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Predictive control is the strategy that has the greatest reported benefits when it is implemented in a building energy management system. Predictive control requires low-order models to assess different scenarios and determine which strategy should be implemented to achieve a good compromise between comfort, energy consumption and energy cost. Usually, a deterministic approach is used to create low-order models to estimate the indoor CO 2 concentration using the differential equation of the tracer-gas mass balance. However, the use of stochastic differential equations based on the tracer-gas mass balance is not common. The objective of this paper is to assess the potential of creating predictive models for a specific room using for the first time a stochastic grey-box modelling approach to estimate future CO 2 concentrations. First of all, a set of stochastic differential equations are defined. Then, the model parameters are estimated using a maximum likelihood method. Different models are defined, and tested using a set of statistical methods. The approach used combines physical knowledge and information embedded in the monitored data to identify a suitable parametrization for a simple model that is more accurate than commonly used deterministic approaches. As a consequence, predictive control can be easily implemented in energy management systems. [ABSTRACT FROM AUTHOR]

Lighting systems are usually one of the largest electrical end-uses in underground metro stations. Taking into account that budget restrictions in publicly owned companies hinder energy efficiency retrofit projects that require high initial investments, affordable energy saving strategies are needed. This paper presents a low-cost approach for reducing lighting electricity use in underground stations, without affecting passengers’ comfort or the metro operator’s service. For this purpose, an adaptive lighting strategy of dimming the illuminance levels of artificial light sources has been developed. Dimming controls are based on the occupancy of the station, and the preventive maintenance and cleaning cycles of the luminaires. The stations’ monthly occupancy patterns are defined through the k-means clustering technique. To illustrate its effectiveness, the method was applied to 115 underground stations of the Barcelona metro network. The results revealed overall electricity savings of 255.47 MW h on a biannual basis, which represents 36.22% of the stations’ baseline lighting consumption. Individual energy savings were found to range from 25 to 87.5 MW h/year in the stations of the Barcelona metro network, depending on the number and profile of station users. The research findings will undoubtedly be useful for the future energy efficiency project plans of worldwide metro operators and managers of other underground spaces. [ABSTRACT FROM AUTHOR]

Several previous research initiatives have highlighted the role of Information and Communication Technologies (ICT) as key enablers for decreasing energy usage in buildings. However, few advances have been achieved in underground public spaces. This paper introduces a novel intelligent energy management system for underground stations. The system implements artificial intelligence solutions for autonomous building system control, based on advanced control algorithms that can learn from previous operations and situations. The robustness needed to operate in public spaces is achieved through a seamlessly integrated monitoring grid with self-diagnosis mechanisms. A middleware platform integrates existing devices, subsystems and newly deployed sensor-actuator networks. Results obtained during the implementation of the system in a prototype underground station showed potential yearly energy savings ranging between 74,336 and 87,339 kW h. The highest energy savings potential was found in the ventilation subsystem (30.6% ± 2.0%), followed by the lighting system (24.1% ± 1.9%) and escalators (8.5% ± 1.9%). [ABSTRACT FROM AUTHOR]

Although energy management systems are expected to result in decreased energy consumption, it is important not to overlook the energy used until commissioning (including raw materials acquisition, manufacturing and transportation) and during the usage phase (including operation and maintenance). This paper examines the energy performance of an intelligent energy management system for underground metro stations. The results show that the energy management system has high energy performance in terms of energy payback time and energy return factor, due to its low cumulative energy demand and its potential for energy savings. When we assumed that the lifespan of energy management systems may vary between 5 and 10 years, their cumulative energy demand was found to range between 505,316 and 852,493 MJ p eq. In all cases, the operating energy was found to far outweigh the embodied energy (68–81%). The energy management system was implemented in a pilot underground station and was found to provide an energy saving of 13.2±1.1% of the total energy consumption of the pilot station. The energy payback time of the energy management system for underground stations was found to range between 40 and 55 days. Consequently, the system pays back between 33 and 91 times the energy invested in it. The results of this research provide valuable information for stakeholders in the energy management systems industry, as they contribute to ascertaining the sustainability of products. [ABSTRACT FROM AUTHOR]

