Life cycle primary energy use and carbon emission of an eight-storey wood-framed apartment building

In this study the life cycle primary energy use and carbon dioxide (CO₂) emission of an eight-storey wood-framed apartment building are analyzed. All life cycle phases are included, including acquisition and processing of materials, on-site construction, building operation, demolition and materials disposal. The calculated primary energy use includes the entire energy system chains, and carbon flows are tracked including fossil fuel emissions, process emissions, carbon stocks in building materials, and avoided fossil emissions due to biofuel substitution. The results show that building operation uses the largest share of life cycle energy use, becoming increasingly dominant as the life span of the building increases. The type of heating system strongly influences the primary energy use and CO₂ emission; a biomass-based system with cogeneration of district heat and electricity achieves low primary energy use and very low CO₂ emissions. Using biomass residues from the wood products chain to substitute for fossil fuels significantly reduces net CO₂ emission. Excluding household tap water and electricity, a negative life cycle net CO₂ emission can be achieved due to the wood-based construction materials and biomass-based energy supply system. This study shows the importance of using a life cycle perspective when evaluating primary energy and climatic impacts of buildings.     

Urban energy generation: Influence of micro-wind turbine output on electricity consumption in buildings

Small scale wind turbines installed within the built environment is classified as microgeneration technology. Such turbines may soon become a commercial reality in the UK as a result of both advancements in technology and new financial incentives provided by the government. In addition, microgeneration technologies, especially those with appreciable resource, have the potential to reduce built environment related CO₂ emissions coupled with reductions in consumers’ electricity costs. In many cases payback on capital investment is within the lifetime of the device. Micro-wind turbines installed in certain areas in the UK will fit within such criteria. The work presented here addresses modelling of such installations around the UK and presents a methodology to assess the suitability and the economic viability of micro-wind turbines for domestic dwellings. A modelling tool “μ-Wind” has been developed specifically for studying both energy yields and the payback periods for micro-wind turbines. μ-Wind predicts wind turbine performance prior to installation according to specific power curves either defined by turbine manufacturers or the user. Numerical consideration of wind speed data at specific UK sites was used to estimate energy yields and the results are projected to real electricity demand data from monitored dwellings in the UK. The results show that it is possible to predict with a good degree of accuracy the expected financial payback period for a typical domestic dwelling. Furthermore, the paper postulates that micro-wind technology could have the potential to make a significant impact upon domestic electricity generation when located at the windiest sites in the UK. The likelihood of a proliferation of these turbines in the urban or suburban environment is low but at coastal or inland high elevation sites the technology appears to have a promising future.     

Towards a sustainable electricity grid: Market and policy for demand-side storage and wind resources

While the net benefit of installing Distributed Energy Resources (DER) is largely locational, this work examines the system value in adding wind turbines and battery storage to a Northern Irish electricity distribution network. The DER – turbines and storage – were deployed in modules: first, for increased self-consumption of wind energy and secondly, for additional services. The results suggest that, given the current market structure, deploying the DER solely for increased self-consumption, while technically achievable, is not economically feasible. The upgrading approaches profitability and sustainability as the storage is deployed for stacked market services – and could be achieved through suitable market policies.     

Micro wind turbines in the UK domestic sector

The micro-scale wind turbine industry is expanding in the UK with institutional support and UK legislation encouraging the development of numerous companies with a profusion of design options. The application of micro wind turbines in urban environment is encouraged in the UK via a grant scheme which provides a proportion of the initial capital costs. This development is predicated on the assumption that micro wind turbines have the potential to reduce built environment CO₂ emissions. Current methods of estimating the wind speed are reported to over predict by approximately 2.0 m/s. The energy yields of a range of typical micro wind turbines (in the 0.4–2.5 kW size range) were estimated here using two wind speed datasets sited within 1 km of each other recorded with a temporal precision of 10 min. The annual energy yield of a 1.5 kW turbine was found to be 277 kWh and 2541 kWh for the two sites analysed indicating the problem with the current method of yield estimation. Between 33 and 55% of the electricity generated would be exported dependant on the dwelling's electrical demand. For the high yield site, the simple economic payback of this turbine was found to be 26.8 years i.e. beyond the likely life time of the turbine with CO₂ savings of 1093 kg CO₂. The research suggests that this technology does represent a possible route for reducing CO₂ emissions but this is unlikely to be realised unless an adequate method is found for more accurately predicting energy yield at a specific site.     

