Energy Retrofit Strategies Research Articles

Historical buildings’ energy conservation potentialities

Purpose Today, about 30 per cent of European existing buildings can be entitled as “historical buildings”. Nowadays, their energy retrofit is important to reach the ambitious European CO2 emissions’ reduction objectives. The purpose of this paper is to outline a methodology to investigate the potential energy savings and the enhancement of historical buildings’ liveability by acting only on their operation, so that the building fabric could be maintained as much as possible as the original evidence. Design/methodology/approach The paper describes the framework’s theoretical phases and their application in two real case studies. The methodology was conceived with a pre-test and post-test design approach. Findings The research demonstrated that the elaborated methodology is flexible and allows the adoption of different energy retrofit strategies for the different cases. Research limitations/implications Limitations arise out of the circumstance that the methodology is based on occupants and technicians willingness to engage in the strategies, so it is not possible to quantify its efficacy ex ante. Practical implications Practical implications can be found in the way of addressing energy retrofit strategies through a user-centric approach with minimum impact on the building itself. Social implications At the same time, the methodology has a strong social aspect with its potential to change people’s attitudes towards energy usage and behaviour. Originality/value This study not only represents the first attempt of applying a systematic energy retrofit strategy based on occupants and technicians behavioural change in historic buildings, but also is one of the first studies dedicated to occupants’ comfort and behaviour assessment in this context.

Energy retrofit scenarios: material flows and circularity

Cities are fast growing and are becoming more and more dependent on external services and supplies to meet their demands. In this context, the building industry can play a major role to reach European and regional targets of low-energy construction and circular design, particularly if considering the need of improving the energy standards and performance of the existing stock. On these premises, this paper presents the findings from recent research and discusses upcoming challenges, in particular: what are the consequences of retrofit operations on material flows, and their impact on circularity and low carbon objectives? In other words, which energy retrofit strategies are being implemented in buildings that could contribute to the production of building’ waste or secondary resources today, but also in the future? The purpose of this paper is to analyse the impact of different retrofitting scenarios on the energy performance of material flows. These scenarios can directly influence the nature and quantity of the materials used (inflows) and discarded (outflows) by upgrading or renewing the existing building stock. They can also lead to different environmental impacts and vary the embodied potential (through reuse or recycling) of resources. The analysis focuses on selected case studies representative of the housing stock in Brussels (Belgium). The overall objective is to inform, sensitize, and lead various stakeholders to responsible and conscious choices when retrofitting a building by adding concerns of resources efficiency while focusing on reducing energy demands.

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.

Assessing the Needs and Gaps of Building Information Technologies for Energy Retrofit of Historic Buildings in the Korean Context

Most domestic modern buildings from the early 1900s have been constructed as heavy mass, and for many years have relied on passive measures for climate control. Since effective passive measures eventually reduce the heating and cooling loads, thus also reducing the system size, passive and hybrid measures are the most preferred Energy Conservation Measures (ECMs). In addition, the domestic situation and climate are additional constraints in energy retrofit decision making, such as a shorter budget and time, poor maintenance history, and uncertainties in vernacular lifestyle. For this reason, the performance improvement and side-effects prior to installing ECMs should be predictable, particularly in case the originality can be damaged. This complexity confirms that simulation-based Measurement and Verification (M&V) would better suit the energy retrofit of domestic historic buildings. However, many domestic investors still believe re-construction has a larger economic value than restoration. Therefore, they are even unwilling to invest in more time than a preset audit period—typically less than a week. Although simulation-based M&V is theoretically favored for retrofit decision making, its process including collecting data, modeling and analysis, and evaluating and designing ECMs could still be too demanding to domestic practitioners. While some manual, repetitive, error-prone works exist in the conventional retrofit process and simulation-based M&V, it is proposed here that enhanced Building Information Technology (BIT) is able to simplify, automate, and objectify, at least the critical steps of the retrofit project. The aim of this study is to find an efficient and effective energy retrofit strategy for domestic historic buildings that appeals to both domestic investors and practitioners by testing selective BIT tools on an actual historic building. This study concludes with the suggestion that software vendors are asked to develop enhanced features to resolve users’ pending demands. It is also suggested that, in the domestic context, how the current practice for each process of the energy retrofit of historic buildings needs to shift to take a full advantage of BIT.

