Carbon Footprint Assessment Initiative and Trees Role in Reducing Emissions

Omar Alelweet ^*

1. Civil Engineering Department, Technical and Vocational Training Corporation, Uniza Technical College, Kingdom of Saudia Arabia

* Correspondence: Omar Alelweet

Academic Editor: Islam Md Rizwanul Fattah

Special Issue: Advances in Environmental Research

Received: October 08, 2024 | Accepted: January 13, 2025 | Published: January 23, 2025

Adv Environ Eng Res 2025, Volume 6, Issue 1, doi:10.21926/aeer.2501009

Recommended citation: Alelweet O. Carbon Footprint Assessment Initiative and Trees Role in Reducing Emissions. Adv Environ Eng Res 2025; 6(1): 009; doi:10.21926/aeer.2501009.

© 2025 by the authors. This is an open access article distributed under the conditions of the Creative Commons by Attribution License, which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is correctly cited.

1. Introduction

The term carbon footprint defined in this study is the total GHG emissions associated with a product or service in its entire life cycle expressed in tons of CO₂e. Wiedmann and Minx [1] stress that such carbon footprints are crucial for assessing environmental impact and applicable in areas including education and construction. The Intergovernmental Panel on Climate Change [2] states that there are eighteen types of GHGs, which have different potentials to contribute to global warming. This underlines the need to build efficient carbon accounting systems to manage emissions on institutional and worldwide levels. In the context of carbon accounting during the Kyoto Protocol and the United Nations Framework Convention on Climate Change [3], other regulations control other substances. However, the commonly used gases include carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), as well as sulfur hexafluoride (SF₆) are the only ones [4].

Since human respiration is the primary carbon dioxide (CO₂) source in indoor air, ventilation and occupant density are critical in determining indoor CO₂ concentrations. Indoor environments with insufficient ventilation can accumulate CO₂ to levels several times greater than background values, which could pose health risks [5]. Lu et al. [6] state that inadequate ventilation often results in elevated CO₂ levels, negatively impacting human health and performance. To reduce heat loss and improve energy efficiency, ventilation rates are being reduced due to rising energy costs and growing concerns about the environmental effects of buildings [5]. However, due to this practice, indoor air pollutants like CO₂ are building up to far greater levels than they were under earlier norms. CO₂ levels may be used as proxies to estimate ventilation rates and the presence of human bio-effluents inside due to the relationship between CO₂ concentration, human occupancy, and ventilation rates [6,7]. Currently, CO₂ is used as a marker to evaluate ventilation since high CO₂ levels indicate inadequate ventilation, which is often associated with worse air quality [8]. As Valls et al. [9] noted, integrating effective ventilation strategies with ecological interventions can mitigate these impacts.

Uniza Technical College was chosen as the study site because it has many different types of buildings, different occupancy patterns, and plants, like trees, that help store carbon. These factors make the campus an ideal model for exploring the relationship between human activities, built environments, and natural carbon mitigation strategies. Additionally, examining these elements offers valuable insights into reducing carbon emissions and promoting sustainability practices in educational institutions.

We often use CO₂ levels as an indicator to assess ventilation rates, as high concentrations indicate poor air quality and insufficient ventilation. Nkwocha and Egejuru [10] associated such high levels with respiratory problems and fatigue. These findings emphasize the importance of managing air quality, especially in educational settings.

According to Leite [11], CO₂ concentrations as high as 4,000 ppm can hurt pupils' ability to focus. Nkwocha & Egejuru [10] did a different analysis, and their findings showed that frequent colds, coughs, phlegm, sinusitis, and bronchitis symptoms linked to elevated CO₂ concentrations are widespread among students. Lethargy, poor coordination, headaches, asthma, and respiratory infections are other symptoms related to insufficient ventilation and high CO₂ levels, according to the Environmental Protection Agency (EPA) [12]. As a result, adequate ventilation and air quality are essential for student's health and academic success [13]. These factors emphasize how crucial it is to use CO₂ as the main indicator for evaluating ventilation and air quality in inhabited rooms.

Despite heightened awareness of carbon emissions, only a few research studies have successfully incorporated carbon footprint evaluations with ecological initiatives like tree planting. In their paper published in 2012, Strohbach et al. [14] stressed that urban green spaces can play a significant role in reducing cities' carbon footprint through biomass sequestration and influencing the energy balance of urban areas, thus helping combat climate change. This study aims to evaluate the effect of tree planting on campus on emissions to fill this gap and provide recommendations for implementing the study.

