Building Life Cycle Assessment Research Articles

Comparative life-cycle assessment of a mass timber building and concrete alternative

The US housing construction market consumes vast amounts of resources, with most structural elements derived from wood, a renewable and sustainable resource. The same cannot be said for all nonresidential or high-rise buildings, which are primarily made of concrete and steel. As part of continuous environmental improvement processes, building life-cycle assessment (LCA) is a useful tool to compare the environmental footprint of building structures. This study is a comparative LCA of an 8360-m2, 12-story mixed-us apartment/office building designed for Portland, OR, and constructed from mainly mass timber. The designed mass timber building had a relatively lightweight structural frame that used 1782 m3 of cross-laminated timber (CLT) and 557 m3 of glue-laminated timber (glulam) and associated materials, which replaced approximately 58% of concrete and 72% of rebar that would have been use in a conventional building. Compared with a similar concrete building, the mass timber building had 18%, 1% and 47% reduction in the impact categories of global warming, ozone depletion, and eutrophication, respectively, for the A1-A5 building LCA. The use of CLT and glulam materials substantially decreased the carbon footprint of the building, although it consumed more primary energy compared with a similar concrete building. The impacts for the mass timber building were affected by large amounts of gypsum board, which accounted for 16% of the total building mass. Both lowering the amount of gypsum and keeping the mass timber production close to the construction site could lower the overall environmental footprint of the mass timber building.

Ecological Footprint of Residential Building in Xining

The construction industry has a very significant environmental impact. Based on the theory of ecological footprint, this paper constructs a building life cycle assessment model, which takes Xining residential buildings as the research object, the ecological footprint of a residential building in Xining was calculated by using the advanced ecological footprint model - “provincial hectare method”. The aim is to understand the impact of buildings on the environment, and strive to resolve environmental pollution from the source. The results show that the ecological footprint of the building is 570.32 hm2, which is 1.52 times its ecological carrying capacity. There is an ecological deficit. The ecological deficit should be reduced by improving the sustainable use of materials to promote the sustainable development of the construction industry.

Comparative Whole Building Life Cycle Assessment of Energy Saving and Carbon Reduction Performance of Reinforced Concrete and Timber Stadiums—A Case Study in China

Many stadiums will be built in China in the next few decades due to increasing public interest in physical exercise and the incentive policies issued by the government under its National Fitness Program. This paper investigates the energy saving and carbon reduction performance of timber stadiums in China in comparison with stadiums constructed using conventional building materials, based on both life cycle energy assessment (LCEA) and life cycle carbon assessment (LCCA). The authors select five representative cities in five climate zones in China as the simulation environment, simulate energy use in the operation phase of stadiums constructed from reinforced concrete (RC) and timber, and compare the RC and timber stadiums in terms of their life cycle energy consumption and carbon emissions. The LCEA results reveal that the energy saving potential afforded by timber stadiums is 11.05%, 12.14%, 8.15%, 4.61% and 4.62% lower than those of RC buildings in “severely cold,” “cold,” “hot summer, cold winter,” “hot summer, warm winter,” and “temperate” regions, respectively. The LCCA results demonstrate that the carbon emissions of timber stadiums are 15.85%, 15.86%, 18.88%, 19.22% and 22.47% lower than those of RC buildings for the regions above, respectively. This demonstrates that in China, timber stadiums have better energy conservation and carbon reduction potential than RC stadiums, based on life cycle assessment. Thus, policy makers are advised to encourage the promotion of timber stadiums in China to achieve the goal of sustainable energy development for public buildings.

Modular approach to multi-objective environmental optimization of buildings

The application of heuristic algorithms with life cycle assessment (LCA) is a promising approach to efficiently optimize the building and minimize the environmental impact even in a very large design space. In this paper, a modular parametric optimization framework combining advanced building modelling, LCA, energy calculation and single- and multi-objective environmental optimization was developed and applied to a multi-apartment house in Hungary. The variables comprise geometry, envelope, fixtures, as well as the heating energy source. The objective is the life cycle environmental impact expressed in terms of the six most common LCA indicators. The results show that a relatively compact shape, large windows to south equipped with shading and very high levels of insulation are optimal from an environmental perspective. It was also proven that focusing only on the embodied or operational impact leads to a suboptimal solution, and the choice of the energy source for the operation of the building has a significant influence on the achievable optimum. Through the optimization, significant environmental savings of 60–80% were achieved compared to the initial design options showing the potential for the application of such methods in architectural design.

