Energy Efficiency in Buildings: Performance Gaps and Sustainable Materials

Energy Efficiency in Buildings: Performance Gaps and Sustainable Materials: Comparison

Please note this is a comparison between Version 2 by Vivi Li and Version 1 by Antonio Benjamim Mapossa.

Real-world energy efficiency in the building sector is currently inadequate due to significant discrepancies between predicted and actual building energy performance. As operational energy is optimized through improved building envelopes, embodied energy typically increases, further exacerbating the problem. This gap underscores the critical need to re-evaluate current practices and materials used in energy-efficient building construction. It is well established that adopting a life cycle view of energy efficiency is essential to mitigate the building sector’s contribution to rising global energy consumption and CO₂ emissions. Therefore, this study aims to examine existing research on sustainable building materials for life cycle energy efficiency. Specifically, it reviews recent research to identify key trends, challenges, and suggestions from tested novel materials. A combination of theoretical analysis and narrative synthesis is employed in a four-stage framework discussing the challenges, context, concepts, and the reviewed literature. Key trends include the growing adoption of sustainable materials, such as bio-fabricated and 3D printed materials, which offer improved insulation, thermal regulation, and energy management capabilities. Multifunctional materials with self-healing properties are also emerging as promising solutions for reducing energy loss and enhancing building durability. The focus on reusing materials from the agricultural, food production, and paper manufacturing industries in building construction highlights the opportunity to facilitate a circular economy. However, the challenges are substantial, with more research required to ascertain long-term performance, show opportunities to scale the implementation of these novel materials, and drive market acceptance.

building performance gap
sustainable materials
engineering
architecture
biowaste

Concerns about supply constraints and environmental effects have emerged, according to the International Energy Agency’s report, which shows a 49% increase in primary energy consumption and a 43% increase in CO₂ emissions over the previous 20 years ^[1]. In 2020, the average annual growth rate of emerging economies’ energy consumption in developing countries was predicted to surpass that of developed countries, which is projected to grow at a rate of 1.1% ^[2]. People presently consume more energy as economies expand and quality of life increases. In other words, there is a strong correlation between economic growth, energy consumption, and carbon emissions ^[3]. This correlation unfolds in various degrees depending on context. For instance, Asian and developing nations are projected to experience potentially more rapid growth trends in the future ^[4]. Despite having low energy use and carbon emissions per capita, China’s primary energy requirement increased from 1978 to 2010, reaching 3200 million tons of standard coal equivalent (Mtce), making it the nation with the highest energy consumption and CO₂ emissions in 2009 ^[5]. According to a study by Li et al. ^[6], China’s total primary energy requirement (PER) will surge to 6200 Mtce by 2050, with fossil fuels accounting for over 70% of emissions. Furthermore, the energy consumption of emerging economies surpassed that of developed nations in Western Europe, North America, Japan, Australia, and New Zealand in 2020 ^[2]. This relationship between population growth, economic development, and energy consumption calls into question international efforts to promote efficiency in policy. Globalization, better living standards, and communication networks encourage the lifestyles of developed and developing countries, increasing building efficiencies, the environment, and energy consumption ^[7].

Around the world, buildings use a large amount of energy and emit CO₂; in the United States of America (USA) and Europe, this percentage is 39% and 40%, respectively ^[8]. As one of the major emitters historically, the building stock made up 24.1% of China’s total energy consumption in 1996; this percentage increased to 27.5% in 2001 and reached 35% by 2020 ^[9]. Building energy consumption forecasting is essential for making decisions to optimize energy use, allowing for a thorough assessment of operational and design options while lowering CO₂ emissions and air pollution ^[10]. Predicting building energy use is essential to minimize ecological impacts and conserve energy. However, energy prediction is difficult because of several variables that affect actual consumption, such as equipment performance, outside weather, occupant energy behavior, and building envelope characteristics ^[11]. The complexity of buildings makes it difficult to predict consumption with precision. These discrepancies between actual and predicted consumption are known as building energy performance gaps (BEPGs).

Performance gaps in buildings are a growing concern in the built environment industry, with significant ramifications. It presents challenges in managing energy demand-and-supply needs in the building sector ^[12]. In some cases, it leads to financial “bottlenecks” between service providers and clients ^[13]. The presence of BEPGs means that the expected performance does not materialize in the real world and implies limited progress towards addressing the building sector’s contributions to climate change. During building performance simulations, more focus is often given to the energy expended in operating the building (i.e., operational energy) because it characteristically accounts for over 80% of a building’s life cycle energy use ^[14]. However, several studies (such as Röck et al. ^[15], which is based on an analysis of over 650 building life cycle cases worldwide) conclude that embodied energy and emissions typically increase when operational energy is optimized [16,17]^[16][17]. Largely related to the construction materials, embodied energy was observed to rise from approximately 20% of life cycle energy use in inefficient buildings to between 50% and 90% in energy-efficient buildings, globally ^[15].

To address BEPGs, many researchers focus on better modeling, engaging accurate data, and improving design and construction practices, amid other avenues ^[18]. Other studies also seek to develop strategies to encourage energy-efficient behavior among building occupants. However, a holistic approach to building design is necessary to ensure that the building sector experiences real-world performance improvements. Innovative technologies like bio-fabrication, 3D printing, and self-healing materials can improve energy efficiency and reduce waste. In other words, sustainable materials are essential for reducing energy consumption, and a life cycle assessment of materials is often beneficial for CO₂ emission reduction. Such approaches could also encourage a circular economy. Stronger regulations and standards are also needed to meet higher energy efficiency requirements. This holistic approach provides the opportunity to consider interactions between systems and materials, continuing the much needed research and development in exploring new materials and strategies ^[19].

