Primary Energy Balance Research Articles

Implementing a dynamic representation of fire and harvest including subgrid-scale heterogeneity in the tile-based land surface model CLASSIC v1.45

Abstract. Canada's forests play a critical role in the global carbon (C) cycle and are responding to unprecedented climate change as well as ongoing natural and anthropogenic disturbances. However, the representation of disturbance in boreal regions is limited in pre-existing land surface models (LSMs). Moreover, many LSMs do not explicitly represent subgrid-scale heterogeneity resulting from disturbance. To address these limitations, we implement harvest and wildfire forcings in the Canadian Land Surface Scheme Including Biogeochemical Cycles (CLASSIC) land surface model alongside dynamic tiling that represents subgrid-scale heterogeneity due to disturbance. The disturbances are captured using 30 m spatial resolution satellite data (Landsat) on an annual basis for 33 years. Using the pan-Canadian domain (i.e., all of Canada south of 76° N) as our study area for demonstration, we determine the model setup that optimally balances a detailed process representation and computational efficiency. We then demonstrate the impacts of subgrid-scale heterogeneity relative to standard average individual-based representations of disturbance and explore the resultant differences between the simulations. Our results indicate that the modeling approach implemented can balance model complexity and computational cost to represent the impacts of subgrid-scale heterogeneity resulting from disturbance. Subgrid-scale heterogeneity is shown to have impacts 1.5 to 4 times the impact of disturbance alone on gross primary productivity, autotrophic respiration, and surface energy balance processes in our simulations. These impacts are a result of subgrid-scale heterogeneity slowing vegetation re-growth and affecting surface energy balance in recently disturbed, sparsely vegetated, and often snow-covered fractions of the land surface. Representing subgrid-scale heterogeneity is key to more accurately representing timber harvest, which preferentially impacts larger trees on higher quality and more accessible sites. Our results show how different discretization schemes can impact model biases resulting from the representation of disturbance. These insights, along with our implementation of dynamic tiling, may apply to other tile-based LSMs. Ultimately, our results enhance our understanding of, and ability to represent, disturbance within Canada, facilitating a comprehensive process-based assessment of Canada's terrestrial C cycle.

A Quantitative Positive Energy District Definition with Contextual Targets

This paper presents the goals and components of a quantitative energy balance assessment framework to define Positive Energy Districts (PEDs) flexibly in three important contexts: the context of the district’s density and local renewable energy supply (RES) potential, the context of a district’s location and induced mobility, and the context of the district’s future environment and its decarbonized energy demand or supply. It starts by introducing the practical goals of this definition approach: achievable, yet sufficiently ambitious, to be inline with Paris 2050 for most urban and rural Austrian district typologies. It goes on to identify the main design parts of the definition—system boundaries, balancing weights, and balance targets—and argues how they can be linked to the definition goals in detail. In particular, we specify three levels of system boundaries and argue their individual necessity: operation, mobility, and embodied energy and emissions. It argues that all three pillars of PEDs, energy efficiency, onsite renewables, and energy flexibility, can be assessed with the single metric of a primary energy balance when using carefully designed, time-dependent conversion factors. Finally, it is discussed how balance targets can be interpreted as information and requirements from the surrounding energy system, which we identify as a “context factor”. Three examples of such context factors, each corresponding to the balance target of one of the previously defined system boundaries, operation, mobility, and embodied emissions, are presented: density (as a context for operation), sectoral energy balances and location (as a context for mobility), and an outlook on personal emission budgets (as a context for embodied emissions). Finally, the proposed definition framework is applied to seven distinct district typologies in Austria and discussed in terms of its design goals.

