Carbon Benchmark for Czech Residential Buildings Based on Climate Goals Set by the Paris Agreement for 2030

Embodied GHG emissions of buildings – The hidden challenge for effective climate change mitigation

Present day European legislation focuses upon the reduction of greenhouse gas (GHG) emissions in buildings through better design and technological solutions, with a view to reduce operational energy use and embodied GHG emissions. Currently, environmental performance assessment tools for buildings lack in assessing these parameters over the entire lifecycle of a building. Life cycle assessment (LCA) is a well-established methodology that gives a clear insight into the potential environmental impacts during the service life of a building. However, architect, engineer and constructor (AEC) professionals consider LCA as complex and time consuming. This paper builds upon a methodology for the development of a parametric analysis tool (PAT), which comprehensively assesses operational energy use and embodied GHG emissions during the lifecycle of a building. In this phase of the PAT’s development, the complexity of the tool has been increased by expanding the number of parameters from four (i.e. insulation thickness, window types, North façade glazing area and South façade glazing area) to seven (i.e. climatic zones, solar shading and electricity emission factors). This has increased the amount of parametric permutations from 1,372 to 12,348. The PAT has been applied to a conceptual two-storey single-family house, developed by the Norwegian ZEB Research Centre, which is assumed to be in either Oslo (Norway) or Lecce (Italy). The results show that the choice of insulation thickness influences total energy use less than the selection of shading types or glazing areas. The results also show the parametric selection with the least amount of operational energy use (34kWh/m2/yr) in the Lecce climate consists of triple-glazed windows (0.5W/m2k), 10m2 of glazing on the north façade, 20m2 of glazing on the south facade. The results show the parametric selection with the lowest total GHG emissions in the Oslo climate (7.8kgCO2eq/m2/yr) consists of triple glazing (0.5W/m2k), 10m2 of glazing on the north facade and 20m2 glazing on the south facade. This is because a lower electricity emission factor (132gCO2eq/kWh for Norway and 290gCO2eq/kWh for Italy) was used for converting operational energy use to GHG emissions, even though the Oslo climate has a higher heating demand compared to Lecce. In conclusion, this paper shows how complex design options can be evaluated in a holistic way through PAT to ascertain the best selection of design criteria for low GHG emissions and low operational energy use.

The body of life cycle assessment (LCA) literature is vast and has grown over the last decade at a dauntingly rapid rate. Many LCAs have been published on the same or very similar technologies or products, in some cases leading to hundreds of publications. One result is the impression among decision makers that LCAs are inconclusive, owing to perceived and real variability in published estimates of life cycle impacts. Despite the extensive available literature and policy need formore conclusive assessments, only modest attempts have been made to synthesize previous research. A significant challenge to doing so are differences in characteristics of the considered technologies and inconsistencies in methodological choices (e.g., system boundaries, coproduct allocation, and impact assessment methods) among the studies that hamper easy comparisons and related decision support. An emerging trend is meta-analysis of a set of results from LCAs, which has the potential to clarify the impacts of a particular technology, process, product, or material and produce more robust and policy-relevant results. Meta-analysis in this context is defined here as an analysis of a set of published LCA results to estimate a single or multiple impacts for a single technology or a technology category, either in a statisticalmore » sense (e.g., following the practice in the biomedical sciences) or by quantitative adjustment of the underlying studies to make them more methodologically consistent. One example of the latter approach was published in Science by Farrell and colleagues (2006) clarifying the net energy and greenhouse gas (GHG) emissions of ethanol, in which adjustments included the addition of coproduct credit, the addition and subtraction of processes within the system boundary, and a reconciliation of differences in the definition of net energy metrics. Such adjustments therefore provide an even playing field on which all studies can be considered and at the same time specify the conditions of the playing field itself. Understanding the conditions under which a meta-analysis was conducted is important for proper interpretation of both the magnitude and variability in results. This special supplemental issue of the Journal of Industrial Ecology includes 12 high-quality metaanalyses and critical reviews of LCAs that advance understanding of the life cycle environmental impacts of different technologies, processes, products, and materials. Also published are three contributions on methodology and related discussions of the role of meta-analysis in LCA. The goal of this special supplemental issue is to contribute to the state of the science in LCA beyond the core practice of producing independent studies on specific products or technologies by highlighting the ability of meta-analysis of LCAs to advance understanding in areas of extensive existing literature. The inspiration for the issue came from a series of meta-analyses of life cycle GHG emissions from electricity generation technologies based on research from the LCA Harmonization Project of the National Renewable Energy Laboratory (NREL), a laboratory of the U.S. Department of Energy, which also provided financial support for this special supplemental issue. (See the editorial from this special supplemental issue [Lifset 2012], which introduces this supplemental issue and discusses the origins, funding, peer review, and other aspects.) The first article on reporting considerations for meta-analyses/critical reviews for LCA is from Heath and Mann (2012), who describe the methods used and experience gained in NREL's LCA Harmonization Project, which produced six of the studies in this special supplemental issue. Their harmonization approach adapts key features of systematic review to identify and screen published LCAs followed by a meta-analytical procedure to adjust published estimates to ones based on a consistent set of methods and assumptions to allow interstudy comparisons and conclusions to be made. In a second study on methods, Zumsteg and colleagues (2012) propose a checklist for a standardized technique to assist in conducting and reporting systematic reviews of LCAs, including meta-analysis, that is based on a framework used in evidence-based medicine. Widespread use of such a checklist would facilitate planning successful reviews, improve the ability to identify systematic reviews in literature searches, ease the ability to update content in future reviews, and allow more transparency of methods to ease peer review and more appropriately generalize findings. Finally, Zamagni and colleagues (2012) propose an approach, inspired by a meta-analysis, for categorizing main methodological topics, reconciling diverging methodological developments, and identifying future research directions in LCA. Their procedure involves the carrying out of a literature review on articles selected according to predefined criteria.« less