The carbon footprint of urban green space—A life cycle approach

Cities play an important role in the global carbon cycle. They produce a large proportion of CO₂ emissions, but they also sequester and store carbon in urban forests and green space. However, sequestration by urban green space is difficult to quantify and also involves emissions. The carbon footprint analysis is an established method for systematically quantifying carbon sinks and sources throughout the lifetime of goods and services. We applied this method to an urban green space project in Leipzig, Germany. To the best of our knowledge it is the first application in this field. We simulated carbon sequestration by growing trees and contrasted it with all related carbon sources, from construction and maintenance over the lifetime of 50 years. In addition, we explored alternative design and maintenance scenarios. Total net sequestration was predicted to be between 137 and 162 MgCO₂ ha⁻¹. Park-like design and maintenance is less effective than forest-like design and maintenance. Much uncertainty is linked to tree growth and tree mortality. Increasing annual tree mortality from 0.5 to 4% reduces sequestration by over 70%. In conclusion, urban green space can act as a carbon sink and the design and maintenance have a strong influence on the carbon footprint. The carbon footprint analysis is a valuable tool for estimating the long-term environmental performance of urban green space projects. Compared to emissions from people, the overall potential for carbon mitigation is limited, even in cities such as Leipzig with widely available space for new urban green space.     

Assessing wind energy potential for electricity generation using WECS in eight selected stations of Ethiopia

Wind utilisation for effective electricity generation has dated since last two decades by means of the modern wind turbines and has proved as a mature, reliable and efficient technology. This paper integrates the wind characteristics and performance of selected wind energy conversion systems (WECSs) from eight selected stations within Tigray region in Ethiopia. The wind speed data were collected over a period between 2002 and 2014. Based on the Paci?c Northwest Laboratory (PNL) classification, all the selected stations fall into Class 1. Therefore, these stations may be advised for small-scale power applications. Furthermore, the highest annual energy output achieved was 3902.31?MWh using VESTAS V110 – 2.0 at Mekele.     

Transport,Housing and Urban Form: The Life Cycle Energy Consumption and Emissions of City Centre Apartments Compared with Suburban Dwellings

Buildings in cities and the activities carried out therein use a significant proportion of a nation's energy consumption and produce substantial quantities of greenhouse gases in the process. Residential buildings are a large contributor, partially as a result of the transport and housing activities of households. In this study, life cycle analysis is used to calculate the total transport and housing energy and emissions from a sample of 41 households in apartment buildings in the city centre of Adelaide, Australia and compare them with suburban households. The purpose of this is to determine whether the urban density option of higher rise dwellings offers a lower environmental impact than conventional housing. The analysis includes delivered energy and greenhouse gas emissions generated by motorised travel and activities within the dwellings, and the energy and emissions embodied in household motor vehicles and the apartment buildings. The total delivered energy consumption of apartment households was found to be lower than suburban households due mainly to higher car usage, particularly in the outer suburbs. However, the analysis of total greenhouse gas emissions provided a somewhat different comparison especially when they were considered on a per capita basis. The total per capita emissions for apartment households varied considerably but, on average, exceeded those of both the inner and outer suburban households. This resulted from lower occupancy rates and higher emissions arising from higher dwelling operational and embodied energy consumption. Overall, it cannot be assumed that centralised, higher density living will deliver per capita emission reductions for residents, once the combined per capita life cycle emissions from housing and transport have been accounted for. A more vigorous educational, promotional and regulatory approach is required to achieve greater operational and embodied energy efficiency in apartment buildings to fully realise the emissions-reducing potential of such buildings in centralised locations.