A Small Modular House as a Response to the Energy Crisis

Energy security is becoming one of the most important issues today. Continuous increases in the prices of fossil fuels, firewood and wood pellets have become commonplace in many countries. One positive effect of this situation is the greater focus on the development of renewable energy technologies and the search for solutions to reduce the heat demands of residential buildings. The purpose of this paper is to present a small modular building that can be a response to the energy crisis and Ukraine’s wave of refugees in Poland. The results of the energy simulations performed in DesignBuilder software showed that this type of house has a primary energy demand of 139.35 kWh/m2. The calculations were performed for the climatic conditions of north-eastern Poland, assuming natural gas as the fuel. The use of a geothermal heat pump reduced this value to 90.14 kWh/m2. In order to achieve a zero primary energy balance, 23.76 m2 of PV panels and 4 m2 of solar thermal collectors should be installed. In addition, the influence of the overhangs and the glazing area on the heat gain from the solar radiation was analyzed. A drop in temperature inside the house in the event of a continuous power failure was also investigated.

Design and performance predictions of plus energy neighbourhoods – Case studies of demonstration projects in four different European climates

The article presents the design of four plus energy neighbourhood demonstration projects located in different climate zones in Europe. The demo projects are a part of the Horizon 2020 project ‘syn.ikia’, which aims to enable the development of sustainable plus energy neighbourhoods in different climates and contexts. In this article, we describe the active and passive building strategies and analyse the robustness of the designs with respect to different scenarios of climate change, user behaviour, and energy flexibility. Analyses were performed based on the primary energy balance, including space heating and cooling, ventilation, domestic hot water, and lighting.The performance predictions indicate that all demonstration projects may attain the plus energy balance according to the syn.ikia definition. This was achieved with high performing envelopes, efficient HVAC systems, and onsite renewable energy systems to cover the energy demand. The analysis shows that there is a significant potential for increased self-consumption of photovoltaic energy by adjusting the heating schedules and including electric vehicle charging. Testing of the designs with respect to varying climates and user-behaviours showed that there could be an increased risk of overheating, and that some of the designs may not achieve the positive energy balance in case of ‘worst case’ user behaviour scenarios.

Hydrothermal carbonization of the wet fraction from mixed municipal solid waste: Hydrochar characteristics and energy balance

Mixed municipal solid waste (MSW) may be pre-treated in a mechanical–biological treatment (MBT) plant to produce an exiting stream with improved combustible characteristics. The process also produces a second waste stream, which is generally separated on a size basis by industrial sieving equipment. It contains fractions with a high moisture content such as residual food waste, soiled paper and cardboard, and small fragments of other materials. Samples of this stream, collected at an existing plant, were characterized and processed by hydrothermal carbonization (HTC) at laboratory scale, at various temperatures (180, 200 and 220 °C), reaction times (1, 4 and 8 h) and solid to water ratios (0.15 and 0.07). The primary energy balance, on a hypothetical industrial scale, was performed. In brief, the results confirmed that the produced hydrochar was a brittle, hydrophobic, solid carbonaceous product which gave a better combustion performance as the residence time of the HTC process was increased. Moreover, the dewaterability of the carbonized waste was greatly improved when compared to raw, wet samples. The results of the primary energy balance confirmed that the energy contained in the produced hydrochar was higher than the energy consumption for the process itself, under all the HTC working conditions. The energy consumed in the process was in the range of 40–70 % of the energy content of the produced hydrochar.

Developing vietnam's oil and gas industry in association with energy and economic security in the international integration period

Oil and gas is a non-renewable resource that plays an important role in the economy. It is forecasted that by the middle of the twenty-first century, oil and gas still holds the leading position in primary energy balance in many countries. The world energy consumption in 2020 was over 4.1 billion tons of oil and 3,853 billion m3 of gas [1].
 During 60 years of construction and development, Vietnam's oil and gas industry has made important contributions to the economy, especially helping the country overcome the energy crisis and budget deficit in the 1990s.
 By the end of 2020, the total production amounted to over 424 million tons of oil and condensate, and over 160 billion m3 of gas; at one time even contributing nearly 30% of the State budget and 22 - 25% of the GDP. Especially, the formation of important coastal petroleum industrial zones and oil and gas projects on the continental shelf have contributed to ensuring national sovereignty and national security.
 The demand for oil and gas in the energy balance increases rapidly with the speed of socio-economic development. It is forecasted that in the near future, Vietnam will no longer be self-sufficient in supply and must import completely to meet the country's energy demand. In parallel with proactively implementing urgent technical and technological solutions, Vietnam's oil and gas industry needs mechanisms to increase reserves and maintain oil and gas output, as well as prepare the next steps for transition to energy forms with low greenhouse gas emissions and renewable energy.

