The current chapter is addressing the subtasks related to the improvement suggestions and guidelines to reduce the energy footprint of targeted SMEs. The results of the desk research conducted in previous subtasks to create a methodological framework for energy footprint management are updated, enriched, and focused on the specific sectors agreed upon by all the project partners, i.e., the construction sector, metal and chemical manufacturing, and food and beverage production. In the next sections, some improvement measures, and guidelines for energy footprint reduction of SMEs are presented. The proposed measures could be simple and cheap (or even free of charge) or more complex and costlier, whereas they could refer to different sections or aspects of the enterprise operation.

4.1. Improvement suggestions and guidelines to reduce energy footprint targeted to office buildings

There may be significant energy-saving potential for enterprises in the buildings they occupy. Making small improvements can also be a useful means to build awareness and involve employees in energy savings. Many small and midsize office buildings could benefit from energy-saving solutions that cost little or nothing at all. It is estimated that companies promoting informative and active events to encourage behavioral change in the office could benefit from about 2% to 10% energy savings.

• Measures related to office equipment

It has been estimated that computers contribute around 20% of overall electricity consumption in office buildings. There are some simple and low-cost or even free measures to manage computers

more efficiently in order to reduce their overall energy consumption. Specifically, they must be switched off when they are not in use, including over weekends, whilst the users should be sure that their power management settings are enabled on all computers and monitors. These settings force the devices to enter in sleep mode after a specific period of inactivity. Effective power management settings could reduce a computer’s electricity consumption roughly in half [54]. Similarly, office equipment and appliances like printers, fax machines, coffee makers, and microwave ovens in common rooms have significant power consumption. Many of these appliances draw phantom power when they are not used or when they are in standby mode. These devices often have energy- reduction settings that can yield substantial savings. These appliances could also be connected to timers to reduce their energy use.

Similarly, drinkable water fountains and coolers do not usually need to provide cold water 24 hours a day unless it is required for health reasons. The cooling systems of the majority of drinking fountains and water coolers could be switched off. It is estimated that the average office water cooler consumes about 800 kWh per year, and much of this energy is from standby mode. The installation and set of a timer so that the cooler operates only when needed is suggested. Likewise, refrigerated vending machines typically run 24-7, using 2,500 to 4,400 kWh per year and adding to cooling loads in the spaces they occupy. Timers or occupancy sensors connected to vending machines could save energy because they allow the machines to turn on only when a customer is present or when the compressor must run to keep the product at the desired temperature [55].

• Measures related to lighting

Lighting is another relatively simple way to save energy. There are many combinations of energy- saving techniques and technologies for lighting. In general, lighting energy savings arise in the following ways [54], [56], [57]:

• There are sensors and automatic devices that can identify human presence in a room/space of a building or a facility. Such devices could be deployed to turn on the lights of the corresponding room/space only when the room/space is occupied.
• There are standards and norms that specify the lighting level in a room/space according to the activity that is being carried out in the room/space. In order to achieve energy savings over- lamping should be
• All incandescent lightbulbs should be replaced by more energy-efficient LED lighting in order to save
• It is often highlighted that company spaces do not exploit to its full potential natural lighting. Designing spaces in such a way so as to use natural light from windows and/or skylights at its maximum, has almost no cost, mitigating at the same time electricity demand for artificial This is why objects that block windows, e.g., filing cabinets, should be relocated, while the space arrangement should always aim at maximizing the use of natural light, e.g., working desks should be positioned near windows.
  • Measures related to the thermal insulation of buildings

There may be significant energy saving potential for enterprises in the buildings they occupy. There are various simple and low cost measures that can enhance the energy efficiency of existing buildings [56], [57]:

• Windows present a common source of heat losses in buildings. For that reason, their frames should be regularly checked and maintained in good condition in order to ensure that they can be closed tightly and are draught-proof. Single glazed windows should be replaced with double or, if it is possible, with triple glazed ones. The application of proper shading systems could also prevent building spaces from over-heating.
• Like windows, doors could also be tested in order to ensure that they are draught-proof and can be closed The replacement of the existing doors with thicker ones and the implementation

of self-closing mechanisms could also help to control the temperature of internal spaces consuming less energy.