     

An environmental assessment of wood and steel reinforced concrete housing construction

Wooden type of housing is ubiquitous in Japan. It is the main structure for housing; however, due to the increase in residential developments, steel reinforced concrete houses are also on the rise. This paper assesses the environmental impacts of these two types of construction. An evaluation of the two types of construction in terms of energy usage and air emissions is done. A comparison of the damage costs due to the generated emissions is also considered. Four types of emissions generated are evaluated, namely carbon emissions (CO₂), nitrogen oxides (NO_x), sulfur oxides (SO_x) and suspended particulate matter (SPM). The life cycle of the two different housing construction types is traced and environmental impacts are determined. External costs are also calculated. Furthermore, different improvement assessment scenarios are simulated to ascertain several emission reduction possibilities. The study looks into the emitted emissions from the housing construction to its final disposal of a typical residential development in Saga, Japan. Results show that much of the environmental impacts from building a house are on the Global Warming Potential due to high carbon emissions. Moreover, the construction phase generated the highest pollutant emissions from nitrogen oxides, sulfur oxides and suspended particulate matter. Steel reinforced concrete (SRC) construction has a higher environmental impact compared to the wooden type of housing construction. A longer design life for a residential house gives a reduction of about 14% in carbon emissions. Using solar energy for the operation phase has gained a reduction of 73% in the total life cycle carbon emissions.     

Methodologies for city-scale assessment of renewable energy generation potential to inform strategic energy infrastructure investment

In support of national and international policies to address climate change, local government actors across Europe and Asia are committed to reducing greenhouse gas emissions. Many recognise the contribution that decentralised renewable electricity production can bring towards reducing emissions whilst also generating revenue. However, these actors are often subject to significant financial pressures, meaning a reliable and compelling business case is needed to justify upfront investment. This article develops a method for rapid comparison of initial project viability for multiple city sites and installation options using data from wind and solar resource prediction techniques. In doing so, detailed resource assessments grounded in academic research are made accessible and useful for city practitioners.Long term average wind speeds are predicted using a logarithmic vertical wind profile. This employs detailed three-dimensional building data to estimate aerodynamic parameters for the complex urban surface. Solar resource is modelled using a Geographical Information System-based methodology. This establishes the location and geometry of roof structures to estimate insolation, whilst accounting for shading effects from other buildings and terrain features. Project viability for potential installations is assessed in terms of the net present value over the lifespan of the technology and associated Feed-in Tariff incentive. Discounted return on investment is also calculated for all sites. The methodology is demonstrated for a case study of 6794 sites owned by Leeds City Council, UK. Results suggest significant potential for small-scale wind and solar power generation across council assets. A number of sites present a persuasive business case for investment, and in all cases, using the generated electricity on site improves financial viability. This indicates that initial installations should be sited at assets with high electricity demands. Overall, the work establishes a methodology that enables large city-level asset holders to make strategic investment decisions across their entire portfolio, which are based on financial assessment of wind and solar generation potential accurate to the individual asset scale. Such tools could facilitate strategic planning within cities and help to ensure that investment in renewable energy is focused at the most viable sites. In addition, the methodology can assist with asset management at the city scale by identifying sites with a higher market value as a result of their potential for renewable energy generation than otherwise might be estimated.     

Energy and exergy analysis of prosumers in hybrid energy grids

Surplus energy can be a recurrent phenomenon in zero-energy buildings (ZEBs) with onsite generation systems, usually resulting in the export of excess electricity. Yet, converting electricity into heat and exporting it could improve the overall energy balance. This study analyses the energy and exergy performance of a Finnish nearly zero-energy building (nZEB) as a heat and electricity prosumer, and proposes alternative energy topologies to improve energy and exergy levels, primary energy demand and CO₂ emissions. The results show that increasing the installed capacity of the photovoltaic systems would lead to zero energy, exergy, emissions and a balance of primary energy. However, by instead using the surplus electricity to drive a heat pump and export heat, the currently installed capacity would lead to a net energy export of over 4000?kWh/a. Thus, energy conversion could significantly enhance the contribution from heat and electricity prosumers to smart energy grids, though not without affecting other criteria. Two management strategies arise: favouring heat export improves the net energy and CO₂ emissions reduction but lessens the net exergy, while favouring electricity export improves the net exergy and primary energy reduction. The findings highlight that energy conversion can enhance nZEB performance and its exchange with hybrid grids.     

