Retrofit Actions Research Articles

Energy Retrofitting Strategies and Economic Assessments: The Case Study of a Residential Complex Using Utility Bills

Promotion of retrofit actions on existing buildings is a goal in Italy, since most of them were built before the 80′s when little attention was paid to energy saving. This paper presents an integrated passive design approach to reduce the heating demand and limit the costs of a representative existing residential complex located in Bologna, in the northern part of Italy. To this purpose, we explored different scenarios upon actions taken on the building structure: (1) High efficiency windows; (2) additional insulation on the external walls; or (3) the simultaneous application of high efficiency windows and improved thermal envelope, on both external walls and roofing. The numerical optimization has been performed dynamically using TRNSYS simulation tool, to evaluate energy consumptions in different structural conditions. Then, the developed model has been calibrated by the real consumption data deduced from energy bills (years 2009–2015). Finally, the energy results obtained in the above mentioned different scenarios have been evaluated under an economic assessment of cost investment: It has been highlighted that the payback time (PBT) results to be strongly influenced by the national policies of fiscal incentives. According to the present model, the most profitable condition is obtained when additional insulation on the external walls is applied: The total amount of energy saving resulted to be equal to 930.4 MWh, with an optimal PBT of roughly six years, when tax refund was contemplated.

A systematic methodology for design of retrofit actions with longevity

This article presents a method for the design of retrofit actions with focus on energy savings that permits a systematic and thorough assessment of potential failures, anticipated maintenance and the expected durability of the retrofit actions. The proposed method combines the use of failure mode and effect analysis (FMEA) to permit identifying likely failure modes from which maintenance actions could be planned and the limit states (LS) method to assess the durability of the given retrofit action. One case study was completed to illustrate the application of: (1) the FMEA and LS method and (2) the proposed method for a retrofit action of an internal insulated solid wall of masonry bonded with lightweight aggregate concrete and floor division of concrete. It was evident that FMEA is useful regarding failure-mode identification and maintenance planning, and the LS method has its strength in durability assessment. Combining the use of both the FMEA and LS methods allowed improved design of new energy-saving retrofit actions, given that a thorough risk assessment was possible that included a decision-making process on maintenance planning, durability assessment and decision on potential redesign of retrofit actions.

Probabilistic Seismic Performance Analysis of RC Bridges

ABSTRACT This paper focuses on the evaluation of the seismic vulnerability of pre-1990 highway concrete bridges, based on the development of analytical fragility curves. The parameters considered are the span length, column height, lap splices, reinforcement yield strength, and concrete compressive strength. Nonlinear response history analyses using 3D models were conducted for each set of bridge samples subjected to earthquake ground motions with different intensities. Moreover, this study analyzes the influence of the earthquake fault type on the seismic vulnerability of the bridges, using as a performance parameter the displacement ductility demand of the piers. Based on this parameter, to support future seismic-risk mitigation efforts fragility curves are utilized to assesses the seismic vulnerability of typical concrete bridge classes in Iran. The selected suite of seismic records originates in strike-slip and reverse fault seismic sources. The bridges subjected to reverse fault records present pier demands and seismic vulnerability larger than the bridges subjected to strike-slip accelerograms. The study shows that the span length, lap splice, column height, and seismic fault type have significant effects on the seismic vulnerability of bridge piers. Additionally, the results are useful to identify and prioritize retrofit actions of the most seismically vulnerable bridges.

Multi-objective optimization of microclimate in museums for concurrent reduction of energy needs, visitors’ discomfort and artwork preservation risks

In museums, hygrothermal conditions must be carefully controlled by HVAC system to avoid artwork degradation. Higher energy requirements are needed for the maintenance of the suitable thermal environment. Moreover, a comfortable thermal sensation is needed for a positive museum experience. In light of current policies on energy efficiency, we propose an original procedure for the concurrent achievement of three goals: artwork preservation, energy efficiency, and human thermal comfort. This procedure is based on the application of multi-objective optimization and aims at correctly choosing temperature and relative humidity setpoints, through the use of dynamic simulations and evaluation of three indexes as objectives. This strategy can be particularly effective in museums hosted in historic buildings, where envelope and HVAC refurbishment is often forbidden or discouraged due to the architectural constraints. Furthermore, the retrofit action is almost costless. A case study is presented: first, a monitoring campaign in an Italian museum has been used for the validation of dynamic simulation models of the building-HVAC system; then, the validated models have been used to show that improvements of artwork lifetime, human thermal comfort and reduction of energy requirements of the HVAC system are possible, if currently-used hygrothermal setpoints (based on technical standards and guidelines) are replaced with those identified by the optimization problem.

