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On-Site Audits vs. Virtual Assessments

Comparing tools for assessing conservation and efficiency potential.

Across the country, commercial energy efficiency is a growing area of focus as utilities seek ways to achieve new efficiency targets, meet demand without increasing capacity and deliver value-added services to customers. According to the Consortium of Energy Efficiency, U.S. utilities spent nearly $3 billion on commercial and industrial (C&I) efficiency programs, a number that has grown 26 percent per year since 2007.

Efficiency budgets are divided into several areas, including incentives to implement energy-reducing measures, marketing, program administration and subsidies to third party providers to deliver qualified leads. Building energy efficiency analysis underpins all of these processes to ensure efficiency programs effectively meet their objectives.

Understanding energy savings potential is critical for targeting the right customers; 35 percent of buildings account for 75 percent of the savings opportunities.

Energy assessments and audits can ensure that programs are properly designed, the highest-value customers participate, viable energy conservation measures are identified, and savings are verified. And, as the efficiency market becomes more competitive and targets become more difficult to achieve, optimizing building energy evaluation becomes critical to driving efficiency programs. Doing it effectively requires an understanding of the classes of energy analysis, when and how they should be used, and how to execute them at scale.

Evaluating Opportunities

There are two broad types of energy analysis, virtual energy assessments and on-site energy audits. A virtual energy assessment is an analysis of the energy efficiency opportunities in a building, or portfolio of buildings, that is conducted without ever going on site. Often, these are referred to as “no-touch” assessments because they require no contact with the building itself or its owners, managers or occupants.

On-site energy audits involve physical walkthroughs of a building, typically by a trained energy engineer or professional, to determine energy consuming characteristics and opportunities.

Virtual assessments and on-site audits can be compared to one another across a variety of dimensions. When comparing and contrasting these two tools, several key questions arise: At what stage(s) in my efficiency program do I use a virtual assessment versus an on-site audit? What data inputs do I need to collect or analyze to execute the evaluation? How much time does each require? What is the spectrum of tools available to help? What are the potential types of recommendations and outcomes can I expect from a virtual assessment versus an on-site audit?

Without an understanding of the current assets in a building, one can’t accurately determine the installed cost or energy savings of a particular measure. 

When developing virtual versus on-site strategies, various evaluation techniques can help to optimize efficiency program resources while also sufficiently meeting objectives. An energy efficiency program has several components to driving savings to individual customers. First, a certain set of customers must be targeted, then they must be engaged and converted, and finally the efficiency opportunities must be evaluated. 

At the target and engage stages, utilities and service providers must try to address many customers -- sometimes thousands or even hundreds of thousands. As such, a virtual assessment is necessary at this stage to gain insight into the potential opportunities at mass scale. Going to each customer or only providing audits to those that proactively ask for one, simply adds too much cost and time to the process. A high-quality virtual assessment can help determine a building’s savings potential and provide considerable insights to opportunities that exist within. Understanding energy savings potential is critical for targeting the right customers, as 35 percent of buildings within a utility portfolio typically account for about 75 percent of the savings opportunities. Knowing the possible opportunities beforehand allows organizations to better engage their customers with specific actionable insights about their buildings and move them to the next step.

Once the right buildings have been targeted and engaged, an on-site audit is required to more comprehensively evaluate savings opportunities. A professional energy engineer can properly collect data and assess its characteristics, assess feasibility, and then make the proper calculations to determine the cost-effective savings potential of various measures.

Data Inputs

At the core of energy efficiency evaluation is data, which allows organizations to identify and quantify opportunities. There are two types of data that can be leveraged during the process, either energy consumption information or building asset data -- which is specific information about the building itself, such as use-type, size and system details.

Utilities always have access to some form of consumption data, be it monthly or granular interval data -- i.e., consumption data in 15-minute or hourly increments -- but often no or limited access to asset data. Fortunately, when interval data is combined with analytics it can deliver significant insight about efficiency potential, in advance of an on-site audit. While many utilities have interval data for larger customers, the availability of interval data is increasing as a result of smart meter deployments throughout the country.

Spreadsheets can be used for most simple energy efficiency calculations, but they typically don’t take into account the interacting effects of a building’s systems.

