Embodied carbon: A framework for prioritizing and reducing emissions in the building industry

Global climate change is one of the most impactful environmental issues in modern times, and the construction industry is known to be one of the largest contributors to carbon emissions—one of the key causes of climate change. Embodied carbon emissions of buildings are an often overlooked, but significant, influencer of a building’s overall carbon footprint. This gives rise to the need for improved life cycle analysis of buildings and identification of opportunities to reduce the total carbon footprint of a building throughout its life cycle. This paper analyzes the current state of the building industry that limits the consideration of reducing embodied carbon in buildings, evaluates opportunities available for identifying low embodied carbon strategies, and offers recommendations for manufacturing optimization, construction best practices, and policy framework implementation to appropriately integrate consideration of all carbon emissions in construction to reduce the overall carbon footprint of the building industry. For successful reduction of embodied carbon, streamlined assessment models must be established and policy must be implemented, in order to encourage innovation for carbon footprint reduction in the marketplace. Proper collaboration, communication, and education are critical for effective, overall carbon reduction

Meeting the challenge of zero carbon homes : a multi-disciplinary review of the literature and assessment of key barriers and enablers

Within the built environment sector, there is an increasing pressure on professionals to consider the impact of development upon the environment. These pressures are rooted in sustainability, and particularly climate change. But what is meant by sustainability? It is a term whose meaning is often discussed, the most common definition taken from the Bruntland report as “sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs” (World Commission on Environment and Development, 1987). In the built environment, the sustainability issues within the environment, social and economic spheres are often expressed through design considerations of energy, water and waste. Given the Stern Report’s economic and political case for action with respect to climate change (Stern, 2006) and the IPCC’s Fourth Assessment Report’s confirmation of the urgency of the climate change issue and it’s root causes (IPCC, 2007), the need for action to mitigate the effects of climate change is currently high on the political agenda. Excess in carbon dioxide concentrations over the natural level have been attributed to anthropogenic sources, most particularly the burning of carbon-based fossil fuels. Over 40% of Europe’s energy and 40% of Europe’s carbon dioxide emissions arise from use of energy in buildings. Energy use in buildings is primarily for space heating, water heating, lighting and appliance use. Professionals in the built environment can therefore play a significant role in meeting targets for mitigating the effects of climate change. The UK Government recently published the Code for Sustainable Homes (DCLG, 2006). Within this is the objective of development of zero carbon domestic new build dwellings by 2016. It is the domestic zero carbon homes agenda which is the focus of this report. The report is the culmination of a research project, funded by Northumbria University, and conducted from February 2008 to July 2008, involving researchers from the Sustainable Cities Research Institute (within the School of the Built Environment) and academics, also from within the School. The aim of the project was to examine, in a systematic and holistic way, the critical issues, drivers and barriers to building and adapting houses to meet zero carbon targets. The project involved a wide range of subject specialisms within the built environment and took a multi-disciplinary approach. Practitioner contribution was enabled through a workshop. The focus of this work was to review the academic literature on the built environment sector and its capabilities to meet zero carbon housing targets. It was not possible to undertake a detailed review of energy efficiency or micro-generation technologies, the focus of the research was instead in four focussed areas: policy, behaviour, supply chain and technology.What follows is the key findings of the review work undertaken. Chapter One presents the findings of the policy and regulation review. In Chapter Two the review of behavioural aspects of energy use in buildings is presented. Chapter Three presents the findings of the review of supply chain issues. Chapter Four presents the findings of the technology review, which focuses on phase change materials. A summary of the key barriers and enablers, and areas for future research work, concludes this report in Chapter Five. Research is always a work in progress, and therefore comments on this document are most welcome, as are offers of collaboration towards solutions. The School of the Built Environment at Northumbria University strives to embed its research in practical applications and solutions to the need for a low carbon economy

An Economic and Life Cycle Analysis of Regional Land Use and Transportation Plans, Research Report 11-25