Energy and carbon dioxide implications of building construction

This paper investigates the amount of energy required to construct buildings, and the resulting carbon dioxide emissions to the atmosphere from the fossil fuel components of that energy. Energy requirements and carbon dioxide emissions are compared for typical commercial, industrial and residential buildings, using New Zealand as an example. A modest change from concrete and steel to more wood construction could lead to a substantial reduction in energy requirements and carbon dioxide emissions, but the sustainability of such a change has significant forestry implications.     

Life cycle emissions analysis of two nZEB concepts

The net-zero emissions building (nZEB) performance is investigated for building operation (EO) and embodied emissions in materials (EE) for Norway's cold climate. nZEB concepts for new residential and office buildings are conceived in order to understand the balance and implications between operational and embodied emissions over the building's life. The main drivers for the CO₂ equivalent (CO₂e) emissions are revealed for both building concepts through a detailed emissions calculation. The influence of the CO₂e factor for electricity is emphasized and it is shown to have significant impact on the temporal evolution of the overall CO₂e emissions balance. The results show that the criterion for zero emissions in operation is easily reached for both nZEB concepts (independent of the CO₂e factor considered). Embodied emissions are significant compared to operational emissions. It was found that an overall emissions balance including both operational and embodied energy is difficult to reach and would be unobtainable in a scenario of low carbon electricity from the grid. In this particular scenario, the net balance of emissions alone is nonetheless not a sufficient performance indicator for nZEB.     

The dynamic impact of carbon reduction and renewable support policies on the electricity sector

Carbon reduction and renewable energy policies are implemented in Europe to improve the sustainability of the electricity sector while achieving security of supply. We investigate the interactions between these policies using a dynamic investment model. Our analysis indicates that both policies are necessary to achieve a sustainable power sector. However, renewable energy generation significantly affects carbon markets and could lead to very low prices. These would attract investments in carbon intensive technologies, locking the sector into future higher emissions. To contrast this effect, policy makers may introduce a floor price in the carbon market or adjust the emissions quota periodically.     

An assessment of roof space solar gains in a temperate maritime climate

New Zealand has a temperate maritime climate. Despite mild winters compared to nations with continental climates, New Zealand houses have been reported to often be at temperatures below internationally recommended levels. Sources of additional heating are therefore of interest to many New Zealand home occupants. Roof space solar gains have been identified as one possible source of heating. This paper investigates the energy gains available in New Zealand homes from ventilation systems drawing air from the roof cavity. Three New Zealand houses were monitored and a computer-based thermal building simulation developed to quantify the heating and cooling energy that might be transferred by home ventilation systems. The computer model simulating the temperature in the roof space and occupied spaces was constructed using MATLAB, and used publicly available weather station data as the inputs. A good match between measured and modelled results was obtained. Small heating and cooling benefits are possible at certain times from pumping roof space air into the living areas of some New Zealand houses. The magnitude of these benefits, however, is not significant compared with the space heating required to maintain reasonable indoor temperatures over the New Zealand winter.     

城市中风力发电与建筑一体化设计

随着全球城市化程度的日益提高,城市所需能源急剧加大,当下对城市中风能利用的研究和应用具有重要的现实意义。通过介绍城市中风力发电与建筑一体化的设计方法,分析风力发电与建筑一体化设计的特点和存在的问题,提出三种一体化设计的方式：风机安装在屋顶上、风机安装在两座建筑物之间和风机安装在建筑物的空洞中。     