• Walls and roofs should be regularly checked in order to spot existing gaps or holes which should be repaired/closed applying appropriate filling materials. Additionally, dedicated audits could be carried out in order to explore the potential of reducing thermal losses through the application of proper thermal insulation.
  • Measures related to heating and cooling

Improving and/or modifying HVAC systems could contribute significantly to achieving energy efficiency in office buildings of SMEs. Some simple and practical measures that ensure good and efficient operating conditions of HVAC systems include [56], [57]:

• Appropriate control systems that regulate room temperature should be Office temperature, for instance, during winter months (heating operation) is recommended to be set to 19°C. Obviously, it could be set lower than 19°C in corridors, storerooms and areas of higher physical activity. In the summer (cooling operation) the corresponding air temperature is recommended not be lower than 24°C. Regarding cooling temperatures, there is an empirical rule according to which an increase of the set cooling air temperature by 1°C will result to an increase of energy consumption of the order of 3% by the chiller.
• Cooling systems release/reject heat to the environment, namely to ambient air. It is evident, therefore, that in order cooling systems to operate efficiently, they should have good and unobstructed access to ambient Thus, the positioning of cooling units with respect to existing furniture, equipment and/or machinery is very important. Space restrictions and/or poor engineering judgment might result in positioning cooling units close to hot air exhausts or in a way that they have restricted ambient air flow, inevitably lowering the overall efficiency of the system. Facility space arrangement should cater for cooling systems to have unobstructed access to the coolest possible ambient air.

4.2. Improvement suggestions and guidelines to reduce energy footprint targeted to food and beverage manufacturing

• Measures related to operational processes and maintenance

Simple processes can be instilled and implemented within an organization to address operational and maintenance matters, such as the following measures [58], [60]:

• Maintenance activities should be carried out by specialized and experienced technical There should be sufficient time to complete the relevant maintenance work according to relevant quality standards. Following a maintenance routine and a mid-term schedule is of outmost importance. In the case of replacement activities, the spare parts to be used should be the most modern and efficient ones.
• In the case of recurring plant failures, it should be ensured that the root causes are identified. For this purpose, experiments and tests should be conducted and everyone must contribute to uncover It is very important to ensure that any root cause should be addressed effectively without causing another failure elsewhere in the facility.
• During the installation of new equipment or machinery, it must be ensured that all the relevant parts and components are installed properly following the guidelines of the manual(s) provided by the manufacturer. Additionally, the actual installation should be reviewed carefully before handover in order to ensure that it is as per design.
• Regarding equipment size, it should be ensured that equipment specifications meet the operational requirements and match the actual demand without excess
• Regarding equipment operation, it should be verified that the relevant machinery can be turned off easily and safely when it is not being used. Facility and equipment safety rules should be strictly There should be safety valves and appropriate protective devices that

‘guarantee’ the safety of the facility and the installed machinery. The ability also to restart facility’s operation at short notice is very important for achieving improved energy efficiency.

• If there is a variety of available machines one should choose to use the ones that exhibit the highest It is evident, therefore, that production managers supervisors, and/or staff should be aware and have good knowledge of the minimum, normal and maximum operating conditions of all the available equipment.
• Production processes should be designed in such a way so as to minimize idle time of Also, there should be an effort to stop machines’ operation as soon as possible and start them as late as possible. Production processes should be carefully monitored and reviewed aiming at identifying potential for efficiency improvement.
• It should be ensured that all thermal and electrical insulation is in good condition minimizing heat losses and eliminating electricity leakages.
  • Measures related to motors systems

According to the U.S. Department of Energy, motor systems are the biggest energy consumers for manufacturing industries, consuming roughly 75% of all electricity in the U.S. industrial sector. As a result, motors should be a key area of focus within any energy footprint management program.

Fortunately, today’s advanced motor management solutions can reduce significantly the overall energy demand. For instance, power optimization tools, such as variable frequency drives, energy- efficient motors, gears, motor controllers, and relevant software could deliver immediate and measurable savings [60].