Techno-economic analysis of photovoltaic-hydrogen refueling station case study: A transport company Tunis-Tunisia

This paper sheds the light on the future of green hydrogen in Tunisia. So, a detailed economic assessment and evaluation of the Levelized Hydrogen Cost (LHC) and the Net Profit (NP) of a Photovoltaic (PV) Hydrogen Refueling Station (HRS) are presented and discussed. Tunisia is characterized by its high PV potential which makes the production of electricity from solar energy an effective alternative source. However, due to the regulations and issues related to the connection of medium PV scale to the power grid, the energy produced from renewable sources (RS) is still less than 3% of the total produced electricity. On the other hand, the price of hydrocarbon fuels is still increasing. The gap between production and total demand in hydrocarbons has created a deficit in the primary energy balance. Therefore, the production of hydrogen from solar energy for refueling Fuel Cell Vehicles (FCV)s consists of a promising solution to boost the development of the country, reduce hydrocarbon fuels consumption, and protect the environment. The sizing of a small PV-HRS to produce 150 kg of hydrogen per day shows the necessity to install PV systems with a total Direct Current (DC) capacity of 1.89 MWp. The Initial Cost (IC) analysis shows that while the PV system cost represents 48.5% of the total IC, the IC of electrolysers represents 41%. The storage system cost is approximately equal to 3.2% of the total IC. The LHC is equal to 3.32€/kg with a total IC of 2.34 million €.

Primary energy efficiency assessment of a coil heat recovery system within the air handling unit of an operating room

Heat recovery systems installed in Air Handling Units (AHUs) are energy efficient solutions during disparate outdoor-to-indoor temperatures. However, they may be detrimental in terms of a primary energy balance when these temperatures get closer, due to the decrease in the thermal energy recovered compared to the global energy consumption required for their operation. AHUs in surgical areas have certain particularities such as their continuous operation throughout the year, the large airflows supplied and the strict exigencies on the supply air quality, avoiding any cross contamination. This work presents the measurements and analysis performed on a coil heat recovery (run-around) loop system installed in the AHU that serves a mixed-air ventilation operating room in a Hospital Complex. A primary energy balance is studied, including the thermal and electric energy savings achieved, considering the electric energy consumption by the recirculation pump and the additional power requirements of fans due to the pressure drop introduced. The obtained value is then used to predict the thermal energy savings achieved by the heat recovery system. Results are extrapolated to the Typical Meteorological Year to provide an order of magnitude of the primary energy and CO2 emissions saved through the operation of the coil heat recovery system.

Review of Zero Energy Building Concept-Definition and Developments in Latin America: A Framework Definition for Application in Panama

In recent decades, European countries have developed concepts, definitions, and construction technologies for Zero Energy Building (ZEB) that are effective and correspond to their specific climates. Latin American countries are still trying to find adequate solutions which respond to the local climatic, cultural, social, technical, and economic context. As such, this paper aims to establish the basis of the minimum energy efficiency and the renewable threshold for the definition of ZEB in order to better understand the application in Panama, based on assessing the energy regulations implemented in Panama. To achieve this aim, a review concentrated on the concept-definition and implementation adopted by Latin American countries is presented first before the paper converges into defining a framework for application in Panama. Finally, a case-study-based theoretical framework proposing a ZEB definition for Panama is discussed. The results of this study showed a net primary energy balance, of which the range falls into a plus energy building definition, indicating that all of the cases studied could supply their electricity needs using Photovoltaic generation. All dwellings studied have the potential to become a plus energy building, depending on the available roof surface area. Finally, a strengths, weaknesses, opportunities and threats analysis is presented in order to assess and support the introduction of such a ZEB definition and framework.

