The objectives of energy audits are to identify and develop measures that will reduce the energy use and carbon footprint of buildings, along with reductions in the cost of operating a building and/or improve the indoor environmental quality experience for the occupants. The results need to be presented in a format that will provide complete information needed by an owner/operator to decide whether or not to implement the recommended measures.

As a general overview, the energy audit of each building should include the following process:

1. Collect and analyze historical energy use.

2. Study the building and gather data on its operational characteristics and indoor environmental quality utilizing ASHRAE Standard 211-2018 (RA2023)

3. Identify potential measures that will reduce energy use and/or cost, and/or will improve the occupants’ indoor environmental quality.

4. Perform an engineering and economic analysis of potential modifications.

5. Prepare a report to document the energy audit, including the analysis process and results.

6. Prepare a report of appropriate and applicable energy reduction measures, and group measures into bundles that will capitalize on potential synergies and cost reductions.

The energy audit may also include additional steps to satisfy specific requirements.

Energy Audits Best Practices

Using a team approach is the best way to ensure that an energy audit results in recommendations that can be implemented at each site and have been customized to each building’s conditions, needs and preferences by its owner/operator. By involving site representatives, the audit takes advantage of each team member’s strengths. By actively involving building staff, for example, the process will ensure that their concerns are heard, their observations about the building add value, and those who will maintain the building are familiar with recommended equipment and controls.

A building’s energy audit needs to provide sufficient information to the owner/operator and/or manager of a site in order to understand the energy use characteristics of the building. This analysis breaks down the total energy use and cost for the facility into various end uses, such as heating, air conditioning, lighting, etc., and shows the potential for energy and cost savings for each end-use.

The engineering analysis needs to also provide the owner/operator with all the information needed to allocate necessary resources to reduce the building’s energy use and/or cost. This includes outlining any changes in the facility’s operation and maintenance (O&M), including different personnel requirements, as well as presenting an economic analysis of any capital improvement projects.

The overall engineering analysis needs to follow a systematic approach in identifying, selecting, ranking, and grouping recommended measures for reducing the energy use and carbon footprint of buildings.

Energy Audits Should Use the Following 4 Steps:

1. Preliminary Energy Use Analysis

• Historical Utility Data

  • Analyzing historical utility data and preliminary building information will provide important insight into current building operation, energy end uses, and performance. This will help in determining if an engineering study and analysis are likely to produce significant energy savings.

• Energy End-Use and Cost Allocation

  • Building energy end-use categories should be created for both electric and natural gas uses. These categories will include the following: space cooling, fans, pumps, interior lighting, exterior lighting, plug and process loads, space heating, domestic hot water (DHW), and other specific equipment such as refrigeration systems, kitchen appliances, and swimming pools. Energy use and demand is allocated to each category based on either a whole-building energy model or a simplified method that uses the size of the equipment in the building and its operating hours. With either method, the total energy and costs associated with the building equipment should be within 5% to 10% of the utility data.

  • Utility data disaggregation creates energy and demand baselines for each energy end-use category. Once the end-use breakdowns have been determined, equipment in categories of high energy use will be targeted during site assessments. In addition, the baseline information will be used later when calculating energy savings. The calculated energy reductions will be compared to the baseline allocated energy use to ensure the savings are reasonable.

• Benchmarking

  • Benchmarks will be established based on historical utility data and building characteristics.  Benchmarks will be compared with similar buildings and will assist in determining the benefits of further analysis.

  • Energy Utilization Index (EUI) will be used for benchmarking each facility. This number is the energy consumption per unit area of the building. The building EUI can be compared against information available from the Commercial Buildings Energy Consumption Survey (CBECS) maintained by the Energy Information Administration (EIA) (EIA 2011).

  • Energy Star® may also be used for benchmarking utilizing Portfolio Manager (EPA 2011a).