Evaluating the environmental adaptability of a nearly zero energy retrofitting strategy designed for Dutch housing stock to a Mediterranean climate

Users’ behaviour and indoor climate are two leading aspects that must be taken into account if we want the retrofitting of the housing stock to contribute to CO2 reduction, comfort improvement and reduction of living costs. The integrated facade module evaluated in this paper, which constitutes an approach to zero energy renovation, includes a preliminary study for the identification of target occupants and their characteristics and requirements that will guide the design decisions. The proposed strategy primarily focuses on the case of social rental multi-family housing stock in the Netherlands, but should provide insights in the application of the concept in Europe. This paper presents the analysis of the adaptability of this solution to the Mediterranean climate, taking into account the specific characteristics of the occupants of this climatic zone.The results showed an improved performance of building after the application of the evaluated solution in southern Spain, but with lower savings on the energy demand than in the Netherlands, so the economic investment should be reduced in this case. Also, the inclusion in the solution of some variables, such as the forced night-time ventilation for passive cooling and the insulation thickness reduction, were tested and proved to be an optimisation of its performance in the Mediterranean climate. Overall, the study concluded that the proposed refurbishment strategy has the potential to be implemented in different climates, particularly if certain modification in the facade operation is considered.

Selection of optimization objectives for decision-making in building energy retrofits

Building energy retrofitting has emerged as a primary strategy for reducing energy use and carbon emissions. The decision about which retrofit measures should be implemented in a particular project is a single- or multi-objective optimization problem subject to many constraints and limitations. Different objective(s) have been used in the literature, however the identification and selection of the objective(s) for this optimization problem is still a challenge. This study develops a decision matrix that guides decision-makers on how to select the objective(s) for a single- or multi-objective optimization problem that results in the selection of the best energy retrofitting strategy, by considering and defining the “investor benefits” term, the type of potential investors, and the type of potential benefits of building energy retrofits. Four types of investors are considered in this study: owner-occupant, absent owner, leaser, and external investor. In addition, a case study is used to illustrate how different types of investors may affect the selection of objective functions and, therefore, the final decisions for optimum energy retrofits. Results show that when the investor is the owner-occupant, a higher investment is suggested for energy retrofits to achieve optimum benefits.

Energy Management Strategies for a Governmental Building in Oman

This work describes the outcome of a study that has been performed to reduce the energy consumption of a library building in a hot climate of Oman. The project follows a systematic approach of collecting data from the project and maintenance department, conducting an energy audit and generating a building simulation model. The building has three floors with a total floor area of 2756 m2 and its average yearly consumption of 1397 MWh. The average energy-use-intensity (EUI) for this building is 507kWh/m2/year. Energy audit has identified many energy-retrofitting strategies including replacing the current florescent lights with LED, switching the air conditioning systems outside the occupancy hours, increase the thermostat setpoint, and reduce the air infiltration. Based on the field measurements and observations, building energy model was generated using DesignBuilder and was subsequently calibrated. Using the calibrated model, several energy management opportunities (EMOs) were evaluated. Only four top most energy management opportunities were top listed because they were technically and economically feasible. The EMOs include adjusting the thermostat setpoint, change the air conditioning operation schedules, replace the fluorescent lights with LED and increase the airtightness. The results show that the energy consumption can be reduced as much as 38.5%.

Architectural Energy Retrofit (AER): An alternative building’s deep energy retrofit strategy

The refinement of architectural space plays a catalytic role in the building’s energy balance. A different configuration on the deep energy building retrofit is presented on this paper, by proposing mainly strategies that hierarchize in a high position the invigoration of the building’s architectural design principals. These space qualities enable diversity of occupancy, environmental variability and facilitate the building envelope to operate efficiently as climate moderator. The main working hypothesis claims that bioclimatic trends, derived from primary architectural decisions of the early design phase, predispose the final energy performance of the existing building.Based on that, the alternative retrofit proposal called Architectural Energy Retrofit (AER) strategy, focuses on the energy genetic code of these basic architectural features. It argues that their holistic revival and refinement, indoors and outdoors will pave the way for the building’s energy retrofit and the space’s regeneration. As a case study to test this theory, an old and energy-consuming school complex is selected. By applying solely architectural interventions, a reduction of 44% energy demands was achieved. The results highlighted the challenges of “quantifying” the energy efficiency of architecture. However, by exploring and focusing on the non-energy, co-benefits, it also seeks to expand the perspective of energy efficiency beyond the traditional measures, by identifying and measuring its impacts across many different spheres. AER, as a counterproposal, wishes to add a new base of discussion on deep energy retrofit strategies as it follows a diametrically opposed direction than the typical practices. The building instead of being “sealed”and its environment kept strictly controlled, it “opens” and interacts with its surroundings.

