Retrofit Measures Research Articles

Multistage Optimization toward a Nearly Net Zero Energy Building Due to Climate Change

Climate change is one of the major problems of the planet. The atmosphere is overloaded with carbon dioxide caused by fossil fuels that are burned for energy. Almost 40 percent of the total energy worldwide is used by the building sector, which comes from non-renewable sources and contributes up to 30% of annual greenhouse gas emissions globally. The building sector in Iran accounts for 33.8% of Iran’s total energy usage. Within the building sector, the energy consumption of Iranian educational buildings is 2.5 times higher than educational buildings in developed countries. One of the most effective ways of reducing global energy consumption and greenhouse gas emissions is retrofitting existing buildings. This study aims to investigate whether a particular energy-optimized design under the present climate conditions would respond effectively to future climate change. This can help designers make a better decision on an optimal model, which can remain optimal over the years based on climate change. For methodological purposes, multistage optimization was used to retrofit an existing educational building. Specifically, the non-dominated sorting genetic algorithm (NSGA-II) was chosen to minimize the cooling and heating load, as well as consider investment costs for present and future weather files, using the jEPlus tool. Furthermore, the TOPSIS method was used to identify the best set of retrofit measures. For this purpose, a four-story educational building in Tehran was modeled on Design Builder software v7.0.0.116 as a case study to provide a better understanding for researchers of how to effectively retrofit a building to achieve a nearly zero energy building considering climate change. The results show that the optimized solution for the present weather file does not remain the optimized solution in 2080. Moreover, it is shown that to have an optimized building in regard to future weather files, the model should be designed for the future weather conditions. This study shows that if the building becomes optimized using the present weather file the total energy consumption will be reduced by 65.14% and 86.18% if using the future weather file. These two figures are obtained by implementing active and passive measures and show the priority of using the future weather file for designers. Using PV panels also, this building is capable of becoming a nearly net zero building, which would produce about 90% of its own energy demands.

Economic Evaluation of Energy-Saving Retrofit of Existing Hotels

With the improvement of China’s economic strength, the energy consumption of public buildings is continually increasing, notably for hotels. The energy consumptin of a hotel accounts for more than 15% of its revenue, and the average energy consumption per floor area is more than 10 times that of urban residents. Therefore, the energy-saving retrofit of existing hotels is imperative. This study investigates the economic evaluation methods for existing hotel retrofit projects, and constructs an economic evaluation model using economic evaluation and cost-effectiveness ratio as the base. The energy-saving retrofit measures of 15 existing hotels in Jiangsu Province, China, are used as a case study to demonstrate the research framework. The results indicate that the heating, ventilation and air conditioning (HVAC) system, monitoring system, lighting system, domestic hot water system, and building envelope system are the five energy-saving retrofit technical measures with the highest application ratio. The average dynamic investment payback period of hotels in Jiangsu Province is 2.96 years, which meets the requirement of no more than 10 years specified in the energy-saving building standard. The cost-effectiveness ratio of different technologies differs significantly. Lighting and kitchen systems have the highest energy-saving efficiency, followed by monitoring systems, while HVAC and domestic hot water systems have the lowest. The research presented in this paper contributes to the economic evaluation of the energy-saving retrofit of hotels.

Sustainable Buildings’ Energy-Efficient Retrofitting: A Study of Large Office Buildings in Beijing

Energy-efficient retrofitting has emerged as a primary strategy for reducing the energy consumption of buildings. Buildings in China account for about 40% of total national energy consumption. Large office buildings account for the most. Less than 5% of the building area of existing office buildings is energy efficient. Energy-efficient retrofitting for sustainable buildings is a complicated system that involves various sustainable dimensions and operational technical schemes. Making multi-criteria decisions becomes a challenging problem for stakeholders. Based on the theory of sustainability, this paper establishes a sustainable analysis framework to guide stakeholders to select an optimal technical combination of energy-efficient retrofit measures for large office buildings. Based on empirical data collected in Beijing, a number of energy efficiency measures are selected, tailored and applied to a virtual model of a typical large office building. Technical features and the energy performance are simulated accordingly. The energy consumption, energy-saving ratio and lifecycle costs are derived to identify the optimal configuration. The outcome of this research offers a feasible technical plan for stakeholders relating to technical design and design making. The study finds that an LED lighting system and frequency conversion device for the cooling water chiller cannot only sufficiently reduce the building’s energy consumption but also perform economically. Different thermal insulation materials for reconstructing the building envelope have no obvious effect on the thermal performance in comprehensive simulations of technology combinations. The sustainable analysis framework offers theoretical and practical support and can be used as a reference for the other types of buildings in future research.