People increasingly recognize academic institutions as crucial contributors to sustainable development. The United Nations emphasizes the role of universities in achieving the Sustainable Development Goals (SDGs), particularly Goal 4 (Quality Education) and Goal 13 (Climate Action) [15]. This study aligns with these global frameworks by integrating carbon monitoring with green initiatives to enhance air quality, serving as a sustainable model for other institutions.

This research is considered innovative as it establishes a framework for measuring emissions, evaluating the potential for natural mitigation, and aligning with global climate action objectives The findings of Uniza-based Technical College contribute to the existing discourse on sustainability by identifying effective measures that can be taken to achieve carbon neutrality for schools.

The primary aim is to conduct an exhaustive assessment and evaluation of CO₂ concentrations in several sites around the campus. By doing this, we want to accomplish the following objectives:

1. Quantify CO₂ emissions: To determine the Uniza Technical College's total carbon footprint, measure and record the CO₂ concentrations in various buildings, labs, classrooms, and public areas.

2. Identify emission sources: Identify specific areas or activities within the Uniza Technical College that contribute significantly to CO₂ emissions, such as energy consumption, transportation, and goods and services.

3. Evaluation of the College's Trees' Contribution to Carbon Emission Reduction: accurately assessing every tree on campus's role in lowering carbon dioxide emissions and promoting environmental protection. Consequently, a strategic plan for planting more trees.

2. Methodology

To accomplish these objectives, we propose the following methodology:

2.1 Measurement

During the first semester of 2023, carbon dioxide levels were measured during the training session for four academic weeks, beginning with the first lecture and ending with the eighth lecture. These measurements were taken using the CO₂ Meter Air Quality Monitor Handheld B01966BZDY device across all college facilities, including workshops, classrooms, labs, administrative offices, and trainers' rooms.

We calibrated the CO₂ meters weekly using a standardized CO₂ reference gas to ensure data accuracy. We also conducted cross-validation with independent air quality monitoring devices. We collected data at varying times of the day to capture fluctuations due to occupancy changes, ensuring the representation of peak and non-peak periods.

2.2 Carbon Dioxide Emissions

A. Energy Consumption, B. Transportation, and C. Goods and services related to the training process. Data was connected to the three previously described activities to identify sources of emissions, and patterns and trends indicating increased carbon dioxide levels were observed. The results were then compared with carbon dioxide concentrations at other colleges and academic institutions around the world that use the same methodology.

2.2.1 Energy Consumption

The campus facilities management team tracked electricity consumption monthly from January to December 2022. We analyzed energy usage across different quarters to account for seasonal variations, such as increased cooling demands during the summer. We collected data on electricity consumption from smart meters installed at key distribution points. We recorded the total electricity consumption for the year 2022 at 381.382 MWh. We calculated the emissions using the Saudi Arabian Grid Emission Factor of 0.654 tCO₂/MWh, which we derived from the research by Lari et al. [16].

The following equation (1) was utilized to calculate carbon emissions resulting from energy use:

\[ \mathrm{E}\,=\,\text {Electricity} \, \text {Consumption} \,(\mathrm{MWh})\, \times \,\text {Grid Emission}\,\text {Factor} \,\left(\mathrm{tCO}_{2} / \mathrm{MWh}\right) \tag{1} \]

2.2.2 Transportation

We calculated the carbon emissions from transportation using the following equation (2):

\[ \begin{aligned}\mathrm{T}\,=\,&(\text{Average Fuel Consumption per 100 km}\,\times\,\mathrm{CO}_2\text{ Emission per Liter }*)\\&\times\,\text{Travel Distance (km)/1000}\end{aligned} \tag{2} \]

*Emission per Liter (Table 1).

Table 1 Carbon Emission Factors Based on Fuel Type Used.

We conducted daily surveys during the first semester of 2023 to gather data on the types of fuel used, travel distances, and vehicle types employed by staff and students. Approximately 95% of the vehicles operated on gasoline, resulting in higher emissions than diesel vehicles. We did not make seasonal adjustments because daily commuting patterns remained consistent throughout the year.

2.2.3 Goods and Services

Based on the following equation (3), it was calculated:

\[ \mathrm{G}\,=\,\text{Quantity of Goods Used}\,\times\,\text{Carbon Emission Factor (EF)} \tag{3} \]

Recent research has established emission factors for frequently used commodities such as printing paper, plastic water bottles, and detergents. Bałdowska-Witos et al. [20] evaluated the life cycle of plastic bottle manufacture, emphasizing its considerable environmental effect. Corbett et al. [21] examined the environmental impact of single-use plastics, highlighting their significant role in emissions. This research indicates that plastic water bottles constituted around 99% of emissions associated with these products, highlighting a substantial opportunity for action.