A Critical Perspective on Positive Energy Districts in Climatically Favoured Regions: An Open-Source Modelling Approach Disclosing Implications and Possibilities

Urban areas have been responsible for the majority of the European Union (EU)-wide primary energy demand and CO2 emissions. To address this issue, the European Union introduced the concept of Positive Energy Districts (PEDs). PEDs are required to have an annual positive primary energy balance. However, if directly addressed in the literature, this energy balance only includes annually fixed primary energy factors and often neglects grid impacts. To bridge this gap, this work proposes a mathematical optimisation approach for PEDs, working towards an open-source model. The model’s main novelty is an hourly primary energy balance constraint. The performed case study on the island La Palma for both an urban and a rural neighbourhood show that the PED concept has a higher net present value (NPV) than solely buying electricity from the grid in all feasible cases. Depending on the space available for PV installations, the NPV increases between 29 and 31% and 25–27% for the rural and urban PED scenarios, respectively. However, in the scenarios with reduced grid impact, the NPV decreases due to the expensive battery installations. Comparing the significantly fossil-based electricity grid mix of La Palma with the renewable-based one of El Hierro shows that the primary energy-based optimisation has more room for flexibility in the high renewable mix. While the dynamic primary energy balance constraint appears promising for operational optimisation, the allocation of correct primary energy factors is crucial.

Energy model-based benchmarking of the drying process in the stenter machine

Stenter machines are used widely in textile dyeing and printing houses for drying and heat setting of fabric. This is one of the most thermal energy-consuming equipment in the textile process. In this paper, the advanced energy model of the stenter machine is developed using primary mass and energy balance equations for ideal conditions as well as standard operating conditions, accounting for various energy losses to understand energy flow. To find out the scope for reduction in energy consumption, energy benchmarking is very important; compared with it, the appropriate energy consumption of a plant can be checked and changed. Furthermore, to eliminate problems such as life, process conditions, and quality of dyeing and printing houses considered during the study, unlike statistical energy benchmarking, in this paper, energy model-based benchmarking is proposed and applied for literature problems. Based on the data given in the literature for conveyor belt, stenter 1 and stenter 2, the specific energy consumption (SEC) for cotton is 4889, 3586, and 4304 kJ/kg of water evaporation, respectively, which is lower than the polywool fabric, having 5185 kJ/kg of water evaporation for another stenter machine. The energy efficiency index (EEI) of conveyor belt dryer, stenter 1, and stenter 2 are 1.56,1.18 and 1.34 for cotton, respectively, and for polywool with another stenter it is 1.92, indicating the polywool process is not energy efficient even polywool do not have bound moisture. Further, Energy flow analysis is carried out for the given stenter and fabric drying process, indicating the highest losses are in the exhaust process even after direct heat recovery by partial recirculation of exhaust gases. By analyzing the energy consumption of stenter machines through energy model based benchmarking and energy efficiency index presents the condition of process and machine from an energy perspective, and energy flow model gives the scope of the energy-saving potential. By using the developed model, the effect of change in atmospheric air temperature and humidity ratio due to season and geographic location on the performance of the stenter machine is investigated and found that there is a variation in performance up to 10% of the total energy required.