Energy performance certificate databases are a key tool for mapping national building stock and thus fostering greater overall energy efficiency. This paper presents an insight into the energy performance of residential and tertiary sector buildings in Spain, through an analysis of the first 129,635 energy performance certificates issued for existing buildings, collected by the Catalan Institute of Energy. Most of the residential buildings or building units that were studied were “E” class (53.6%). Single-family houses were found to use more energy on average (248.0 kWh p /m 2 ) than individual dwellings (183.2 kWh p /m 2 ). Tertiary sector buildings were found to have slightly better energy performance (26.4% of buildings were rated “D class”), with an average energy consumption of 317.8 kWh p /m 2 . Modern buildings consume less energy, as they must meet the higher energy performance requirements stated in thermal building regulations. Residential buildings or building units located in hotter climate zones consume slightly less energy than those located in colder zones, mainly because heating accounts for a high percentage of overall energy expenditure (70–75% in residential buildings). A significant proportion of the energy consumed in tertiary sector buildings is for lighting (37.2%). This research defines the current energy consumption baseline of existing buildings in Spain. The results can help to prioritize energy conservation efforts according to building type, construction period, climate zone and specific end-uses. They may also help public authorities to plan future energy policies, and construction practitioners to identify market segments and business strategies. [ABSTRACT FROM AUTHOR]

This paper presents for the first time the results of a life cycle assessment study for an intelligent energy management system. We considered material acquisition, manufacturing, transportation, assembly, operation and maintenance stages. The results show that the assembly phase had an environmental impact of 897 Eco-indicator 99 points that was mainly due to the monitoring subsystem (87.80%). When the analysis was extended to cover the use phase, the environmental impact ranged from 1963 (useful life of 5 years) to 3029 Eco-indicator 99 points (useful life of 10 years). The environmental impact of the use stage was found to represent 54–70% of the total, whereas the assembly stage represented 46–30%. The maintenance phase contributed to a very small extent to the total environmental impact (less than 0.5%). In any case, the impact on resources was the largest (about 51%), whereas the human health damage category amounted to approximately 35% and the ecosystem quality damage category represented about 14% of the total impact. [ABSTRACT FROM AUTHOR]

Abstract: The research findings fill a gap in the body of knowledge by presenting an effective way to evaluate the significance of on-site environmental impacts of municipal engineering works prior to the construction stage. First, 42 on-site environmental impacts of municipal engineering works were identified by means of a process-oriented approach. Then, 46 indicators and their corresponding significance limits were determined on the basis of a statistical analysis of 25 new-build and remodelling municipal engineering projects. In order to ensure the objectivity of the assessment process, direct and indirect indicators were always based on quantitative data from the municipal engineering project documents. Finally, two case studies were analysed and found to illustrate the practical use of the proposed model. The model highlights the significant environmental impacts of a particular municipal engineering project prior to the construction stage. Consequently, preventive actions can be planned and implemented during on-site activities. The results of the model also allow a comparison of proposed municipal engineering projects and alternatives with respect to the overall on-site environmental impact and the absolute importance of a particular environmental aspect. These findings are useful within the framework of the environmental impact assessment process, as they help to improve the identification and evaluation of on-site environmental aspects of municipal engineering works. The findings may also be of use to construction companies that are willing to implement an environmental management system or simply wish to improve on-site environmental performance in municipal engineering projects. [Copyright &y& Elsevier]

Abstract: The most common challenges and obstacles encountered by construction organizations during the process of implementing and using environmental management systems are related to the inherent peculiarities of the construction sector. Several studies have shown that one of the issues involving the greatest level of uncertainty is the identification and assessment of environmental impacts. In order to improve the identification of the significance of environmental impacts of construction projects and sites, which will lead to greater efficiency and robustness in environmental management systems, this paper extends the systematic approach for identifying and assessing potential adverse environmental impacts at the pre-construction stage presented in Gangolells et al. (2009) by introducing the assessment of the concerns of interested parties. By considering concerns amongst internal and external interested parties, one can assess the significance of environmental impacts taking into account not only the severity of the impacts but also local perceptions and international challenges, thereby ensuring that the determination of the impacts’ significance is appropriate to the particular socioeconomic and biophysical environments surrounding construction sites. In order to quantitatively measure concerns among internal and external interested parties for each of the 37 environmental impacts related to a construction project, we developed corresponding indicators and assessment scales with the help of a panel of experts. A series of χ 2 tests conducted over 76 new-start construction projects clearly revealed that the severity of environmental impacts is not correlated with the concerns of interested parties. The development of a formal quantitative method and the subsequent definition of a threshold make it possible to obtain advance knowledge of the significance – and, therefore, the acceptability – of each potential environmental impact for a particular construction project. A total score for each construction project alternative is also obtained, so the improved methodology provides a consistent basis for comparing construction companies and construction sites. Finally, two case studies are presented in order to demonstrate the benefits of the improved methodology. [Copyright &y& Elsevier]

