Search Results (20)

Confronted with the climate emergency, reducing CO₂ emissions has become a priority for all nations of the world because the follow-up of humanity depends on it. Most European Union (EU) member states have pledged to cut their net greenhouse gas emissions by at least 55% by 2030 and reach full carbon neutrality by 2050, using 1990 as the baseline year. Despite this common effort, there is still a lack of effective decision-making on carbon neutrality strategies applied throughout the life cycle of a building in all EU countries. A common strategy is proposed in this study to fill this gap in the literature. The building sector is a real lever for reducing the carbon footprint and saving energy. Currently, the methodology for achieving large-scale carbon neutrality is well established. However, there is only a limited number of experts worldwide who have mastered this technology, making it challenging to develop a standardized approach for all nations. The absence of extensive, regular, and consistent data on carbon emissions has considerably hindered the understanding of the root causes of climate change at both the building and neighborhood levels. Is it not it time to break this barrier? With this in mind, this study was carried out with the intention of proposing a common method to achieve carbon neutrality at the neighborhood scale in European Union countries. The most significant parameters having a direct impact on carbon emissions have facilitated the adaptation of the three types of neighborhood in the different capitals of the EU countries, in particular, local building materials, microclimate, the energy mix of each country, and the mode of daily transport. The life cycle assessment of the three districts was conducted using the Plaides LCAv6.25.3 tool in combination with Meteonorm software version 8.2.0, considering a 100-year lifespan for the buildings. In addition, the cost of the various environmental impacts is assessed based on the monetary indicators for European Committee for Standardization indicators method. The main results showed that the distribution of carbon dioxide is 73.3% higher in urban areas than in sustainable neighborhoods and 39.0% higher in urban districts than in rural districts. Nearly zero emissions in the next decade are again possible by applying the scenario involves global warming combined with the complete (100%) renovation of all buildings and the transition to 100% electric vehicles along with the use of solar panels. This strategy makes it possible to reduce between 90.1% and 99.9% of the emission rate in residential districts regarding EU countries. Full article

This paper explores the development of positive energy communities using Eordaia, Greece, as a case study. The approach combines building and district-level energy analysis to achieve nearly zero energy performance through retrofitting, district-level storage systems, and renewable energy technologies. A parametric analysis utilizing RETSCREEN Expert and EnergyPlan software determines the optimal mix of technologies based on technical and financial parameters, with Eordaia, a region in energy transition and part of the RESPONSE Horizon project, illustrating the practical benefits. It includes a neighborhood of 105 mixed-use properties and two municipal buildings where a range of renewable energy sources and energy efficiency measures are applied. Insulation, photovoltaic systems, LED lighting, predictive thermostats, and windows coated with nanotechnology are some of the key interventions considered. The findings show considerable reductions in CO₂ emissions and energy use, with payback periods ranging from 8.7 to 9.6 years. This study underscores the value of district-level strategies over individual building retrofits, highlighting cost savings and improved energy performance. These findings offer valuable insights for urban planners and policymakers aiming to transform urban areas into sustainable, positive energy districts, supporting the EU’s 2050 net-zero emissions goals. Full article

Nearly zero energy buildings (NZEBs) might play a significant role in addressing current global environmental problems, i.e., greenhouse gas (GHG) emissions. Buildings are one of the main electricity consumers. With current electricity production coming mainly from fossil fuel power plants, buildings contribute indirectly to GHG emissions. This report shows potential energy-saving alternatives (thus reducing the carbon footprints) for an 18-story office building in South Jakarta’s central business district. Four alternatives are considered, namely cooling tower and CWP pump replacement, BAS installation, LED dim light replacement, and solar panel installation. The project that implements all four alternatives indeed produces the biggest emissions savings. However, its net present value (NPV) is negative, which means the project is not economically feasible. Furthermore, any combination of projects involving solar panel installation will produce negative NPVs. The combination of cooling tower and CWP pump replacement, BAS installation, and LED dim light replacement will be the best option, with an NPV of IDR 437,853,822, an energy consumption index (IKE) value of 11.76 (meaning the “efficient” building category) and a carbon emissions reduction of 1172.65 tons of CO₂. Full article