Improving energy efficiency in existing school building: the case study of Lecco

Existing school buildings energy retrofit is one of the most sensitive current issues concerning the Italian public property. The presented research analyse 38 school buildings of Lecco Municipality with different educational level, age of construction and typological design. The methodology developed allows dividing the sampled schools in homogeneous clusters, each one represented by a reference building, used as base case for cost/benefit analysis. The present work investigates optimal energy retrofit strategies to be implemented from both an economic and an energy efficiency point of view.

A comparison of an energy/economic-based against an exergoeconomic-based multi-objective optimisation for low carbon building energy design

This study presents a comparison of the optimisation of building energy retrofit strategies from two different perspectives: an energy/economic-based analysis and an exergy/exergoeconomic-based analysis. A recently retrofitted community centre is used as a case study. ExRET-Opt, a novel building energy/exergy simulation tool with multi-objective optimisation capabilities based on NSGA-II is used to run both analysis. The first analysis, based on the 1st Law only, simultaneously optimises building energy use and design's Net Present Value (NPV). The second analysis, based on the 1st and the 2nd Laws, simultaneously optimises exergy destructions and the exergoeconomic cost-benefit index. Occupant thermal comfort is considered as a common objective function for both approaches. The aim is to assess the difference between the methods and calculate the performance among main indicators, considering the same decision variables and constraints. Outputs show that the inclusion of exergy/exergoeconomics as objective functions into the optimisation procedure has resulted in similar 1st Law and thermal comfort outputs, while providing solutions with less environmental impact under similar capital investments. This outputs demonstrate how the 1st Law is only a necessary calculation while the utilisation of the 1st and 2nd Laws becomes a sufficient condition for the analysis and design of low carbon buildings.

An optimization framework for building energy retrofits decision-making

Buildings are major consumers of energy in the United States. One way to improve building's energy efficiency is through energy retrofitting. The selection of a combination of retrofitting measures for a specific building is a complex process. Despite of the numerous resources that provide advice on how to retrofit a facility, the study of important variables affecting this decision remains limited. Further research is needed on the development of decision-making models to select the optimum energy retrofitting strategy in order to maximize energy retrofitting benefits. This study proposes a decision-making framework that: (1) calculates the economic benefits of energy retrofitting in terms of reduction of life-cycle cost for a specific building during its service life; (2) determines the optimum retrofitting budget that minimizes the total life-cycle cost of the building during its service-life; and (3) selects the optimum energy retrofitting strategy (among available energy retrofitting measures) to maximize the homeowner economic benefits during service-life of the building based on available investments. This study contributes to the body of knowledge in three aspects: (1) considering a comprehensive economic objective for decision-making in energy retrofits that includes majority of cost-related components of building life-cycle cost; (2) introducing a novel simplified energy prediction method by integrating dynamic and static modeling; and (3) incorporating energy retrofitting decision-making uncertainties to reach more accurate results. In order to demonstrate the implementation of the framework, a case study exercise of a house built in 1960's in Albuquerque, New Mexico is used.

An exergoeconomic-based parametric study to examine the effects of active and passive energy retrofit strategies for buildings

The paper describes a systematic framework that uses exergoeconomic theory integrated into ‘building energy retrofit’ (BER) design. An exergoeconomic module, based on the SPECO method, has been embedded into ‘EXRETOpt’, a recently developed retrofit-oriented exergy simulation tool based on EnergyPlus. Both active and passive technologies were analysed using two calibrated archetype non-domestic buildings as case studies (an office and a primary school). A novel cost-benefit indicator which accounts for building exergy destruction cost, retrofit annual capital cost, and project annual revenue is presented. This indicator is employed to account for best exergoeconomic performance technologies and to further develop deep BER packages. Compared to typical practice, exergoeconomics combined with cost-benefit provides a powerful tool for exploration and design improvement of building energy systems. In both cases, final product cost for heating and cooling processes were substantially reduced. In addition, the office case presented improvements in energy use by 67%, CO2 emissions by 53%, thermal comfort by 22%, exergy destructions by 42%, and the overall building exergy efficiency was improved from 14.8% to 20.0%. The school case presented similar results with an improvement of building exergy efficiency from 8.2% to 11.1%, and the potential to generate income due to current government incentives.