Abstract: Introduction: Research and practice have demonstrated that decisions made prior to work at construction sites can influence construction worker safety. However, it has also been argued that most architects and design engineers possess neither the knowledge of construction safety nor the knowledge of construction processes necessary to effectively perform Construction Hazards Prevention through Design (CHPtD). Method: This paper introduces a quantitative methodology that supports designers by providing a way to evaluate the safety-related performance of residential construction designs using a risk analysis–based approach. The methodology compares the overall safety risk level of various construction designs and ranks the significance of the various safety risks of each of these designs. The methodology also compares the absolute importance of a particular safety risk in various construction designs. Results: Because the methodology identifies the relevance of each safety risk at a particular site prior to the construction stage, significant risks are highlighted in advance. Thus, a range of measures for mitigating safety risks can then be implemented during on-site construction. Impact on industry: The methodology is specially worthwhile for designers, who can compare construction techniques and systems during the design phase and determine the corresponding level of safety risk without their creative talents being restricted. By using this methodology, construction companies can improve their on-site safety performance. [Copyright &y& Elsevier]

Abstract: This paper introduces a systematic approach for dealing with potential adverse environmental impacts at the pre-construction stage. The proposed methodology serves as an assessment tool for construction projects to measure the environmental performance of their construction activities. It also provides a consistent basis for comparisons and for future eco-labelling and environmental benchmarking among construction companies and construction sites. Within the methodological framework, nine categories of environmental aspects are proposed: atmospheric emissions; water emissions; waste generation; soil alteration; resource consumption; local issues; transport issues; effects on biodiversity; and incidents, accidents and potential emergency situations. The methodology includes 20 performance indicators developed with the help of a panel of experts. In order to avoid a typical shortcoming in environmental assessments methods, these environmental indicators, both direct and indirect, are always based on quantitative data available in the project documents. Significance limits for environmental aspects are also developed based on a statistical analysis of 55 new-start construction projects. Four case studies are provided to illustrate the practical use of the proposed methodology. [Copyright &y& Elsevier]

Elderly people are vulnerable to cold environments, due to aging's impact on the density of nerve fibers. Nevertheless, automatic controls of HVAC systems do not consider the user's real-time thermal sensation and most of algorithms were tested in manikins using climatic chambers or simulated by CFD. Indeed, a standardization of a non-invasive technique as infrared thermography (IRT) for human body responses was not detected in the literature review. This paper proposes a method to determine the indoor thermal comfort of elderly people by IRT. The campaigns took place in a nursing home of the Mediterranean Climate during Winter. A total of 15 old adults were monitored to measure the skin temperature of four face points (nose, forehead, cheekbone and chin) and clothing temperature. A thermal sensation questionnaire and indoor conditions were also collected. The results demonstrated that the IRT model could estimate the thermal exchange from three body-segments (head, back-pelvis, thorax-limbs) to the surroundings by user's features and environmental parameters. The thermal neutrality was achieved when all facial points reached a skin temperature of 35 °C, the clothing temperature was equal to 31 °C, and the operative temperature and relative humidity were 23.5 °C and 54% respectively. Statistically, 31.70% of the variance of PMV could be attributed to increases of facial skin temperature, while changes in user's features could have minor influence (from 0.88 to 6.40%). As regards the main contributions of heat losses, they were given by respiration (11–21%), convection (20–32%) and radiation (35–39%). Finally, an innovative HVAC control strategy was posed. • A IRT method for determining indoor thermal comfort of elderly people is proposed. • Fifteen European older adults were monitored in a nursing home during Winter season. • The human model assessed the thermal exchange from three body-segments to the surroundings. • Thermal neutrality was achieved when all facial points reached 35 °C. • A personalized HVAC control strategy was posed. [ABSTRACT FROM AUTHOR]

