Study on Carbon Emissions Produced by Reinforced Concrete and Modular Construction

This article reviews a study on the carbon emissions produced by modular construction methods versus those using traditional reinforced concrete. The researchers, writing in the journal Buildings, used a Korean case study to investigate their hypothesis. 

Study: Comparison of the Embodied Carbon Emissions and Direct Construction Costs for Modular and Conventional Residential Buildings in South Korea. Image Credit: tsyklon/Shutterstock.com

Most buildings in South Korea are currently constructed using traditional wet construction methods, such as reinforced concrete (RC) construction, even though this can result in productivity issues due to a lack of functional engineering capabilities, skilled workers, and unfavorable weather conditions.

It is hardly surprising that construction companies are becoming increasingly interested in modular construction methods, in which pieces are made in factories under regulated conditions and then transferred to the construction area for assembly.

Modular construction is a high-tech, dry-construction process that boosts construction productivity and efficiency. Off-site construction, which includes modular construction, refers to the pre-fabrication or manufacture of discrete units that are then assembled on-site to form the finished structure.

The benefits of modular construction, like its integrated design approach, productivity, and structure, have been the focus of most research in this area. Since the building industry contributes to more than 30% of global carbon dioxide emissions, it is essential that carbon pollution from the industry is reduced.

In-depth research on factors such as environmental effect assessments and economic evaluation of modular construction methods are required to assure the overall sustainability of modular construction techniques.

Modular construction methods. Image Credit: Lim, 2016

Modular construction methods. Image Credit: Kamali and Hewage, 2016; du Chayla, et al., 2021

As a result, this study compares the embodied carbon emissions and direct construction cost of a modular residential building during the production phase to those of a traditional residential building. Researchers concentrated on the material production phase because it has been shown that in modular building approaches this step produces more embodied carbon emissions than other project stages.

Methodology

Principal drawings and design details of the modular residential building chosen for this study were created. Table 1 and Figure 3 provide an overview and front view of the project, respectively.

Figure 3. Front view of target building. Image Credit: Jang, et al., 2022

Table 1. Project overview. Source: Jang, et al., 2022

The common section, designated A-Wing, was constructed using the traditional RC construction method, while the residential parts, which included portions of the B-Wing and the C-Wing, each with 20 houses, were constructed using two alternative modular construction methods.

As a result of modular and RC construction methods, Table 2 compares the embodied carbon emissions normally produced by construction materials used for residential buildings.

Table 2. Quantity of major construction material using the two building systems. Source: Jang, et al., 2022

The Korea Environmental Industry and Technology Institute (KEITI) developed embodied carbon emission parameters that were used to assess embodied emissions in the manufacturing stages of modular and RC residential buildings. Table 3 shows the embodied carbon emission factors for several important construction materials during the manufacturing process. The unit costs of major construction materials are shown in Table 4.

Table 3. Embodied carbon emission factors in the production phase for major construction materials. Source: Jang, et al., 2022

Table 4. Unit material cost of major construction materials. Source: Jang, et al., 2022

* 1 United States Dollar (USD) = 1240 Korea Won (KRW).

Results and Discussion

The results of the embodied carbon emissions assessment of the primary construction materials utilized in this study are shown in Table 5. Figure 5 presents a comparison of the embodied carbon emissions for the modular and RC construction methods.

Table 5. Results of the assessment of the embodied carbon emissions. Source: Jang, et al., 2022

Figure 5. Comparison of the modular and RC building embodied carbon emissions. Image Credit: Jang, et al., 2022

The direct building expenses of the modular and RC construction methods are shown in Table 6 and Figure 6.

Figure 6. Comparison of modular construction and RC construction costs. Image Credit: Jang, et al., 2022

Table 6. Direct construction costs for the modular and RC construction methods. Source: Jang, et al., 2022

* 1 USD = 1240 KRW.

Even though the direct building cost was slightly greater, the outcomes of this study revealed that modular construction can lower embodied carbon emissions throughout the material production phase when compared to an equal RC structure.

As shown in Table 7, the environmental impact of RC structures is higher compared to modular structures.

Table 7. Characteristics summary table of RC method and modular method. Source: Jang, et al., 2022

Conclusion

The results of the modular and RC construction methods were compared and assessed, as well as the embodied carbon emissions and direct construction expenses incurred at the time of the material production phase of a residential building.

The study identified that when compared to the traditional RC approach, the modular construction method decreased embodied carbon emissions in the material production stage by around 36%.

It also observed that when direct construction costs for modular and RC building methods were compared, the modular method was more expensive.