Environmental assessment of brick production in Greece

Brick constitutes one of the major materials used for the construction of buildings. The present study analyses the different stages followed during brick production and the materials and energy used in each stage. The purpose is to identify ‘hot-spots’, i.e. parts of the life cycle that are important to the total environmental impact. The analysis is performed using life cycle assessment (LCA) methodology, which is a method used to identify and quantify the environmental performance of a process or a product from “cradle to grave”. LCA methodology provides a quantitative basis for assessing potential improvements in environmental performance of a system throughout the life cycle. The system investigated includes raw material acquisition, industrial production, packaging and transportation. Energy use and emissions are quantified and the potential environmental effects are assessed. The main energy inputs to the production system are electricity, diesel and solid fuel (Pet-Coke). The environmental burdens that arise from the operation of a brick industry are mainly due to air emissions derived from fossil fuel utilization.     

Likelihood of wind energy assisted hydrogen production in three selected stations of Fiji Islands

ABSTRACT

Majority of the people have been paid attention towards renewable and clean sources of energy like wind. Due to the uncertainties related to wind turbines, issues of energy storage are noteworthy. One of the aptest methods of energy storage is the production of hydrogen from the wind. The main aim of this paper is to investigate the potential of wind energy assisted hydrogen production in three selected stations of Fiji Islands using various wind turbines. From the analysis of results and discussion, Vestas V110-2.0 provides acceptable capacity factors among all inspected wind turbines with the highest value of 77.06% for the station at Labasa. Additionally, the highest energy production was from the Vestas V110-2.0 wind turbine with an annual production of 13,501,620?kWh. The conversion system used in this study resulted in a linear relationship between generated wind energy and the amount of hydrogen produced. Therefore, the highest amount of yearly hydrogen production (240.19 ton-H) is related to the largest examined wind turbine, installed in the station at Labasa.     

An Analysis of Energy Consumption in an Adelaide Suburb with Different Retrofitting and Redevelopment Scenarios

Improving energy efficiency of the existing dwelling stock of towns and cities will increasingly be part of the effort to moderate fossil fuel energy consumption in the decades to come. At the same time, residential areas may be subject to densification to better utilise the existing urban infrastructure whilst accommodating a larger population. The analysis of energy consumption arising from these trends offers the potential for optimising built forms and assisting in development decisions for urban renewal to encourage lower energy outcomes. This article describes the application of a model which uses a life cycle approach to the analysis of energy consumption in a residential suburb. The results indicate that the inclusion of embodied energy expended during redevelopment can be substantial and should be considered when modelling future energy consumption scenarios.

     

Clean-energy policies and electricity sector carbon emissions in the U.S. states

State governments in the United States have enacted various clean-energy policies to decarbonize electric utilities, diversify energy supplies, and stimulate economic development. With a panel data set for 48 continental states from 1990 to 2008, fixed-effect panel regressions are estimated to test the impacts of clean-energy policies on total carbon emissions, electricity consumption, and carbon intensity. The results indicate that supply-side policy tools, such as RPS and EERS, are negatively correlated with carbon intensity in the electricity sector. More aggressive policies are needed to reduce total carbon emissions.     

Environmental impact of building-related and user-related energy consumption in dwellings

Energy consumption in dwellings contributes significantly to their total negative environmental impact. This paper quantitatively assesses the environmental impact of building-related and user-related gas and electricity consumption in a Dutch apartment dwelling using life cycle assessment (LCA) methodology. Several scenarios for gas and electricity consumption are compared to assess what effect changes in building characteristics and user behaviour have on the environmental impacts of energy consumption. This study shows that gas consumption significantly contributes to four environmental impact categories, which can be most effectively countered by reducing the heat demand of the dwelling. A 23% reduction in gas consumption leads to up to 13% less overall environmental impacts. Particularly in buildings with low heat demand, electricity consumption dominates all environmental impact categories. These can most effectively be reduced by changing the electricity demand of the user: 47% less electricity consumption leads to a 9–45% reduction in the total environmental impact. However, since electricity consumption continues to rise, the environmental effects of electricity use may be better reduced by changing the environmental impact of the electricity supply. Theoretically, when electricity consumption remains the same, over 90% less environmental impact could be reached by using 100% wind power to generate electricity.