Optimization and BIM-based lifecycle assessment integration for energy efficiency retrofit of buildings

A retrofit plan for improving the energy efficiency of an existing building can contribute to a sustainable built environment. This study presents a novel framework for integrating mathematical optimization, 6D-Building Information Modeling (BIM), and Life Cycle Assessment to enhance existing buildings' energy efficiency through applying energy retrofit measures. This framework aims to (1) integrate life cycle cost, and environmental impacts analysis (2) identify energy-efficient alternatives for buildings' energy retrofit (3) make the decision-making process straightforward for decision-makers and investors (4) discover the primary energy efficiency agents that impose the most energy waste on existing buildings. This study contributes to the body of knowledge by applying effective retrofit measures and alternative material choice and empowers decision-making by analyzing life cycle cost and environmental impacts of building envelopes by combining mathematical optimization, BIM, and LCA. The BIM energy model compares the cooling and heating loads of the building's components before and after applying retrofitting measures. The results show that inefficient buildings' envelopes and evaporative coolers play a significant role in energy consumption. A developed mathematical optimization model estimates the economic benefits of energy efficiency upgrades to minimize the total lifecycle cost of a building during its lifetime. Moreover, it provides an optimum energy retrofitting scenario that leads to reductions of 24%–58.2% in energy consumption. In conclusion, the Life Cycle Assessment Comparison between the building before and after retrofitted measures demonstrates that over 45% of global warming impacts could be reduced in the well-established building.

An innovative retrofit Motivation-Objective-Criteria (MOC) approach integrating homeowners’ engagement to unlocking low-energy retrofit in residential buildings

According to the EU Commission projection (2016/547/EU), the current average renovation rate is far below the expected rate of 3% to achieve carbon neutrality in building sectors by 2050. This is due to the fact that, during the building retrofit optimisation process, the decision-making criteria and objectives are generally optimised separately, and homeowners' motivations are often ignored or not carefully defined in most research. Limitations existed with a lack of in-depth and comprehensive understanding of the homeowners’ motivations in undertaking building retrofit. To address this, we propose an inclusive Motivation-Objective-Criteria (MOC) approach, aiming to bring forward optimised decision-making for building renovation, accommodating different homeowners’ retrofit motivations, objectives and criteria. Retrofit motivations are categorised into three typical types: 1) Self-living, 2) Rental or sale, and 3) Investment, under five objectives: Energy Reduction Rate (ERR), Initial Investment (II), Discounted Payback Period (DPP), Bills Reduction Rate (BRR) and Carbon Reduction Rate (CRR). A novel Multi-motivation Performance Factor (MPF) concept is proposed to assess the holistic post-retrofit building performance with comprehensive retrofit combinations. A UK semi-detached house is applied as the reference building to investigate the impact of homeowners’ engagement on the decision-making of various retrofit measures.According to the cost-optimal results neglecting homeowners’ motivation, it is evident that the mismatch of optimal retrofit combinations occurs between the minimum Initial Investment (II) and Discounted Payback Periods (DPP), with optimal ERR of 72%-79% and 82%-93%, respectively. Comparing cost-optimal with multi-objective optimisation results, it is concluded that homeowners’ retrofit priorities have an apparent influence on selecting optimised retrofit measures. Besides, party wall insulation is fundamental for self-living- and rental or sale-motivated types. The solar-assisted heat pump and air–water heat pump are not necessary under the retrofit motivation of the “investment” type. Moreover, the attic floor and external wall insulation are imperative for rental or sale- and investment-motivated types. The sensitivity analysis results are conducted in this research, indicating that the optimal retrofit measures and baseline energy consumption input are in good agreement, with a 10% discrepancy. Thus, the proposed inclusive Motivation-Objective-Criteria approach can incorporate homeowners’ engagement in the building retrofitting design process, serving as a decision-making supporting tool to accelerate building retrofit with maximised user acceptance and market penetration.