The direct construction cost of the modular construction technique was 477,332 USD, which was approximately 8.1% higher than the RC construction method; according to an examination of the two methods’ direct construction costs.

However, the benefits of modular design such as ease of maintenance and high recycling rates were not addressed in this study. Amore comprehensive cost analysis will be required to acquire a full life-cycle perspective.

Journal Reference:

Jang, H., Ahn, Y., Roh, S. (2022) Comparison of the Embodied Carbon Emissions and Direct Construction Costs for Modular and Conventional Residential Buildings in South Korea. Buildings, 12(1), p. 51. Available Online: https://www.mdpi.com/2075-5309/12/1/51/htm

References and Further Reading

1. Tam, V. W., et al. (2015) Best practice of prefabrication implementation in the Hong Kong public and private sectors. Journal of Cleaner Production, 109, pp. 216–231 doi.org/10.1016/j.jclepro.2014.09.045.
2. Kim, K T & Lee, Y H (2011) Economic Feasibility Study on the Unit Modular Fabrication Method According to the Life Cycle Costing Methodology, Journal of Structural and Construction Engineering, 27, pp. 207–214.
3. Jaillon, L C & Poon, C S (2009) The evolution of prefabricated residential building systems in Hong Kong: A review of the public and the private sector. Automation in Construction, 18, pp. 239–248. doi.org/10.1016/j.autcon.2008.09.002.
4. Xu, X & Zhao, Y (2010) Some Economic Facts of the Prefabricated Housing; Industry Report; Rutgers Business School: Newark, NJ, USA.
5. Mao, C., et al. (2016) Cost analysis for sustainable off-site construction based on a multiple-case study in China. Habitat International, 57, pp. 215–222. doi.org/10.1016/j.habitatint.2016.08.002.
6. Kamali, M., et al. (2018) Life cycle sustainability performance assessment framework for residential modular buildings: Aggregated sustainability indices. Building and Environment, 138, pp. 21–41. doi.org/10.1016/j.buildenv.2018.04.019.
7. Li, Z., et al. (2014) Measuring the impact of prefabrication on construction waste reduction: An empirical study in China. Resources, Conservation and Recycling, 91, pp. 27–39. doi.org/10.1016/j.resconrec.2014.07.013.
8. Baldwin, A., et al. (2009) Designing out waste in high-rise residential buildings: Analysis of precasting methods and traditional construction. Renewable Energy, 34, pp. 2067–2073. doi.org/10.1016/j.renene.2009.02.008.
9. Li, Z., et al. (2014) Critical review of the research on the management of prefabricated construction. Habitat International, 43, pp. 240–249. doi.org/10.1016/j.habitatint.2014.04.001.
10. Nahmens, I & Ikuma, L H (2012) Effects of Lean Construction on Sustainability of Modular Homebuilding. Journal of Architectural Engineering, 18, pp. 155–163. doi.org/10.1061/(ASCE)AE.1943-5568.0000054.
11. Kamali, M & Hewage, K (2016) Life cycle performance of modular buildings: A critical review. Renewable and Sustainable Energy Reviews, 62, pp. 1171–1183. doi.org/10.1016/j.rser.2016.05.031.
12. Ahn, Y H & Kim, K T (2014) Sustainability in modular design and construction: A case study of ‘The Stack’. International Journal of Sustainable Building Technology and Urban Development, 5, pp. 250–259. doi.org/10.1080/2093761X.2014.985758.
13. Ganiron, T U & Almarwae, M (2014) Prefabricated Technology in a Modular House. International Journal of Advanced Science and Technology, 73, pp. 51–74. doi.org/10.14257/ijast.2014.73.04
14. Pervez, H., et al. (2021) A quantitative assessment of greenhouse gas (GHG) emissions from conventional and modular construction: A case of developing country. Journal of Cleaner Production, 294, p. 126210. doi.org/10.1016/j.jclepro.2021.126210.
15. Atmaca, N (2016) Life-cycle assessment of post-disaster temporary housing. Building Research & Information, 45, pp. 524–538. doi.org/10.1080/09613218.2015.1127116.
16. Giriunas, K., et al. (2012) Evaluation, modeling, and analysis of shipping container building structures. Engineering Structures. 43, pp. 48–57 doi.org/10.1016/j.engstruct.2012.05.001.
17. Masson-Delmotte, V., et al. (2021) Global warming of 1.5 C. An IPCC Special Report on the Impacts of Global Warming of 2018, 1. Available at: https://www.ipcc.ch/sr15/.
