Building Life Cycle Assessment Research Articles

Life-Cycle Assessment of Apartment Buildings Based on Standard Quantities of Building Materials Using Probabilistic Analysis Technique.

Given the increasingly serious nature of environmental problems, many countries have recently declared carbon neutrality policies and expended efforts to implement them. The domestic building industry aims to reduce its environmental impact using life-cycle assessments (LCAs) of buildings according to the Green Standard for Energy and Environmental Design. However, it is difficult to perform efficient LCAs because the required quantity takeoff process is complex, and the quantity takeoff sheet may not exist during the building’s design phase. In this study, 21 building LCAs were used to simplify and improve the efficiency of the proposed method and enable building LCAs even when there was no quantity takeoff sheet. Furthermore, a standard quantity database of building materials was constructed based on the analysis of the input quantities of building materials per unit area, and the apartment buildings LCA method was proposed using this database. The input quantities of building materials were analyzed using the probabilistic analysis technique. The probability distribution was derived using Monte Carlo simulations, and the goodness-of-fit was verified. Finally, the reliability of the proposed building LCA method was verified using a case study.

A Framework for User Centric LCA Tool Development for Early Planning Stages of Buildings

As the high greenhouse gas (GHG) emissions caused by the construction and real estate sector receive more attention, more and more countries include an environmental assessment of buildings based on Life Cycle Assessment (LCA) in their building regulations. Sweden introduced mandatory climate declarations in January 2022, for example. To support stakeholders in conducting the climate declarations and using the results to reduce GHG emissions, user-friendly tools for early planning stages are needed. The aim of this study is to develop and test a framework for user centric development of such tools. The framework builds on three steps; 1) interviewing stakeholders to define tool requirements, 2) developing a prototype tool according to the requirements, and 3) evaluating it based on user feedback. We developed and tested the framework in the Swedish context to provide a blueprint applicable to other countries and contexts. The primary target users are architects with computational design experience but also engineers and real estate developers working in early phases. The results show that the users’ expectations can be met when the requirements are integrated from the very beginning. In the current version, the developed building LCA tool only targets the embodied GHG emissions from the production and construction phase of the building, but it could be extended to include further life cycle phases in the future.

Development of comprehensive energy usage impact and carbon footprint parameters for green building life cycle assessment

PurposeThe purpose of this study is to develop a set of parameters universally acceptable for assessing design and construction strategies for reducing operational energy usage and its associated greenhouse gas (GHG) emission. Also, the parameters are intended to estimate the quantity of energy and its associated GHG emission reduction over the assessment period.Design/methodology/approachThis study used five steps framework comprising definition of purpose, selecting the candidate parameters, criteria selection and description, selecting proposed parameters and defining the proposed parameters. The criteria used were the parameter’s prevalence, measurability, preference and feasibility toward adaptability to the relevant stakeholders.FindingsThis study consolidated 11 parameters. Seven cover designs and construction strategies comprising energy monitoring, natural lighting and ventilation design. Others are building thermal performance, efficient equipments, renewable energy and energy policy. The remaining four consider operational energy consumption, GHG emission quantification and their reduction over time.Practical implicationsProviding suitable indicators for assessing direct and indirect GHG emission with easily accessible data is essential for assessing built environment. The consolidated parameters can be used in developing rating systems, monitoring GHG inventories and activities of building related industries.Originality/valueThis study was conducted at the CEIES UTHM and used 11 existing rating systems open for research purposes, International Panel for Climate Change reports and GHG protocol report and guides and several other standards.