A Comparison of Energy and Daylighting Performances of Different Window Glazing Types Used in the Traditional Harput House

A review of the history of glass that dates back to the mid-2000 BC pursuant to the archaeological data suggests that the effects of the thermophysical properties of window glass on building energy performance could have been understood only over time. Today, the optimum combinations of thermophysical parameters help significantly reduce the energy demand of the buildings. Furthermore, the energy sustainability is also achieved by increasing building energy efficiency during the early design phase, using building simulation tools. The present study was aimed to comprehensively review the improvements in glazing technologies from past to present. Furthermore, the energy and daylighting performances of the retrofitted traditional Harput house in Turkey were analyzed using a building simulation tool. The results indicated that the use of retrofit measure, i.e., the triple-glazed window with low-e coating filled with Argon gas combined with daylighting control system improved the annual primary energy performance of the building in question located in a cold climatic region of Turkey by %8.20. In addition, it was found that the illuminance of indoors increased by means of higher visible transmittance ensured by the retrofit measure.

Quantifying pedestrian retrofit measures of car-oriented settlements: The case of Pardis new town phase 11

Car-oriented settlements have a negative impact on human beings and the environment. In many places, planners already try to densify such areas and retrofit infrastructure for pedestrians. While such measures are generally accepted for the improvement of liveability, it is still difficult to evaluate their impact. This paper aims to quantify proposed retrofit interventions for pedestrians in the new town of Pardis, Iran. Interventions are: introducing pedestrian zones, relocating parking spaces, traffic calming, removing barriers and decentralising facilities. Two different methods are used: 1) walking distances in combination with detour factors; and 2) space syntax. The results show that these methods are effective to quantify improvement for pedestrian retrofit measures. Even simple interventions such as removing fences have a measurable positive impact.

How IoT and Artificial Intelligence can improve energy efficiency in hospitals - a North Italian case study

Because of the COVID-19 pandemic, healthcare facilities have experienced pressure of increasing occupancy rates and more demanding Indoor Air Quality requirements in recent months. In this context, the efficient management of the HVAC system in these buildings has become a crucial topic to address. The retrofit project was the result of the joint effort of a digital solution provider, Enerbrain, and the Hospital’s energy services provider, Edison. By exploiting IoT and ICT technologies and cloud-based machine learning algorithms, the HVAC-related control features of the main heating and ventilation systems of the hospital have been upgraded with no major modifications to the existing setup. The implemented solution allows energy managers to remotely verify the real-time indoor comfort conditions and to control the upgraded systems, which, thanks to the machine learning adaptive algorithms, are now effectively meeting the required set-points through advanced optimization strategies. This paper presents the implementation of a retrofit measure applied to the HVAC Building Management System of a big public hospital in Lombardy and the energy savings achieved in the 2020-2021 heating season.

Machine Learning Techniques Focusing on the Energy Performance of Buildings: A Dimensions and Methods Analysis

The problem of energy consumption and the importance of improving existing buildings’ energy performance are notorious. This work aims to contribute to this improvement by identifying the latest and most appropriate machine learning or statistical techniques, which analyze this problem by looking at large quantities of building energy performance certification data and other data sources. PRISMA, a well-established systematic literature review and meta-analysis method, was used to detect specific factors that influence the energy performance of buildings, resulting in an analysis of 35 papers published between 2016 and April 2021, creating a baseline for further inquiry. Through this systematic literature review and bibliometric analysis, machine learning and statistical approaches primarily based on building energy certification data were identified and analyzed in two groups: (1) automatic evaluation of buildings’ energy performance and, (2) prediction of energy-efficient retrofit measures. The main contribution of our study is a conceptual and theoretical framework applicable in the analysis of the energy performance of buildings with intelligent computational methods. With our framework, the reader can understand which approaches are most used and more appropriate for analyzing the energy performance of different types of buildings, discussing the dimensions that are better used in such approaches.