Many industrial applications, like fans, pumps, compressors, and conveyor belts are mainly operate at partial loads. However, these devices use traditional (mechanical) control methods like valves, brakes, and throttles for speed control. In this case, motors provide more work than the requires, and as a consequence significant energy amount is lost due to the mechanical speed control. Variable speed drives (VSDs) offer a more efficient way for applications operating at partial loads because

they can directly control the speed and torque of the electric motor. Thus, the required mechanical speed control is eliminated, and the use of oversized motors is avoided. The application of motor direct control allows to match the provided and the actual process demand, enabling the equipment to operate more efficiently and at a range of different speeds. As a result, the implementation of VSDs can significantly improve energy footprint throughout whole production chains [62].

Specifically, high-horsepower, centrifugal loads can achieve significant energy savings with the highest reduction in energy consumption resulting from just lowering speed or flow by 20%. If a small reduction in the flow does not impact the manufacturing process and the plant can use half as much energy doing so, then users can achieve high cost savings. In any manufacturing process that requires less than 100% of the designed speed, manufacturers should consider implementing variable frequency drives. In this case, the proper application of VSDs would significantly reduce energy costs, whilst they could help remove the need for valves, increase pump seal life, reduce power surge during start-up, and contribute to more flexible operation [60].

• Measures related to refrigeration

There are several easy measures for minimizing refrigeration energy use [63]:

• Overstocking should be avoided, while air grills should remain unobstructed
• Products must not be allowed to warm up during the transfer
• Lighting and anti-condensation devices should be switched off when it is not required
• Thermostat and defrost should be set to match the required conditions
• Heat gain from other equipment and sunlight should be reduced

Additionally, many refrigeration units would benefit from improved insulation. It has to be ensured that coolant pipes and potential areas of heat gain are well insulated. Insulation panels for walls, ceilings, and doors should have an R-value of at least 4.5, which corresponds to 140 mm of rigid foam insulation. For freezer rooms, panels should be at least R6 (175 mm thick). Transparent

windows and doors should be double-glazed in cool rooms and triple-glazed in freezers, with heat- reflective external treatments.

If the refrigeration system is more than 10 years old, its replacement should be considered. The installation of an efficient new system could save up to 30% in their energy consumption. In the case of the system’s replacement, the layout and planning of the installed systems should be according to the following guidelines [63]:

• Avoid excessive pipe lengths and uninsulated pipework
• Reduce the time that the personnel needs to be in cool areas
• Ensure that cooling equipment is not installed near to heat sources
• Optimize lighting by using LED and occupancy sensors where it is possible
• Arrange the evaporator so cold air does not blow straight out the door
• Locate condensers and heat exchangers in a way that there is good airflow and heat can be discharged
• Optimize routing of suction lines to avoid pressure drop, liquid retention, or unstable flow

• Measures related to other production processes

There are several different processes used in food and beverage production with energy footprint reduction potential.

Some options that could be implemented to improve the efficiency of boiler systems include [64]:

• Insulating boiler valves
• Installing steam and condensate return pipes and storage units
• Pre-heating entry water from excess heat or solar powered hot water systems
• Selecting boilers that can modulate their output
• Implementing efficient sequencing controls if multiple boilers are in use

Ovens are also energy-intensive devices used in food manufacturing. Many commercial ovens are poorly insulated or have metal joints forming a thermal bridge for heat loss. By increasing oven insulation to an R-value of at least 2.5 and reducing thermal bridging, radiated heat can be reduced by up to 75%.

Regarding the drying processes, traditional food drying techniques include spray drying, hot air drying, and freeze drying. These all require large amounts of energy and other inputs such as gases. Some options to improve efficiency in the drying process are:

• Low-temperature evaporation
• Waste heat recovery and heat exchangers
• Purpose-built efficient heat pump dryers and dehumidifiers
• Solar and microwave-assisted drying

These improvements can sometimes be combined with older methods to create a more efficient hybrid process.