In the face of the unfolding climate crisis, the role and importance of reducing Greenhouse gas (GHG) emissions from the building sector is increasing. This study investigates the global trends of GHG emissions occurring across the life cycle of buildings by systematically compiling life cycle assessment (LCA) studies and analysing more than 650 building cases. Based on the data extracted from these LCA studies, the influence of features related to LCA methodology and building design is analysed. Results show that embodied GHG emissions, which mainly arise from manufacturing and processing of building materials, are dominating life cycle emissions of new, advanced buildings. Analysis of GHG emissions at the time of occurrence, shows the upfront ‘carbon spike’ and emphasises the need to address and reduce the GHG ‘investment’ for new buildings. Comparing the results with existing life cycle-related benchmarks, we find only a small number of cases meeting the benchmark. Critically reflecting on the benchmark comparison, an in-depth analysis reveals different reasons for cases achieving the benchmark. While one would expect that different building design strategies and material choices lead to high or low embodied GHG emissions, the results mainly correlate with decisions related to LCA methodology, i.e. the scope of the assessments. The results emphasize the strong need for transparency in the reporting of LCA studies as well as need for consistency when applying environmental benchmarks. Furthermore, the paper opens up the discussion on the potential of utilizing big data and machine learning for analysis and prediction of environmental performance of buildings.

Whole-building life-cycle analysis with a new GREET® tool: Embodied greenhouse gas emissions and payback period of a LEED-Certified library

Interrogating greenhouse gas emissions of different dietary structures by using a new food equivalent incorporated in life cycle assessment method

The construction of tall buildings generates a high spatial and temporal concentration of greenhouse gas (GHG) emissions. Research has shown that as building height increases, more resources per floor area are required to withstand the increasing effects of wind and earthquake loads. This has major implications for the environmental performance of tall buildings since the embodied GHG emissions (EGHGE) of structural systems tend to represent the greatest portion of the life cycle GHG emissions of tall buildings. In mitigating the effects of climate change, life cycle assessment (LCA) has been proposed as an early stage design tool to facilitate the choice of structural systems for tall buildings. However, international standards on LCA do not specify which of the three main life cycle inventory (LCI) approaches to use - process analysis, environmentally-extended input-output analysis or hybrid analysis. The aim of this paper is to evaluate the influence of LCI approaches on the choice of structural systems for tall buildings to minimise their embodied GHG emissions.The effects of LCI approaches on the choice of structural systems for tall buildings are evaluated using 10 tall buildings, ranging in height from 10 to 50 storeys, parametrically designed using finite element modelling. Two alternative structural systems are proposed and various LCI approaches are used to compare their EGHGE. The paper demonstrates that varying the LCI approach can significantly influence the values of EGHGE of structural systems for tall buildings by up to 116%. Notably, the paper demonstrates that, in minimising EGHGE, the adopted LCI approach can influence the choice of structural systems for tall buildings. The findings of this study confirm the need for clarity, transparency and comprehensiveness in the use of LCI approaches for comparative LCA studies, particularly in the structural design of tall buildings.

