Environmental Measures and Efficiency! 5 Ways to Reduce CO2 and Costs Simultaneously on Construction Sites

Introduction

In recent years, the civil engineering and construction industry has been required to implement environmental measures such as CO2 emission reductions and resource conservation. At the same time, streamlining construction operations is an unavoidable challenge in response to labor shortages and rising costs. Traditionally, environmental consideration has often been seen as a trade-off with efficiency and cost. However, by leveraging the latest technologies and practical measures, there are increasing cases where reducing environmental impact and improving construction efficiency and cost savings can be achieved simultaneously.

This article introduces five concrete ways to reduce CO2 and costs simultaneously at construction sites, aimed at a wide audience—from major contractors to small and medium-sized construction companies, municipal engineers, and site managers and environmental officers. We cover topics from introducing energy-efficient heavy machinery and recycling construction by-products, to optimizing construction using ICT, adopting decarbonized materials, and improving management efficiency through smart surveying. For each method, we explain effects, case studies, implementation costs and benefits, and related technologies in detail.

1. Introducing Energy-Efficient Heavy Machinery and Improving Operating Efficiency

The first method is to introduce energy-efficient construction machines with superior fuel economy and improve heavy machinery operating efficiency. Heavy equipment used on construction sites—such as hydraulic excavators and bulldozers—consume large amounts of diesel fuel and emit substantial CO2. Therefore, switching to the latest models equipped with engine energy-saving technologies, hybrid machines, or electric machines is effective.

For example, major manufacturers are accelerating electrification of their equipment toward decarbonization. Komatsu obtained the Ministry of Land, Infrastructure, Transport and Tourism’s GX construction machinery certification in 2023 for seven electric construction machines, including a “battery-powered electric hydraulic excavator.” Such electric construction machines can not only effectively reduce CO2 emissions during operation to near zero, but also bring benefits such as reduced fuel costs and lower noise and vibration, improving the surrounding environment. Hitachi Construction Machinery has expanded its electric excavator “ZE” series up to mid-size classes, and Tadano has released the world’s first fully electric crane, indicating that energy-efficient heavy machinery is spreading across the industry.

Although energy-efficient machines generally have higher upfront costs than conventional machines, they are expected to offer long-term cost advantages through reduced fuel costs and lower maintenance expenses. In fact, a quarry in Sweden reported an approximately 98% reduction in CO2 emissions after introducing an all-electric fleet of heavy machinery. Additionally, reduced noise enables night work, contributing to greater flexibility in construction scheduling—an efficiency benefit not to be overlooked.

Moreover, even existing machines can achieve better fuel efficiency through operational improvements. For example:

• Thorough idling stop: Stop engines during standby to cut unnecessary fuel consumption and emissions.

• Practice eco-driving: Avoid sudden starts, rapid acceleration, and harsh braking; operate at appropriate power levels for the task to improve fuel economy.

• Proper maintenance: Regularly change oil and air filters, manage tire pressure, and perform routine upkeep. Preventing performance deterioration and fuel efficiency decline leads to reduced CO2 emissions.

• Digitalize operation management: Equip machines with IoT sensors or telematics devices to visualize operating hours and idling time and drive management improvements.

By combining the introduction of advanced machines with operational improvements, it is possible to significantly reduce fuel-derived CO2 emissions while achieving fuel cost savings and shorter working times. Utilizing subsidies and tax incentives can also help reduce the initial investment, so consider these options actively.

2. Reusing Construction By-products and Implementing Circular Resource Construction

The second method is to reuse construction by-products generated on site and implement circular resource-oriented construction. Civil and building works generate a wide variety of by-products—excavated soil, demolished concrete and asphalt chunks, and waste materials (wood, metal, etc.). Instead of treating these as industrial waste for disposal, effectively utilizing them as much as possible on-site or off-site can yield significant environmental and cost benefits.