In this study, the performance of different cooling technologies from energy and economic perspectives were evaluated for six different prototype residential Nearly Zero Energy Buildings (NZEBs) within a planned future city district in central Sweden. This was carried out by assessing the primary energy number and life cycle cost analysis (LCCA) for each building model and cooling technology. Projected future climate file representing the 2050s (mid-term future) was employed. Three cooling technologies (district cooling, compression chillers coupled/uncoupled with photovoltaic (PV) systems, and absorption chillers) were evaluated. Based on the results obtained from primary energy number and LCCA, compression chillers with PV systems appeared to be favorable as this technology depicted the least value for primary energy use and LCCA. Compared to compression chillers alone, the primary energy number and the life cycle cost were reduced by 13%, on average. Moreover, the district cooling system was found to be an agreeable choice for buildings with large floor areas from an economic perspective. Apart from these, absorption chillers, utilizing environmentally sustainable district heating, displayed the highest primary energy use and life cycle cost which made them the least favorable choice. However, the reoccurring operational cost from the LCCA was about 60 and 50% of the total life cycle cost for district cooling and absorption chillers, respectively, while this value corresponds to 80% for the compression chillers, showing the high net present value for this technology but sensitive to future electricity prices. Full article

Enhancing contractual construction project documents with sustainability and green building requirements reflects growing concerns for the majority of organizations in hot zone districts. The aim is to provide a healthy, best functional performance, safe environment with occupant comfort, and an efficient building performance as an environmental-friendly building. This research study develops a holistic evaluation system for the façade composite of contractual documents. The aim of the current study was to enhance building energy performance under the sustainability rating system focusing on adapting active envelope energy applications. The research used technical evaluation with energy simulation based PVsyst V7.1.0 software and contractual status evaluation for an ongoing unique case study project in Saudi Arabia. Feasibility analysis was carried out for a sustainable active envelope using the adopted specifications of the Building Integrated Photovoltaics (BIPV) façade item instead of the contractual passive item in the Giftedness and Creativity Center project. The project was registered in the sustainability rating system called Leadership in Energy and Environmental Design (LEED). The results showed that using BIPV facades as an active renewable energy source enhances building energy performance over the project life cycle. Additionally, it generates 68% of energy demand as a nearly-zero energy project. Several other advantages include lower cost than tender cost without any contractual conflicts, energy savings per year, project upgrade to the platinum certificate, added value to the public investment, CO₂ emission reduction, and barrels of oil saved. Full article

Net-zero climate districts are gaining wide attention at the European and international levels. Urban regeneration competitions have been launched recently to stimulate development; nevertheless, the literature does not yet provide a shared scope definition (i.e., product system). Using the process-based life cycle assessment method, the authors evaluate the climate profile of a new district in Milan (14 buildings with 36,000 m² of gross surface area in total) aiming to become the first net-zero social housing project in Italy. The authors show in the results section how climate neutrality is achieved on the part of the real estate operator by varying the scope. The most conservative scenario (including all the emission sources considered in the analysis) indicates that the net-zero climate target is reached only by purchasing voluntary carbon credits. The authors also highlight: (i) a district composed of nearly-zero energy buildings is far from the definition of a net-zero climate emissions district; (ii) a net-zero climate emissions district may not be a positive energy district and vice-versa; and (iii) constraints linked with the lack of space in a densely populated city due to insufficient area to install renewables on site. Full article