18. Han, Y., et al. (2017) A Market Equilibrium Supply Chain Model for Supporting Self-Manufacturing or Outsourcing Decisions in Prefabricated Construction. Sustainability, 9, p. 2069. doi.org/10.3390/su9112069.
19. Mao, C., et al. (2013) Comparative study of greenhouse gas emissions between off-site prefabrication and conventional construction methods: Two case studies of residential projects. Energy and Buildings, 66, pp. 165–176. doi.org/10.1016/j.enbuild.2013.07.033.
20. Cao, X., et al. (2015) A comparative study of environmental performance between prefabricated and traditional residential buildings in China. Journal of Cleaner Production, 109, pp. 131–143. doi.org/10.1016/j.jclepro.2015.04.120.
21. Thormark, C (2000) Including recycling potential in energy use into the life-cycle of buildings. Building Research & Information, 28, pp. 176–183. doi.org/10.1080/096132100368948.
22. Kamali, M & Hewage, K (2017) Development of performance criteria for sustainability evaluation of modular versus conventional construction methods. Journal of Cleaner Production, 142, pp. 3592–3606. doi.org/10.1016/j.jclepro.2016.10.108.
23. Tumminia, G., et al. (2018) Life cycle energy performances and environmental impacts of a prefabricated building module. Renewable and Sustainable Energy Reviews, 92, pp. 272–283. doi.org/10.1016/j.rser.2018.04.059.
24. Wang, S & Sinha, R (2021) Life Cycle Assessment of Different Prefabricated Rates for Building Construction. Buildings, 11, p. 552. doi.org/10.3390/buildings11110552.
25. Velamati, S (2012) Feasibility, Benefits and Challenges of Modular Construction in High Rise Development in the United States: A Developer’s Perspective. Master’s Thesis, Massachusetts Institute of Technology, Cambridge, MA, USA.
26. Generalova, E., et al. (2016) Modular Buildings in Modern Construction. Procedia Engineering, 153, pp. 167–172. doi.org/10.1016/j.proeng.2016.08.098.
27. Lim, S.-H (2016) A Current State of Apartment Construction Technology Development with the Application of Modular Technology. Review of Architecture and Building Science, 60, pp. 16–21.
28. Schoenborn, J M (2012) A Case Study Approach to Identifying the Constraints and Barriers to Design Innovation for Modular Construction. Master’s Thesis, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA, 27.
29. Lacey, A., et al. (2019) Review of bolted inter-module connections in modular steel buildings. Journal of Building Engineering, 23, pp. 207–219. doi.org/10.1016/j.jobe.2019.01.035.
30. Lacey, A. W., et al. (2018) Structural response of modular buildings—An overview. Journal of Building Engineering, 16, pp. 45–56. doi.org/10.1016/j.jobe.2017.12.008.
31. Srisangeerthanan, S., et al. (2020) Review of performance requirements for inter-module connections in multi-story modular buildings. Journal of Building Engineering, 28, p. 101087. doi.org/10.1016/j.jobe.2019.101087.
32. Aye, L., et al. (2012) Life cycle greenhouse gas emissions and energy analysis of prefabricated reusable building modules. Energy and Buildings, 47, pp. 159–168. doi.org/10.1016/j.enbuild.2011.11.049.
33. Thirunavukkarasu, K., et al. (2021) Sustainable Performance of a Modular Building System Made of Built-Up Cold-Formed Steel Beams. Buildings, 11, p. 460. doi.org/10.1016/j.enbuild.2011.11.049.
34. Chiang, Y. H., et al. (2006) Prefabrication and barriers to entry—a case study of public housing and institutional buildings in Hong Kong. Habitat International, 30, pp. 482–499. doi.org/10.1016/j.habitatint.2004.12.004.
35. Xu, Z., et al. (2020) Comparative analysis of modular construction practices in mainland China, Hong Kong and Singapore. Journal of Cleaner Production, 245, p. 118861. doi.org/10.1016/j.jclepro.2019.118861.
36. Faludi, J., et al. (2012) Using life cycle assessment methods to guide architectural decision-making for sustainable prefabricated modular buildings. Journal of Green Building, 7, pp. 151–170. doi.org/10.3992/jgb.7.3.151.
37. Lawson, R & Ogden, R (2010) Sustainability and process benefits of modular construction. In Proceedings of the TG57-Special Track 18^th CIB World Building Congress, Salford, UK, 10–13 May; p. 38.