Specific reuse measures include the following:

• Effective use of excavated soil: Large volumes of excavated soil (construction-generated soil) can be reused for on-site backfilling or embankment materials. Matching services can also supply this soil to other development or land reclamation projects, reducing the cost and CO2 associated with transporting and disposing of unwanted soil.

• Recycling concrete chunks: Demolished concrete can be crushed and used as recycled aggregate (recycled crusher run) or recycled sand for road base materials and backfill. This reduces the need for new quarrying and can lower waste disposal costs.

• Recycling asphalt waste: Removed asphalt can be reprocessed by heating and reblending into recycled asphalt mixtures for repaving. Increasing the recycling rate reduces the use of new asphalt mixes.

• Reuse of construction wood waste: Demolition wood can be chipped and used as plywood or paper raw material, or as fuel for biomass power generation. Temporary works materials and formwork should be reused as much as possible to curb new wood consumption and waste.

• Sorting and 3R for other waste: Metals, glass, and ceramic waste should be carefully sorted and recycled where possible (e.g., selling metal scrap or using recycled glass raw materials). Installing an on-site sorting yard increases recycling rates even for mixed waste.

In Japan, the "Act on the Promotion of Recycling of Construction Material Resources (Construction Recycling Act)" was enforced in 2002, making recycling of specific construction material waste—such as concrete chunks, asphalt/concrete chunks, and construction wood waste—mandatory for projects above a certain scale. Against this backdrop, general contractors prepare “construction by-product utilization plans” for each site to improve recycled resource utilization rates. The Ministry of Land, Infrastructure, Transport and Tourism’s Construction By-product Information Exchange System (COBRIS) enables real-time information exchange of by-products and searches for facilities that can use them, supporting matching between sites that generate and sites that need excavated soil or waste materials.

The environmental benefits are clear: reduced CO2 emissions from avoiding new resource extraction and industrial waste processing, along with preventing illegal dumping and extending the life of final disposal sites. Economically, savings can be expected from reduced soil disposal costs, lower new material expenses, and proceeds from selling waste materials, contributing to total project cost reductions. For example, in a large tunnel project where 1 million cubic meters of construction sludge were used in land reclamation in Osaka Bay, disposal cost savings on the order of several hundred million yen were reported.

A key to successfully implementing circular resource construction is to incorporate reuse planning from the design and planning stages. Use BIM/CIM to simulate total material input and by-product generation across the project, and pre-identify reuse destinations and storage locations. Coordination with subcontractors and other sites is also important. This establishes a workflow that makes the most of what is generated and enables sustainable construction from both environmental and cost perspectives.

3. Construction Optimization Using ICT (Equipment Placement and Route Optimization)

The third method is to use ICT (information and communication technology) to optimize construction processes. Visualize and automate heavy equipment movements and placements, and material transport routes with digital technology to reduce unnecessary movements and waiting times. This area is highlighted as part of the Ministry of Land, Infrastructure, Transport and Tourism’s promotion of "i-Construction" and construction DX efforts, and it can deliver significant environmental load reductions and productivity improvements.

Here are some concrete ICT application examples:

• Machine guidance / machine control (MG/MC): Using GPS and 3D design data to automatically control blades and buckets on heavy equipment enables precise grading and excavation. This can eliminate the need for manual batter boards and repeated checking, shortening work time. In one experiment, using an ICT-enabled hydraulic excavator reduced direct work time by about 43% compared to conventional methods, and one operator could complete tasks that previously required three, leading to lower fuel consumption and CO2 emissions.

• Visualizing heavy equipment operation: Systems exist that attach GNSS transmitters to site equipment and display each machine’s position and trajectory in real time on a cloud-based 3D site model. For example, Toda Corporation uses the [Heavy Equipment Operation Visualization System](https://www.toda.co.jp/tech/cutting/machinery.html) to view bulldozer and dump truck travel routes and waiting times at a glance, helping optimize equipment placement and the number of units required. As a result, fuel use per task has been reduced, shortening construction time and cutting costs.