Energy retrofit strategies for housing sector in the arid climate

This paper discusses sustainable strategies have been implemented to improve the energy performance for the housing sector in arid climate, especially villas. A practical case study along with field measurements is presented in order to highlight the behavior of the energy performance after implementing energy conservation measures in practice. The residential sector in arid climate especially in GulfCountries has a significant share of carbon emissions. Millions of householders occupy villas and town houses. The harsh hot weather of this region is one of the reasons for a high demand on the cooling energy and the electricity consumption in the housing sector. Thus, there is a real potential to retrofit the existing houses with practical energy conservation measures. These techniques are affordable and feasible economically. Also, they play a substantial role to increase the energy efficiency of the residential units on the demand side. This study discusses the results of 12 months were monitored after implementation of energy savings measures on selected 10 villas in the capital of UAE – Abu Dhabi. This research highlights different responses by each villa against the implemented energy savings opportunities. The target of these executed strategies is to improve the energy performance of these selected villas after conducting a detailed energy assessment and implementing its recommendations. A detailed analysis of the electricity performance of the baseline and the monitoring period has been performed by using the actual readings of the existing power meters according to the international performance measurement and verification protocol. This research presents the energy data for the entire year before and after the implementation of the energy conservation measures – ECMs. These ECMs show the potential of improvement of energy performance in the housing sector by increasing the energy efficiency by 25.1% in average through low and medium cost techniques. The percentage of savings varies from 14.4% to 47.6% of the total electricity according to the individual operating conditions for each villa and the behavior of occupants. As a result, they contribute reducing the carbon and GHG emissions, and open new perspectives of energy savings for housing sector in arid climates.

An exergy-based multi-objective optimisation model for energy retrofit strategies in non-domestic buildings

While the building sector has a significant thermodynamic improvement potential, exergy analysis has been shown to provide new insight for the optimisation of building energy systems. This paper presents an exergy-based multi-objective optimisation tool that aims to assess the impact of a diverse range of retrofit measures with a focus on non-domestic buildings. EnergyPlus was used as a dynamic calculation engine for first law analysis, while a Python add-on was developed to link dynamic exergy analysis and a Genetic Algorithm optimisation process with the aforementioned software. Two UK archetype case studies (an office and a primary school) were used to test the feasibility of the proposed framework. Different measures combinations based on retrofitting the envelope insulation levels and the application of different HVAC configurations were assessed. The objective functions in this study are annual energy use, occupants' thermal comfort, and total building exergy destructions. A large range of optimal solutions was achieved highlighting the framework capabilities. The model achieved improvements of 53% in annual energy use, 51% of exergy destructions and 66% of thermal comfort for the school building, and 50%, 33%, and 80% for the office building. This approach can be extended by using exergoeconomic optimisation.

A process for developing deep energy retrofit strategies for single-family housing typologies: Three Toronto case studies

Energy consumption of existing single-family homes in cold climate urban centers needs to be reduced. This research presents a process for developing and analyzing retrofit strategies for specific housing archetypes using Toronto (Canada) as a case study. The process was applied to three Toronto urban archetypes with two separate energy intensity goals for heating and cooling: (1) 75kWh/m2 and (2) Passive House EnerPHit estimated equivalency. Building data was collected through field study and calibrated baseline energy models (EnergyPlus) were created. Retrofit strategies were identified and costs were estimated in consultancy with several experienced Toronto-based retrofit contractors. The process utilized a Brute Force method for retrofit selection considering the cost/benefit of each strategy. Furnace and select building envelope parameters were shown to be priorities while windows were not. Energy use reductions of 64–67% and 88–89% from a baseline were achieved when meeting the 75kWh/m2 and EnerPHit equivalency targets, respectively. The capital costs of $30,000–$80,000 to achieve the retrofit targets are likely to be prohibitive for homeowners, suggesting that a government funded program is necessary to achieve deep energy retrofits of this nature and to ensure early adoption leading to widespread market growth.

Life cycle assessment of energy retrofit strategies for an existing residential building in Turkey

Energy consumption in residential buildings contributes significantly to neg ative environmental impacts such as climate change and ozone depletion, and the implication for carbon dioxide emissions reductions in buildings during the construction phase as the embodied carbon and the operation phase in the form of operational carbon are widely acknowledged. Investment on creating a sustainable built environment especially through energy retrofit strategies for buildings has been progressively increasing over the last decade. To identify optimum energy retrofit strategies for reducing both energy consumption and CO 2 emissions, this paper presents a simplified life cycle model and implements this to a case study focused on different climate regions of Turkey. The objective of this study is to develop effective strategies on the improvement of building energy perfor mance for different climate regions, which is important for optimum use in the sense of country resources and decision makers. Also the energy and environmental performances of the residential buildings regarding these strategies are assessed on the basis of a comparative method in the framework of life cycle. In this study based on life cycle energy and environmental performance, the alternatives related to energy retrofit strategies were evaluated in order to improve the energy performance of the existing residential buildings. In this context, the effect of each measure on life cycle energy consumption and CO 2 emissions was determined by using the “Life Cycle Energy (LCE)” and “Life Cycle CO 2 (LCCO 2 )” analyses developed based on the life cycle assessment (LCA) method.

