A spatio-temporal life cycle assessment framework for building renovation scenarios at the urban scale (original) (raw)
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Explorative life-cycle assessment of renovating existing urban housing- stocks
Building and Environment, 2019
Urban building-stocks are responsible for a significant share of resource and energy use. To quantify the potential for reducing energy and environmental impact, building-stock modelling (BSM) is commonly used. Recently, the focus of BSM has expanded to include environmental impacts and life-cycle assessment (LCA). However, impact categories are often limited to climate change and representative buildings are often used. In addition, the future state of the stock is often calculated as a step-change to highlight the technical potential of an ideal future state. The aim of this paper is to assess the environmental impact of the future development of an urban housing-stock under business-as-usual scenarios using a building-specific GIS based model applied to the multi-family building stock of the City of Gothenburg. This paper uses an explorative LCA to account for environmental impacts based on dynamic uptake of common renovation measures and resulting energy savings until 2050. Two main scenarios are used where the renovation logic is based on either end-of-life of components or cost-effectiveness and further divided using limiting factors regarding investment capacity and annual share of the stock to be renovated. Results show possible energy savings of up to 23% and a corresponding 31% reduction in greenhouse-gas emissions. Greenhouse-gas emissions avoided due to reduced energy demand are offset by up to 65% by accounting for material use due to construction related renovation measures. For scenarios that favour construction related interventions, PV panels are responsible for the major part of the environmental impact across the 15 mid-point indicators used.
Energy and Buildings, 2016
A dynamic building stock model is applied to simulate the development of dwelling stocks in 11 European countries, over half of all European dwellings, between 1900 and 2050. The model uses time series of population and number of persons per dwelling, as well as demolition and renovation probability functions that have been derived for each country. The model performs well at simulating the long-term changes in dwelling stock composition and expected annual renovation activities. Despite differences in data collection and reporting, the modelled future trends for construction, demolition and renovation activities lead to similar patterns emerging in all countries. The model estimates future renovation activity due to the stock's need for maintenance as a result of ageing. The simulations show only minor future increases in the renovation rates across all 11 countries to between 0.6-1.6%, falling short of the 2.5-3.0% renovation rates that are assumed in many decarbonisation scenarios. Despite this, 78% of all dwellings could benefit from energy efficiency measures by 2050, either as they are constructed (31%) or undergo deep renovation (47%). However, as no more than one deep renovation cycle is likely on this timeframe, it is crucial to install the most energy efficient measures available at these opportunities.
Energy and Buildings, 2017
In the building sector, the energy and the greenhouse gases embodied in the building materials are becoming increasingly important. Combined with the operational primary energy demand and the endof-life, the whole life cycle of buildings can be assessed. In this paper, a comprehensive method for calculating the life cycle of individual buildings is presented. First, their material composition has been determined and generic values for the embodied energy, embodied greenhouse gases, energy needed and greenhouse gases emitted during disposal of the different building materials have been calculated. Subsequently these values have been integrated into an urban energy simulation software to simulate energy and emission values for buildings. A given building geometry with four different building standards was considered. The results can help to decide between building refurbishment or demolition and new construction. For example it could be shown that the share of the life cycle stage production compared to the total value rises with a better building insulation standard, as the share of the use stage decreases. The highest building refurbishment standard resulted in the best life cycle performance when compared with less ambitious refurbishment or construction of a new building of today's standards.
Building and Environment, 2021
The thermal retrofit of buildings plays a key role to limit global warming. However, the spatial and temporal dynamics of urban-scale renovation are not well understood. This paper proposes a new methodology that is based on a bottom-up building stock model. It links dynamic Material Flow Analysis with dynamic Life Cycle Assessment to include the temporal dynamics of emissions and renovation activity, and the spatial dynamics of the building stock. Alternative renovation scenarios for a Lisbon neighborhood are analyzed over the next 100 years. Thee scenarios include renovation rates, electricity grid transformation and material choice: Conventional renovation systems are compared to bio-based systems (using cork, wood and straw). A need-based prioritization of poorly insulated buildings is suggested and the effect of different energy grid transitions analyzed. The results show that bio-based systems, especially made with fast-rotation biomass, are beneficial regarding radiative forcing. The straw-and wood-based system ("TES"), combined with an increased renovation rate, result in a cumulative radiative forcing of − 45.4 * 10 − 8 kW/m 2 for embodied impacts in 2050, compared to 3.5* 10 − 8 kW/ m 2 with a conventional system and a business-as-usual renovation rate. A fast and radical transition of the energy grid is crucial to meet the carbon budget to limit global warming to 2 • C.
Proceedings of EnviroInfo and ICT for Sustainability 2015, 2015
The building sector represents one of the major sources of environmental impact due especially to space and domestic hot water heating and construction works. A number of studies focused so far on estimating the energy savings and carbon emissions reduction potential achievable by retrofitting urban building stocks, nevertheless a shift to life cycle assessment is needed to properly assess the environmental impacts in a more holistic way. The aim of this study is to develop a geospatial data model for the life cycle assessment of environmental impacts of building stocks at the urban scale. The methodology includes: geospatial processing of building-related data to characterize urban building stocks; a spatiotemporal database to store and manage data; life cycle assessment to estimate potential environmental impacts. The methodology was tested for a case study in Luxembourg and preliminary results regarding the retrofitting stage of residential buildings were provided for one entire city. The data model is part of a wider bottom-up framework being developed to support decision about building stock retrofitting for sustainable urban planning.