Energy poverty methodology based on minimal thermal habitability conditions for low income housing in Spain

Energy poverty affects an increasing number of households in the European Union. It is urgent the development of definitions and methods adapted to regional conditions that gather important housing construction and climatic differences between Northern and Southern countries beyond different income levels. Mainstream energy poverty methods are focused on heating requirements influenced by health risks derived from living in cold homes. However, the evaluation of energy poverty in warmer climates must also consider health impacts related to households’ exposure to indoor overheating and consequent cooling needs that will likely be exacerbated by temperature increase due to climate change.The present research is aimed at developing a method for evaluating energy poverty in low income dwellings adapted to the Spanish context that gathers climatic, building and socioeconomic particularities of the country. The research was conducted through the evaluation of three representative social housing blocks of vulnerable households located in three different climates and regions. The proposed method is focused on the energy expenditure required to achieve minimal thermal habitability conditions in low income dwellings. Hence, both heating and cooling needs are appraised according to adaptive comfort criteria.The resulting method constitutes a useful tool for the identification of households suffering from energy poverty as well as the degree of the need they require (Fig. 1). Finally, the method poses an aid in the decision-making processes related to dwelling energy retrofitting actions and policy development.

Risk-based cost-benefit analysis for the retrofit of bridges exposed to extreme hydrologic events considering multiple failure modes

Bridges exposed to flooding, hurricanes, tsunamis, and other extreme hydrologic events have been observed to fail due to deck dislodgement, pier failure, or foundation failure. However, the risk assessment and retrofit methodologies for these bridges have typically only been developed around a single failure mode. This paper addresses this gap by integrating the three observed failure modes for bridges vulnerable to extreme hydraulic events into a comprehensive risk assessment framework. Through the use of an event tree, the methodology accounts for the different consequences of failure associated with different failure modes. Bridge management strategies are investigated to determine the effectiveness of the retrofit actions with respect to their benefit (i.e. reduction in risk) and costs. An illustrative example for riverine bridges under various exposure scenarios is presented. The risk assessment and benefit-cost analysis elucidate the need to incorporate all pertinent failure modes of the structure by highlighting the competing nature of different failure modes. The illustrative example shows that the effective management of structures is site-specific and, that the intensity of the hazard at the bridge location affects which management strategy is preferred. The sensitivity to exposure level indicates that the optimal management of the structure should incorporate considerations for potential future changes in the intensity and frequency of the hazard.

Application of low-invasive techniques and incremental seismic rehabilitation to increase the feasibility and cost-effectiveness of seismic interventions

The high seismic risk connected to the existing construction heritage requires a wide-scale renovation action to ensure structural resilience and avoid future human and economic losses. Given the urgency and the scale of the problem and the lack of available resources, a new strategy for the renovation of the obsolete European building stock should be envisioned, accounting for both safety and environmental, social and economic sustainability. This research aims at exploring new cost-effective seismic retrofit solutions based on the principles of low-invasiveness and incremental seismic rehabilitation, as envisioned by FEMA P-420 (2009). The incremental rehabilitation approach allows to plan repair and retrofit actions along with the maintenance works expected during the building's lifetime, thereby spreading them in time and reducing costs. In addition, low-invasiveness of the solutions is required to reduce the impacts on the functionality of the building, thus cutting the costs connected to downtime. A possible solution is represented by the introduction of an exoskeleton entirely carried out from outside. In this paper, a new sustainable technique is proposed, where the existing structure is connected to a self-supporting exoskeleton adopting demountable dry techniques, which may be assembled and activated in different phases of the building lifetime. As a proof of concept, the approach is then applied to a school building.