• Measures related to process design and energy supply

The highest energy savings come from a step change either in process design, energy supply, or both. This is the costliest and carries the highest business risks compared to other measures. These changes could be the implementation of combined heat and power plants, the refitting of the production line with a new process technology, the application of dynamic simulation and predictive controls, and the extension of the energy or waste heat into a district heating or cooling network.

Combined heat and power

Conventional (thermo-electric) power generation technologies, exhibit relatively low fuel-to-power efficiencies, simply because considerable amounts of high-temperature heat are lost to the

environment through the stack. This is the reason why common conventional (thermal) engines exhibit energy efficiency rates which do not normally exceed 38% – 40%. Specifically, energy efficiency rates for reciprocating engines are in the range of 28% – 38%. Energy efficiency rates of small gas turbines (nominal power up to 5 MW) vary between 20% to 25%, whilst the corresponding efficiency figures for bigger gas turbines (nominal power between 5 MW and 500 MW) are in the range of 25% to 35%. Modern gas turbine power plants with a nominal power higher than 500 MW might reach efficiency rates close to 50%. CHP technology captures and utilizes the thermal energy (heat) which is released (lost) to the environment. The captured thermal energy can be used to produce steam, which in turn can drive a steam turbine to generate electricity. At a smaller scale, CHP systems, industrial gas turbines or reciprocating engines fuelled by gas or oil are employed. Apart from electricity generation, the captured heat can be used in other thermal processes such as steam generation or water heating. Typically, the overall efficiency of CHP plants is much higher than the one exhibited by conventional power plants, namely of the order of 75% – 85% [58].

Heat recovery

It is estimated that 20-50% of industrial energy input is lost as waste heat in the form of hot exhaust gases, cooling water, or heat loss from equipment surfaces and heated items. Any industrial process which uses heat can reduce energy use by using heat exchangers to transfer the heat somewhere else to where it is useful in another process. The most common use of recovered heat is to preheat inputs to heat chambers. Heat may either be reused within the same or a different process or sometimes by a neighbouring industrial facility. Numerous technologies are commercially available for waste heat recovery. For it to be successful, an accessible source of waste heat, the correct recovery technology, and the use of the recovered energy need to be present. Facilities may need specialist help in identifying these and in evaluating the feasibility of waste heat recovery [58].

Waste heat to power

Where energy-intensive heat sources must be used, efficient heat recovery (including the latent heat of water vapour) is critical. Steam traps and boiler blow-down recovery save water and boiler heating requirements. The returned condensate is much hotter than feedwater and may not require treatment. While there is a large upfront cost, heat recovery measures often repay the investment in under 3 years [64].

Renewable energy and storage

Many businesses in the food and beverage sector have installed on-site rooftop solar PV systems. As a greater proportion of plant processes are electrified, loads can be matched with periods of high solar generation. As loads increase, PV systems can be expanded accordingly. Solar water heating can also be used as an alternative for heating or pre-heating. This allows water to be heated well above 80˚C. Onsite battery storage may also be worth considering as prices decline. Batteries enable greater onsite use of solar PV throughout the day and provide a backup option in the event of grid failure. Energy can also be stored thermally in water, phase change materials (PCM), or in the bulk mass of food products in refrigeration [64].

Food waste-to-energy plant

Most food waste has the potential for reuse as an energy source. Organic waste can be used in the generation of renewable energy through anaerobic digesters. Anaerobic digestion occurs when microorganisms break down organic material in the absence of oxygen, producing biogas (methane) and a rich fertilizer. When this biogas is captured, it can reduce methane emissions from manure decomposition by up to 95%. Anaerobic digestion and biogas recovery are best suited to large food processing plants with high-strength wastewater, such as dairy processing plants or breweries [64].