Life cycle assessment (LCA) based concept design method for potential zero emission residential building

Regardless a large number of published researches on environmentally friendly building design, realized buildings with a low or zero-emission balance throughout the whole life cycle are rare. Life cycle assessment during building design is not considered a creative but merely calculating task with no direct relation to architecture itself. This research offers an iterative design method, based on life-cycle assessment for buildings, allowing during concept phase to set path for achieving low or zero environmental impact levels. The paper analyses the interrelation of main aspect fields of life-cycle assessment, such as: emission reduction, energy and cost saving as well as implementation of renewable resources during concept design phase for residential buildings. The applicability of the developed LCA based concept design method, its effectiveness for the environmental quality of buildings and influence on architectural factors is examined in a case study project for the hot and dry climate of Cairo. The authors consider, that a combined application of digital environmental assessment tools in initial project phases creates synergies for architectural quality and environmental performance. A combined use of digital tools for the three main aspects; emissions, renewable energy and economic factors allows architects with reasonable effort to design low emission buildings with strong incentives for the creative architectural design process.

Net energy and cost benefit of transparent organic solar cells in building-integrated applications

Transparent photovoltaics is a new technology that can be used in buildings applications to simultaneously save energy and produce electricity. This study evaluates the potential of transparent photovoltaic (TPV) in window and skylight applications for four cities in the United States: Detroit, Los Angeles, Phoenix and Honolulu. Building energy demand simulation, photovoltaic generation, and life cycle assessment (LCA) are combined to evaluate the net energy benefit (NEB). The use of TPV on windows is evaluated for both new windows, for which the solar cell is deposited in the interior surface of the glass pane, and for the refurbishment of existing windows, for which plastic encapsulated solar cells are placed on the interior surface of existing windows. The NEB was found to be positive for all scenarios considered, and the cradle to gate energy to manufacture a transparent organic photovoltaic module was found to be negligible. The NEB was used to calculate the energy return on investment (EROI) and the energy payback time (EPBT). Both were found to be either better or comparable to other photovoltaic technologies. For glass modules, the best EROI was 102 in Phoenix for window and 208 in Honolulu for skylights. The EPBT varied from 51 days to 1.1 years, depending on the location and type of module. The use of transparent photovoltaics in the US was found to have both environmental and cost benefits due to the combined reduction in building energy consumption and electricity production.

Environmental Payback of Renovation Strategies in a Northern Climate—the Impact of Nuclear Power and Fossil Fuels in the Electricity Supply

The aim of this study is to assess how the use of fossil and nuclear power in different renovation scenarios affects the environmental impacts of a multi-family dwelling in Sweden, and how changes in the electricity production with different energy carriers affect the environmental impact. In line with the Paris Agreement, the European Union has set an agenda to reduce greenhouse gas emissions by means of energy efficiency in buildings. It is estimated that by the year 2050, 80% of Europe’s population will be living in buildings that already exist. This means it is important for the European Union to renovate buildings to improve energy efficiency. In this study, eight renovation scenarios, using six different Northern European electricity mixes, were analyzed using the standard of the European Committee for Standardization for life cycle assessment of buildings. This study covers all life cycle steps from cradle to grave. The renovation scenarios include combinations of photovoltaics, geothermal heat pumps, heat recovery ventilation, and improvement of the building envelope. The results show that while in some electricity mixes a reduction in the global warming potential can be achieved, it can be at the expense of an increase in radioactive waste production, and, in mixes with a high share of fossil fuels, the global warming potential of the scenarios increases with time, compared with that of the original building. It also shows that in most electricity mixes, scenarios that reduce the active heat demand of the building end up in reducing both the global warming potential and radioactive waste, making them less sensitive to changes in the energy system.