2. Site Visit

Site visits are a critical part of any energy audit. The components of a site visit typically include:

• Preassessment Interview

  • Prior to the site visit, it is beneficial for the auditing team to begin the data collection process.

• Interviews

  • Interviews with site staff are an essential part of any comprehensive energy audit. In addition to collecting specific information about equipment and controls, the assessment team should ask about the following items during their on-site interviews:

    • Equipment condition

    • General maintenance procedures

    • Persistent comfort issues

    • Indoor air quality (IAQ) problems

    • Malfunctioning equipment (including excessive O&M expenses, excessive noise, etc.)

    • Planned upgrades and capital expenditures for infrastructure

    • Potential Energy Efficient Measures (EEMs)

    • Previous energy assessments

• Photographs

• Building Automation System (BAS)

  • The BAS makes it possible to quickly collect a lot of information about the energy-using systems in the building.

  • The BAS will be helpful in investigating:

    • scheduling for mechanical equipment and lighting;

    • design control sequences;

    • existing setpoints;

    • existing control strategies, including supply air temperature control and chilled-water/heating-water/condenser-water temperature control;

    • economizer operation;

    • simultaneous heating and cooling;

    • an overview of the operation of fans and pumps (VFDs, damper and valve controls, variable-air-volume [VAV] systems, etc.); and

    • room and/or zone temperature control.

• Preparation Activities

  • Proper preparation before the first site visit will help the team make the most of the time on site. It is important to be efficient at the facility to reduce the audit costs and minimize the impact on staff resources.  In preparing for a site visit, it may make sense to do a brief phone interview with site staff, as discussed previously. If the staff can make building plans available prior to the audit, this will save a great deal of time reviewing them on-site. It will also be advantageous to complete the preliminary energy analysis or benchmarking to have an idea of the approximate energy use intensity of the facility and how it compares to other typical buildings of the same type.

  • Data that should be assessed prior to a site visit include the following:

    • Facility data: building name, use, floor area, year of construction, renovations, and schedules of use (daily and weekly), as well as the number of building occupants.

    • Site drawings

    • Online mapping images

    • Utility rates and suppliers

    • Utility metering (where energy and water meters are and how metering data are available)

    • Energy consumption data (in kilowatt-hours, British thermal units, therms, gallons, or pounds of steam, as appropriate; two to three years of data is preferable)

    • Monthly consumption

    • Monthly peak demand data (in kilowatts or therms per hour)

• Initial Walk-Through

  • A walk-through audit is a brief investigation of a facility.

• Detailed Audit Procedures

  • The procedure for conducting a detailed site investigation (e.g., a Level 2 or Level 3 audit) follows the same basic activities as outlined for a walk-through audit. The primary difference is depth. During a detailed investigation, the auditor goes into much greater depth to collect information to assess the site energy use and to estimate energy savings and project costs for proposed recommendations. Reference ASHRAE Standard 211-2018 (RA2023) – Standard for Commercial Building Energy Audits

• Practical Arrangements for Site Work

  • The energy auditor should make sure that the site staff is aware of the practical arrangements for the site visit well before the visit occurs. Good communication before the visit ensures the team has access to the site and can save a lot of time during the actual fieldwork.

  • Before the team arrives, the site staff should be aware of the following:

    • Who is in charge of getting the information the team needs before the visit

    • Who will be present when the team is on-site

    • Where the team will work (working space and facilities)

    • Who attends in-briefings and exit briefings

    • Whether the team will have free access to the buildings or need an escort

    • Restrictions for operating on-site

    • Whether the team will have their own keys to technical rooms

    • How the building’s occupants will be informed of the assessment team’s visit

• Safety

  • Use of appropriate PPE when working around devices in electrical equipment.