4.3. Improvement suggestions and guidelines to reduce energy footprint targeted to metal and chemical manufacturing

• Measures related to operational processes and maintenance

Simple processes can be instilled and implemented within an organization to address operational and maintenance matters, such as the following measures [58], [60] :

• Maintenance activities should be carried out by specialized and experienced technical There should be sufficient time to complete the relevant maintenance work according to relevant quality standards. Following a maintenance routine and a mid-term schedule is of outmost importance. In the case of replacement activities, the spare parts to be used should be the most modern and efficient ones.
• In the case of recurring plant failures, it should be ensured that the root causes are identified. For this purpose, experiments and tests should be conducted and everyone must contribute to uncover It is very important to ensure that any root cause should be addressed effectively without causing another failure elsewhere in the facility.
• During the installation of new equipment or machinery, it must be ensured that all the relevant parts and components are installed properly following the guidelines of the manual(s) provided by the manufacturer. Additionally, the actual installation should be reviewed carefully before handover in order to ensure that it is as per design.
• Regarding equipment size, it should be ensured that equipment specifications meet the operational requirements and match the actual demand without excess
• Regarding equipment operation, it should be verified that the relevant machinery can be turned off easily and safely when it is not being used. Facility and equipment safety rules should be strictly There should be safety valves and appropriate protective devices that ‘guarantee’ the safety of the facility and the installed machinery. The ability also to restart facility’s operation at short notice is very important for achieving improved energy efficiency.

• If there is a variety of available machines one should choose to use the ones that exhibit the highest It is evident, therefore, that production managers supervisors, and/or staff should be aware and have good knowledge of the minimum, normal and maximum operating conditions of all the available equipment.
• Production processes should be designed in such a way so as to minimize idle time of Also, there should be an effort to stop machines’ operation as soon as possible and start them as late as possible. Production processes should be carefully monitored and reviewed aiming at identifying potential for efficiency improvement.
• It should be ensured that all thermal and electrical insulation is in good condition minimizing heat losses and eliminating electricity leakages.
  • Measures related to motors systems

According to the U.S. Department of Energy, motor systems are the biggest energy consumers for manufacturing industries, consuming roughly 75% of all electricity in the U.S. industrial sector. As a result, motors should be a key area of focus within any energy footprint management program.

Fortunately, today’s advanced motor management solutions can reduce significantly the overall energy demand. For instance, power optimization tools, such as variable frequency drives, energy- efficient motors, gears, motor controllers, and relevant software could deliver immediate and measurable savings [61].

Many industrial applications, like fans, pumps, compressors, and conveyor belts are mainly operate at partial loads. However, these devices use traditional (mechanical) control methods like valves, brakes, and throttles for speed control. In this case, motors provide more work than the requires, and as a consequence significant energy amount is lost due to the mechanical speed control. Variable speed drives (VSDs) offer a more efficient way for applications operating at partial loads because they can directly control the speed and torque of the electric motor. Thus, the required mechanical speed control is eliminated, and the use of oversized motors is avoided. The application of motor

direct control allows to match the provided and the actual process demand, enabling the equipment to operate more efficiently and at a range of different speeds. As a result, the implementation of VSDs can significantly improve energy footprint throughout whole production chains [62].

Specifically, high-horsepower, centrifugal loads can achieve significant energy savings with the highest reduction in energy consumption resulting from just lowering speed or flow by 20%. If a small reduction in the flow does not impact the manufacturing process and the plant can use half as much energy doing so, then users can achieve high cost savings. In any manufacturing process that requires less than 100% of the designed speed, manufacturers should consider implementing variable frequency drives. In this case, the proper application of VSDs would significantly reduce energy costs, whilst they could help remove the need for valves, increase pump seal life, reduce power surge during start-up, and contribute to more flexible operation [61].

• Measures related to operating temperatures and pressures

The percentage yield and rate of chemical reactions are highly dependent on temperature and pressure. Energy savings would be achieved by reviewing optimal temperatures and pressures for specific chemical processes. Ongoing innovations in catalysts can lower the activation energy barrier for chemical reactions. This reduces the temperatures and pressures required [55].

In this context, it has to be ensured that chemical distillation is being carried out under the optimal conditions and that products are not being over-purified. To do this, the following guidelines could be followed [55]:

• Decrease processing temperature
• Optimise cooling temperature
• Set thermostats to the appropriate temperature

Specifically, a decrease of 1ºC in average space temperature could reduce fuel consumption by almost 8%. Attention should be given to the storage of polymer granules at low temperatures.