Where the following table's carbon emission factor is found in Table 2:

Table 2 Carbon Emission Factors for College-used Goods and Services.

2.3 Trees’ Carbon Sequestration Potential

Trees use their roots to absorb water and minerals, which they then transfer to their leaves during photosynthesis. Leaves also absorb light and carbon dioxide. After that, leaves use solar energy and chlorophyll to transform carbon dioxide and water into glucose.

We categorized the growth stages into saplings, semi-mature, and mature trees. Local climatic conditions, characteristic of a semi-arid environment, were considered to adjust the carbon sequestration rates. These calculations followed the guidelines set by Nowak et al. [27,28,29,30]. Following the release of oxygen, the tree uses the glucose to fuel itself:

1. Calculate the tree's overall (green) weight.
2. The tree's dry weight was calculated.
3. The weight of carbon that is contained in the tree.
4. Calculating the mass of carbon dioxide stored within the tree.
5. Every year, the weight of carbon dioxide stored in the tree is determined.

3. Results and Discussions

3.1 Measuring the CO₂ Levels in the Training Facility's Workshops, Training Rooms, Labs, and Administrative Offices

The research indicated that academic buildings' mean carbon dioxide (CO₂) concentration was 499 parts per million (ppm), as shown in Figure 1, a safe level according to international norms. CO₂ concentrations fluctuated around the campus due to several environmental conditions.

Figure 1 Shows the CO₂ levels in training facilities, workshops, labs, and administrative offices.

1. Ventilation Rates: Effective ventilation systems reduce CO₂ concentrations, while poor ventilation causes higher levels. Proper ventilation regulates indoor CO₂ levels by diluting and eliminating contaminants [31].

2. Occupant Density: Areas of concern include high-traffic areas, such as schools during peak times, where high levels of CO₂ are emitted from human breathing. This information can be used to monitor occupancy and assess ventilation performance [32].

3. The heating, ventilation, and air conditioning (HVAC) systems: Temperature settings can significantly impact indoor CO₂ levels. Demand-controlled ventilation adjusts airflow based on real-time CO₂ concentrations, improving indoor air quality and energy efficiency [33].

These results highlight the importance of considering environmental factors such as ventilation rates, occupant density, and HVAC operations when evaluating indoor CO₂ levels. The average of 499 ppm supports safe circumstances; however, boosting ventilation in busy places could enhance indoor air quality. To fully measure indoor air quality, future research must monitor several environmental indicators in real time.

Carbon dioxide levels are categorized as safe when they are less than 700 ppm (CO₂ < 700 ppm) and dangerous when they exceed 1000 parts per million (CO₂ > 1000 ppm), according to major global environmental and sustainability organizations (Figure 2) [34,35,36,37]:

Figure 2 Carbon Dioxide (CO₂) Levels in Indoor Air Risk Classification Diagram [38].

The training rooms of Building 6 (General Studies) had the highest measured concentration of carbon dioxide (CO₂), with an average of 646 parts per million (ppm). It is still below the typical threshold of 700 ppm despite this increment. It is observed that this location has a 0.33 student density.

However, in other buildings, the carbon dioxide emissions range was 571 to 548 ppm (23%) higher. There was a reported disparity of around 30% in the training workshops and roughly 27% in the training laboratories. With a student density of 0.80, a CO₂ level of 493 ppm was observed in the cafeteria.

As a result, the research suggests the following:

• Sensor Installation: This entails positioning very accurate carbon dioxide monitoring equipment in key areas of colleges, workshops, labs, and office buildings. Additionally, with the appropriate authorities, sensors that detect the degree of danger should be installed and set to open windows and air fans.
• Data collection: Acquiring data on the continuous concentration of carbon dioxide over a long period, recording variations at various periods of the day, week, and year. Regular data recording intervals from the devices will guarantee correctness and dependability.
• Data analysis: examining patterns and trends in the long-term data collection that indicate increases in carbon dioxide levels. Determining the origins of emissions by connecting the data to particular events, actions, or other variables.

