How to Optimize Energy Consumption: A Case Study of an Energy Audit in a Transport and Earthmoving Company

An energy audit is a systematic analysis of the energy consumption of a company, building, or facility aimed at identifying areas of inefficiency and proposing solutions to reduce energy consumption and costs while simultaneously improving environmental impact.

Below are the reference regulations:

• European Directive 2012/27/EU on Energy Efficiency: Establishes the obligation to conduct periodic energy audits for large enterprises (with more than 250 employees or an annual turnover exceeding €50 million) and promotes the sustainable management of energy.
• Legislative Decree 102/2014: Transposes the European Directive into Italian law and defines the procedures for conducting energy audits for companies, specifying deadlines and implementation methods.

Energy audits are mandatory for energy-intensive companies and must be carried out every four years.

Below is a list of the required content for compiling an Energy Audit for a Transport and Earthmoving company in compliance with current regulations.

This company, although not falling under the legal category of energy-intensive enterprises, has voluntarily decided to implement an Energy Audit.

The items highlighted in yellow will be the subject of this technical analysis to provide evidence of a professional analytical methodology.

• General context and reference regulations.
  1. Introduction.
  2. Information on the audit report author.
  3. Identification of the site subject to the audit.
  4. Data collection methodology.
  5. Reference standards.
  6. Units of measurement and reference values/adjustment factors.

• General description of the company.
  1. General data and organizational structure.
  2. Production site.
  3. Description of processing types, production data, and reference indicators.

• Description of equipment and energy utilities.
  1. Types of existing equipment.
  2. Main activities.
  3. General services.
  4. Auxiliary services.

• Energy carriers and energy consumption.
  1. Characterization of the company’s energy model and energy carriers.
  2. Electricity consumption and historical data.
  3. LPG consumption and historical data.
  4. Diesel fuel consumption for vehicles and vehicle fleet information.

• Characteristic energy indicators for the company.
  1. Evaluation of indicators and baseline definition.
  2. Comparison with reference indicators.
  3. Calculation of performance indicators.
  4. Company baseline.

 

• Detailed analysis of the “vehicle fleet” sector: results and reference performance indicators.

 

• Efficiency improvements carried out in the past and recently.
  • Replacement of electric motors carried out in the past.
  • Installation of a photovoltaic system.
  • Recent interventions on the vehicle fleet.

• Identification of new interventions.
  • Replacement of obsolete vehicles with more efficient ones.
  • Identification of new measures to improve performance related to the vehicle fleet.
  • Installation of LED lamps to replace traditional ones.

Data Collection Method

The method for collecting data related to the various characteristic energy vectors is primarily based on the readings provided in the utility bills/invoices associated with supply contracts.

The energy vectors are as follows:

• Electricity: for power, air conditioning, and lighting.
• LPG: for heating and domestic hot water.
• Diesel fuel: for automotive use.

The fiscal meters dedicated to these vectors are as follows:

Site A:

• Electricity vector: POD code IT001E98787097. The supply is in LV, with an available capacity of 9.90 kW and a committed capacity of 9.00 kW. This meter measures all the electricity withdrawn from the facility.

No other vectors are to be considered, as the heating system is powered by an electric heat pump. At the time of drafting this document, no data on diesel fuel for automotive use is available, and therefore this vector is not included in the analysis.

Site B:

• Electricity vector: POD code IT001E41445194. The supply is in LV, with an available capacity of 11.00 kW and a committed capacity of 10.00 kW. This meter measures all the electricity withdrawn from the facility.
• LPG vector: Meter serial number 5828901, located near the storage tank.
• Diesel fuel vector: Tax warehouse equipped with a meter, with a capacity of 9,000 liters.

The consumption measurements for LPG are based on purchase invoices.

For diesel fuel used in vehicles, the measurements are also based on purchase invoices for tank loading. For unloading, that is, the refueling of vehicles and machinery, the quantities dispensed for each individual vehicle are recorded at the time of refueling.

Additionally, for the refueling of machinery, which takes place directly on-site, it is carried out “indirectly” via 500-liter tanks mounted on the beds of certain vans.

In this case as well, the quantity of fuel dispensed for each machine is recorded at the time of refueling.