Climate Mitigation in the Swedish Single-Family Homes Industry and Potentials for LCA as Decision Support

Decision support tools for incentivizing environmentally sound decisions in building design, such as LCA (life cycle assessment), have been highlighted as an essential feature for enhancing the realization of more sustainable buildings. Nevertheless, the use of LCA to support decisions in building design is still limited in practice. A better understanding of the social dynamics and detailed contexts of the decisions leading up to a final building design is therefore critical for better integration of LCA-based information in the decision-making processes. This paper reports a qualitative, semi-structured interview study of single-family home producers in Sweden and their decision-making in relation to climate mitigation, with a particular focus on embodied carbon mitigation. By studying a specific branch of the building and construction sector, a more in-depth record can be obtained of the particularities of implementation contexts and decision-making situations in which LCA may, or may not, have a role in driving climate mitigation. Four primary decision contexts in which LCA may have an influential role to drive embodied carbon reduction include: (1) the development of building systems, (2) development and offering of house models, (3) the selection of construction products for the building system as well as for the offer of add-on products to customers, and (4) the dialogues in the individual house-buyer projects. Decision-making that affects sustainable outcomes in this part of the sector is very much dependent on a supporting regulatory context. Over the years, using building LCA in early design stages, for optimization towards low-impact final buildings, has been a repeatedly promoted recommendation both in academia and practice. This study, however, reveals that such a conclusion is too simplistic. The different overarching decision contexts identified for this particular branch display the variety of needs for life cycle-based information.

A Case Study on the Impact of Transportation of Mass Timber Products on the Cradle-to-Gate LCA Results for an Institutional Building

Mass timber products (MTPs) are being adopted in new building constructions and remodels in the last three decades, credited to their renewable and low carbon footprint characteristics. However, there are no mass timber manufacturers currently existing in Atlantic Canada. Extended distances of transporting MTPs to this region from other Canadian provinces may sacrifice the environmental benefits of using MTPs. This study was aimed to understand, via conducting a cradle-to-gate life cycle assessment (LCA), the environmental impacts of a mid-rise institutional building, which is located in the Province of New Brunswick Canada. By comparing the current steel frame design of this building with an alternative mass timber building design with the same height range and function including the transportations of major building materials. It was found that the mass timber building design could still have environmental advantages over the steel structure, as much as 19.5% lower global warming impact and 16.8% lower ozone depletion impact, even with MTPs delivered from the furthest location considered in this study. However, the disadvantages in other impact categories, such as 31.9% higher smog impact, 13.6% higher acidification impact, and 248.2% higher eutrophication impact were found when using the TRACI impact assessment in this whole building LCA study.

Life cycle assessment of a residential building in China accounting for spatial and temporal variations of electricity production

Life cycle assessment (LCA) is widely used to reduce a building's environmental impacts in the design phase. Buildings consume a lot of electricity, and heat pumps are often proposed as a way to reduce greenhouse gases emissions. The electricity production mix is therefore an important aspect in building's LCA. Many studies use a static national average mix, ignoring its variations in space and time. This might be questioned in a large country undergoing energy transition such as China. A comprehensive study on this topic for China is lacking, therefore this article aims at filling this gap by investigating how the variations of the energy mix at spatial (five regions in five climate zones) and temporal (four future energy mix scenarios) scales influence the LCA results. A model is proposed to evaluate local future energy mixes. The life cycle inventory (LCI) database was contextualised considering different local energy mixes. Environmental impacts calculated using the local energy mixes and the national average energy mix were compared in the static approach and the dynamic approach (future scenarios are considered) for a residential building. The results indicated that using a national average mix instead of a local mix in the static approach brought non-negligible differences for most provinces, e.g. the overestimation of global warming potential (GWP) reached 500% in Yunnan. Similarly, differences between the static and dynamic approaches are large for most environmental impact indicators, e.g. the difference in GWP could reach around 900% in Guangdong. The differences highly depend on the prospective future scenarios and showed regional features. This paper highlights the importance of the choice of energy mix in buildings' LCA in China regarding both spatial and temporal scales, which is beneficial for more reasonable decisions.