3.2 Measure and Calculate the Technical College's Contribution in Onaizah to Carbon Dioxide Levels

3.2.1 Emissions from Energy

The Technical College in Onaizah has implemented efficient carbon emission strategies since it has a total footprint of 521 tCO₂-eq. Compared to institutions of similar size and infrastructure, Onaizah’s emissions are relatively low. For example, the University of Cape Town, which has a student and staff population of 2,077, emitted 59,603 tCO₂-eq [39]. Based on the total population, Onaizah’s emissions amount to only 1.82% of those at Cape Town, indicating that the college consumes less energy and operates on a smaller scale.

Nevertheless, while this comparison highlights Onaizah’s strengths, understanding the complexities requires comparisons with other institutions in similar climate zones and with similar facilities. These comparisons may help identify the most effective and efficient energy management strategies and potential measures for enhancing carbon mitigation.

3.2.2 Emissions Resulting from Transportation

Cars are the primary means of transportation utilized to get to and from the campus. A total of 172 people took part in the survey, administered throughout the morning and evening hours of the first semester of the academic year 2023 to trainers, administrators, and trainees. The distribution of fuel types used for daily transportation to the institution is shown in Figure 3.

Figure 3 Daily Transportation Mode Distribution by Students and Staff.

Figure 4 illustrates the amount of carbon emissions resulting from car usage as a means of transportation. The total carbon emissions resulting from transportation were 0.79 tCO₂-eq. Since 95% of the transportation used gasoline, the carbon emissions were higher than those from diesel cars.

Figure 4 Carbon emissions by Students and Staff.

3.2.3 Emissions Resulting from Goods and Services

A total of 271 tCO₂-eq (Table 3), was emitted from products and services, with approximately 99% of the emissions stemming from plastic water bottles. This presents a significant concern that requires attention. As a result, the study suggests avoiding increasing their use and switching to refrigerators that use readily recyclable or recyclable cups in their place. The report also recommends utilizing recyclable trash bags.

Table 3 Carbon Emission Factors Based on Fuel Type Used.

The analysis conducted in sections 1, 2, and 3 found that the total carbon emissions amounted to 521 tCO₂-eq, which is considered low compared to 85,000 tCO₂-eq at the University of Cape Town, where the number of students and faculty members was 2077. Additionally, the carbon emissions from the Technical College in Onaizah were compared to several other universities and academic institutions worldwide using the same methodology (Figure 5). The college in Onaizah ranked the lowest at 0.18% [27], calculated by dividing the total carbon emissions by the number of students and staff.

Figure 5 Carbon emissions by Students and Staff.

3.3 Contribution of Trees to Carbon Emission Reduction

Trees play a crucial role in environmental protection, preservation of natural resources, enhancing biodiversity [28], promoting biological security, improving air quality and quality of life, and purifying the air [29]. Additionally, trees contribute to soil stabilization and carbon dioxide reduction through photosynthesis [30].

Based on the calculations in section (c) regarding the contribution of the Technical College in Onaizah to carbon dioxide levels, which amounted to 521 tCO₂-eq, the contribution of trees in the college to reduce these emissions was found to be 2930 kg/year for a total of 303 trees. Therefore, based on the agreement signed between the General Organization for Technical and Vocational Training and the Ministry of Environment, Water, and Agriculture in the Qassim region, the study recommends planting 178 trees to achieve balance. The suggestion of planting 178 trees to counteract the college’s carbon footprint of 521 tCO₂-eq is both audacious and viable. However, for this to be effectively achieved and implemented, other factors must be considered, such as the species of trees to be planted, the maintenance required, and whether there is enough space.

To discuss the entire process of selecting and maintaining tree species for sustainability in Onaizah, it is crucial to choose species that are suitable for Onaizah's semi-arid climate. Recommended trees include Acacia tortilis and Ziziphus spina-christi, as they are drought-resistant, require low amounts of water, and have high carbon sequestration potential. The initiative should ensure that only native tree species are used to promote biodiversity, minimize adverse environmental impacts, and ensure that management practices are tailored to local conditions.

Many factors affect tree growth, including water, diseases, pests, and pruning, particularly in the early years. These factors must be incorporated into the college's business processes to ensure that resources and personnel are appropriately allocated to guarantee the success of the initiative.

3.3.1 Considering Several Alternative Strategies for Carbon Mitigation

To this end, this study also looked at several other options that, if implemented, could also help reduce the carbon footprint of the college:

Energy Efficient Technologies. Energy consumption is the most significant factor contributing to college emissions, accounting for 47.9% of the total emissions, which equals 249.42 tCO₂-eq. Some measures include Installing energy-saving lights such as motion sensors in corridors and classrooms and upgrading air conditioning systems to energy-efficient ones, which could also help reduce energy consumption. Also, since the region has high solar irradiance, solar panels are another means of shifting from fossil fuel use.