The need for efficient buildings to contribute to sustainable development has led to the proposal of goals and regulations in different countries linked to net zero energy objectives, following approaches specific to their regions. Such regulations are not yet developed in a developing country such as Panama. Thus, this study develops the first framework for Zero Energy Districts (ZED) in Panama based on passive and active solutions through dynamic simulation. For this, an existing urbanization area consisting of 34 residential buildings, called the existing case (EC), was studied. After undergoing a design based on the bioclimatic methodology, a redesigned case (RC) is proposed to maintain thermal comfort and reduce energy consumption. Key redesign factors are the buildings’ shape, orientation, glazing, the use of shadows, material of the walls, and the air conditioning configuration. Results showed energy consumption decreases by 37.5% when considering all buildings with natural ventilation, reaching ranges of positive net energy (+356.50 kWh/m²y). In the case of nearly ZED in Panama, the ranges could be considered between 14 and 180 kWh/m²y. This balance indicates that there is potential on site to develop zero energy districts. Full article

Increasing awareness of climate issues in recent decades has led to new policies on buildings’ energy consumption and energy performance. The European Union (EU) directive 2010/31/EC, i.e., the energy performance of buildings directive (EPBD), is one of the measures initiated to achieve climate and energy goals by reducing energy use and greenhouse gas emissions in the building sector. The EPBD required all new buildings to be nearly zero-energy buildings (nZEBs) by 2021. Nearly zero-energy buildings (nZEBs) are buildings with a very-high-energy performance and nearly zero or low-energy requirements covered to a very significant extent by energy from renewable sources produced on-site or nearby. The utilisation of solar photovoltaic (PV) panels is a common approach for achieving the nZEB standard. The carbon footprint of PV panels is often not discussed as a parameter. This paper aimed to analyse the environmental performance of an existing nearly zero-energy university building in a Norwegian use case scenario. This analysis is performed by assessing annual electricity and heat consumption from both energetic and environmental perspectives. The energy required for the building during the studied period is then used to analyse the environmental and energy performance of the building. When it comes to the environmental assessment, the commercial software SimaPro was used. The proposed revision EPBD and nZEB definition from 2021 suggests that nZEBs should also consider operational greenhouse gas emissions and life-cycle global warming potential from 2027. The life cycle assessment (LCA) of the building’s energy sources looks at the global warming potential (GWP) and greenhouse gas (GHG) emissions, and how they compare to Norwegian grid electricity. The results of the analysis highlights potential challenges to justifying the use of alternative energy sources to fulfil the criteria of nZEBs. When installing solar PV, it is important to consider the energy mix of the country where the solar PVs are produced. To solely consider the energy performance of the building, the installation of solar PV panels in countries with a high share of renewable energy may result in a reduced impact in terms of emission reduction from a life cycle perspective. Full article

Nearly Zero Energy Building (NZEB) is becoming a standard for new and renovated buildings throughout the European Union (EU). Through the ongoing implementation of directives related to energy efficiency and NZEB-compliant buildings, the EU commission has established that new and renovated NZEB-compliant buildings shall be implemented cost-effectively. This is assessed by linking the Life Cycle Cost (LCC) and energy demand calculations, representing them in a cost-optimality plot, and finding the optimal solution from the resulting Pareto front. Given that the results of an LCC calculation are quite dependent on the calculation model’s scope and inputs, this study takes an explorative approach to determine the most influential parameters in LCC calculations for a pre-selected cost-effective package. This is achieved by varying the inputs using local and global variation methods. The local variation approach consists of varying the inputs one-at-a-time (OAT), whereas with global variation, all the selected inputs are variated simultaneously. The OAT approach identified the amount and unit cost of the utility supply (district heating, electricity, and gas) as the most influential parameters to the output. The OAT results were further used to rank the next five most sensitive parameters and perform a global sensitivity analysis using Monte Carlo (MC) simulations. A regression analysis of the MC results revealed high R2 values (≥0.98), suggesting a linear correlation between the output and the variable inputs. The sensitivity analysis determined the unit price of attic insulation, the gas price, and the lifetime of the Heat Pump (HP) as the most sensitive parameters in the three investigated models. Full article