Towards low-carbon cities through building-stock-level carbon emission analysis: a calculating and mapping method

• A bottom-up method is proposed to calculate and map carbon emissions from urban building stock. • Building types and geometry are extracted to derive life cycle carbon emission inventories. • The calculation result is verified with a modified top-down method. • The method improves calculation accuracy and facilitates low-carbon urban planning. Building stock represents the primary source of urban carbon emissions. However, the amount and spatial distribution of building-stock-level carbon emissions remain unclear when formulating detailed carbon emission reduction goals for cities. In present study, a bottom-up method was established for calculating and mapping carbon emissions from urban building stock, which involves: (1) using inventory data to derive an aggregated reference model for calculating urban building carbon emissions and sinks with a building life cycle assessment model and a building archetype method; and (2) mapping and assessing carbon emissions from building stock to support low-carbon urban planning. The method was applied in Xi'an, China. The embodied carbon emissions from building stock in Xi'an were calculated as 4.13 million tCO 2 e·a –1 , the operational emissions as 20.45 million tCO 2 e·a –1 , building and natural carbon sinks as 0.067 million tCO 2 e·a –1 and 0.014 million tCO 2 e·a –1 , respectively. The method was validated with municipal statistical data for Xi'an. In addition, carbon emissions from urban building stock were mapped to identify carbon reduction hot spots. The proposed method allows municipalities to assess the environmental performance of urban building stock and urban planning schemes, thereby supports the sustainable development of cities.

Low-energy buildings in combination with grid decarbonization, life cycle assessment of passive house buildings in Northern Ireland

This paper implements a Life Cycle Assessment of several low-energy/passive house buildings located in Northern Ireland. This work aims (i) to assess the environmental performance of the buildings and (ii) to evaluate the effect of electricity decarbonization on the dwellings’ global warming potential (GWP). Three different future electricity mix scenarios have been used and compared to a static scenario where the current electricity mix remains constant. The LCA results of the static scenario reveal that applying passive-house standards could reduce the impact of dwellings while it does not necessarily provide a positive environmental outcome. The building operation phase contributed the most to the environmental impact, while negligible impact comes from the end-of-life stage. The electricity decarbonization leads to a significant reduction of GWP in all cases, with the highest value achieved for the passive house using the highest share of electricity, 58%-70% GWP reduction compared to the static scenario. Moreover, electricity decarbonization increases the relative share of the production stage to the overall building emission. Therefore, close attention should be paid to construction material selection in any effort aiming to achieve further environmental benefits. The buildings' environmental and operational energy performances were also compared to the RIBA 2030 Climate Challenge.

Correction to: Functional unit influence on building life cycle assessment

Correction to: Functional unit influence on building life cycle assessment

Sustainable early design exploration of mid-rise office buildings with different subsystems using comparative life cycle assessment

Minimizing environmental impacts over a building's life cycle is critical to achieving sustainable communities. Early design is the most critical step to improve construction's sustainability, as the majority of important decisions have not yet been made. However, the implementation of sustainability assessment in early design is data- and effort-intensive, resulting in limited whole building life cycle assessments. Previous studies have mainly focused either on single residential structures, included only a subset of building components, or investigated early design parameters mostly associated with energy efficiency. Whereas, comparison of alternative building subsystems at early design received less attention. This study aims to provide and utilize benchmark data for the life-cycle impacts of mid-rise office buildings, focusing on the impact of building subsystem selection at early design exploration. Environmental impacts were compared across six professionally-designed archetypes comprising compatible combinations of foundation, floor, and structural assemblies for a site in Charleston, South Carolina. Detailed operational energy modeling was performed using the EnergyPlus framework, where a range of code-compliant envelope systems are studied and paired with other assemblies. Lastly, sensitivity assessment and statistical analysis are performed to quantify uncertainty associated with the use of such data for early design guidance. The results suggest that decisions associated with the use phase (such as envelope selection) dominates life cycle impacts and should be prioritized. Additionally, no single subsystem governs all embodied impacts across different buildings. Lastly, it is critical to consider a large number of alternatives at the early design stage, as excluding a combination of subsystems might close pathways to reaching a more environmentally suitable alternative during design iterations/optimization.