Retrofit analysis of historical buildings to net-zero energy: Case study of the Ain village, Saudi Arabia

Renovating disused heritage buildings to serve new functions is an effective approach to preserve their architectural value. In this study, an analysis approach and associated results of converting an unused ancient village located in the south-western part of Saudi Arabia to a net-zero energy hotel complex are presented. Energy efficiency and on-site power generation measures are evaluated as retrofit measures for the Ain village based on a series of sensitivity analyses. Four levels of retrofits are proposed with and without the addition of thermal insulation to exterior walls and roofs. All the considered measures are considered non-intrusive and should not negatively affect the visual character of the historic village. The analysis results indicated that energy retrofit measures excluding thermal insulation can reduce the total Ain village energy consumption by 47% relative to the baseline case when the buildings are converted to hotel spaces. Deploying a fixed PV system with a capacity of 206 kW on-site can achieve net zero energy status for the retrofitted village. However, lower PV capacities would be needed to achieve net zero energy status for the Ain village when utilizing one-axis and two-axis tracking systems.

Seismic fragility of approach backfill differential settlement for statewide bridges in California

This study develops the first-of-its-kind seismic fragility models for estimation of approach backfill differential settlement for statewide bridges in California. Seismic compression analysis is carried out through a multi-step framework that estimates seismic-induced shear strain profiles for backfills, converts them to volumetric strains, and computes soil settlement through depth integration. As a crucial step, three independent methods are advanced on a uniform basis to estimate soil shear strains under earthquake loading: a simplified one-dimensional (1D) Static approach, a 1D Dynamic method from site response analysis, and a two-dimensional (2D) Dynamic method that accounts for the trapezoidal shape of the bridge embankment. Subsequently, seismic fragility models are derived using the multiple-stripe analysis (MSA) approach that convolves the seismic demands of backfill settlement with capacity models for several broad groupings of approach-slab designs having different abutment and abutment-foundation types, and abutment-connection details. A survey of California's bridge inventory provides stochastic data inputs that quantify various sources of uncertainties in backfill profile, embankment geometry, and both approach slab and abutment designs. Finally, a combined fragility model is developed by considering an equal methodological contribution from each mentioned approach. The final fragility models suggest that the lowest differential-settlement fragility is achieved by combining regular abutments on spread footings with long-length approach slabs connected to the bridge abutment, while the worst case occurs where bridge abutments on deep foundations are not connected with abutting pavements. The proposed seismic fragility models offer a sound basis for first-order estimation of approach-fill differential settlement which may lead to reduced ride quality, traffic speed reductions, and in extreme cases, temporary roadway closure. These represent one of many seismic fragility models for the full range of bridge components needed for prioritizing seismic retrofit measures, facilitating post-hazard inspections and repair actions, as well as assessing the network mobility for resilience quantification.

Long-term carbon emission reduction potential of building retrofits with dynamically changing electricity emission factors

Buildings account for approximately 36% of the United States’ total carbon emissions and building retrofits have great potential to reduce carbon emissions. Current research adopts a constant electricity emission factor although it changes over time due to the increase of renewable energy generation. To accurately predict emission reduction potential of building retrofits, this study develops a novel method by using dynamically changing electricity emission factors. Using medium office buildings as an example, we predicted emission reduction of eight building retrofit measures from 2020 to 2050 in five locations in the U.S. with distinct climates and renewable adoption rates. To evaluate emission reduction potential sensitivity to the compositions of electricity generation, five scenarios for renewable energy adoptions are investigated. The results reveal several new phenomena on emission reduction potential of building retrofits for medium offices in the U.S.: (1) it decreases from 2026 to 2050; (2) it has the same trend with coal usage; and (3) it reaches the maximum under the high renewable cost scenario. Based on the results, it is recommended that building retrofits should focus on 1) improving lighting and equipment efficiency; 2) locations with higher coal usage rate, and 3) buildings under the high renewable cost scenario. The new method can also be used for predicting emission reduction potential of the building sector in the U.S. by applying to other building types and regions.