Uncertainties related to the replacement stage in LCA of buildings: A case study of a structural masonry clay hollow brick wall

Abstract The construction of even simple buildings, such as housing, consumes great amounts of nonrenewable resources throughout their service life. Generally, a building has a long life-cycle, determining the impact generated due to the production of materials and building use is only part of the problem. To predict the building elements that must be replaced over the life span of a building into a model is complicated and this step often receives less attention than expected. As a part of its use stage in a Life Cycle Assessment (LCA), the research reported herein aims to quantify the uncertainties related to incorporating a building’s replacement and repair needs into a model and defines different substitution scenarios based on international data. Inventory data uncertainty was also analyzed by comparing Global life cycle inventory with Brazilian regionalized data. One square meter of structural clay hollow brick wall was studied, with a scope encompassing a cradle-to-grave scenario, assuming a 50-year life span. Results obtained indicate the life cycle inventory choice affects the results significantly. How the service life is modeled may cause high variations the LCAs results. The use stage impact ranges from between 6% and 72%, depending on the assessed scenario, life cycle inventory, and impact category. Scenarios that applied the design life criteria generated greater impact than those based on documented service life data. Definitions about the service life used to model building elements replacement are essential to reduce uncertainties and will set the stage to refine these models, thereby improving their accuracy.

BIM-based life cycle assessment and life cycle costing of an office building in Western Europe

The main aim of this research is to enhance the integration of life cycle assessment (LCA) and life cycle costing (LCC) methodologies with building information modelling (BIM), as existing approaches still have limitations (e.g. interoperability issues, non-editable databases). For that purpose, an automatic LCA/LCC analysis within a BIM-based environment is proposed. A BIM-based environmental and economic life cycle assessment (BIMEELCA) prototype tool was developed by the authors to improve the integration of BIM with LCA and LCC. Moreover, a pilot case study located in the Netherlands was used to validate the work developed in this research, thus demonstrating the usefulness of this approach for the construction industry. This study unveiled the potential of BIM-based simulations for the assessment of the environmental and economic impacts of buildings by integrating semantic information in the model. The work presented in this research is expected to contribute to the development of automatic sustainability simulations, creation of tailor-made BIM objects’ libraries, and use of historical data contained within data-rich models for predictive analyses (i.e. analyses that identify the most suitable solutions based on the data from previous projects).

Dynamic life cycle assessment modelling of a NZEB building

Most of the developed countries are struggling to reduce carbon emissions into the atmosphere to meet the international agreements. One of the strategies to reduce climate change impacts is the decarbonisation of the electricity production: generation mixes are more and more based on renewable energy sources that are replacing the traditional fossil fuels.The effect of the electricity decarbonisation production reflects in the life cycle impacts of buildings, particularly if they are strongly dependent on the electrical energy as the main energy vector. The traditional Life Cycle Assessment (LCA) cannot capture the effect of lowering emission factors for electricity generation since only static values are considered. Moreover, also the grid-building interaction should be properly taken into account in the life cycle assessment of buildings using dynamic calculations. A dynamic life cycle analysis is the methodology that can overcome these limitations through the introduction of dynamic parameters within the life cycle inventory and in the life cycle impact assessment stages.A Dynamic Life Cycle Assessment (DLCA) is proposed in order to evaluate the consequences of electricity decarbonisation on the LCA of an “all electric” Nearly Zero Energy Building (NZEB). A comparison with literature results about similar constructions is finally provided.

An analytical method for evaluating and visualizing embodied carbon emissions of buildings

Greenhouse gas emissions associated with buildings constitute a large part of global emissions, where building materials and associated processes make up a significant fraction. These emissions are complicated to evaluate with current methodologies due to, amongst others, the lack of a link between the material inventory data and the aggregated results.This paper presents a method for evaluating and visualizing embodied emission (EE) data of building material production and transport, including replacements, from building life cycle assessments (LCAs). The method introduces a set of metrics that simultaneously serve as a breakdown of the EE results and as an aggregation of the building's inventory data. Furthermore, future emission reductions due to technological improvements are modeled and captured in technological factors for material production and material transport. The material inventory is divided into building subparts for high-resolution analysis of the EE. The metrics and technological factors are calculated separately for each subpart, which can then be evaluated in relation to the rest of the building and be compared to results from other buildings. Two methods for evaluating and visualizing the results are presented to illustrate the method's usefulness in the design process.A case study is used to demonstrate the methods. Key driving factors of EE are identified together with effective mitigation strategies. The inclusion of technological improvements shows a significant reduction in EE (−11.5%), reducing the importance of replacements. Furthermore, the method lays the foundation for further applications throughout the project phases by combining case-specific data with statistical data.