Transportation Policies. Transportation emissions were estimated at 0.79 tCO₂-eq, reflecting the proximity of students and staff to the campus. To further reduce transportation emissions, measures such as encouraging carpooling, promoting the use of public transport, and supporting the adoption of electric vehicles could be implemented.

Sustainable Consumption Practices. Goods and services were calculated to emit 271 tCO₂-eq, with plastic water bottles alone accounting for 99% of these emissions. Some of the measures include encouraging reusable plastics and ensuring that water refill stations are provided on the campus, which can help reduce these emissions. Such initiatives also contribute to achieving sustainability goals and create awareness of environmental issues among the students and staff.

3.3.2 Addressing Data Uncertainties

The study presents several viable suggestions. However, it also has certain limitations of the data:

• Emission Calculations: There is a possibility of errors when using standard emission factors, as the factors set by the standards may need to be revised. For instance, energy generation sources or transportation use may vary and influence the calculations. Real-time monitoring systems could also enhance the accuracy of the data and differentiate between the conditions of planting the proposal areas in detail.
• Estimated Tree growth Growth rates Variability: The ability of trees to sequester carbon can be affected by several factors, including soil quality, water intake, and the type of trees used. To mitigate these risks, future research should focus on monitoring tree growth and CO₂ uptake over time.

3.3.3 Strengthening the Proposal

The recommendation to plant 178 trees is still at the forefront of the college’s strategy for reducing its carbon footprint. By choosing the drought-tolerant local varieties of trees, including Acacia tortilis and Ziziphus spina-christi, the initiative is feasible given Onaizah’s semi-arid climate and low input needs. The feasibility of having sufficient land has been examined, and it has been determined that there are ample spaces on the campus that can accommodate the planting of additional trees. This expansion will not interfere with college operations or other community activities that promote sustainable consumption. Practices will support the tree using planting of ideal energy, thus saving and providing equipment with an overall encouraging approach to carbon management. This approach is consistent with the current international conventions on sustainability and reflects the college’s determination to mitigate emissions.

4. Conclusion

This study thoroughly evaluates carbon emissions at Uniza Technical College, emphasizing its relatively lower emissions than other universities. It underscores the pivotal role educational institutions can play in promoting environmental sustainability. The study, projecting a carbon footprint of 521 tCO₂-eq, underlines the imperative, such as enhancing energy efficiency, reducing single-use plastic usage, and increasing tree planting initiatives. These efforts are not only actionable locally but also align with global sustainability frameworks such as the United Nations’ Sustainable Development Goals, particularly Goal 13 (Climate Action) and Goal 15 (Life on Land).

By integrating carbon monitoring with ecological interventions, the study demonstrates a scalable model for other institutions, emphasizing the potential for educational facilities worldwide to adopt similar measures. The proposal to plant 178 trees and select species appropriate for semi-arid regions provides a reproducible strategy for attaining carbon neutrality. This endeavor can inform policy, directing institutions to establish effective environmental management systems suited to their specific circumstances.

This work connects institutional actions with global climate objectives, offering a framework that facilitates the transition to a more sustainable future. Academic institutions must exemplify leadership by cultivating a culture of environmental stewardship and innovation. Subsequent studies should investigate real-time monitoring systems and cross-institutional comparisons to augment the scalability and efficacy of these programs.

Acknowledgment

The author expresses profound gratitude to all members of the college who have contributed to the initiative's success and the hard work to reach its current position. Special recognition goes to the Dean En. Abdullah Al-Saikhan, Mr. Khaled Al-Humaidi, and Eng. Mohammed Al-Samanan for their exceptional support. Additionally, the author would like to thank the head of the department, Eng. Mishal Al-Mutairi, as well as collegemates Eng. Abdullah Al-Fayez, Eng. Mansour Al-Humaidan, and Ms. Mashael Al-Atni. The trainees, including Sami Al-Harbi, Saif Al-Mutairi, and Mohammed Al-Mutairi, are appreciated for their tireless efforts that have helped make this initiative successful. The author extends heartfelt gratitude to everyone involved, as their invaluable contributions have been instrumental in the success of this initiative.

Author Contributions

The author did all the research work of this study.

Competing Interests

The author has declared that no competing interests exist.