Decision-Support Tool for Retrofitable Flood Resilience

Abstract Flooding is increasingly global challenge due to climate change and urban development practices. It can also be devastating to those affected. In the United Kingdom, it is projected that the number of people at high risk of flooding could rise from 1.5 to 3.5 million by 2080. Currently 400,000 homes and 75,000 businesses in England have an annual chance of flooding. In the UK, the Environment Agency provides useful information on flood risks for a given location. This information is supported with different guides by the local Councils on how to prepare for, and get help during flooding. What remains unclear and easy to access are customisable retrofit actions based on local flood risks, necessary for an individual or household to implement anticipatory retrofit actions, thereby improving the resilience of their homes. With this in mind, and knowing that studies about flood impacts focuses more on new construction or infrastructure solutions, this study aimed to provide a tangible solution to raise the awareness of people living in a flood area about the level of risk they are exposed to, and to aid decision-making about effective preventive solutions specifically designed for their house, in an autonomous way. The output is a decision-support tool developed to consolidate information about flood risks and present customised retrofit measures. The tool refers to the notions of damage and vulnerability of private housing to inform its operational diagnostic methodology. The output is a “to do list” of retrofitable work to increase resilience of the house against flood. 40 potential users evaluated and delivered positive feedback on the usefulness and functionality of the tool to raise awareness and improve resilience action. Future studies aim to fine-tune the tool and scale up the study.

Life cycle perspective in RC building integrated renovation

Enormous resources are invested in Europe for the transition into a sustainable, low carbon, and resilient society. In the construction sector, these concepts are slowly being applied to the renovation of the existing building stock by enforcing their deep and holistic renovation targeting sustainability, safety and resilience.Effectiveness of such an approach to the renovation with respect to traditional retrofit actions emerges when broadening the time frame of the analyses, shifting from the construction time to a life cycle perspective. In this case, the potential of the holistic approach becomes clear in reducing costs, impacts on the inhabitants and impacts on the environment over the building life cycle.Within such a new perspective, new technology options are needed to innovatively combine structural retrofit, architectural restyling and energy efficiency measures. Furthermore, a new design approach conjugating the principles of sustainability, safety and resilience over the building life cycle is required. In such a transition, synergistic and cooperative work of researchers, design professionals, and all the stakeholders in the construction sector is required.In this paper, the basic features of an expanded Life Cycle Thinking (eLCT) approach will be presented, which not only entails the use of recyclable/reusable materials, but also encourages interventions carried out from the outside the buildings to reduce building downtime and avoid inhabitant relocation. In addition, such an expanded LCT fosters the adoption of reparable, easy maintainable, adaptable and fully demountable solutions, such as those featuring dry, demountable and pre-fabricated components. Finally, it addresses the need to account for the End of Life scenario from the initial design stages to guarantee selective dismantling and reuse or recycle to reduce construction waste. Finally, a discussion on the main barriers and challenges in the transition towards this new approach to the renovation of existing building stock is briefly presented.

Façade retrofitting: from energy efficiency to climate change mitigation

Since climate changes are now evident, it is not only important to achieve high level of energy efficiency, but also to think about retrofit actions in order to mitigate the natural hazard impacts and to make buildings resilient. The paper focuses on climate change effects in summer and investigates how it is possible to reduce them through façade retrofitting solutions (external insulation, PCM, green wall, cool materials) in Mediterranean climate. The goal is to develop a set of climatic resilience indicators for opaque envelopes in order to consider resilience ability against climate change, both inside and outside of buildings.

Integration time step issue in Mediterranean Historic Building energy simulation

The European target towards Zero Energy buildings is focusing on the energy retrofit of existing buildings. Often, in Mediterranean countries, existing buildings have historical relevancies, involving constraints, when dealing with their energy renovation, due to conservation reasons. To analyze possible energy retrofit actions, building energy performance simulation tools (BEPSt) are valuable. However, old buildings are often made of large stone walls whose resolution through conduction transfer function (CTF) used for sub-hourly time step simulation might be critical. This paper analyses how EnergyPlus and TRNSYS address such problem, explaining the differences between them and the reasons for low quality results.