The energy industry has been trying to reduce the use of fossil fuels that emit carbon and to proliferate renewable energy as a way to respond to climate change. The attempts to reduce carbon emissions resulting from the process of generating the electric and thermal energy needed by a building were bolstered with the introduction of the concept of nZEB (nearly zero-energy building). In line with such initiatives, the South Korean government made it mandatory for new buildings to have an nZEB certificate as a way to promote the supply of renewable energy. The criteria for Energy Independence Rate, which is one of the nZEB certification criteria in South Korea, is to maintain the share of renewable energy as at least 20% of the primary energy sources for the building. For a new building in South Korea to have an nZEB certificate, it is required to establish an energy plan that would allow the building to meet the Energy Independence requirement. This optimally reflects the cost of installation for renewable energy facilities and the cost of purchasing energy from external sources, such as the national grid or district heating companies. In South Korea, the base retail rate of energy is calculated based on the peak demand per hour over the year, rather than the contracted energy. This has produced difficulties in standardizing the process with a mathematical model; in addition, there have not been many preceding studies that could be used as a reference. In this regard, this paper analyzed a modeling strategy for developing a realistic yet optimized energy plan in consideration of the unique conditions of the retail energy rates of South Korea, and analyzed the impact of the rates based on peak demands upon the total energy plan. In this study, our research team analyzed the electric billing system, conducted a case study, and analyzed the impact of the billing system that is based on the peak demand upon the optimal cost. By utilizing the restrictions for reaching the 20% Energy Independence goal, this paper calculated the proper energy supply facility capacity for renewable energy. Then, the cases in which the maximum demand modeling was used and the cases without one were compared to confirm the cost benefits observable when the suggested model is added or implemented. Full article

Retrofitting existing buildings to be a nearly zero energy building (nZEB) is an effective solution for greenhouse gas emissions and primary energy consumption reduction. A hybrid approach that integrates the building energy simulation method and orthogonal array testing (OAT) to renovate buildings to nZEB is proposed in this paper. Within a residential building in Changchun, Jilin of China, the total energy consumption index (TECI) and CO₂ emission factor for heating are used as evaluation criteria. The reliability of the building energy model is validated and adopted to forecast the energy performance of different building renovation strategies. According to OAT, four passive measures can be ranked by their influence on TECI in descending order as follows: external wall heat transfer coefficient, airtightness, window heat transfer coefficient, and roof heat transfer coefficient. The optimal renovation solution of the studied building can reduce the TECI by 43.18% by only reducing the external wall heat transfer coefficient from 0.5 to 0.2 W/m²·K and the infiltration N₅₀ from 3.6 to 0.4 ac/h. Besides, combined heat and power (CHP) utilities emit less CO₂ than heat pumps in providing heating under the current CO₂ emission factor of the power grid in China, making it impossible to give up district heating systems until carbon emissions of electricity generation have declined significantly. The results can provide a reference for the application of the nZEB standard in actual retrofitting projects. Full article

Nearly-zero energy buildings are now a standard for new constructions. However, the real challenge for a decarbonized society relies in the renovation of the existing building stock, selecting energy efficiency measures considering not only the energy performance but also the economic and sustainability ones. Even if the literature is full of examples coupling building energy simulation with multi-objective optimization for the identification of the best measures, the adoption of such approaches is still limited for district and urban scale simulation, often because of lack of complete data inputs and high computational requirements. In this research, a new methodology is proposed, combining the detailed geometric characterization of urban simulation tools with the simplification provided by “building archetype” modeling, in order to ensure the development of robust models for the multi-objective optimization of retrofit interventions at district scale. Using CitySim as an urban scale energy modeling tool, a residential district built in the 1990s in Bolzano, Italy, was studied. Different sets of renovation measures for the building envelope and three objectives —i.e., energy, economic and sustainability performances, were compared. Despite energy savings from 29 to 46%, energy efficiency measures applied just to the building envelope were found insufficient to meet the carbon neutrality goals without interventions to the system, in particular considering mechanical ventilation with heat recovery. Furthermore, public subsidization has been revealed to be necessary, since none of the proposed measures is able to pay back the initial investment for this case study. Full article