A scenario analysis of the life cycle greenhouse gas emissions of a new residential area
Environmental Research Letters, 2012
While buildings are often credited as accounting for some 40% of the global greenhouse gas (GHG) emissions, the construction phase is typically assumed to account for only around one tenth of the overall emissions. However, the relative importance of construction phase emissions is quickly increasing as the energy efficiency of buildings increases. In addition, the significance of construction may actually be much higher when the temporal perspective of the emissions is taken into account. The construction phase carbon spike, i.e. high GHG emissions in a short time associated with the beginning of the building's life cycle, may be high enough to question whether new construction, no matter how energy efficient the buildings are, can contribute to reaching the greenhouse gas mitigation goals of the near future. Furthermore, the construction of energy efficient buildings causes more GHG emissions than the construction of conventional buildings. On the other hand, renovating the current building stock together with making energy efficiency improvements might lead to a smaller construction phase carbon spike and still to the same reduced energy consumption in the use phase as the new energy efficient buildings. The study uses a new residential development project in Northern Europe to assess the overall life cycle GHG emissions of a new residential area and to evaluate the influence of including the temporal allocation of the life cycle GHG emissions in the assessment. In the study, buildings with different energy efficiency levels are compared with a similar hypothetical area of buildings of the average existing building stock, as well as with a renovation of an area with average buildings from the 1960s. The GHG emissions are modeled with a hybrid life cycle assessment. The study suggests that the carbon payback time of constructing new residential areas is several decades long even when using very energy efficient buildings compared to utilizing the current building stock. Thus, while increasing the overall energy efficiency is important in the long term, the construction of new energy efficient buildings cannot be used as a means to achieve the short term and medium term climate change mitigation goals as cities and governments often suggest. Furthermore, given the magnitude of the carbon spike from construction and its implications, the climate change mitigation strategies should set reduction targets for the construction phase emissions alongside the ones for the use phase, which currently receives almost all of the attention from policy-makers.
Energy, 2022
The environmental performance of existing buildings can have a major role in achieving significant reductions in CO2 emissions: In the UK, around 75% 2050's housing stock has already been built. While building performance improvement efforts mostly focus on operational performance, buildings environmental impact is the result of processes that occur throughout their life cycle. To achieve significant emission reductions in an economically viable way, this study uses Life Cycle Performance approaches to carry a cross-comparison between the refurbishment and replacement of two housing archetypes in London: mid-terrace-house and a bungalow. Specifically, the study integrates Life Cycle Carbon Footprint (LCCF) and Life Cycle Cost (LCC) protocols (EN 15978:2011 and BS ISO 15686-5), thermal simulations (EnergyPlus), building generative design framework (PLOOTO-Parametric LayOut Organisation generator) and mathematical optimisation algorithms (NSGA-II). Results show that the optimal refurbishment archetypes generally performed better than replacements (Refurbishments LCCF ranges between 1,100-1,500 kgCO2e/m 2 and LCC 440-680 £/m 2 , compared to that of the replacements scenarios, ranging 1,220-1,850 kgCO2e/m 2 and 550-890 £/m 2). The study also highlights benefit of incentivising re-use to achieve quicker emissions reductions. The study lastly discusses a range of embodied and operational performance issues.
Energies
The scope of this study is to assess how different energy efficient renovation strategies affect the environmental impacts of a multi-family house in a Nordic climate within district heating systems. The European Union has set ambitious targets to reduce energy use and greenhouse gas emissions by the year 2030. There is special attention on reducing the life cycle emissions in the buildings sector. However, the focus has often been on new buildings, although existing buildings represent great potential within the building stock in Europe. In this study, four different renovation scenarios were analyzed with the commercially available life cycle assessment software that follows the European Committee for Standardization (CEN) standard. This study covers all life cycle steps from the cradle to the grave for a residential building in Borlänge, Sweden, where renewable energy dominates. The four scenarios included reduced indoor temperature, improved thermal properties of building materi...
Life-cycle costs and impacts on energy-related building renovation assessments
International Journal of Sustainable Building Technology and Urban Development
Many regulations and initiatives to promote the reduction of energy consumption and carbon emissions have been implemented in the building sector. However, they are mostly targeted at new buildings. In order to reach the goals that are being established, while it is necessary to implement measures in new buildings, this is doubly the case for existing buildings, which correspond to the majority of the European building stock. Building renovation improves buildings' energy performance and reduces the carbon emissions related to the operation of the building, but this involves adding new materials and technical systems. The production process of these new materials uses energy (embodied energy) and releases carbon emissions. In this sense, to evaluate the relevance of the embodied energy in building renovation, the International Energy Agency Energy in Buildings and Communities (IEA EBC) project, Annex 56, developed a methodological framework to evaluate the cost-effectiveness of building renovation solutions that includes a life-cycle impact assessment (LCIA). Thus, using a particular case study, different renovation solutions are compared both with and without consideration of the embodied energy. The results show that the embodied energy does not have a major impact on the evaluation of the cost-effectiveness of the renovation solutions, but that as the renovation energy target gets closer to a zero non-renewable energy level, its relevance increases.