Whole building life cycle assessment at the design stage: a BIM-based framework using environmental product declaration

PurposeWhole building life cycle assessment (WBLCA) is a key methodology to reduce the environmental impacts in the building sector. Research studies usually face challenges in presenting comprehensive LCA results due to the complexity of assessments at the building level. There is a dearth of methods for the systematic evaluation and optimization of the WBLCA performance at the design stage. The study aims to develop a design optimization framework based on the proposed WBLCA method to evaluate and improve the environmental performance at the building level.Design/methodology/approachThe WBLCA development method is proposed with detailed processes based on the EN 15978 standard. The environmental product declaration (EPD) methods were adopted to ensure the WBLCA is comprehensive and reliable. Building information modeling (BIM) was used to ensure the building materials and assembly contributions are accurate and provide dynamic material updates for the design optimization framework. Furthermore, the interactive BIM-LCA calculation processes were demonstrated for measuring the environmental impacts of design upgrades. The TOPSIS-based LCA results normalization was selected to conduct the comparisons of various building design upgrades.FindingsThe case study conducted for a residential building showed that the material embodied impacts and the operational energy use impacts are the two critical factors that contribute 60–90% of the total environmental impacts and resource uses. Concrete and wood are the main material types accounting for an average of 65% of the material embodied impacts. The air and water heating for the house are the main energy factors, as these account for over 80% of the operational energy use. Based on the original WBLCA results, two scenarios were established to improve building performance through the design optimization framework.Originality/valueThe LCA results show that the two upgraded building designs create an average of 5% reduction compared with the original building design and improving the thermal performance of the house with more insulation materials does not always reduce the WBLCA results. The proposed WBLCA method can be used to compare the building-level environmental performances with the similar building types. The proposed framework can be used to support building designers to effectively improve the WBLCA performance.

An overview of the remaining challenges of the RILEM TC 274-TCE, testing and characterisation of earth-based building materials and elements

Based on the RILEM Technical Committee 274-TCE work, this paper is a discussion of the remaining engineering challenges faced by earthen architecture. The assessment of earth material performances requires the development of appropriate procedures and standards. This is discussed in particular for the characterisation, hygrothermal behaviour, mechanical behaviour, and durability of earth materials. One other important challenge, since one of the main advantages classically put forward, is its ecological performance, is a proper assessment of life cycle assessment of earth materials, elements and buildings. Moreover, the paper develops why the approach to earthen construction must be different compared to the dominant construction materials, to preserve its ability to contribute to the ecological transition in the construction sector. In particular, the needs of using local soils, with an architectural approach coping with the limits of the materials, and developing an architectural optimisation to preserve the earthen materials multifunctionality rather than selecting a sole property to be maximised. Lastly, the findings of the paper can be used to develop a holistic approach to earthen construction to foster the development of new earthen architecture projects.

A Comparative Study on the Life Cycle Assessment of New Zealand Residential Buildings

In New Zealand, housing is typically low density, with light timber framing being the dominant form of construction with more than 90% of the market. From 2020, as a result of the global pandemic, there was a shortage of timber in New Zealand, resulting in increased popularity for light steel framing, the main alternative to timber for housing. At the same time, the New Zealand government is committed to sustainability practises through legislation and frameworks, such as the reduction of whole-of-life carbon emissions for the building industry. New Zealand recently announced reducing its net greenhouse gas emissions by 50% within 2030. Life cycle assessment (LCA) is a technique for assessing the environmental aspects associated with a product over its life cycle. Despite the popularity of LCA in the construction industry of New Zealand, prior research results seem varied. There is no unified NZ context database to perform an LCA for buildings. Therefore, in this paper, a comprehensive study using LCA was conducted to quantify and compare the quantity of carbon emissions from two commonly designed houses in the Auckland region, one built from light timber and the other from light steel, both designed for a lifespan of 90 years. The cradle-to-cradle system boundary was used for the LCA. From the results of this study, it was found that the light steel house had 12.3% more carbon in total (including embodied and operational carbons) when compared to the light timber house, of which the manufacturing of two houses had a difference of 50.4% in terms of carbon emissions. However, when the end-of-life (EOL) analysis was included, it was found that the extra carbon could be offset due to the steel’s recyclability, reducing the amount of embodied carbon in the manufacturing process. Therefore, there was no significant difference in carbon emissions between the light steel and the light timber building, with the difference being only 12.3%.