Tracing the environmental impact origin within the existing building portfolio of prevailing building typologies

As circular economy (CE) is becoming a growing focus in the building industry due to the industries large resource consumption, waste production and environmental impacts a better understanding of buildings material composition, resource consumption and resulting environmental performance becomes increasingly important in order to support the transition towards CE. The research presented here is a stepping stone in order to investigating the existing building portfolio and the conducted analysis. It is used to get further information on what is included and where there is lack of information, in order to understand what is missing or what is needed to develop CE design strategies. Although, life cycle assessment (LCA) is increasingly used by the industry to assess these aspects, the lack of a systematic analytical approach as well as the high building complexity and diversity between buildings limits generalised knowledge from these studies. However, it is assumed that there are certain commonalities between the existing portfolio of prevailing building typologies which can be deducted. The study at hand is a part of a larger research project that aims at developing industry specific tools to support designers and decision makers select CE design strategies that improve the environmental performance and resource consumption of buildings. On the basis of a comprehensive systematic literature review (SLR) of whole building LCAs the paper at hand aims at tracing the environmental impact origin within the existing building portfolio of prevailing building typologies. To identify potentially important building parameters relevant to the resulting environmental impact performance and resource consumption of different building typologies. Based on 39 building LCA case studies that matched the specific inclusion and exclusion criteria of the SLR a focus on global warming and climate change was detected. It was found that even though buildings have different characteristics (size, typology, storeys, reference study period and location), for most of the buildings’ environmental impacts were predominantly related to the production of structurally important concrete components e.g. the structural frame, the external envelope, floor slabs and walls. To point towards which CE design strategies should be used to improve the environmental performance of buildings; the environmental information from the studies was insufficient due to lack of detailed information.

Conventional versus modular construction methods: A comparative cradle-to-gate LCA for residential buildings

Traditional on-site and modular off-site methods are the main construction methods in the residential building sector. Regardless of different advantages and disadvantages offered by each of these two construction methods, the overall environmental trade-offs between them are still unclear. This paper applies a cradle-to-gate life cycle assessment (LCA) to benchmark the environmental performance of conventional and modular construction methods. To this end, three single-family buildings (one conventional and two modular) designed and constructed in the Okanagan, British Columbia, Canada, were used as representatives of typical houses built by on-site and off-site methods in the region. The required data such as raw materials, material and workforce transportation, and energy resources was collected from the corresponding homebuilders through a questionnaire survey. Then, the environmental impact measures such as global warming potential were calculated through LCA analyses. Subsequently, the calculated impact measures along with their importance weights were incorporated into an analytic hierarchy process (AHP) based framework to develop a set of environmental impact indices for the material production phase, the construction phase, and summation of these phases (i.e., cradle-to-gate). Furthermore, a sensitivity analysis was performed to eliminate the human subjectivity involved in AHP. Eventually, individual impact measures and also the developed impact indices were compared and contrasted between the benchmarking buildings. The analyses revealed that construction of the first modular building resulted less environmental impacts than the other two buildings. Nevertheless, the lowest environmental performance was due to the second modular building. This disclosed that none of the modular and conventional construction methods is the absolute option for environmentally friendly construction. However, implementation of strategies such as optimal designs and decrease in material and worker transportation of both modular and conventional building projects and increase in annual production of modular manufacturing centers can reduce the material and energy consumption and the subsequent environmental impacts. This paper also provides a basis to create a benchmarking database by adding future LCA studies for new modular and conventional building projects.