Primary Energy Balance driven Integrated Energy Design Process of Positive Energy Building

The ISO 52000–1:2017 is the overarching Energy Performance of Buildings (EPB) standard, providing the general framework of the EPB assessment. It is applicable to the assessment of overall energy use of a building, by measurement or calculation, and the calculation of energy performance in terms of primary energy or other energy-related metrics. ISO 52000–1 provides general profound guidelines, but also gives the freedom to adapt the guidelines with national standards and regulations. This article focuses on design stage energy performance assessment in the framework of syn.ikia project, which aims to deliver a blueprint for an Integrated Design Process of sustainable plus energy buildings and neighbourhoods, leading the way to plus energy districts and cities. This project has four demonstration sites and the one being in focus of this article is located in Catalonia, Spain. Even though this project and Spanish Technical code both are based on ISO 52000–1, the criteria of calculation boundaries of those two vary in some degree, and that can cause great difference in the primary energy balance. In the calculation of the energy balance the criteria of syn.ikia considers all common energy uses in a building, including heating, cooling, ventilation, dehumidification, domestic hot water and lighting, while the Spanish Technical Code excludes lighting consumption. The main difference however is caused due to the fact that in syn.ikia hypothesis the exported energy is being considered in the calculation of how much non-renewable energy is avoided from the grid, while Spanish Technical Code excludes it. For the evaluation of these differences, a simplified monthly primary energy calculation tool is developed during the evaluation framework of key performance indicators of the project. The analysis of the calculation framework hypothesis is presented, analyzing the effects of the assessment boundaries, different primary energy balance calculation hypothesis and building design alternatives.

Glyphosate-Based Herbicide Toxicophenomics in Marine Diatoms: Impacts on Primary Production and Physiological Fitness

Glyphosate is the main active component of the commercial formulation Roundup®, the most widely used chemical herbicide worldwide. However, its potential high toxicity to the environment and throughout trophic webs has come under increasing scrutiny. The present study aims to investigate the application of bio-optical techniques and their correlation to physiological and biochemical processes, including primary productivity, oxidative stress, energy balance, and alterations in pigment and lipid composition in Phaeodactylum tricornutum, a representative species of marine diatoms, using the case study of its response to the herbicide glyphosate-based Roundup® formulation, at environmentally relevant concentrations. Cultures were exposed to the herbicide formulation representing effective glyphosate concentrations of 0, 10, 50, 100, 250, and 500 μg L−1. Results showed that high concentrations decreased cell density; furthermore, the inhibition of photosynthetic activity was not only caused by the impairment of electron transport in the thylakoids, but also by a decrease of antioxidant capacity and increased lipid peroxidation. Nevertheless, concentrations of one of the plastidial marker fatty acids had a positive correlation with the highest concentration as well as an increase in total protein. Cell energy allocation also increased with concentration, relative to control and the lowest concentration, although culture growth was inhibited. Pigment composition and fatty acid profiles proved to be efficient biomarkers for the highest glyphosate-based herbicide concentrations, while bio-optical data separated controls from intermediate concentrations and high concentrations.

ДИНАМІКА СПОЖИВАННЯ ПЕРВИННИХ ЕНЕРГЕТИЧНИХ РЕСУРСІВ ТА ВИКИДІВ ВУДИНАМІКА СПОЖИВАННЯ ПЕРВИННИХ ЕНЕРГЕТИЧНИХ РЕСУРСІВ ТА ВИКИДІВ ВУГЛЕКИСЛОГО ГАЗУ В СВІТІГЛЕКИСЛОГО ГАЗУ В СВІТІ

Research and analysis of the dynamics of actual consumption of primary energy resources, their structure and production volumes from own resources and reserves in the world from 2007 to 2018 are presented. In 2018 84.6% of global PER consumption is hydrocarbons, including 57.4% oil and gas, and approximately the same ratio of hydrocarbon consumption has remained over the past eleven years. Similar studies and analysis have been carried out for Europe and for individual countries: 1) which produce the largest GDP (USA, China and Japan); 2) ensure the volume of PER consumption by extraction from its own resources (the USA, excluding oil); 3) do not provide the volume of PER consumption by extraction from own resources (Japan, Europe, India and China) and 4) have a different economic structure. Studies of the dynamics of CO2 emissions in these countries and the world, in general, over the period 2007-2018. It is shown that the high rate of increase in the use of renewable energy sources does not compensate for the increase in CO2 emissions, and this problem becomes relevant, especially for the energy production sector. Keywords: primary energy resources, fuel and energy balance, oil, natural gas, coal, consumption, extraction from own resources, renewable energy sources, emissions, carbon dioxide