Stochastic comparative LCA of smart buildings

Driven by the energy and digital transitions, the concept of smart buildings is gaining importance. In most cases, these buildings are designed with the aim of reducing the consumption of energy resources during the operation phase, while improving the occupants’ comfort and safety. However, smart sensors and actuators themselves have impacts on other environmental indicators and life cycle stages. In this work, the environmental performances of a smart multifamily house and of a standard one are compared using both dynamic building energy simulations and life cycle assessments (LCA). Two insulation levels are possible for the building and the alternatives’ comparison includes uncertainties and variabilities related to occupancy. It turns out that smart building has less impacts than conventional one over their entire life cycle, but their benefit decreases when the level of insulation increases.

Stakeholders’ perspectives on BIM and LCA for green buildings

There is growing concern about the environmental impacts of buildings on climate change. In this regard, the concept of integrating building technologies and environmental assessment methods, namely Building Information Modelling (BIM) and Life Cycle Assessment (LCA), has arisen as an innovative approach to improve building environmental assessment at the design phase. Recent studies made attempts to develop theoretical frameworks for BIM and LCA integration focusing on the technical aspects and the challenges of this integration. However, the stakeholders' perspectives on this integration of BIM and LCA for building environmental assessment have been overlooked. Therefore, there is a pressing need to understand the stakeholders' perspectives on BIM and LCA and their value for improving green building design and assessment. This study contributes to the existing knowledge on the potential implementation of an integrated BIM-LCA framework for building environmental assessment. To this end, this study investigates (1) the current applications of BIM and LCA in green buildings from the stakeholders' perspectives and (2) the stakeholders' level of awareness and agreement on the significance of BIM and LCA for green building design and assessment. In order to achieve this goal, a national survey was conducted among multiple stakeholders in the New Zealand building industry. The results indicate that BIM and LCA applications for green buildings are still immature. A statistically significant correlation is observed between the importance of BIM and LCA applications for green buildings. The stakeholders perceive BIM and LCA potentials and their integration positively. However, the current practices and applications of BIM and LCA do not align with the stakeholders’ perceptions. Massive efforts are still required for a wide implementation of BIM and LCA and their potential integration for green buildings.

Comparative Life Cycle Assessment of Mass Timber and Concrete Residential Buildings: A Case Study in China

As the population continues to grow in China’s urban settings, the building sector contributes to increasing levels of greenhouse gas (GHG) emissions. Concrete and steel are the two most common construction materials used in China and account for 60% of the carbon emissions among all building components. Mass timber is recognized as an alternative building material to concrete and steel, characterized by better environmental performance and unique structural features. Nonetheless, research associated with mass timber buildings is still lacking in China. Quantifying the emission mitigation potentials of using mass timber in new buildings can help accelerate associated policy development and provide valuable references for developing more sustainable constructions in China. This study used a life cycle assessment (LCA) approach to compare the environmental impacts of a baseline concrete building and a functionally equivalent timber building that uses cross-laminated timber as the primary material. A cradle-to-gate LCA model was developed based on onsite interviews and surveys collected in China, existing publications, and geography-specific life cycle inventory data. The results show that the timber building achieved a 25% reduction in global warming potential compared to its concrete counterpart. The environmental performance of timber buildings can be further improved through local sourcing, enhanced logistics, and manufacturing optimizations.