38. Hartley, A & Blagden, A (2007) Current Practices and Future Potential in Modern Methods of Construction; Full Final Report WAS003-001; Waste & Resources Action Program, AMA Research LtD.: London, UK.
39. Dong, Y. H., et al. (2015) Comparing carbon emissions of precast and cast-in-situ construction methods–A case study of high-rise private building. Construction and Building Materials, 99, pp. 39–53. doi.org/10.1016/j.conbuildmat.2015.08.145.
40. Kamali, M., et al. (2019) Conventional versus modular construction methods: A comparative cradle-to-gate LCA for residential buildings. Energy Build, 204, p. 109479. doi.org/10.1016/j.enbuild.2019.109479.
41. Hong, J., et al. (2016) Life-cycle energy analysis of prefabricated building components: An input–output-based hybrid model. Journal of Cleaner Production, 112, pp. 2198–2207. doi.org/10.1016/j.jclepro.2015.10.030.
42. Blanquet du Chayla, C., et al. (2021) A Method to Qualify the Impacts of Certifications for Prefabricated Constructions. Buildings, 11, p. 331. doi.org/10.3390/buildings11080331.
43. Park, J. Y., et al. (2014) A Comparative Analysis on Life Cycle CO Emission between a Modular Housing and a R.C. Apartment Housing. Journal of the architectural institute of Korea planning & design, 30, pp. 35–43. doi.org/10.5659/JAIK_PD.2014.30.5.035.
44. Kim, D (2008) Preliminary Life Cycle Analysis of Modular and Conventional Housing in Benton Harbor; University of Michigan: Ann Arbor, MI, USA.
45. Balasbaneh, A. T., et al. (2019) Sustainable materials selection based on flood damage assessment for a building using LCA and LCC, Journal of Cleaner Production, 222, pp. 844–855. doi.org/10.1016/j.jclepro.2019.03.005.
46. Bovea, M & Vidal, R (2004) Increasing product value by integrating environmental impact, costs and customer valuation. Resources, Conservation and Recycling, 41, pp. 133–145. doi.org/10.1016/j.resconrec.2003.09.004.
47. Xie, H.-B., et al. (2018) Life-time reliability based optimization of bridge maintenance strategy considering LCA and LCC, Journal of Cleaner Production, 176, pp. 36–45. doi.org/10.1016/j.jclepro.2017.12.123.
48. Shi, J., et al. (2019) An integrated environment and cost assessment method based on LCA and LCC for mechanical product manufacturing. The International Journal of Life Cycle Assessment, 24, pp. 64–77. doi.org/10.1007/s11367-018-1497-x.
49. Pons, O & Wadel, G (2011) Environmental impacts of prefabricated school buildings in Catalonia. Habitat International, 35, pp. 553–563. doi.org/10.1016/j.habitatint.2011.03.005.
50. ISO I. ISO-14040 (2006) Environmental Management–Life Cycle Assessment–Principles and Framework, International Organization for Standardization: Geneva, Switzerland.
51. Lee, J. M., et al. (2014) Study on Recognition and Satisfaction of Modular Housing through the Post Occupancy Evaluation. Journal of the Korean housing association, 25, pp. 63–71. doi.org/10.6107/JKHA.2014.25.5.063.
52. Soust-Verdaguer, B (2016) Simplification in life cycle assessment of single-family houses: A review of recent developments. Building and Environment, 103, pp. 215–227. doi.org/10.1016/j.buildenv.2016.04.014.
53. Ben-Alon, L (2021) Life cycle assessment (LCA) of natural vs conventional building assemblies. Renewable and Sustainable Energy Reviews, 144, p. 110951. doi.org/10.1016/j.rser.2021.110951.
54. Li, D., et al. (2016) Development of an automated estimator of life-cycle carbon emissions for residential buildings: A case study in Nanjing, China. Habitat International, 57, pp. 154–163. doi.org/10.1016/j.habitatint.2016.07.003.
55. Ahmed, I M & Tsavdaridis, K D (2018) Life cycle assessment (LCA) and cost (LCC) studies of lightweight composite flooring systems. Journal of Building Engineering, 20, pp. 624–633. doi.org/10.1016/j.jobe.2018.09.013.
56. Bribian, I Z (2009) Life cycle assessment in buildings: State-of-the-art and simplified LCA methodology as a complement for building certification. Building and Environment, 44, pp. 2510–2520. doi.org/10.1016/j.buildenv.2009.05.001.
57. Pan, W (2008) Rethinking system boundaries of the life cycle carbon emissions of buildings. Renewable and Sustainable Energy Reviews, 90, pp. 379–390. doi.org/10.1016/j.rser.2018.03.057.