Model-Assisted Bird Monitoring Based on Remotely Sensed Ecosystem Functioning and Atlas Data

Urgent action needs to be taken to halt global biodiversity crisis. To be effective in the implementation of such action, managers and policy-makers need updated information on the status and trends of biodiversity. Here, we test the ability of remotely sensed ecosystem functioning attributes (EFAs) to predict the distribution of 73 bird species with different life-history traits. We run ensemble species distribution models (SDMs) trained with bird atlas data and 12 EFAs describing different dimensions of carbon cycle and surface energy balance. Our ensemble SDMs—exclusively based on EFAs—hold a high predictive capacity across 71 target species (up to 0.94 and 0.79 of Area Under the ROC curve and true skill statistic (TSS)). Our results showed the life-history traits did not significantly affect SDM performance. Overall, minimum Enhanced Vegetation Index (EVI) and maximum Albedo values (descriptors of primary productivity and energy balance) were the most important predictors across our bird community. Our approach leverages the existing atlas data and provides an alternative method to monitor inter-annual bird habitat dynamics from space in the absence of long-term biodiversity monitoring schemes. This study illustrates the great potential that satellite remote sensing can contribute to the Aichi Biodiversity Targets and to the Essential Biodiversity Variables framework (EBV class “Species distribution”).

Measurements and Simulation Study of Daylight Availability and Its Impact on the Heating, Cooling and Lighting Energy Demand in an Educational Building

This paper deals with the impact of the use of daylight on the overall energy demand for heating, cooling, and lighting in educational buildings. The energy performance of buildings is currently of the utmost importance as current European regulations, starting from 31st December 2020 impose that all new buildings must meet nearly zero-energy building requirements. This paper presents a study of the illuminance distribution in an educational room obtained from measurements and simulation results using two different models. One of the models, integrated with a thermal simulation software, was used to estimate the impact of daylight on the energy demand. The analysis included the use of various window types, lighting control system, reference point location, and daylight calculation model for a sample room in an educational building. Results of the analysis indicate that, due to the high share of lighting demand (reaching up to 78% of the primary energy balance), there is a need to take into account the efficiency of lighting systems during the design process to correctly determine the actual energy balance of a building, increase the quality of the design of lighting systems, as well as to select the optimal parameters of windows.

DynACof: A process-based model to study growth, yield and ecosystem services of coffee agroforestry systems

The DynACof model was designed to model coffee agroforestry systems and study the trade-offs to e.g. optimize the system facing climate changes. The model simulates net primary productivity (NPP), growth, yield, mortality, energy and water balance of coffee agroforestry systems according to shade tree species and management. Several plot-scale ecosystem services are simulated by the model, such as production, canopy cooling effect, or potential C sequestration. DynACof uses metamodels derived from a detailed 3D process-based model (MAESPA) to account for complex spatial effects, while running fast. It also includes a coffee flower bud and fruit cohort module to better distribute fruit carbon demand over the year, a key feature to obtain a realistic competition between sinks.The model was parameterized and evaluated using a highly comprehensive database on a coffee agroforestry experimental site in Costa Rica. The fluxes simulated by the model were close to the measurements over a 5-year period (nRMSE = 26.27 for gross primary productivity; 28.22 for actual evapo-transpiration, 53.91 for sensible heat flux and 15.26 for net radiation), and DynACof satisfactorily simulated the yield, NPP, mortality and carbon stock for each coffee organ type over a 35-year rotation.