Life Cycle Assessment of a building using Open-LCA software

The Building Construction industry has high energy consumption and is the major contributor for the environmental impacts like ozone depletion, Green House Gas emissions, Carbon foot print etc. Life Cycle Assessment (LCA) of buildings is a method to evaluate the environmental impacts generated by building throughout its life cycle. This paper presents a case study of a G + 5 residential building in a metropolitan city of India and determines the impacts on the environment resulting from the construction phase using Open-LCA software. The Life Cycle Assessment software gives the impacts caused on the environment due to all components and the materials used in construction. The common building materials used in construction are clay brick, aggregates, cement, and steel. Therefore, this paper evaluates the environmental impact by using common building materials and alternate building materials. The comparative results of reduction in environmental impact are presented and attempted to develop sustainable building construction.

Mass Timber Building Life Cycle Assessment Methodology for the U.S. Regional Case Studies

The building industry currently consumes over a third of energy produced and emits 39% of greenhouse gases globally produced by human activities. The manufacturing of building materials and the construction of buildings make up 11% of those emissions within the sector. Whole-building life-cycle assessment is a holistic and scientific tool to assess multiple environmental impacts with internationally accepted inventory databases. A comparison of the building life-cycle assessment results would help to select materials and designs to reduce total environmental impacts at the early planning stage for architects and developers, and to revise the building code to improve environmental performance. The Nature Conservancy convened a group of researchers and policymakers from governments and non-profit organizations with expertise across wood product life-cycle assessment, forest carbon, and forest products market analysis to address emissions and energy consumption associated with mass timber building solutions. The study disclosed a series of detailed, comparative life-cycle assessments of pairs of buildings using both mass timber and conventional materials. The methodologies used in this study are clearly laid out in this paper for transparency and accountability. A plethora of data exists on the favorable environmental performance of wood as a building material and energy source, and many opportunities appear for research to improve on current practices.

A Conceptual Framework for Estimating Building Embodied Carbon Based on Digital Twin Technology and Life Cycle Assessment

Low-carbon building design requests an estimation of total embodied carbon as the environmental performance metric for comparison of different design options in early design stages. Due to a lack of consensus on the system boundaries in building life cycle assessment (LCA), the carbon estimation results obtained by the current methods are often disputable. In this regard, this paper proposes a method for estimating building embodied carbon based on digital twin technology and LCA. The proposed method is advantageous over others by providing (1) a cradle-to-cradle LCA and (2) an automated data communication between LCA and building information modelling (BIM) databases. Because data for the processes in the life cycle are collected via digital twin technology in a standard and consistent way, the obtained results will be considered credible. So far, a conceptual framework is developed based on a comprehensive literature review, which consists of three parts. In the first part, formulas for LCA are given. In the second part, a hybrid approach combining semantic web with a relational database for BIM and radio-frequency identification (RFID) integration is described. In the third part, how to design the LCA database and how to link LCA with BIM are described. The conceptual framework proposed is tested for its reasonableness by a small hypothetical case study.

Comprehensive assessment of embodied environmental impacts of buildings using normalized environmental impact factors

Buildings are responsible for many environmental issues during construction. Although many studies have evaluated buildings' life cycle embodied environmental impacts (LCEEI), the difference in units usually results in isolation and separation of impact assessments. Assessment results of different indicators and environmental issues often cannot be compared with each other. This paper proposed a building LCEEI evaluation approach by integrating building information modeling (BIM) and life cycle assessment (LCA). In the proposed approach, 24 environmental impact factors (EIFs) from the cradle to the grave are firstly calculated and then linked to 10 building-related environmental issues. The comprehensive assessment of embodied environmental impacts is conducted with a three-step normalization process, including characterization, nondimensionalization, and quantitation. A reinforced concrete structure building is selected as a case to demonstrate the proposed approach. The case indicates that mineral resource consumption, timber consumption, and fossil fuel consumption contribute the top 3 largest proportions (over 80%) to the LCEEI of reinforced concrete structure buildings. The material production stage is the most crucial stage to improve a building's environmental performance. Concrete, steel, and timber are the top 3 materials generating the most EIF. The study enriches the knowledge of sustainable construction by proposing a BIM-LCA integration approach to comprehensively evaluate the LCEEI of buildings at the design stage.