58. Minunno, R., et al. (2021) Investigating the embodied energy and carbon of buildings: A systematic literature review and meta-analysis of life cycle assessments. Renewable and Sustainable Energy Reviews, 143, p. 110935. doi.org/10.1016/j.rser.2021.110935.
59. Asdrubali, F., et al. (2020) An Evaluation of the Environmental Payback Times and Economic Convenience in an Energy Requalification of a School. Buildings, 11, p. 12. doi.org/10.3390/buildings11010012.
60. Chau, C. K., et al. (2015) A review on Life Cycle Assessment, Life Cycle Energy Assessment and Life Cycle Carbon Emissions Assessment on buildings. Applied Energy, 143, pp. 395–413. doi.org/10.1016/j.apenergy.2015.01.023.
61. Islam, H., et al. (2015) Life cycle assessment and life cycle cost implication of residential buildings—A review. Renewable and Sustainable Energy Reviews, 42, 129–140. doi.org/10.1016/j.rser.2014.10.006.
62. Salehian, S., et al. (2020) Assessment on Embodied Energy of Non-Load Bearing Walls for Office Buildings. Buildings, 10, p. 79. doi.org/10.3390/buildings10040079.
63. Tae, S., et al. (2011) The development of apartment house life cycle CO₂ simple assessment system using standard apartment houses of South Korea. Renewable and Sustainable Energy Reviews, 15, pp. 1454–1467. doi.org/10.1016/j.rser.2010.09.053.
64. Venkatraj, V & Dixit, M (2021) Life cycle embodied energy analysis of higher education buildings: A comparison between different LCI methodologies. Renewable and Sustainable Energy Reviews, 144, p. 110957. doi.org/10.1016/j.rser.2021.110957.
65. Mohammad, M., et al. (2020) Concrete Printing Sustainability: A Comparative Life Cycle Assessment of Four Construction Method Scenarios. Buildings, 10, p. 245. doi.org/10.3390/buildings10120245.
66. Satola, D., et al. (2020) Life Cycle GHG Emissions of Residential Buildings in Humid Subtropical and Tropical Climates: Systematic Review and Analysis. Buildings, 11, p. 6. doi.org/10.3390/buildings11010006.
67. Korea Life Cycle Inventory Database (2004) Korea Environmental Industry and Technology Institute (KEITI): Seoul, Korea.
68. Shin, H. K., et al. (2019) Economic Feasibility Study on the Modular Apartment Housing According to the Life Cycle Costing Methodology: A Case Study on the Modular Apartment Housing in Cheonan. Korea Facility Management Association, 14, pp. 15–24.
69. Ristimäki, M., et al. (2013) Combining life cycle costing and life cycle assessment for an analysis of a new residential district energy system design. Energy, 63, pp. 168–179. doi.org/10.1016/j.energy.2013.10.030.
70. Dhaif, M & Stephan, A (2021) A Life Cycle Cost Analysis of Structural Insulated Panels for Residential Buildings in a Hot and Arid Climate. Buildings, 11, p. 255. doi.org/10.3390/buildings11060255.
71. D’Incognito, M., et al. (2015) Actors and barriers to the adoption of LCC and LCA techniques in the built environment. Actors and barriers to the adoption of LCC and LCA techniques in the built environment. Built Environment Project and Asset Management, 5, pp. 202–216. doi.org/10.1108/BEPAM-12-2013-0068
72. Guoguo, L (2009) Integration of LCA and LCC for Decision Making in Sustainable Building Industry; Chalmers University of Technology: Gothenburg, Sweden.
73. Hromada, E., et al. (2021) Residential Construction with a Focus on Evaluation of the Life Cycle of Buildings. Buildings, 11, p. 524. doi.org/10.3390/buildings11110524.
74. Petrović, B., et al. (2021) Life Cycle Cost Analysis of a Single-Family House in Sweden. Buildings, 11, p. 215. doi.org/10.3390/buildings11050215.
75. Oladazimi, A., et al. (2020) Comparative Life Cycle Assessment of Steel and Concrete Construction Frames: A Case Study of Two Residential Buildings in Iran. Buildings, 10, p. 54. doi.org/10.3390/buildings10030054.
76. Quale, J., et al. (2012) Construction Matters: Comparing Environmental Impacts of Building Modular and Conventional Homes in the United States. Journal of Industrial Ecology, 16, pp. 243–253 doi.org/10.1111/j.1530-9290.2011.00424.x.
77. Loizou, L., et al. (2021) Quantifying Advantages of Modular Construction: Waste Generation. Buildings, 11, p. 622. doi.org/10.3390/buildings11120622