Reply to L Aleksandrowicz et al.

None of the indicators underlying the 169 targets of the 17 UN Agenda 2030 Sustainable Development Goals (SDGs) allow for the tracking of buildings´ greenhouse gas (GHG) emissions. Due to the continuously decreasing GHG budget and the significant contribution of the building sector to GHG emissions, in this study a new indicator and implementation steps for its practical application are proposed. By the application of the indicator GHG emissions have to be determined once during the building submission procedure and ultimately after completion of the building to obtain a usage permit. Finally, the results must be available to the statistical offices. A simplified Life Cycle Assessment (LCA) is used to calculate the GHG emissions of buildings. The GHG emission benchmark values for comparison are derived by carbon budget approaches. The study presents the theoretical process for the implementation of the proposed indicator in the course of the building submission and introduces the necessary methods. In addition, the decision scenarios after the submission are highlighted as well as a step-by-step time frame for the practical implementation of the indicator and the necessary implementation measures are presented. The developed indicator and the proposed tracking strategy help to address the current lack of effective monitoring mechanisms for GHG emissions from buildings and further improve the emissions database in the buildings sector. Given the importance of the building sector as a significant contributor to GHG emissions and the continuous decrease in global GHG budgets, it is crucial to establish effective tools to measure and monitor these emissions.

Buildings contribute to greenhouse gas (GHG) emissions throughout their life—from material extraction and production to building demolition and disposal. Current GHG emission reduction efforts largely focus on building operation, typically ignoring embodied emissions. One of the main barriers affecting the uptake of embodied GHG emissions considerations is the uncertainty related to the economic value of a building with reduced life-cycle GHG emissions. A conceptual approach is presented for integrating the life-cycle GHG emissions of a building into an economic evaluation. A case study detached residential dwelling located in Melbourne, Australia, is used to demonstrate the approach using a range of economic valuation approaches. One approach, using a carbon tax, shows that the effective cost for a single household would be over A$2000 for the first year, rising to almost A$5000 in 10 years. Across the range of evaluation approaches considered, the total cost to the householder is found to be between A$4600 and A$7860. With the embodied GHG emissions accounting for over 66% of the case study’s life-cycle GHG emissions, the majority of the economic liability for the householder relates to the initial construction and ongoing material replacement of the building. Policy relevance This research provides a comprehensive and integrated approach to GHG emissions and economic assessment of residential buildings. This could be used to drive better decisions in building construction and operation through policy improvement, generating greater understanding of the GHG emissions of buildings and the economic value of GHG emissions. By quantifying the total GHG emissions over a building’s life-cycle and examining ecological and financial implications, new data can provide the basis for policy measures that transform the value of GHG emissions in property. The total life-cycle approach to GHG emissions can be used by developers or builders, for example, to demonstrate the potential financial implications of their choices. However, given its current format, there is a need to improve policy measures such as improved carbon tax strategies and the generation of an annual tax for the economic value implications to be realised.

Forests play a crucial role in achieving net-zero greenhouse gas (GHG) emissions as they can act as carbon sinks. Harvesting wood for building construction has been promoted as a strategy to reduce embodied GHG emissions in buildings. However, recent research shows the significance of carbon opportunity costs, which potentially outweighs the embodied GHG emissions substitution benefits of using wood in comparison to alternative building materials over the life cycle. Currently, there is limited research on this topic, with a recently published study focusing on single-family homes in Austria. Through this work, we deepen the knowledge in this field by applying a novel climate optimum concept to various building typologies. We apply life cycle assessment (LCA) to calculate GHG emission substitution factors for representative archetypes and compare these with the carbon balance indicators representing forest carbon opportunity costs for Austria. We show the results for functional equivalent archetype pairs and provide an overview of the range of GHG emission substitution as well as the carbon opportunity costs in the Austrian forest. Our results show that carbon opportunity costs exceed the embodied GHG emission substitution achieved by mass timber archetypes, suggesting that leaving wood in forests to further absorb carbon dioxide offers greater climate benefits than using it for the construction of mass timber buildings. When observing archetypes representing lightweight timber buildings including fast-growing biobased materials as insulation material representing ‘best-case’ scenarios, we see that GHG emission substitution effects achieved per unit of wood are in the range of unrealized carbon removal potential in the forest system. The results point towards finding the optimum solutions for use of wood in building construction and emphasize the importance of looking beyond the system boundary of traditional building LCAs, to properly model the dynamics underlying ambitions to reach net-zero GHG emissions.