Several studies have evaluated the literature on the BEPG research focus areas. However, a critical analysis of the literature on sustainable building materials is lacking, especially from the perspective of their potential to improve real-world energy performance and mitigate energy-related CO₂ emissions in the building sector. Therefore, this paper presents a comprehensive review to address this gap. Specifically, the aim of this paper is to further develop the understanding of energy efficiency in buildings by critically reflecting on the challenge of energy performance gaps and the potential of sustainable materials. This study examines and provides a view of existing research into six bio-waste materials and their reuse in the construction industry. The insights potentially support the development of energy-efficient buildings and facilitate a circular economy.

The remaining sections of the study adopt the following structure: Section 2 outlines the method implemented in this paper, showing a clear framework. Section 3 discusses the context of climate change and emissions, explores why the building sector persists as a major contributor by unpacking the challenge of performance gaps, and highlights the critical role of sustainable materials for life cycle energy efficiency. Section 4 highlights the application of novel bio-waste materials as sustainable substitutes in the building sector and their potential based on research testing. Section 5 reflects on the challenges and directions for future research, recommending concerted efforts to promote energy efficiency and sustainability.

References

Florini, A. The International Energy Agency in global energy governance. Glob. Policy 2011, 2, 40–50.
Sadorsky, P. The impact of financial development on energy consumption in emerging economies. Energy Policy 2010, 38, 2528–2535.
Sinton, J.E.; Fridley, D.G. What goes up: Recent trends in China’s energy consumption. Energy Policy 2000, 28, 671–687.
Kellstedt, P.M.; Zahran, S.; Vedlitz, A. Personal efficacy, the information environment, and attitudes toward global warming and climate change in the United States. Risk Anal. Int. J. 2008, 28, 113–126.
Zhang, B.; Qu, X.; Meng, J.; Sun, X. Identifying primary energy requirements in structural path analysis: A case study of China 2012. Appl. Energy 2017, 191, 425–435.
Li, R.; Wang, Q.; Liu, Y.; Jiang, R. Per-capita carbon emissions in 147 countries: The effect of economic, energy, social, and trade structural changes. Sustain. Prod. Consum. 2021, 27, 1149–1164.
Zameer, H.; Shahbaz, M.; Vo, X.V. Reinforcing poverty alleviation efficiency through technological innovation, globalization, and financial development. Technol. Forecast. Soc. Chang. 2020, 161, 120326.
Lucon, O.; Ürge-Vorsatz, D.; Ahmed, A.Z.; Akbari, H.; Bertoldi, P.; Cabeza, L.F.; Eyre, N.; Gadgil, A.; Harvey, L.D.D.; Jiang, E.Y.; et al. Buildings. In Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change; Edenhofer, O., Pichs-Madruga, R., Sokona, Y., Farahani, E., Kadner, S., Seyboth, K., Adler, A., Baum, I., Brunner, S., Eickemeier, P., et al., Eds.; Cambridge University Press: Cambridge, UK; New York, NY, USA, 2014; pp. 671–738.
Pérez-Lombard, L.; Ortiz, J.; Pout, C. A review on buildings energy consumption information. Energy Build. 2008, 40, 394–398.
Antonakakis, N.; Chatziantoniou, I.; Filis, G. Energy consumption, CO2 emissions, and economic growth: An ethical dilemma. Renew. Sustain. Energy Rev. 2017, 68, 808–824.
Omer, A.M. Energy, environment and sustainable development. Renew. Sustain. Energy Rev. 2008, 12, 2265–2300.
Zou, P.X.W.; Xu, X.; Sanjayan, J.; Wang, J. Review of 10 years research on building energy performance gap: Life-cycle and stakeholder perspectives. Energy Build. 2018, 178, 165–181.
Heo, Y. Bayesian Calibration of Building Energy Models for Energy Retrofit Decision-Making under Uncertainty. Ph.D. Thesis, Georgia Institute of Technology, Atlanta, GA, USA, 2011.
Anderson, J.E.; Wulfhorst, G.; Lang, W. Energy analysis of the built environment—A review and outlook. Renew. Sustain. Energy Rev. 2015, 44, 149–158.
Röck, M.; Saade, M.R.M.; Balouktsi, M.; Rasmussen, F.N.; Birgisdottir, H.; Frischknecht, R.; Habert, G.; Lützkendorf, T.; Passer, A. Embodied GHG emissions of buildings—The hidden challenge for effective climate change mitigation. Appl. Energy 2020, 258, 114107.
Koezjakov, A.; Urge-Vorsatz, D.; Crijns-Graus, W.; van den Broek, M. The relationship between operational energy demand and embodied energy in Dutch residential buildings. Energy Build. 2018, 165, 233–245.
Rebane, K.; Reihan, A. Promoting building materials that have lower embodied carbon and energy in public procurements. Manag. Environ. Qual. Int. J. 2016, 27, 722–739.
Hu, S.; Yan, D.; Azar, E.; Guo, F. A systematic review of occupant behavior in building energy policy. Build. Environ. 2020, 175, 106807.
Diakaki, C.; Grigoroudis, E.; Kolokotsa, D. Towards a multi-objective optimization approach for improving energy efficiency in buildings. Energy Build. 2008, 40, 1747–1754.