Reference Standards

The specific standards referenced, among others, include but are not limited to the following:

• Legislative Decree No. 192/05: “Implementation of Directive 2002/91/EC on the energy performance of buildings” and subsequent amendments.
• Legislative Decree No. 115/08: “Implementation of Directive 2006/32/EC on energy end-use efficiency and energy services and repeal of Directive 93/76/EEC.”
• UNI CEI/TR 11428:2011: Energy management – Energy audits – General requirements for energy audit services.
• UNI CEI EN 16247-1:2012: “Energy audits – Part 1: General requirements.”
• UNI CEI EN 16247-2:2014: “Energy audits – Part 2: Buildings.”
• UNI CEI EN 16247-3:2014: “Energy audits – Part 3: Processes.”
• UNI CEI EN 16247-4:2014: “Energy audits – Part 4: Transport.”
• UNI CEI EN 16247-5:2015: “Energy audits – Part 5: Competence of energy auditors.”
• UNI CEI EN 16212:2012: Energy efficiency and savings calculation methods.
• UNI CEI EN 16231:2012: “Energy efficiency benchmarking methodology.”
• ISO 50001:2011 standard.
• Legislative Decree No. 102/2014.
• Ministerial Decree (MISE) dated December 21, 2017, followed by the related ARERA Resolution No. 921/2017/R/eel.
• Legislative Decree No. 73/2020 (published in the Official Gazette No. 175 of July 14, 2020), implementing “Directive (EU) 2018/2002 amending Directive 2012/27/EU on energy efficiency.”

Additionally, for the refueling of operational machinery, which occurs directly on-site, it is carried out “indirectly” via several 500-liter tanks mounted on the beds of certain vans.

In such cases, the amount of fuel supplied to each machine is recorded at the time of refueling.

Units of Measurement and Reference Values/Adjustment Factors

Below are the units of measurement and the conversion factors into tons of oil equivalent (as per the Ministry of Economic Development circular dated December 18, 2014).

For the preparation of the Energy Audit, the units of measurement prescribed by the International System of Units (SI) were used, along with, where necessary, technical units such as bar, kWh, t, and kcal.

Characterization of the Corporate Energy Model and Energy Carriers

This section describes the company’s Energy Structure, identifying the relevant energy carriers.

The energy scheme outlined below provides a comprehensive and detailed overview of the corporate reality through a multi-level structured approach.

Analyzing the energy structure of the production site also allows for an examination of the usage of each energy carrier within specific boundaries defined for the purpose of the energy audit.

The corporate structure is organized based on the functional areas present at the site. Specifically, three main categories are distinguished:

• Core Activities: These are activities directly related to the company’s primary production processes.
• Auxiliary Services: These are activities supporting the core activities.
• General Services: These are activities connected to the production process or services offered, where energy demands are not directly linked to the primary activities.

Figure 9 below illustrates the company’s energy structure, representing the energy model:

 

 

In light of the operations carried out by the company under analysis, the relevant energy carriers are as follows:

• Electricity, used to power the equipment necessary for office operations and for general and auxiliary services.
• LPG, used as a fuel for the boiler to provide heating during the winter and for domestic hot water.
• Diesel fuel, used as a fuel for vehicles, company machinery, and construction site equipment.

The consumption associated with these energy carriers is detailed in the following section.

Electricity Consumption and Historical Data – SITE A

Regarding electricity, consumption is sourced from external supplies, specifically through withdrawals from the local distribution network, as there is no self-production from photovoltaic systems.

The tables and figures below provide data for 2021, 2022, and 2023, broken down by tariff band, including the corresponding invoice amounts (excluding VAT):

 

The company’s total energy consumption at the site in 2023 amounted to 7,536 kWh, with a predominant share attributed to the F3 band, accounting for 3,078 kWh, or 40.8% of the total, as illustrated in the following figure:

 

The table below provides a summary of annual consumption, expressed in TOE (tonnes of oil equivalent).

A decline in consumption is observed in 2023 compared to 2022.

Electricity Consumption and Historical Data – Site B

Electricity consumption includes external supply, specifically referring to withdrawals from the local distribution grid, as well as the photovoltaic system installed on the roof of the warehouse, with a nominal capacity of 38.87 kW.

Table 4 – Electricity Consumption at Site BThe company’s total energy consumption at the site in 2023 amounted to 7,900 kWh, with a predominant share attributed to the F3 time band, accounting for 4,350 kWh, or 55.1% of the total, as illustrated in the following figure:

In the following table and figure, a summary of the annual consumption, expressed in toe, is provided.

There is a rather consistent trend, indicating that the electrical usage is not influenced by external factors.

With reference to the photovoltaic system installed on the roof and connected to the existing electrical system, it undoubtedly contributes to the company’s electricity needs, particularly during the summer months.

In fact, observing the monthly trend in electricity withdrawals, it is evident that during the summer months there is a decrease in the electricity drawn from the grid, despite an increase in consumption due to air conditioning systems.

