may be dozens for larger facilities. Investment levels can range from tens of thousands to tens of millions of dollars. In most cases, since this cannot be clearly determined or accurately estimated in advance, the recommendation and scope definition for a Level-3 audit usually is an outcome of the Level-2 process. And that is why a building owner should start with a Level-1 and move upward from there as needed.
The ASHRAE Level-3 audit focuses on a “whole-building computer simulation”. This computer model is used to very accurately simulate the way the brick-and-mortar building would respond to changes in the energy systems, whether those are major HVAC retrofits or architectural modifications to walls, windows, and roof. The ASHRAE Level-3 audit involves much more detailed data collection over the course of weeks or months. Data loggers typically will be placed temporarily to monitor the operation of pumps and motors, temperatures of affected spaces, lighting levels, switching behavior, and other factors. These data are used to calibrate the computer model of the facility, so that the computer model responds to inputs and changes the same way the building could be expected to respond in the real world. This calibration is checked and validated by simulating a year or more of past, minute-by-minute climate conditions to see if power and energy usage in the model mirrors actual energy power and energy usage.
Once the three-dimensional computer model is responding like the real building, changes to energy systems can be simulated with very accurate results. Combining that process with construction-grade cost estimating supports informed investment decisions. In other words, the cost estimating provides the cash-out part of the financial model, and the audit provides the offsetting cash-in part. Together they will be used to calculate Internal Rate of Return (IRR), straight-line payback, improvement to cap rate, or other factors that are factual and meaningful to the owner’s team.
The table below summarizes each level.
| Type of Audit | Highlights |
|---|---|
| Level 1 | Rapid assessment of building energy systems; Creating an energy benchmark; High-level definition of energy system optimization opportunities; Outline applicable incentive programs |
| Level 2 | Detailed building survey of systems and operations; Breakdown of energy source and end use; Identification of EEMs for each energy system; Range of savings and costs for the EEMs; Spotlight on Operational Discrepancies; Outlining priorities for limited resources, next steps, and identification of EEMs requiring more thorough data collection and analysis (ASHRAE Level-3) |
| Level 3 | Longer term data collection and analysis; Whole-building computer simulation calibrated with field data; Accurate modeling of EEMs and power/energy response; Bid-level construction cost estimating; Investment-grade, decision-making support |
Before beginning an energy audit for a building or portfolio of buildings, we recommend a preliminary energy-use analysis to compare the Energy Usage Index (EUI) of each building with the national average and to identify both high and low energy performers. This usually is done using the Energy Star Portfolio Manager ® benchmarking tool. This analysis requires access to energy consumption and cost data for the last 12-36 months. Once this “benchmarking” analysis is completed a recommendation is made as to which buildings should be audited first and the type of audits to be carried out.