Condensation could form when the granules are moved into a warmer factory space. This can result in greater drying requirements before processing.

Regarding the pressure of the equipment, it should be monitored and adjusted. For example, a boiler feedwater pump may produce higher pressure than it is required to supply water to the boiler.

Slowing the pump down is a no capital investment and would reduce steam use while still having adequate supply pressure for boiler feedwater.

• Measures related to steam generation and distillation

One of the most common processes in industrial chemical plants is distillation to separate chemical mixtures. This requires large quantities of steam to be generated. The production and distribution of steam can cause substantial heat loss, requiring more energy to maintain boiler temperatures. Most of the external energy and heat loss in distillation units occurs in condensers which are usually cooled by water or air. Inefficient distillation and steam generation systems can also increase air- conditioning cooling loads. Boiler systems should have effective steam traps and condensate return. This can save water and help conserve the heat of the water in the boiler because the returned condensate is hotter than the feedwater and as a result no additional treatment is required [55].

Additionally, the heat losses could be further minimized by [55]:

• The thermal insulation of boiler valves, pipes, taps, and storage units
• The replacement of defective steam traps
• Use other process streams to cool the condensers
• The application of waste to heat technologies for steam production
• The use of alternative separation technologies such as reactive distillation and membrane

• Measures related to process design and energy supply

The highest energy efficiency improvements could be achieved through extensive changes related to process design and/or energy supply. Compared to simpler measures, extensive changes are always associated with high (investment) cost and the corresponding high business/financial risk. Such changes might include the implementation of appropriate CHP plants, the redesign of production lines and/or procedures, the application of sophisticated prediction, simulation and control techniques, and the connection of the facility to the local heating or cooling network to channel waste energy or heat.

Combined heat and power

Conventional (thermo-electric) power generation technologies, exhibit relatively low fuel-to-power efficiencies, simply because considerable amounts of high-temperature heat are lost to the environment through the stack. This is the reason why common conventional (thermal) engines exhibit energy efficiency rates which do not normally exceed 38% – 40%. Specifically, energy efficiency rates for reciprocating engines are in the range of 28% – 38%. Energy efficiency rates of small gas turbines (nominal power up to 5 MW) vary between 20% to 25%, whilst the corresponding efficiency figures for bigger gas turbines (nominal power between 5 MW and 500 MW) are in the range of 25% to 35%. Modern gas turbine power plants with a nominal power higher than 500 MW might reach efficiency rates close to 50%. CHP technology captures and utilizes the thermal energy (heat) which is released (lost) to the environment. The captured thermal energy can be used to produce steam, which in turn can drive a steam turbine to generate electricity. At a smaller scale, CHP systems, industrial gas turbines or reciprocating engines fuelled by gas or oil are employed. Apart from electricity generation, the captured heat can be used in other thermal processes such as steam generation or water heating. Typically, the overall efficiency of CHP plants is much higher than the one exhibited by conventional power plants, namely of the order of 75% – 85% [58].

Heat recovery

It is estimated that waste heat represents about 20% – 50% of the overall industrial energy consumption. This is because waste heat can be generated in several forms within an industrial SME, e.g., as hot exhaust gases, cooling water, or heat loss from equipment surfaces and heated components. All thermal industrial processes may reduce their heat demand by utilizing part of these heat losses, appropriately termed as recovered (waste) heat, employing heat (recovery) exchangers. The captured heat is commonly used to preheat the inputs to heat chambers reducing the overall energy demand of the relevant process. Recovered heat may be used by a neighbouring industrial facility. Currently, there are various heat recovery technologies available that can be implemented in industrial plants. In order this technological option to be successful, there should be an easily accessible source of waste heat and a relevant industrial or commercial heat demand to be satisfied, as well as the appropriate recovery technology. SMEs that intend to implement waste heat recovery technologies, should carry out special audits by appropriate staff and/or advisors in order to determine the requirements of their industrial facility and evaluate the technoeconomic feasibility of this solution [58], [66].