• Optimizing material transport routes: Coordinate with subcontractors to optimize dump truck routes and schedules using ICT. By using map apps and logistics management systems to direct routes and timing that avoid congestion and waiting, driving distances and idling time can be cut. Joint material deliveries with nearby sites can reduce empty backhauls and the total number of trucks required.

• Construction planning simulation: Simulate construction steps and machine movements in software beforehand to devise efficient work sequences. By minimizing waiting and overlapping tasks between processes and planning completion with the least necessary movement, on-site trial-and-error is reduced. When operators follow simulation-based instructions, it prevents wasted fuel and time.

The effects of ICT-driven construction optimization provide CO2 reduction and cost savings hand in hand. Fewer unnecessary movements mean lower fuel consumption and shorter work times, which also saves labor and equipment costs. Digitalization also enables construction that does not rely solely on experience or intuition, so quality and efficiency can be maintained despite a shortage of skilled workers. Initial investments are required for surveying drones, GNSS devices, and specialized software, but there are national and municipal subsidies and scoring benefits for ICT-utilized projects, so phased adoption while utilizing available support is advisable.

4. Adopting Decarbonized Materials and BIM Integration

The fourth method is to switch construction materials themselves to decarbonized options and maximize effects through BIM integration. A significant portion of CO2 emissions associated with construction actually occurs during the manufacturing stage of materials. Cement production and steelmaking, in particular, are energy-intensive processes, so reducing the embodied carbon of these construction materials is a key challenge on the path to carbon neutrality.

In recent years, a variety of low-carbon construction materials have been developed and offered by various companies, such as:

• Low-CO2 cement and concrete: Eco-cements that blend blast furnace slag or fly ash (coal ash) with cement can reduce manufacturing CO2 by 30–40% compared to conventional cement. There are also specialized concretes that absorb CO2 during curing (CO2-absorbing concrete) that are advancing toward practical use.

• Green steel: Development is underway for "green steel"—producing steel with hydrogen instead of coal during smelting—to dramatically reduce CO2 emissions. Replacing structural steel for buildings or bridges with such steel in the future can yield significant indirect CO2 reductions.

• Promoting use of wood: Wood stores carbon absorbed during growth, exhibiting a "carbon storage" effect. Using mass timber (e.g., CLT) in medium- to large-scale construction instead of steel or concrete is gaining momentum. In civil engineering, actively using wood for temporary structures and landscape elements can reduce concrete usage.

• Use of recycled materials: Actively use recycled construction materials mentioned earlier as part of new material inputs. Recycled aggregate concrete reduces the amount of new aggregate needed and, if performance standards are met, can be applied to structural elements. Recycled asphalt reduces use of new, fuel-derived asphalt.

Currently, these low-carbon materials tend to be more expensive, so widespread adoption requires support measures such as "priority adoption in public works" or using revenues from carbon pricing. It is also necessary to stimulate demand across the supply chain rather than simply using the materials in isolation. As prices are expected to fall in the future and environmental regulations are likely to tighten, it is important to begin trial adoption now to accumulate know-how.

BIM (Building Information Modeling) and CIM (Construction Information Modeling) are tools to leverage here. By linking material information to 3D models on BIM/CIM, you can visualize the CO2 emissions (embodied carbon) of each component from the design stage. For example, it becomes easy to simulate CO2 reductions by switching from reinforced concrete to timber, or to compare the effects of substituting a different low-carbon concrete. Maeda Corporation has developed an LCA evaluation system linked to BIM data called "[CO2-Scope](https://www.maeda.co.jp/news/2024/07/05/5504.html)" to quickly calculate carbon footprints during design and support optimal material selection.

Furthermore, BIM helps with accurate ordering of material quantities and construction planning. Calculating detailed quantities prevents over-ordering, reducing unnecessary material production; prefabrication and standardization reduce on-site waste. Sharing information on BIM among designers, contractors, and manufacturers allows pre-understanding of the properties (strength and construction conditions) of new decarbonized materials and optimizes construction sequencing—another major advantage.