Eventually, building asset data will need to be collected, particularly for any retrofits or capital measures. Without an understanding of the current assets in a building, one can’t accurately determine the installed cost or energy savings of a particular measure. For example, the payback of controls-based LED lighting must be compared to the current lighting in the building, such as T12s with no controls. Asset information can be collected either before doing a building walkthrough or during the on-site audit phase on buildings that have demonstrated good potential.

Virtual assessments and on-site audits differ considerably in terms of how long each takes. Virtual assessments can take as little as minutes, which is important when deciding which buildings to target over a large portfolio of buildings. On-site audits, on the other hand, can range from hours to weeks to even months. This variability stems from the types of recommendations being generated and the tools employed to execute the analysis. The analysis for both virtual assessments and on-site audits is driven in part or in whole by some sort of software technology, ranging from basic spreadsheets, to complex building-simulation software, to emerging sophisticated energy analytics.

During the virtual assessment phase, when pure consumption data is being analyzed, the options include energy analytic software and spreadsheets. Energy analytic software can automatically correlate consumption data to multiple weather variables and GIS data, as well as large data-sets of similar buildings performing efficiently. Highly trained engineers can replicate some of these simpler analyses in spreadsheets, albeit at a much slower place. Engineering calculations from on-site audits leveraging building asset data are typically executed in either spreadsheets, traditional energy modeling software, or new solutions that combine analytics with rapid energy modeling.

Traditional building energy modeling can generate a very accurate representation of building consumption, but it requires significant time and cost. 

Spreadsheets can be used for most simple energy efficiency calculations, such as lighting projects, and can be practical for estimating the energy savings of individual measures. Spreadsheets, however, typically don’t take into account the interacting effects of a building’s systems, such as how changing lighting equipment can influence heating and cooling savings opportunities, and can be complex and unwieldy when multiple measures are evaluated or advanced HVAC equipment is present.

Traditional building energy modeling can generate a very accurate representation of building consumption when used by a skilled professional, but it requires significant time and cost when used for an audit. This type of software is best reserved for certain situations that might arise during an investment grade audit (IGA) of a large, highly complex building. Software that combines energy data analytics with rapid modeling can be used for on-site audits and is able to accurately evaluate a wide variety of energy conservation measures. These tools help streamline data collection, make complex calculations of energy conservation measures (ECM), and automate the time-consuming reporting process.

Exceeding Goals

Before any energy evaluation is undertaken, those involved with the project should be able to answer a very simple question: “What type of recommendations and end results are we driving toward?”

The goal of a virtual assessment should be what we refer to as energy conservation indicators (ECI) -- insights about potential no- and low-cost operational opportunities, as well as capital improvements to investigate further. Examples of ECIs include reports that building systems are coming on too early and staying on too late relative to occupancy; that heating and cooling systems are operating simultaneously in the building; or that lighting, cooling, and ventilation systems are consuming too much energy, relative to a similar efficient building, along with the related data to support each report.

Thinking strategically about what tools to use will allow utilities to more effectively target and engage customers

On-site audits should deliver ECMs, which are implementable recommendations that have been evaluated to the point where a building owner can cost effectively invest in a specific retrofit. Such recommendations might also include utility program rebates and credits toward conservation and efficiency goals. Examples of ECMs include upgrading lighting fixtures and controls, installing variable-speed drives on chillers, or optimizing outdoor air strategies using demand controlled ventilation or economizers.

ECMs differ from ECIs in that feasibility has been completely assessed and financial paybacks have been calculated for ECM recommendations.

Virtual assessments and on-site audits both play a critical role in helping drive commercial energy efficiency programs. Thinking strategically about when to employ each type of evaluation and determine what data and tools to use in achieving conservation and efficiency goals will allow utilities to more effectively target and engage customers -- and drive deeper energy savings with each project. Ultimately, advanced analytics will help utilities meet and exceed increasing efficiency goals today and in the future.

ABOUT THE AUTHORS: Richard Huntley is vice president of sales at Retroficiency. Previously, he held executive positions at Vertex, Nexus Energy Software (now Aclara), and SPL WorldGroup (now Oracle). Hugh Gaasch is vice president of energy engineering at Retroficiency. Previously, he founded iEnergyData, and served as chief engineer, energy efficiency group at NSTAR.