Consumption peaks occur primarily during the winter months, with the exception of a peak recorded in August 2021.

Below is the graph showing the monthly trend of electricity consumption at site B.

 

The production data from the last three years of the plant is presented in the following chart.

The data was sourced from the GSE portal:

The monthly trend of electricity produced, self-consumed, and fed into the grid is presented in the following tables, with data sourced from the e-distribuzione portal.

As shown, 13.8% of the energy produced is self-consumed to meet the needs of the Magione facility, while the remaining 82.6% is fed into the grid.

Regarding energy costs, the average value was €0.285/kWh excluding VAT for 2022, and €0.312/kWh excluding VAT for 2023.

Below is the monthly trend of the unit cost.

LPG Consumption and Historical Data

The company uses LPG at the Magione site for heating systems and thermal energy production, whereas at the Ozieri site, the systems are electric heat pumps.

The table and figure below provide an overview of the consumption data.

 

As observed, consumption has remained virtually constant over the years.

Diesel Fuel Consumption and Vehicle Fleet

The company, as previously mentioned, operates various vehicles used for transporting materials and equipment, as well as company cars and typical construction machinery.

All vehicles are powered by diesel, which is stored in a 9,000-liter tank.

Below is a list of vehicles, including both motor vehicles and construction machinery, related to the Magione site for the years 2021, 2022, and 2023. The list includes details on fuel consumption, distance traveled, and hours worked.

From the tables presented above, it is evident that the distance traveled per liter of fuel consumed is greater for company cars and vans compared to trucks, for obvious reasons.

It is not considered appropriate to compare the specific data mentioned above with a potential “market average” since operating conditions, such as the weight of transported materials, the characteristics of the roads traveled, and driving styles, vary too significantly from standard reference conditions.

The following table and figure, however, present the total annual fuel consumption.

As shown, the trend is characterized by a decrease in 2022 and 2023 compared to 2021, primarily due to the contribution of operating machinery.

This is mainly attributable to the effects of implementing virtuous procedures and behaviors, as well as the use of more efficient operating machinery, which will be further explored later.

This efficiency improvement process is still ongoing and has also been extended to vehicles, as will be discussed in the final sections.

Below is a table presenting the quantities of diesel fuel unloaded into the tank and the corresponding average unit price.

Diesel Monitoring
Fuel monitoring for transportation purposes is carried out as follows:

• Fuel Tank Loading: Quantities are recorded through purchase invoices for tank refills.
• Fuel Tank Unloading (Refueling): The amounts dispensed to each vehicle or piece of machinery are recorded at the time of refueling.

For operational machinery, which is refueled directly on-site, the process occurs indirectly using 500-liter tanks positioned on the flatbeds of certain vans. In these cases as well, the quantity of fuel supplied to each machine is logged during refueling.

Conclusions
The conclusions of an energy audit are based on the analysis of consumption and the identification of inefficiencies, proposing practical solutions to enhance efficiency. Typical conclusions include the following:

1. Identification of Energy Inefficiencies
   • Inefficient Processes and Equipment: Identification of machinery, heating systems, lighting, air conditioning, and other equipment with high consumption relative to standards.
   • Energy Losses and Wastage: Detection of heat loss, distribution network inefficiencies (e.g., heating pipes or electrical circuits), and energy waste due to poor maintenance.
   • Inefficient Behaviors and Operational Practices: Analysis of personnel behaviors that impact energy consumption, such as suboptimal use of machinery, systems, or lighting.
2. Improvement Proposals and Technological Solutions
   • System Optimization: Suggestions to improve the efficiency of existing systems, such as installing automatic control systems, replacing outdated components, or revising operational processes.
   • Low-Consumption Technologies: Introduction of more efficient technologies, including LED lights, high-efficiency motors, inverters, heat recovery systems, etc.
   • Renewable Energy Sources: Assessment of opportunities to adopt solar, wind, or other renewable energy solutions to reduce dependence on fossil fuels and cut energy costs.
   • Energy Management Systems (EMS): Proposal for implementing or upgrading an energy management system compliant with ISO 50001 standards to continuously monitor consumption and optimize energy performance.

3. Estimation of Economic and Environmental Benefits

• • Energy Savings: Quantification of the potential energy savings resulting from the proposed solutions, expressed both in terms of kWh and economic value.
  • Reduction of CO2 Emissions: Estimation of greenhouse gas emission reductions achieved through the adoption of energy efficiency measures and the potential use of renewable energy sources.
  • Return on Investment (ROI): Calculation of the payback period for each improvement measure, assessing the economic feasibility of the interventions.