Energy efficiency measures for buildings in Hebron city and their expected impacts in the distribution grid

The energy efficiency in buildings could represent one of the main opportunity, within a wide strategic scenario, to achieve energy independence of Palestine. In fact, the reduction of building energy demand due to the implementation of energy efficiency measures leads to a consequent decrease of the energy provision needs. For this reason an analysis of the potential reduction of the energy consumption in building need to be performed and a possible estimation of costs should be identified for defining a energy strategic plan of Palestine. This paper intends to highlight the potential of the energy efficiency measures in different building typologies of Hebron city in Palestine and their impact in the electrical distribution grid. The effectiveness of the different measures are estimated by means of software simulations and their optimal combination is also identified in order to maximize the reduction of energy demands. Finally, the variation of power losses in the distribution grid due to the retrofit action and a preliminary estimation of possible economic effort for the implementation of the proposed actions are also exposed.

Social Housing Policies and Best Practice Review for Retrofit Action - Case Studies from Parma (IT)

The paper aims at investigating the most suitable Energy Saving Measures –ESMs– for the retrofitting of Social Housing Stock –SHS– in Europe. A global awareness has been increasing, as well as education and training among architects and building sectors employees, in order to identify tailored financing schemes and advanced integrated retrofitting solutions. Several European financed programmes have been tested so far and the results are here summarized and deeply investigated in order to increase the energy performance of social housing buildings, to improve knowledge of problems associated with the retrofitting of these households, in order to provide the most appropriate solutions to be applied. Afterward, the best practices selected have been applied to some study cases in Italy, to demonstrate that the large variety of SH programmes in Europe can seriously be used, promoting the best practises’ application. A lot of theoretical and analytical work has been carried out by many European projects in the last decade, defining different approaches according to typologies of social housing buildings, focusing on national or regional regulation, on existing typologies and building techniques, on retrofitting solutions, on energy saving strategies and other managing approaches and energy saving devices. Due to the high participation of social housing organisations –SHO– and related European financed programmes, this academic research is focused on the most effective ESMs in order to encompass a large variety of needs and related solutions, even though some of them are still on course and other ones have already been completed. This research clearly demonstrates the valuable contribution these kinds of programme have in exchanging and sharing of knowledge and experience in the field of retrofit of Social Housing building across Europe, in order to primary improve the energy performance of the existing building stock and the quality of life of their inhabitants.

Assessing the adoption of the house as a system approach to residential energy efficiency programs

The traditional model of taking single actions when components reach their end of life or provide inadequate service has enabled the residential sector to gradually improve its energy efficiency over time. However, to achieve the large potential reductions in energy consumption and greenhouse gas emissions in residential buildings, a deeper systematic approach is required. The house as a system approach to energy retrofits emphasizes that for the greatest improvements in energy performance, multiple retrofit actions must be taken, and the order is important. This was the core concept in the Canadian residential energy efficiency programs, EnerGuide for Houses (1998–2006) and ecoEnergy (2007–2012). In this study, a systematic analysis of a large dataset that documents 19,552 residential energy evaluations conducted by a single agency in Waterloo, Canada, allows for a more nuanced description of how well the energy retrofit actions taken by participants followed the house as a system approach. The findings are encouraging in that participants did respond to the multiple recommendations given to them by energy advisors. In particular, a higher number of recommendations were associated with households arranging follow-up evaluations and taking more action under the performance-based grant program. However, the results also illustrate that participants frequently did not attend to the retrofits in the combinations associated with the house as a system approach. Insulation to reduce heat losses should have been the first priority in the systemic approach, but was often not upgraded, and the extent or depth of the upgrade was often less than what had been recommended. Furnaces and windows, which should have been upgraded in combination with or after the building envelope, were often upgraded as singular actions, demonstrating the persistence of the traditional model in some households. Time-limited grants do not appear compatible with encouraging the house as a system approach; it appears that staged approaches and careful attention to the building envelope retrofits would allow these programs to promote the house as a system approach to encourage deep retrofits and achieve low-carbon housing.