• A model to identify energy retrofitting measures for offices stock has been devised. • Real reference offices are identified from energy performance certificate databases. • Life-cycle energy, economic and environmental impacts are assessed. • A user-friendly interface to support decision-makers is designed. The European Green Deal establishes the need to renovate buildings in an energy efficient way, to address climate and environmental challenges. The purpose of this study was to devise a model for identifying environmental, cost-effective retrofitting measures by assessing their energy, economic and environmental impact when they are applied to the entire office stock. The methodology builds upon the energy performance certificate scheme to identify the life-cycle energy, economic and environmental impacts of a set of energy renovation measures for each representative office. The results can then be applied to the entire office stock. For any real office, a dozen characteristics are entered. Then, a user-friendly interface provides information about the expected performance of the renovation measures in that case along with the representativeness of the results. This methodology was implemented in a Spanish case study of 13,701 energy performance certificates. The findings showed that the most efficient energy renovation measures are heat pump replacement (18.1 %) and replacement of lamps with LEDs (14.4 %). Although the most effective retrofitting solutions depended on the evaluation criteria (energy, economic or environmental), 99.5 % of the cost-effective measures also reduced emissions during the life cycle. [ABSTRACT FROM AUTHOR]

• Lessons learnt from the EU-funded EnerGAware research project are presented. • An innovative serious game was developed to promote reduced energy consumption. • The game was deployed and validated in a sample of European social housing. • Best practices for future serious game interventions are outlined. The application of gamification to encourage energy conservation behaviour in house occupants is an emerging field of research. However, empirical evidence of its effectiveness is lacking. This paper presents lessons learnt from the EU-funded EnerGAware research project, in which an innovative serious game (a game designed for purposes other than purely entertainment) was developed to promote reduced energy consumption and carbon emissions by changing social housing tenants' energy efficiency behaviour. The game was validated in a sample of European social housing using a longitudinal, two-stage experimental design, employing both pre-post and control group approaches. While some aspects of the game did not work as intended, there were nevertheless some positive impacts. The intervention increased social housing tenants' awareness and engagement in certain energy saving behaviour and provided an average electricity saving of 3.46% and an average gas saving of 7.48%. Although savings were found not to be statistically significant, an effect size was detected (0.2). Therefore, future steps should exploit all available opportunities to replicate the pilot and increase the sample size so as to gain stronger evidence of the game's impact. Preliminary results support the utility of gaming investment in the household energy efficiency field, and provide useful insights and pathways that could be incorporated into the development of future serious game interventions to foster their effectiveness. [ABSTRACT FROM AUTHOR]

• A replicable methodology for identifying reference buildings is presented. • The k -means clustering method is applied to the energy performance certificate database. • To illustrate the methodology, an EPC database including 13,701 offices is used. • Sixteen clusters and corresponding representative offices are identified. • Representative offices can be used for cost-optimal retrofitting analysis of the entire stock. A large number of buildings must be evaluated to formulate energy retrofitting policies for existing building stock. In this context, it is crucial to identify reference buildings that can effectively represent the entire stock, since such buildings can then be used to assess the individualized cost-effectiveness of retrofitting measures. This paper presents a novel approach for identifying and defining a set of reference buildings by applying the k -means clustering method to energy performance certificate databases. To this end, a four-step methodology has been envisaged. First, an energy performance certificate database is prepared and variables that have an impact on energy consumption are pre-selected. Selected data are then pre-processed. Next, the k -means clustering method is applied. Finally, the resulting cluster centroids are used to identify the closest energy performance certificates in the database, in other words, the representative buildings that will then be used for cost-optimal retrofitting analysis. The methodology is illustrated using the energy performance certificate database managed by the Catalan Institute of Energy (ICAEN), which includes a sample of 13,701 offices. Due to the large number of missing values in the database, the k -means clustering algorithm was finally performed over 6,083 energy performance certificates. Seven representative office blocks and offices in industrial buildings and nine representative offices in residential buildings were identified. The results establish the basis for supporting strategic decision-making for energy saving retrofit interventions in existing Spanish offices. [ABSTRACT FROM AUTHOR]

The urban management industry has recently shown interest in implementing digital twins in cities to improve urban planning, optimize asset management and create secure, sustainable cities. Built on the knowledge gained with the development of smart cities and the implementation of digital twins in other industries, urban digital twins have experienced a significant expansion in just a few years. However, this rapid growth has led to a fragmented situation where the definition of the concept of urban digital twin is not clear and implementations share few similarities. For this reason, the main objective of this paper was to contribute to the conceptualization of the digital twin in urban management. To do so, existing initiatives were mapped in terms of applications, inputs, processing and outputs. Requirements were elicited and the basic structure of a city digital twin was defined. Benefits, open issues and key challenges were also identified. This paper will be useful for stakeholders within the urban management area as it establishes the basis for the future design, development and widespread adoption of urban digital twins. • Existing approaches on urban digital twins have been reviewed. • The present capability to act on the physical twin is limited. • Standardization is needed to achieve interoperability between digital twins. • Benefits, open issues and key challenges are discussed. [ABSTRACT FROM AUTHOR]