Waste heat to power

The temperatures involved in production processes of certain industrial sectors might be above 1,000°C. Typical examples of such industrial sectors are steel and cement industries. Their corresponding waste heat generated is associated with temperatures reaching 750°C. In some other processes, such as CHP plants and boilers, waste heat might be available at considerably lower temperatures ranging between 160°C and 180°C. The generated waste heat can be converted to power, following the approach that is commonly known as Waste Heat to Power (WHP) technology. Different WHP technologies can be implemented depending on the temperature of the available waste

heat. Waste heat available at high temperatures, for instance, is appropriate for the preparation of steam which may be used for electricity generation employing a steam turbine. On the other hand, waste heat available at relatively lower temperatures may be also used to generate electricity with a technology quite similar to the one of steam turbines. In this latter case, however, the working fluids to be used, should have a boiling point much lower than that of water. It is evident, therefore, that industrial SMEs that generate high temperature waste heat should certainly investigate WHP options in their effort to enhance their energy efficiency and reduce their energy footprint [58].

Renewable energy

Solar water heating could save energy by preheating boiler feedwater in steam boilers for a wide range of chemical and plastic manufacturing operations. The boiler feed can be heated in solar panels up to 80ºC before going to the boiler. Larger combined solar thermal generators would concentrate enough energy to produce steam and electricity [55].

4.4.   Guidelines to reduce energy footprint targeted to construction

Energy used in the construction sector includes large volumes of diesel for machinery operation as well as electricity for powering buildings and tools, presenting many opportunities to save on energy. The energy-efficient design and construction practices could lead to various benefits [57]. The measures that construction SMEs could implement to improve their energy footprint are given in the following sections.

• Measures related to diesel machinery and vehicles

Because of diesel’s superior combination of power density, performance, and reliability, it is currently the preferred fuel in the construction sector, with a share of more than 75% of all heavy construction equipment. At the same time, newer diesel machines offer higher efficiency compared

to equipment older than 15 years and advanced emissions control technology. Additionally, ensuring machinery is well maintained greatly assists in reducing fuel consumption. For instance, filters are low-cost items that could be regularly replaced in order to maximize efficiency.

Regarding the construction sites, connecting them to the grid earlier could also help minimize diesel use by mitigating the need for powered generators.

• Measures related to project planning

On average, equipment on construction sites is idle around 25% of the time, while construction trucks are idle up to 50% of the time. Engine idling can be a significant operating cost due to the unnecessary fuel consumption and the increased maintenance requirements. The implementation of effective project planning and logistics could help reduce idling time. In this context, installing automatic engine shutdown devices and offering fuel-efficiency training for drivers and operators are some measures that would easily be implemented [57].

• Measures related to accommodation

The use of onsite cabins represents one of the biggest opportunities to reduce energy-related costs. Energy demand for accommodation could be reduced by almost 50% with better shading, insulation, lighting, and appliances. Additionally, onsite solar PV could then be used to meet or offset the remaining energy demand, minimizing the onsite diesel-powered generators and reducing carbon emissions [57].

Another strategy that could be followed to reduce energy footprint is the use of prefabricating components for a construction project. Offsite construction typically takes place in specialized, semi-automated environments designed for waste minimization and increased productivity. The prefabrication strategies could also lead to better quality construction which helps reduce downstream energy use and emissions [57].

• Measures related to the use of renewable energy and biodiesel

Many diesel-powered construction machines could run on biodiesel blends of up to 20%. Biodiesel does not cost more than ordinary diesel but would substantially reduce CO2 emissions. Although, advanced forms of biodiesel are also emerging. The so-called renewable diesel fuels are similar in their chemical constitution to conventional diesel and therefore no blending is necessary.

Remarkably, the use of 100% renewable diesel could reduce lifecycle CO2 emissions by almost 50% [57].

When connecting to the grid is unfeasible or the required electric loads are not very large, a temporary solar panel installation might be able to provide the needed power. Solar panel installations are environmentally friendly and suitable to reduce carbon emissions and lower fossil fuel consumption. Once the solar panels are in place, they can be used to charge certain power tools and operate machinery. However, solar panel installations do not work properly if the construction company primarily works at night or if more power is needed than the solar panels are capable to produce [58].