In order to achieve the necessary reduction of greenhouse gas (GHG) emissions and decarbonization of building construction and operation, both high- and low-tech building design strategies are promoted. Amongst particularly promising strategies are the deployment of energy efficiency measures, for reducing operational energy use and related impacts, as well as the application of low-carbon, bio-based construction materials, for reducing embodied impacts.In part two of our study on the life cycle assessment (LCA) of regenerative design strategies, LCA is applied to investigate the environmental impacts and reduction potentials of strategies at building level by analyzing two low-tech, passive building concepts – the be2226 building and the N11 SolarHouse – in both their original designs as well as optimized alternatives applying bio-based material solutions.The analysis includes three steps. In a first step the life cycle GHG emissions of the original buildings are assessed, revealing strengths and weaknesses on both operational and embodied GHG emissions. Environmental hotspots are identified across environmental indicators, life cycle stages and building elements. In a second step the case studies are remodeled with bio-based building element alternatives showing substantial embodied GHG emissions reduction potential compared to the original case studies. Finally, the results of all building variants are compared with climate targets for buildings revealing that the N11 building meets established climate targets already in its original version, and that a straw-based material optimization can even enable meeting more ambitious climate targets.

Embodied GHG emissions of high speed rail stations: Quantification, data-driven prediction and cost-benefit analysis

Residential buildings generate significant greenhouse gas (GHG) emissions and consume energy throughout their life cycle. In recent years, research on GHG emissions and energy consumption of buildings has developed rapidly in response to the growing climate change and energy crisis. Life cycle assessment (LCA) is an important method for evaluating the environmental impacts of the building sector. However, LCA studies of buildings show widely varying outcomes across the world. Besides, environmental impact assessment from a whole life cycle perspective has been undeveloped and slow. Our work presents a systematic review and meta-analysis of LCA studies on GHG emissions and energy consumption in the preuse, use, and demolition stages of residential buildings. We aim to examine the differences among the results of diverse case studies and demonstrate the spectrum of variations under contextual disparities. Results show that residential building emits about 2928kg GHG emission and consumes about 7430 kWh of energy per m2 of gross building area on average throughout the life cycle. Residential buildings have an average GHG emission of 84.81% in the use phase, followed by the preuse phase and demolition phase; the mean energy consumption in the use stage occupied the largest share of 84.52%, followed by preuse stage and demolition stage. GHG emissions and energy use vary significantly in different regions due to different building types, natural conditions, and lifestyles. Our study stresses the compelling requirement to slash GHG emissions and optimize energy consumption from residential buildings by use of low carbon building materials, energy structure adjustment, consumer behavior transformation, etc.

New energy and renewable widely available in Indonesia. One of them is the biomass that can be used with gasification technology. Biomass is an organic matter to which derived from biological materials. This research was used integration gasification system with a gas engine, which works more properly with CO, and H2. The advantage of this biomass power plant compared the environmental impact on other types of plants such as coal-fired power plants, diesel power plants, etc. Therefore the potential of environmental impacts was generated, it is necessary to calculate quantitatively through the life cycle assessment methods. This research aimed to calculate impact assessment on electricity production from a Biomass Power Plant system through a life cycle assessment with boundary cradle to grave in Indonesia. The study revealed that greenhouse gas (GHG) emission of electricity production from an empty fruit bunch palm oil mill was 0.15 kg CO2-eq kWh–1. The gas engine was the highest GHG emission contributor during its life cycle. Empty fruit bunch as a source of biomass for electricity production was considered as climate-friendly power plant system due to its potential in reducing GHG emission from palm oil production and released lower GHG emission.