Artificial Neural Networks to assess energy and environmental performance of buildings: An Italian case study

Abstract Approximately 40% of the European energy consumption and a large proportion of environmental impacts are related to the building sector. However, the selection of adequate and correct designs can provide considerable energy savings and reduce environmental impacts. To achieve this objective, a simultaneous energy and environmental assessment of a building's life cycle is necessary. To date, the resolution of this complex problem is entrusted to numerous software and calculation algorithms that are often complex to use. They involve long diagnosis phases and are characterised by the lack of a common language. Despite the efforts by the scientific community in the building sector, there is no simple and reliable tool that simultaneously solves the energy and environmental balance of buildings. In this work, the authors address this challenge by proposing the application of an Artificial Neural Network. Due to the high reliability of learning algorithms in the resolution of complex and non-linear problems, it was possible to simultaneously solve two different but strongly dependent aspects after a deep training phase. In previous researches, the authors applied several topologies of neural networks, which were trained on a large and representative database and developed for the Italian building stock. The database, characterised by several building models simulated in different climatic conditions, collects 29 inputs (13 energy data and 16 environmental data) and provides 7 outputs, 1 for heating energy demand and 6 of the most used indicators in life cycle assessment of buildings. A statistical analysis of the results confirmed that the proposed method is appropriate to achieve the goal of the study. The best artificial neural network for each output presented low Root Mean Square Error, Mean Absolute Error lower than 5%, and determination coefficient close to 1. The excellent results confirmed that this methodology can be extended in any context and to any condition (other countries and building stocks). Furthermore, the implementation of this solution algorithm in a software program can enable the development of a suitable decision support tool, which is simple, reliable, and easy to use even for a non-expert user. The possibility to use an instrument to predict a building's performance in its design and planning phase, represent an important result to support decision-making processes toward more sustainable choices.

Integrating climate change in life cycle assessment of buildings: literature review

The operational energy use and related greenhouse gas emissions of buildings are typically influenced by changes during the building service life such as climate change, technological evolution and energy mix evolution. Only few LCA studies consider these temporal variations. This paper investigates how climate change is currently considered in LCA studies. Three aspects related to the influence of climate change on the life cycle impact of buildings are focused on: (1) changes in operational energy use (heating and cooling) due to changes in the climatic context of the building, (2) changes in operational energy use due to technological evolution or climate regulations and (3) changes in energy mix due to climate regulations. All three influence the energy use and related environmental impact but the extent of the effect depends on the considered region, time step and environmental indicators. It is hence recommended to choose an appropriate time period when considering climate change in LCA and consider variations within a time period via dynamic building simulations or to include a static correction. A holistic set of impact categories should be focussed on to avoid burden shifting and the most influencing parameters should be checked via a sensitivity analysis.

Step-by-step implementation of BIM-LCA: A case study analysis associating defined construction phases with their respective environmental impacts

Building Information Modelling (BIM) supports construction processes by dealing with the variety and complexity of design in a single virtual model. The model may also be complemented by the static and energy performance of buildings. Facing the growing demand of sustainability strategies in the construction sector, the consideration of environmental information within the planning process influences the decision making of planners and stakeholders. Nevertheless, the life cycle assessment of buildings has been so far excluded in BIM, due to the high variety of accurate information and time required. In this paper, a systematic framework is presented and applied to a case study. BIM-LCA assists actors along the planning and designing phase, from the building conception as a whole, up to the elements’ details and materials’ definition. BIM and LCA intertwine in an application scheme of seven phases for integral planning and four levels of structural composition of a building. With respect to these, involved actors examine potential solutions through a tool which exploits alternative specifications in order to assess the environmental impacts. The goal of this paper is to demonstrate the application of a BIM-LCA model regarding decision making for reliable values of environmental impact in a given structural level of the building. The main findings of this framework are due to the multitude of actors and information orchestrated, namely to uncertainties which characterize the whole planning process and data handling. Through BIMLCA, actors are assisted by ensuring flexibility of models and consistency of results throughout planning and designing.

Regionalized inventory data in LCA of public housing: A comparison between two conventional typologies in southern Brazil