Travel and emissions models are commonly applied to evaluate the change in passenger and commercial travel and associated greenhouse gas (GHG) emissions from land use and transportation plans. Analyses conducted by the Sacramento Area Council of Governments predict a decline in such travel and emissions from their land use and transportation plan (the “Preferred Blueprint” or PRB scenario) relative to a “Business-As-Usual” scenario (BAU). However, the lifecycle GHG effects due to changes in production and consumption associated with transportation and land use plans are rarely, if ever, conducted. An earlier study conducted by the authors, applied a spatial economic model (Sacramento PECAS) to the PRB plan and found that lower labor, transport, and rental costs increased producer and consumer surplus and production and consumption relative to the BAU. As a result, lifecycle GHG emissions from these upstream economic activities may increase. At the same time, lifecycle GHG emissions associated with the manufacture of construction materials for housing may decline due to a shift in the plan from larger luxury homes to smaller multi-family homes in the plan. To explore the net impact of these opposing GHG impacts, the current study used the economic production and consumption data from the PRB and BAU scenarios as simulated with the Sacramento PECAS model as inputs to estimate the change in lifecycle GHG emissions. The economic input-output lifecycle assessment model is applied to evaluate effects related to changes in economic production and consumption as well as housing construction. This study also builds on the findings from two previous studies, which suggest potential economic incentives for jurisdictional non-compliance with Sustainable Communities Strategies (SCSs) under Senate Bill 375 (also known as the “anti-sprawl” bill). SB 375 does not require local governments to adopt general plans that are consistent with the land use plans included in SCSs, and thus such incentives could jeopardize implementation of SCSs and achievement of GHG goals. In this study, a set of scenarios is simulated with the Sacramento PECAS model, in which multiple jurisdictions partially pursue the BAU at differing rates. The PRB is treated as a straw or example SCS. The scenarios are evaluated to understand how non-conformity may influence the supply of housing by type, and holding other factors constant, the geographic and income distribution of rents, wages, commute costs, and consumer surplus

Citywide Transportation Greenhouse Gas Emissions Inventories: A Review of Selected Methodologies

Outlines the methodological issues in creating transportation emissions inventories and how they affect the results, reviews currently used methodologies, and explores ways to integrate inventories with climate policies to inform reduction strategies

Stakeholder engagement in sustainable housing refurbishment in the UK

The UK government is committed to effectively implement a viable sustainable agenda in the social housing sector. To this end housing associations and local authorities are being encouraged to improve the environmental performance of their new and existing homes. Whilst much attention has been focused on new housing (e.g. the Code for Sustainable Homes) little effort has been focussed on improving the 3.9 (approx) million homes maintained and managed by the public sector (in England), which, given the low rate of new build and demolition (<1% in England), will represent approximately 70% of the public housing stock in 2050. Thus, if UK is to achieve sustainable public housing the major effort will have to focus on the existing stock. However, interpreting the sustainability agenda for an existing housing portfolio is not a straight foreword activity. In addition to finding a ‘technical’ solution, landlords also haveto address the socio-economic issues that balance quality of expectations of tenants with the economic realities of funding social housing refurbishment. This paper will report the findings of a qualitative study (participatory approach) that examined the processes by which a large public landlord sought to develop a long-term sustainable housing strategy. Through a series of individual meetings and group workshops the research team identified: committed leadership; attitudes towards technology; social awareness; and collective understanding of the sustainability agenda as key issues that the organisation needed to address in developing a robust and defendable refurbishment strategy. The paper concludes that the challenges faced by the landlord in improving the sustainability of their existing stock are not primarily technical, but socio-economic. Further, while the economic challenges: initial capital cost; lack of funding; and pay-back periods can be overcome, if the political will exists, by fiscal measures; the social challenges: health & wellbeing; poverty; security; space needs; behaviour change; education; and trust; are much more complex in nature and will require a coordinated approach from all the stakeholders involved in the wider community if they are to be effectively addressed. The key challenge to public housing landlords is to develop mechanisms that can identify and interpret the complex nature of the social sustainability agenda in a way that reflects local aspirations (although the authors believe the factors will exist in all social housing communities, their relative importance is likely to vary between communities) whilst addressing Government agendas

Techno-economic and environmental evaluation of producing chemicals and drop-in aviation biofuels via aqueous phase processing

Novel aqueous-phase processing (APP) techniques can thermochemically convert cellulosic biomass into chemicals and liquid fuels. Here, we evaluate these technologies through process design and simulation, and from a techno-economic and environmental point of view. This is the first peer-reviewed study that conducts such an assessment taking into account different biomass pretreatment methods, process yields, product slates, and hydrogen sources, as well as the historical price variation of a number of core commodities involved in the production. This paper undertakes detailed process simulations for seven biorefinery models designed to convert red maple wood using a set of APP technologies into chemicals (e.g. furfural, hydroxymethylfurfural and gamma-valerolactone) and liquid fuels (e.g. naphtha, jet fuel and diesel). The simulation results are used to conduct a well-to-wake (WTW) lifecycle analysis for greenhouse gas (GHG) emissions, and minimum selling price (MSP) calculations based on historical commodity price data from January 2010 to December 2015. An emphasis has been given towards aviation fuels throughout this work, and the results have been reported and discussed extensively for these fuels. It is found that the WTW GHG emissions and the MSP of jet fuel vary across the different refinery configurations from 31.6–104.5 gCO2e per MJ (64% lower and 19% higher, respectively, than a reported petroleum-derived fuel baseline) and $1.00–6.31 per gallon ($0.26–1.67 per liter, which is 61% lower and 146% higher, respectively, than the average conventional jet fuel price of the above time frame). It has been shown that the variation in the estimated emissions and fuel selling prices is primarily driven by the choice of hydrogen source and the relative production volumes of chemicals to fuels, respectively. The latter is a consequence of the fact that the APP chemicals considered here have a higher economic value than the liquid transportation fuels, and that their production is less carbon intensive compared to these fuels. However, the chemical market may get saturated if they are produced in large quantities, and increasing biofuel production over that of chemicals can help the biorefinery benefit under renewable fuel programs