The main purpose of this paper is to investigate the contributions of building-integrated photovoltaic (BIPV) systems to the notion of nearly zero-energy cities in the capitals of the European Union member states (EU), Norway, and Switzerland. Moreover, an in-depth investigation of the barriers and challenges ahead of the widespread rollout of BIPV technology is undertaken. This study investigates the scalability of the nearly zero-energy concept using BIPV technology in moving from individual buildings to entire cities. This study provide a metric for architects and urban planners that can be used to assess how much of the energy consumed by buildings in Europe could be supplied by BIPV systems when installed as building envelope materials on the outer skins of buildings. The results illustrate that by 2030, when buildings in the EU become more energy-efficient and the efficiency of BIPV systems will have improved considerably, BIPV envelope materials will be a reasonable option for building skins and will help in achieving nearly zero-energy cities. This study reveals that in the EU, taking a building skin to building net surface area ratio of 0.78 and a building skin glazing ratio of 30%, buildings could cover their electricity consumption using BIPV systems by 2030. Eighteen challenges and barriers to the extensive rollout of BIPV systems are recognised, classified, and discussed in this study in detail. The challenges are categorised into five stages, namely the decision, design, implementation, operation and maintenance, and end of life challenges. Full article

This paper presents a novel evaluation framework to assess the effectiveness of city transformation projects related to energy efficiency and sustainable mobility actions. The evaluation framework is part of an Urban Regeneration Model designed to accelerate the urban transformation toward the smart city concept, taking into account all aspects of sustainability. This model has been developed and validated in the three EU cities (Valladolid, Spain; Nottingham, United Kingdom; and Tepebaşı, Turkey) where interventions in the energy, mobility, and ICT fields have been deployed. This model relies on an Evaluation Framework to support its main phases considering two levels of evaluation: city level, to assess globally the smartness and sustainability of the city, and project level, to support the decision-making and assess the impacts of specific implementations. This paper is focused on the second level and its application through the evaluation-supporting tool STILE in the assessment of the energy efficiency and sustainable urban mobility actions implemented in the city of Valladolid. The assessment analysis has allowed assessing how the energy efficiency interventions carried out in the Valladolid district have reduced the energy consumption, increased the use of renewable energies, and reduced the CO₂ emissions. In addition, it has allowed evaluating other aspects such as the air quality, thermal comfort, and energy bill, which have been also improved for the residents. Considering the analysis of the sustainable mobility interventions, the evaluation framework supports the assessment of the reduction of emissions and air pollutants and how the actions have converted electro-mobility into a real option for citizens. The evaluation of results after the implementation of this kind of actions is key to ensuring that successful actions can be replicated in other places achieving smarter and more sustainable cities. Full article

Without decarbonizing cities energy and climate objectives cannot be achieved as cities account for approximately two thirds of energy consumption and emissions. This goal of decarbonizing cities has to be facilitated by promoting net-zero/positive energy buildings and districts and replicating them, driving cities towards sustainability goals. Many projects in smart cities demonstrate novel and groundbreaking low-carbon solutions in demonstration and lighthouse projects. However, as the historical, geographic, political, social and economic context of urban areas vary greatly, it is not always easy to repeat the solution in another city or even district. It is therefore important to look for the opportunities to scale up or repeat successful pilots. The purpose of this paper is to explore common trends in technologies and replication strategies for positive energy buildings or districts in smart city projects, based on the practical experience from a case study in Leipzig—one of the lighthouse cities in the project SPARCS. One of the key findings the paper has proven is the necessity of a profound replication modelling to deepen the understanding of upscaling processes. Three models analyzed in this article are able to provide a multidimensional representation of the solution to be replicated. Full article