Energy efficient urban districts: A multi-criteria application for selecting retrofit actions

The definition of the new paradigm for transition strategies toward sustainable development and low-carbon cities is crucial, mainly, in the built environment sector which is the key driver of energy consumption and carbon emission. Starting from the energy characterization of the urban environment, the paper proposes a multi-criteria decision aiding model as a support tool for promoting the energy retrofitting of urban districts. The PROMETHEE methodology has been applied to a case study in the city of Torino for outranking five different proposed alternatives for buildings refurbishment that allows to achieve 20% energy saving. Three main phases characterize the study: i. analysis of the buildings stock and alternatives identification; ii. criteria definition and quantification; iii. model implementation and result discussion. The model fits well the purpose of the analysis and highlights that Multi-Criteria Decision methods can provide relevant feedbacks and considerable help to building designers, planners and decision makers for ranking complex design energy options and select the most energy savings retrofitting scenario

Cost optimal analysis of lighting retrofit scenarios in educational buildings in Italy

The European Energy Performance of Buildings Directive (EPBD) recast proposes, a comparative methodology to calculate cost-optimal levels of minimum energy performance requirements for buildings. This paper presents a method able to select the best retrofit action for lighting system, selectively analysing the daylight conditions and applying the cost-optimal methodology for different scenarios proposed for two existing educational buildings located in Italy. With the aim to improve both energy efficient and visual comfort conditions, the retrofit scenarios include lighting solutions with different combinations. They consider the replacement of lamps with more efficient lighting sources and the application of lighting control.

An approach for shake table performance evaluation during repair and retrofit actions

SummaryLarge‐scale, servo‐hydraulic shake tables are a central fixture of many earthquake engineering and structural dynamics laboratories. Wear and component failure from frequent use may lead to control problems resulting in reduced motion fidelity, necessitating repairs and replacement of major components. This paper presents a methodology to evaluate shake table performance pre‐ and post‐repair, including the definition of important performance metrics. The strategy suggested is presented in the context of the rebuilding of a 4.9 × 3.1 m, 350‐kN‐capacity uniaxial shake table. In this case, the rebuild consisted of characterization of wear to table components, replacement of worn bearing surfaces, and replacement of hydraulic accumulators. To assess the effectiveness of the repair actions, sinusoidal and triangular waves, white noise, and earthquake histories were run on the table before and after the rebuild. The repair actions were successful in reducing the position and velocity dependence of friction, improving the ability of control algorithms to accurately reproduce earthquake motions. The maximum and average response spectral misfits in the period range of 0.1–2 seconds were reduced from approximately 50% to 15%, and from 5% to less than 2.5%, respectively.

An optimization tool for energy efficiency of street lighting systems in smart cities

This paper develops a decision making tool to support the public decision maker in selecting the optimal energy retrofit interventions on an existing street lighting system. The problem statement is based on a quadratic integer programming formulation and deals with simultaneously reducing the energy consumption and ensuring an optimal allocation of the retrofit actions among the street lighting subsystems. The methodology is applied to a real street lighting system in Bari, Italy. The obtained results demonstrate that the approach effectively supports the city governance in making decisions for the optimal energy management of the street lighting.

Probabilistic Modeling Framework for Prediction of Seismic Retrofit Cost of Buildings

AbstractThis study presents a framework that utilizes Bayesian regression to create probabilistic cost models for retrofit actions. Performance improvement is the key parameter introduced in the pr...

Artificial neural network decision support tool for assessment of the energy performance and the refurbishment actions for the non-residential building stock in Southern Italy

The public buildings sector represents one of the most intensive items of EU energy consumption; the application of retrofit solutions in existing buildings is a crucial way to reduce its impact. To facilitate the knowledge of the energy performance of existing non-residential buildings and the choice of the more adequate actions, Public Administrations (PA) should have the availability of proper tools. Within the Italian project “POI 2007-13”, a database and a decision support tool, for easy use, even to a non-technical user, have been developed. A large set of data, obtained from the energy audits of 151 existing public buildings located in four regions of South Italy have been analysed, elaborated, and organised in a database. This was used to identify the best architectures of two ANNs and to train them. The first ANN provides the actual energy performance of any building; the second ANN assesses key economic indicators. A decision support tool, based on the use of these ANNs is conceived for a fast prediction of the energy performance of buildings and for a first selection of energy retrofit actions that can be applied.