Changing Significance of Embodied Energy: A comparative study of material specifications and building energy sources

Despite the increasing significance of embodied impacts of buildings, efforts to reduce their environmental footprints have been concentrated on the operational impacts of buildings. This study investigates the changing significance of embodied carbon over the entire life cycle of whole buildings. A case study of an office building was modelled with Revit, and sensitivity analyses of the modelled building were performed by varying the material specification and energy use pattern for seven other typologies. Using Revit, BIMWASTE tool, ATHENA Impact Estimator and Green Building Studio, comparative life-cycle analyses were carried out for the eight building typologies. The study suggests that notwithstanding the enormous impacts of the operational stage on life-cycle carbon of fossil fuel-based buildings, embodied impacts could vary between 8.4 and 22.3%. A key determinant of the proportional impacts of embodied energy is the nature of materials used for building construction. Similarly, embodied impacts of buildings become more significant and could contribute up to 60% of their life cycle impacts as they become more energy-efficient during their operational stage. As the study confirms the varying significance of embodied energy as construction materials and energy use patterns change, it implies the need for policy measures based on a whole life assessment methodology, instead of the usual ways of giving sole importance to the operational impacts of buildings. With buildings becoming more energy-efficient during their operational stage, there is an urgent need for an increased focus on the embodied impacts of buildings, especially as renewable energy resources are becoming widely adopted

Life Cycle GHG Emissions of Residential Buildings in Humid Subtropical and Tropical Climates: Systematic Review and Analysis

Improving the environmental life cycle performance of buildings by focusing on the reduction of greenhouse gas (GHG) emissions along the building life cycle is considered a crucial step in achieving global climate targets. This paper provides a systematic review and analysis of 75 residential case studies in humid subtropical and tropical climates. The study investigates GHG emissions across the building life cycle, i.e., it analyses both embodied and operational GHG emissions. Furthermore, the influence of various parameters, such as building location, typology, construction materials and energy performance, as well as methodological aspects are investigated. Through comparative analysis, the study identifies promising design strategies for reducing life cycle-related GHG emissions of buildings operating in subtropical and tropical climate zones. The results show that life cycle GHG emissions in the analysed studies are mostly dominated by operational emissions and are the highest for energy-intensive multi-family buildings. Buildings following low or net-zero energy performance targets show potential reductions of 50–80% for total life cycle GHG emissions, compared to buildings with conventional energy performance. Implementation of on-site photovoltaic (PV) systems provides the highest reduction potential for both operational and total life cycle GHG emissions, with potential reductions of 92% to 100% and 48% to 66%, respectively. Strategies related to increased use of timber and other bio-based materials present the highest potential for reduction of embodied GHG emissions, with reductions of 9% to 73

Analysis of Equivalent CO2 Emissions of the Irrigation System—A Case Study

This work aims to assess the emissions related to the useful life of the irrigation network on the campus of the University of Alicante (Spain). A life cycle assessment has been developed employing the One Click LCA software to calculate material proportion, repair rate, energy consumption, water volume, transport, and irrigation surface. This has been used in a real pressurised irrigation network, such as the one at the University of Alicante delivering water to the grass. Two potential cases which consider the pipelines made of polyvinyl chloride (variant 1) and high-density polyethene (variant 2) have also been analysed. Energy consumption had the most influence on emissions discharges (42%), followed by materials (37%) and repairs (18%) in the current water irrigation network. Variant 1 shows higher emissions produced in network materials (47%), energy consumption (27%), and repairs (24%). Variant 2 has high emissions because of energy consumption (47%), materials manufacturing and transport (34%), and repairs (17%). It has been determined that a network of disposed polyethene pipes will reduce the total Global Warming Potential emitted into the atmosphere. Materials (127.9 Tn CO2e) and energy (145.5 Tn CO2e) are the stages where the highest Global Warming Potential is produced. Other stages that also stand out are repairs (62 Tn CO2e), construction (6.3 Tn CO2e), and transport of materials (3.5 Tn CO2e). Renewable energy sources could reduce energy consumption. Variant 2 has 11% lower emissions than the current network (variant 0), making it a workable choice for infrastructure design.This work has been funded by the research project “Hi-Edu Carbon” Erasmus Plus Programme, Key Action KA22021, action type (2021-1-SK01-KA220-HED-000023274)