3. Measurements

• Data

  • Data are vital to quantifying operating parameters and performance. The first requirement is to define the information needed to characterize the systems and support further analyses. Data might range from setpoints and conditions (e.g., temperatures and humidity) to loads (e.g., heating load, outdoor air ventilation load, etc.) to efficiencies (e.g., boiler efficiency and cooling coefficient of performance [COP]). Types of data might vary from one-time snapshots to load profiles and periodic totals. Defining building characteristics and the level of required accuracy are key to defining data needs.

• Operational Characteristics

  • Setpoints

    • Setpoints are typically determined from the building controls. However, some values might not be accessible to the user, requiring someone with access to the controls programming. Setpoints should be reviewed for consistency with how the building is intended to be operated. Typical setpoints include the following:

      • Space temperature

      • Space humidity

      • Space lighting levels

      • Minimum outdoor airflow rates

      • Carbon dioxide levels

      • Economizer limits

      • Boiler temperature

      • Chiller temperature

      • DHW storage and delivery temperatures

      • Fan system flow control static pressure

      • Water loop system flow control static pressures

      • Heating and cooling systems enabled conditions

  • Operational Schedules

    • Examples of schedule-related data are as follows:

      • Occupied/unoccupied hours in each controlled zone

      • Warm-up and cooldown periods

      • Unoccupied override conditions and timers

      • Flow control resets (e.g., fan static pressure with VAV box dampers)

      • Equipment operating temperature resets (e.g., boiler with outdoor air)

      • Cooling tower condenser water resets

  • Operating Conditions

    • Loads

      • Some typical loads of interest to energy efficiency are:

        • Heating and cooling loads

        • Peak loads

        • System start-up loads

        • Lighting power density

        • Fan and pumping power loads

  • Equipment Performance

    • Equipment efficiency directly relates to the loading of the energy use. Typical efficiencies to be evaluated are:

      • combustion efficiency,

      • cooling efficiency, and

      • energy recovery efficiency.

4. Developing Initial Recommendations

• Analysis

  • The following factors should be considered when choosing a calculation methodology or energy analysis tool:

    • Accuracy

    • Sensitivity

    • Versatility

    • Speed and cost

    • Reproducibility

    • Ease of use

• Energy Efficiency Measure Types

  • No-Cost/Low-Cost Measures

  • Demand Response Measures

  • Demand Shifting and Load Shifting Measures

  • Self-Generation Measures

  • Co-Generation Measures

• Energy Calculation Methodology

  • The energy calculation methodology outlines the principles and procedures that are used to determine energy savings and economic impacts.  These elements should be considered when selecting the analysis tool:

    • Energy end-use analysis

    • Utility rate treatment

    • Measure interactions

    • Measure order

    • Measure lifetime

    • Cost estimates

    • Utility incentives

    • Tax incentives

    • Weather data normalization and annualization of results

    • Analysis tools

      • Steady State Calculations

      • Bin Method

      • Modeling/Simulation

• Economic Evaluation

  • Life-cycle cost analysis (LCCA) should be the best practice standard to be followed in an energy audit’s economic analysis. While a simple payback model is a quick and easy evaluation typically used for very short payback or simple scenarios, the LCCA model accounts for the time value of money and will compare alternatives with different lifetimes and cash flows and make a much more informed decision.

• Establishing a Capital Improvement Baseline

  • There are two principal reasons why it’s recommended to establish a capital improvement baseline:

    • It informs the financial performance evaluation of measures and packages. The baseline differentiates the costs of maintaining basic building functionality or meeting other goals not associated with energy efficiency versus significantly improving efficiency.

    • It showcases the particular opportunities for efficiency measures.

Conclusion

Energy audits that are designed to be appropriate for a building’s specific needs can result in applicable and actionable reductions in the building’s carbon footprint, energy use, and operational costs, as well as improvements in a building’s indoor air quality. If you would like to learn more about how a comprehensive energy audit can benefit your facility, please contact us or call (800) 508-8034 to speak with one of our energy audit professionals.

Authors

KERAMIDA Energy Audits Team

Contact us at info@keramida.com

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