Decision-support method for profitable residential energy retrofitting based on energy-related occupant behaviour

Low-carbon energy retrofitting in buildings plays an important role because 75% of European buildings are considered inefficient and more than 40% are currently over 50 years old. The economic reinvestment of energy retrofit actions through reduced energy bills, as energy directives promote, greatly depends upon the energy consumption patterns. In support of the decision-making process towards a low-carbon energy transition in multi-family buildings, this paper introduces a novel assessment method that evaluates the profitability of energy efficiency measures, according to standard operating conditions derived from energy performance certificate procedures and real occupant energy consumption scenarios, through a parametric analysis. The aim is to assess the real energy and economic savings of retrofitting actions, depending on different energy-related occupant scenarios, and to enable comparisons with other buildings, providing a valuable model to identify the most feasible and low-carbon energy strategies in residential energy retrofitting. A Spanish multi-family building from 1942 is taken as the reference case study. The results show that energy savings for dwellings vary up to 80%, and the net present value per dwelling differs by up to 20,000V between different energy consumption patterns. The most appropriate energy efficiency measures according to low, medium or high consumption scenarios are highlighted

Innovative Use of Hydrogen in Energy Retrofitting of Listed Buildings

Existing buildings represent the major challenge in energy efficiency strategies applied to the building stock. Moreover, architectural and landscaping constraints related to listed buildings are further limitations to possible interventions. When listed buildings are used as museum, achieving the same effectiveness level of typical energy efficiency measures is very difficult and, if possible, very expensive. In order to couple preservation of cultural heritage and CO2 emission reduction, the approach would move to energy supply rather than modifications in building envelope or installation of new HVAC components. So, this study focuses on the opportunity to green NG supply of existing heating systems by means of Power to Gas option at district level. Thus, the recent advancements in Hydrogen enriched Natural Gas produced by RES electricity excess offer a zero-impact strategy to decarbonize the listed buildings using existing energy infrastructures. At the same time, the absence of changes in building features and the introduction of a renewable share in the supply address the sustainability issues of cultural heritage. In conclusion, a first original attempt was made towards the future crucial task of museum's deep energy refurbishment

DECISION-MAKING FRAMEWORK FOR THE SELECTION OF SUSTAINABLE ALTERNATIVES FOR ENERGY-RETROFITS

Buildings are major consumers of energy worldwide. On the other hand, over 60% of the US housing inventory is over 30 years old and a large number of these homes are energy inefficient. Therefore, it is essential to target the existing building stock for energy efficient interventions as a key to substantially reduce the adverse impacts of buildings on the environment and economy. Building energy retrofitting has emerged as a primary strategy for reducing energy use and carbon emissions in existing buildings. An energy retrofit can be defined as a physical or operational change in a building, its energy-consuming equipment, or its occupants\u27 energy-use behavior to convert the building to a lower energy consuming facility. Energy retrofitting could result in additional sustainable benefits such as reducing maintenance costs, reducing air emissions, creating job opportunities, enhancing human health, and improving thermal comfort among others. One of the main challenges in building energy retrofitting is that several combinations of applicable energy consumption reducing measures can be considered to retrofit a building and it is a difficult task to choose the best retrofit strategy. Although numerous resources provide advice on how to retrofit a building, decisions regarding the optimal combination of retrofitting measures for a specific building are typically complex. In addition, most of the decisions for energy retrofits are based on limited cost categories rather than environmental and social considerations. The main goal of this study is to develop a decision support system that integrates sustainable criteria (i.e. economic, environmental, and social benefits) in decision-making in energy retrofits. This goal will achieved through following objectives: (1) Determining the impact of building life-cycle on energy retrofitting decision-making; (2) Identifying and quantifying the sustainable benefits of building energy retrofitting to be used as an objective function in optimization problems; (3) Developing a systematic approach to select among different sustainable decision criteria for energy retrofitting decision-making; and (4) Developing and demonstrating a decision-making optimization model to select the best energy retrofitting alternative for a specific building while maximizing its sustainable benefits. First a life-cycle cost analysis of the case study is presented in terms of energy retrofitting. This life-cycle cost analysis is used to explore the process of decision-making in energy retrofits. Then, a comprehensive study on identifying and quantifying the sustainable benefits of energy retrofits is performed that can be used in decision-making. Different tools such as literature review, surveys, Delphi technique, concept mapping approach, hedonic price modeling, and statistical analysis are used in this step. After that, a Sustainable Energy Retrofit (SER) decision support system is proposed. Finally, the application of this decision support system on a case study of a house located in Albuquerque, New Mexico is explored. This research contributes to the body of knowledge by: (1) Integrating sustainable impacts of building energy retrofits (i.e. Economic, Environmental, and social) in decision-making; (2) Proposing a decision matrix that guides decision-makers on how to select the objective function(s) to formulate an optimization problem that results in the selection of the best energy retrofitting strategy, considering the benefits to investors; (3) Introducing a novel simplified energy prediction method by integrating dynamic and static modeling; (4) Measuring the implicit price of energy performance improvements in the US residential housing market; (5) Identifying, categorizing, and mapping the social sustainability criteria of energy improvements in existing buildings; and last but not least (6) Developing a decision-support system for energy retrofitting projects that integrates the above approaches. The energy retrofitting decision-making model developed in this research can be implemented for different types of buildings to help decision-makers select the optimum energy retrofit strategy that not only maximizes monetary benefits, but also maximize environmental and social benefits. The presented research can also help homeowners to plan or evaluate their retrofitting strategies

Energy planning for metropolitan context: potential and perspectives of sustainable energy action plans (seaps) of three italian big cities