New town hall in Freiburg (D): concept, performance and energy balance after the first year of monitoring of a large net plus-energy building

The town-hall building (Rathaus im Stühlinger: RIS) of the city of Freiburg (D) has been designed and built with the objective of a plus-energy balance and has been handed over to the city in November 2017. With a net floor area (NFA) of 22.650 m2, it is to date one of the largest designed and built plus-energy building in Europe. The boundaries considered in the annual energy balance are limited to the loads of the heating, ventilation and cooling systems (HVAC), of the domestic hot water (DHW) and of the lighting; user-dependent energy demands are not considered. To achieve a positive primary energy balance, the building envelope is highly insulated, the energy supply is based on a low-exergy concept and onsite energy is generated by a large Building Integrated Photovoltaic (BIPV) plant combined with photovoltaic-thermal combined collectors (PVT). The central component of the heat generation is a ground-water coupled heat pump system supplying thermal activated concrete slabs, heating ceilings and air handling units (AHUs). Cooling is ensured over the geothermal well. To the date of this publication, the building has been intensively monitored for one-and-a-half year. Here, we present the energy concept as well as the results of the first monitoring period and provide an assessment of the energy balance in comparison to the plus-energy objective as well as an initial analysis of the load curves and of the heating and cooling systems.

Towards the nearly zero and the plus energy building: Primary energy balances and economic evaluations

In the construction sector, responsible for the greatest amounts of energy consumption and greenhouse gas emissions, nowadays a significant turning point in the current scenario that qualifies building approach is taking place. In recent years, the ambitious nZEB (nearly Zero Energy Building), a building with very high energy performance, in which energy saving, cost-optimal vision and user well-being are assessed in a comprehensive way, has found legislative and operational implementation. Moreover, the adoption of increasingly challenging energy targets today offers important opportunities for the energy requalification and improvement of the overall quality of the building stock, particularly in the field of renewable plants.Within this frame in the paper, as a contribution to the analysis of benefits deriving from the use of RES (Renewable Energy Sources) plants in buildings, in terms of primary energy, cost, and greenhouse gas emissions, an intervention aimed at the satisfaction of the electric demand of a residential building through a photovoltaic plant, in different configurations (grid connected, stand-alone and storage on grid) has been analysed. For each configuration, balances between energy rates (production, load, grid exchange and/or battery store/withdrawal) have been hourly assessed in order to evaluate the Net Present Cost at the end of plant life.Moreover, a yearly primary energy balance has been determined, taking into account also thermal energy required to guarantee thermal needs (provided by a methane boiler), together with produced CO2 emissions.

Effects of end-of-life management options for materials on primary energy and greenhouse gas balances of building systems

In this study we have analysed the life cycle primary energy and greenhouse gas (GHG) balances of concrete-frame and timber-frame multi-storey building alternatives, designed to meet the current Swedish building code, considering different end-of-life scenarios. The scenarios include recycling of concrete and steel, cascading by recycling of wood into particle board and energy recovery at the end-of-life of the board, energy recovery of wood by combustion, and landfilling of wood with and without landfill gas (LFG) recovery. The energy recovered is assumed to replace fossil coal or gas. Our analysis accounts for energy and GHG flows in the production and end-of-life phases. We estimate the GHG emission changes achieved per unit of difference in finished wood in buildings or in harvest forest biomass between the timber buildings and the concrete building. The results show that the timber building systems give significantly lower life cycle primary energy balances than the concrete building system for all the end-of-life options. The concrete building system gives higher life cycle GHG balances than the timber alternatives for all the end-of-life options, except when wood is landfill without LFG recovery. The end-of-life primary energy and GHG benefit of wood materials is most significant for energy recovery while the benefit of cascading is low. However, replacing fossil gas instead of fossil coal significantly reduce the carbon benefits of the timber alternatives. The benefits of recycling steel and concrete are small. This study shows that end-of-life options for building materials can offer opportunities to reduce energy use and GHG emissions in the built environment.