In short, this is an approach that promotes decarbonization and efficiency through both materials and digital technology. Adopting low-carbon materials lowers environmental impact over the entire life cycle, including future disposal and recycling, and BIM integration makes it feasible to implement these choices on site without friction.

5. Smart Surveying and Management Efficiency (Simple Surveying with LRTK)

The fifth and final method is to introduce smart surveying technologies to improve construction management efficiency. Frequent site tasks—such as surveying, as-built control, and quality inspection—can be performed easily and with high accuracy using the latest devices and software. This can greatly reduce the time and labor required for site management, leading to shorter schedules, fewer mistakes, and cost savings.

Recently, particular attention has been paid to simple surveying systems using smartphones and tablets. For example, the startup Reflexia developed a pocket-sized RTK-GNSS receiver called LRTK that attaches to an iPhone/iPad. With LRTK, anyone’s smartphone can become a versatile surveying instrument with centimeter-level accuracy. Tasks previously carried out by specialist surveyors using total stations can now be completed by site managers or workers alone and in a short time.

Smart surveying devices like LRTK offer the following features and benefits:

• High-precision positioning: RTK allows positioning errors on the order of several centimeters to millimeters. Using this for establishing reference points and as-built measurement drastically reduces surveying errors that cause rework.

• Easy operation: Intuitive smartphone apps let users take measurements with the push of a button. This makes the devices usable even without specialized knowledge, helpful where experienced surveyors are scarce.

• Portability and responsiveness: Lightweight devices (around 125 g) can be carried in a pocket and used immediately when needed. The ability to "measure whenever you want" increases measurement frequency and speeds up progress control and inspections.

• Multifunctionality: Beyond coordinate surveying, combining with a smartphone’s built-in LiDAR enables point-cloud measurements or AR marking for layout (staking). For example, visualizing the positions of buried utilities in AR while excavating helps prevent accidental digging and improves efficiency.

• Real-time sharing: Measured data can be automatically uploaded to the cloud and shared in real time with the office and clients. Compared to the old practice of returning with paper drawings for manual calculations and reporting, instant confirmation and use of data enables faster decision-making.

Introducing smart surveying tools can be seen as part of site management DX. While it may not appear to address environmental measures directly, improving the efficiency of surveying and inspections reduces work time and personnel, which in turn reduces the site’s overall energy consumption (shorter operating hours for equipment and vehicles). Increased measurement frequency also reduces errors and rework, contributing to lower material and fuel waste.

Beyond smart surveying, various IoT and AI technologies are emerging in site management. For example, installing sensors on site to automate environmental monitoring of concrete curing temperature, noise, vibration, and dust concentration, or using AI to analyze drone-captured progress images to check as-built conditions—these and other site management smartification efforts can be combined to reduce management burdens while improving quality, ultimately contributing to labor and energy savings.

Conclusion

Above, we introduced five methods to simultaneously reduce CO2 emissions and costs at construction sites. Each measure—improving fuel efficiency through energy-efficient heavy machinery, reducing waste by recycling construction by-products, eliminating waste via ICT-driven construction, lowering carbon footprints by adopting decarbonized materials, and improving operations through smart surveying and management—has standalone effects, but combining them creates synergies.

As calls for carbon neutrality and the SDGs grow louder, environmental measures are now a corporate social responsibility, and efforts to address environmental considerations are evaluated even in public works procurement. Fortunately, advances in digital technology and new materials are increasingly enabling the alignment of environmental benefits with productivity gains. Use the methods covered here as a reference and start implementing what you can at your own sites—begin with what’s possible and visualize progress.

Balancing environment and efficiency is the key to a sustainable construction industry. Simultaneously reducing CO2 and costs will directly strengthen your company’s competitiveness. The construction sites of the future will naturally be environmentally friendly and smart. Take a step-by-step approach and start challenging that future today.