4. Corrective Actions and Continuous Monitoring

• • Action Plans: Detailed description of the actions to be undertaken, prioritizing interventions based on urgency and economic impact.
  • Monitoring Program: Recommendations on how to track energy consumption over time to ensure the maintenance and effectiveness of the implemented improvements.
  • Training and Awareness: Suggestions for staff training on energy efficiency practices and raising awareness of how their daily behavior affects energy consumption.

5. Implementation Plan

• • Timeline and Required Resources: Detailed implementation schedule for each intervention, specifying the required resources (human, technological, and financial).
  • Responsibilities and Goals: Assignment of specific responsibilities for each intervention and definition of measurable short- and long-term objectives.

An energy audit concludes with a series of recommendations aimed at reducing energy consumption, cutting costs, and improving environmental impact. These recommendations are supported by economic estimates, environmental benefits, and a detailed implementation plan.

In the Case at Hand (Transportation and Earthmoving Company), the Conclusions Were as Follows:

Speed Limiter on Vehicles

The installation of a speed limiter set at 85 km/h could result in an estimated 5% fuel consumption savings, while setting it at 80 km/h could increase the advantage to 8–8.5%.
This solution might be considered for short routes; however, it is clear that for long-distance routes, such a drastic measure is not economically viable. It could be evaluated, however, for medium-range distribution (including highway segments), where driving hours typically exceed working hours, allowing for slower speeds.

Eco-Driving Training

This is undoubtedly a cost-effective solution, with significant benefits if truck drivers fully adopt the techniques taught. Estimated fuel savings are approximately 10%.

Acquisition of Low-Fuel-Consumption Trucks and Machinery

The market is increasingly prioritizing fuel efficiency due to high fuel costs.
Some manufacturers offer trucks with various fuel-saving solutions, such as LED lighting, gearboxes with Start&Stop systems, exhaust heat recovery (via steam or electrical systems), downsizing to reduce drivetrain weight, and devices like air compressors with automatic deactivation, variable-speed alternators, and electric power steering pumps.

For operating machinery, available solutions include satellite geolocation, real-time monitoring of workloads (e.g., lifted or transported quantities), and smart communication systems.
When replacing a vehicle or nearing that point, the company will consider acquiring tractors and operating machinery with these features.

Constant Monitoring of Tire Pressure

A study by a leading tire manufacturer revealed that a 1-bar reduction in tire pressure increases fuel consumption by 0.85%, while a 2-bar reduction leads to increases significantly exceeding 1.7%.
Since underinflation is widespread and a 1-bar difference is imperceptible, investing in a tire pressure monitoring system is undoubtedly worthwhile. Furthermore, underinflation compromises the structural integrity of the tire casing, reducing its quality for retreading.

Axle Alignment Control

A misalignment of just one degree (invisible to the naked eye) on either the trailer or the tractor can lead to a 2% increase in fuel consumption. If opposing misalignments occur simultaneously, fuel consumption can skyrocket to 5%, and tire life can decrease by up to 10%.
Although axle alignment checks are time-consuming and costly, they deliver immediate benefits, including more even tire wear and improved safety.

Installation of LED Lighting in Place of Traditional Bulbs

The company has already initiated a program to replace traditional bulbs in the facility with LED technology, achieving significant benefits.
Consequently, the possibility of using LED technology throughout the industrial site has been considered.
This choice involves replacing existing systems with new-generation equipment, which, given the rapid improvements in LED performance, will enable significant energy savings without compromising lighting quality. Specific expected benefits include reducing power consumption for outdoor and office lighting while maintaining the required average illumination levels. Additionally, light pollution in outdoor areas will decrease by adjusting the installation of lighting fixtures where feasible.

Key details of the planned intervention are as follows:

• Pre-Intervention Light Points to Replace: 10
• Pre-Intervention Total Lighting Power: 5 kW
• Pre-Intervention Energy Consumption for Lighting: 6,000 kWh/year
• Post-Intervention Light Points: 10
• Post-Intervention Total Lighting Power: 2.5 kW
• Post-Intervention Energy Consumption for Lighting: 3,000 kWh/year
• Average Value of Energy Saved (Not Purchased): €0.32/kWh
• Energy Saved: 3,000 kWh/year
• Savings from Reduced Energy Consumption: €960/year
• Savings from Reduced Maintenance Costs: €500/year
• Total Savings: €1,460/year
• Estimated Intervention Cost: €6,000

Prepared by Ing. Andrea Girelli – Energy Management & Renewables