The production of mineral resources from quarrying is vital and irreplaceable for providing raw materials for a wide range of economic sectors. Additionally, today's society demands a supply of mineral resources that is as sustainable as possible. This paper presents a comprehensive LCA study comparing two commonly used techniques to extract mineral resources for quarrying, using the cradle-to-gate approach. The global warming potential (GWP) is used as the main indicator, although all the other potential emissions from the extraction process are also calculated. The results obtained reveal that blasting techniques have a lower impact on global warming (−28%) and generate less fuel metal emissions (−75%) than mechanical extraction. However, the emissions of PM2.5, PM10 and TSP are 2–3 times higher. Hence, the most optimal type of quarrying, regarding the environmental constraints, depends on the impacts in each specific case. In all of the scenarios analysed, the ore loading and handling stage is one of the main GWP contributors, while the contributions of the extraction system (e.g., mechanical or drill and blast) and mineral processing vary depending on the extraction technique used and the product analysed (e.g., aggregates or natural stone). The suggested approach can be used as a powerful tool to assess each case and determine the best choice regarding the environmental impacts of the mineral extraction process, as well as to reduce its emissions. [Display omitted] • Comparison between mechanical and drill and blast extraction techniques. • Quarry optimization based on the environmental constraints. • Emission analysis for the production of aggregates and natural stones. [ABSTRACT FROM AUTHOR]

This research contributes to the assessment of on-site fuel consumption and the resulting carbon dioxide emissions due to earthworks-related processes in residential building projects, prior to the start of the construction phase. Several studies have been carried out on this subject, and have demonstrated the considerable environmental impact of earthworks activities in terms of fuel consumption. However, no methods have been proposed to estimate on-site fuel consumption during the planning stage. This paper presents a quantitative method to predict fuel consumption before the construction phase. The calculations were based on information contained in construction project documents and the definition of equipment load factors. Load factors were characterized for the typical equipment that is used in earthworks in residential building projects (excavators, loaders and compactors), taking into considering the type of soil, the type of surface and the duration of use. We also analyzed transport fuel consumption, because of its high impact in terms of pollution. The proposed method was then applied to a case study that illustrated its practical use and benefits. The predictive method can be used as an assessment tool for residential construction projects, to measure the environmental impact in terms of on-site fuel consumption. Consequently, it provides a significant basis for future methods to compare construction projects. [ABSTRACT FROM AUTHOR]

Abstract: Despite the increasing efforts made by the construction sector to reduce the environmental impact of their processes, construction sites are still a major source of pollution and adverse impacts on the environment. This paper aims to improve the understanding of construction-related environmental impacts by identifying on-site causal factors and associated immediate circumstances during construction processes for residential building projects. Based on the literature and focus group findings, we have developed a construction-related Environmental Impact Causal Model consisting of a process-oriented causal network of thirty-nine environmental impacts, forty-five causal factors and over two hundred causal relationships. It is intended to contribute to a reduction in construction-related environmental impacts on building sites by supporting contractors and other decision-makers in the early identification of factors that are likely to lead to impacts or to exacerbate their consequences, as well as the later environmental performance evaluation and control. The causal model is validated by investigating over a hundred environmental incidents. Finally, possible methods to improve construction-related environmental performance are suggested. [Copyright &y& Elsevier]

The measurement of ventilation air change rate is a difficult, expensive task in buildings. Usually, the tracer-gas mass balance equation is used to determine ventilation air change rates. This method uses an ordinary differential equation. Consequently, it cannot deal with disturbances that enter the system, such as the influence of unrecognized and unmodelled inputs or the measurement noise. The use of the stochastic grey-box modelling approach, which is less common in the ventilation field, can help to deal with disturbances that can affect the system. The objective of this paper is to assess the potential of using the stochastic grey-box modelling approach to estimate the ventilation air change rate. The modelling is based on the stochastic differential equation of tracer-gas mass balance. The results show that this approach produces robust estimations to determine the ventilation air change rate of a room. [ABSTRACT FROM AUTHOR]