Abstract Life Cycle Assessment (LCA) can provide the environmental impact of buildings from its initial construction until its demolition. Of particular interest are the environmental impacts of public housing as developing economies are facing the growing need for housing. However, the validity of the LCA results is directly related to how representative is the inventory data to regional characteristics. Existing LCA of buildings in Brazil frequently ignores regional data when compiling the LCA and there is a lack of study on this topic. This study performs an LCA that compares two types of public housing in southern Brazil: single-family dwellings (house condominium) and multi-family dwellings (apartment condominium). The unit areas compared are of similar size, and the construction methods and materials used are also similar. The LCA was performed using regionalized and non-regionalized inventory data based on ISO 14040/44 and EN 15804 (modules A to C). Data from the Ecoinvent database v.3.3 was used with adaptations that reflected regional characteristics of Brazilian construction practices. Results show that the use stage (module B) is the most relevant in all environmental impact categories considered, particularly relevant are the electricity consumed (module B6) and replacement of constructions materials (module B4). Despite similar overall impacts, the single-family dwelling exhibited higher impact numbers compared to the multi-family dwelling, largely due to design and construction characteristics (module A). Regionalized data strongly influenced the results when compared to non-regionalized background data; therefore, the results obtained using non-regionalized data may lead to inconsistent decision-making. This study is one of the first LCA of buildings in Brazil using inventory data regionalized to local conditions and demonstrates the importance of regionalization since environmental impacts can vary significantly.

Impact of dynamic CO2 emission factors for the public electricity supply on the life-cycle assessment of energy efficient residential buildings

Climate change and its effects are the reasons for the energy transition in Germany and lead to an increasing exploitation of renewable energy sources. At the same time, energy efficient buildings reduce the heat demand significantly and allow for the operation of electricity based heating systems. With the aid of dynamic CO2 emission factors, the life-cycle assessment (LCA) for buildings can be adapted to reflect the fluctuating nature of renewable energy sources and the dynamics of heating power demand during the use phase more precisely. A case study using dynamic building simulation and static as well as dynamic emission factors for the year 2017 shows deviations of 3.4 % in the building’s GHG emissions. Furthermore, two emission factors for 2030 and 2050, which reflect the national 80 % carbon dioxide reduction target, are developed and applied to the case study. For these emission factors, the overall building’s GHG emissions decline drastically, whereas the deviation between the LCA using static or dynamic emission factors increases significantly. It can be seen that the application of a more dynamic approach for LCA adds substantial value to the investigation. However, further investigation on a broader set of dynamic input parameters for the LCA of energy efficient buildings seems to be reasonable.

Scenario uncertainties assessment within whole building LCA

Uncertainties evaluation is increasingly gaining traction within life cycle assessment (LCA), due to its key role as environmental decision support tool. When applied at whole-building scale, the large variety of materials, subjective choices and long lifespans introduce parameter, scenario and model uncertainties throughout the life cycle. Since normative choices are unavoidable within whole-building LCA (wbLCA), in this article we carried out a so-called ‘scenario’ uncertainty assessment for one illustrative case study. First, three uncertainty sources were selected, to include the two drivers most frequently cited in literature (reference service life and end of life management alternatives) and material wastage, a relevant issue to factor in variable construction optimization levels in contexts like Brazil. Cumulative energy demand (CED) and CML 2001 v.2.05 methods were used for calculating deterministic values of non-renewable embodied energy and global warming potential in SimaPro 7.3 The uncertainty assessment combined scenario analysis, stochastic modelling (Monte Carlo simulation of triangular probability distributions for the uncertainty drivers investigated) and global sensitivity analysis (GSA). The GSA confirmed the dominant contribution of the operational phase - strongly influenced by components replacement rate - to of life cycle non-renewable embodied energy and global warming potential result variance, whilst construction and end of life stages showed no correlation with life cycle results. Findings from this research also highlight the strategic importance of gathering service life information adherent to the assessed context. Building components replacement rates induced by the Brazilian standard are overestimated relatively to international figures used in LCAs worldwide.

Digitalization of building LCA and international activities – in the context of German assessment system for sustainable building

In this paper it is shown how digitalization and the establishment of an online infrastructure for life cycle assessment (LCA) in the context of the assessment system for sustainable building (BNB) by the German government forms starting point for an open international data network, as brought forward by the activities of InData (“International Open Data Network for Sustainable Building”). The establishment of the ILCD+EPD data format for EPD, the provision of interfaces, the development of workflow structures, guidelines and rules, which are openly published, internationally allow to access data from several databases. All these aspects are subject of the InData activities, and are decisive for a harmonization of LCA for sustainable building. With this concept of digitalization the propagation of the use of environmental product declarations (EPD) in building LCA was enhanced, and also new applications for using EPD data are offered, e.g. in BIM or other context.