A case study for the evaluation of realistic energy retrofit strategies for public office buildings in the Southern Hemisphere

The building sector offers significant opportunities for reducing the energy consumption with considerable economic, environmental and health benefits. Governments can lead the way by retrofitting existing public buildings to reinforce their commitment to improve energy efficiency. Similar design standards, end-uses and operational profiles are usually established for public buildings based on the services they offer. Retrofitting a public building can therefore serve as an ideal test-bed for energy efficiency measures for other buildings within a particular service category. This study first analysed the current electricity consumption of a public office building in Mauritius, located in the Southern Hemisphere. A complete model of the building was created, validated and then simulated to investigate the impact of realistic retrofit strategies on the electricity consumption. Results showed that lighting retrofit achieved the most significant reduction while measures that improved the thermal envelope of the building resulted in smaller energy savings. The possibility of exploiting solar energy was explored by simulating a 70 kWp photovoltaic system installed on the roof. An equivalent of 8.5% of the annual electricity consumption of the building could thus be generated. A financial analysis is also presented for all retrofit scenarios in terms of annual return and payback period.

A Study on Life Cycle Assessment of Energy Retrofit Strategies for Residential Buildings in Turkey

In this study based on life cycle energy and environmental performance, the alternatives related to energy retrofit strategies were evaluated in order to improve the energy performance of the existing residential buildings. In this context, the effect of each measure on life cycle energy consumption and CO2 emission was determined by using the “Life Cycle Energy (LCE)” and “Life Cycle CO2 (LCCO2)” analyses developed based on life cycle assessment (LCA) method.

Interconnection between Scales for Friendly and Affordable Sustainable Urban Districts Retrofitting

The EU FP7 project FASUDIR (Friendly and Affordable Sustainable Urban Districts Retrofitting) supports the mobilization of the building retrofitting market towards 2020-2050 EU-targets through an Integrated Decision Support Tool (IDST), a software based on a new methodology that will help decision makers identify the best energy retrofitting strategy to increase the sustainability of the whole district. Improving the sustainability of urban environments is a interscalar problem, addressed through a multiscalar and multidirectional approach. A comprehensive urban scale strategy considers the working scale, but the measures at building scale have to be coherent with the global objectives at district and city scale. The FASUDIR IDST and methodology interconnect and visualize information across scales, ensuring comprehensive diagnoses and proper implementation of strategies. Due to the complexity of urban sustainability, interscalarity and multiscalarity, first it has been necessary to identify the possible scales of analysis, to capture various themes and to highlight the horizontal and vertical interconnections between different components. Multiscalarity and Interscalarity affect the three phases of the sustainable retrofitting cycle: diagnosis, decision making and management. The identification of the impact of district solutions on buildings (and vice versa) and their compatibility across scales has been addressed through interconnected building and district Key Performance Iindicators (KPIs). The intervention phases at building level generate new information about specific buildings, enabling more accurate decision making at district level. The methodology articulates the structure of the new information and the feedback generated during the process. To allow information interconnection a strategic information management is key. A multiscale information model based on CityGML, a standard data model issued by the OGC (Open Geospatial Consortium), will be the baseline structure for all the district-scale information (geometric and semantic) that is necessary for decision making and management, organized into a single interoperable data model that will integrate information from different fields and at different levels of detail.The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007- 2013) under grant agreement n̊ 609222.

Benchmarking energy performance of residential buildings using two-stage multifactor data envelopment analysis with degree-day based simple-normalization approach

Being able to identify detailed meta factors of energy performance is essential for creating effective residential energy-retrofitting strategies. Compared to other benchmarking methods, nonparametric multifactor DEA (data envelopment analysis) is capable of discriminating scale factors from management factors to reveal more details to better guide retrofitting practices. A two-stage DEA energy benchmarking method is proposed in this paper. This method includes (1) first-stage meta DEA which integrates the common degree day metrics for neutralizing noise energy effects of exogenous climatic variables; and (2) second-stage Tobit regression for further detailed efficiency analysis. A case study involving 3-year longitudinal panel data of 189 residential buildings indicated the proposed method has advantages over existing methods in terms of its efficiency in data processing and results interpretation. The results of the case study also demonstrated high consistency with existing linear regression based DEA.