Energy retrofitting of existing building stock and new expansion of urban settlements entail a new relationship between consumption and production sites. Especially, new production facilities linked to the renewables boom are not taken into account by the urban governance. Energy planning instruments could be the viable tool to manage the new energy transition focusing on territorial resources. The Sustainable Energy Action Plan is the most common and widespread due to its voluntary nature. The study analysed the SEAPs of three big Italian Cities to assess an integrated framework for planning renewables at the metropolitan scale

Towards an Energy Assessment on an Urban Scale for Retrofitting the Housing Stock in Mediterranean Cities

According to European Directive 2012/27/EU energy retrofitting of the current housing stock is being promoted. However, few studies have been carried out characterizing housing stock energy performance in order to incorporate energy retrofitting in cities in the southern Mediterranean area. The aim of this paper is to propose an energy assessment methodology on urban scale and to apply it to the southern Spanish province of Cadiz. This is followed by the generation of a predictive model for energy assessment in Mediterranean cities which could be further developed and used in the future to estimate overall energy efficiency on an urban scale

Local Energy Efficiency Interventions by the Prioritization of Thermal Zones in an Historical University Building

Architectural constraints are a crucial aspect in energy retrofitting of historic buildings. Usual global interventions are often not allowed since preserving historical values of the building stock is mandatory. In this paper, the authors provide an alternative procedure by identifying the most profitable local interventions in order to maintain the architectural values during the restoration and energy retrofitting operations. So, thermal zones prioritization is the key element considered in this study. Its aim is to analyse which energy efficiency measures could be applied to a listed building, but at certain technological elements rather than a unique choice for the entire building envelope. Thus it will prove that you can work with individual elements of the building without compromising the protection of architectural good. The attention was placed in promoting single measures and improving the quality of the built environment. The case study is an historical building in Rome, currently used for university purposes. The analysis was carried out through a building simulation model so that to assess the building energy performance before and after the selected interventions. The chosen software is TRNSYS. This approach shows how interventions, usually not applicable at the building scale, would be beneficial if applied at local scale such as a single thermal zone or a single technological unit. The authors built a reference scenario and, for each identified thermal zone, tested the energy efficiency improvement in terms of heating demand reduction coming from the hypothesized local intervention

OptEEmAL: Decision-Support Tool for the Design of Energy Retrofitting Projects at District Level

Designing energy retrofitting actions poses an elevated number of problems, as the definition of the baseline, selection of indicators to measure performance, modelling, setting objectives, etc. This is time-consuming and it can result in a number of inaccuracies, leading to inadequate decisions. While these problems are present at building level, they are multiplied at district level, where there are complex interactions to analyse, simulate and improve. OptEEmAL proposes a solution as a decision-support tool for the design of energy retrofitting projects at district level. Based on specific input data (IFC(s), CityGML, etc.), the platform will automatically simulate the baseline scenario and launch an optimisation process where a series of Energy Conservation Measures (ECMs) will be applied to this scenario. Its performance will be evaluated through a holistic set of indicators to obtain the best combination of ECMs that complies with user's objectives. A great reduction in time and higher accuracy in the models are experienced, since they are automatically created and checked. A subjective problem is transformed into a mathematical problem; it simplifies it and ensures a more robust decision-making. This paper will present a case where the platform has been tested.This research work has been partially funded by the European Commission though the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No 680676. All related information to the project is available at https://www.opteemal-project.eu

TRC SANDWICH SOLUTION FOR ENERGY RETROFITTING

Concerning energy improvement of existing façades, a favourable system involves prefabricated multilayer panels, made of internal insulation core and outer textile reinforced concrete layers. It is a convincing alternative to external thermal insulation composite systems (ETICS) and ventilated façades, and it meets all the requirements for façade systems. The main advantage is the possibility to apply the panel using a crane, without any scaffolding. The paper considers two solutions: the former uses expanded polystyrene (EPS) as insulating material; the latter substitutes EPS with an innovative green insulation material made of inorganic diatomite. The paper aims at comparing the solutions in terms of mechanical properties of the components and behaviour of the composite sandwich at lab-scale level. Numerical models, previously calibrated, will be instrumental for the discussion

Two-Stage Multi-Objective Meta-Heuristics for Environmental and Cost-Optimal Energy Refurbishment at District Level

Energy efficiency and environmental performance optimization at the district level are following an upward trend mostly triggered by minimizing the Global Warming Potential (GWP) to 20% by 2020 and 40% by 2030 settled by the European Union (EU) compared with 1990 levels. This paper advances over the state of the art by proposing two novel multi-objective algorithms, named Non-dominated Sorting Genetic Algorithm (NSGA-II) and Multi-Objective Harmony Search (MOHS), aimed at achieving cost-effective energy refurbishment scenarios and allowing at district level the decision-making procedure. This challenge is not trivial since the optimisation process must provide feasible solutions for a simultaneous environmental and economic assessment at district scale taking into consideration highly demanding real-based constraints regarding district and buildings’ specific requirements. Consequently, in this paper, a two-stage optimization methodology is proposed in order to reduce the energy demand and fossil fuel consumption with an affordable investment cost at building level and minimize the total payback time while minimizing the GWP at district level. Aimed at demonstrating the effectiveness of the proposed two-stage multi-objective approaches, this work presents simulation results at two real district case studies in Donostia-San Sebastian (Spain) for which up to a 30% of reduction of GWP at district level is obtained for a Payback Time (PT) of 2–3 years.Part of this work has been developed from results obtained during the H2020 “Optimised Energy Efficient Design Platform for Refurbishment at District Level” (OptEEmAL) project, Grant No. 680676