Cost-related analysis of implementing energy-efficient retrofit measures in the residential building sector of a middle-income country – A case study of Bosnia and Herzegovina

This study presents an in-depth analysis of the cost structure when planning EE retrofit measures in the residential sector in Bosnia and Herzegovina. The analysis showed that implementing EE retrofit measures would result in substantial energy savings in single-family houses, however, the specific cost of implementing EE retrofit measures per resident for single-family houses is on average 2.8 times higher than for the other three categories; multi-family houses, apartment buildings, and high-rise buildings. When considering the ratio between the investment costs and GDP per capita showed that the citizens in Bosnia and Herzegovina have four times lower ability to finance EE retrofit measures compared to three other representatives EU members and therefore government subsidy schemes may be inevitable for successfully implementing EE retrofit strategies. The general conclusion based on the cost-effective analysis is that EE retrofit investments, may not be financially viable in single-family houses, multi-family houses, and apartment buildings even if supported by government subsidies due to the very low prices of energy sources (coal and wood) used in these specific building prototypes. On contrary, high-rise buildings, that are mainly driven by natural gas and light distillate fuel oil, show a great EE retrofit-driven profitability in. Looking at the financial assessment outcomes, the most significant benefits are mainly related to retrofit scenario that accounts for improvement in the external wall insulation, window glazing, and improving the heating station efficiency. Looking at the carbon emission outcomes, the most significant benefits in reducing the relative and averaged CO2 emission are strongly related to replacing the existing partly coal-burned furnaces (80% firewood + 20 % coal) in single-family houses with exclusive firewood fueled heating systems. This measure may have an enormous impact on reducing the CO2 emission from single-family houses (minimum 83.1 %), which cover 93.1 % of the total residential building stock in Bosnia and Herzegovina. This study may benefit low and middle-income governments in their aim to translate potential EE retrofit measures in the residential sector to a nationwide economic energy-saving policy.

Performance of smart glazed overhang systems for US residential buildings

In this paper, the application of smart glazing systems as shading devices is evaluated for US residential buildings. Specifically, static and dynamic overhangs are considered using smart glazing that can change their tint state to reduce the heating and cooling thermal loads for prototypical housing units in high-rise apartment buildings. The tint settings as well as the overhang tilt angles are specified on hourly, daily, and monthly basis depending on the window orientation and the time of the year to minimize the annual energy demand for the housing units. The performance of smart glazed overhang systems is compared to both static and dynamic shading devices made-up of conventional opaque materials. In addition, the impacts of various design and climatic conditions are considered to assess the energy performance of the smart glazed overhangs. The results of the analysis indicate that the annual energy consumption for existing housing units with conventional windows located in Boulder, CO, can be reduced by over 7% for static smart glazed overhangs and by over 22% for dynamic smart glazed overhangs. These savings are even higher with larger windows and wider differentials between optical properties between clear and dark states. The smart glazed overhangs allow the use of low-cost smart glazing as a retrofit measure for existing buildings. Moreover, the smart glazed overhangs allow the specification of large windows for new constructions with limited energy penalties.

Interstitial hygrothermal analysis for retrofitting exterior concrete wall of modern heritage building in Korea

Retrofitting modern heritage buildings aims at not only energy conservation, but also restoration and preservation of an architectural artefact. However, if envelope construction is adjusted and HVAC systems are replaced, the temperature and humidity profiles and air-tightness can also be transitional, thus condensation could occur on the surface and/or inside the structure. It is continuously emphasized to assess retrofit measures’ expected transitions in the hygrothermal performance of envelope and their potential condensation problems, prior to actual retrofit. The present study measured the surface moisture content of the concrete structure and built environment of three modern heritage buildings in Seoul. These results were used as the initial conditions for the hygrothermal analysis of insulations and vapor retarder. One modern heritage school was chosen for retrofit, then mock-up test, ISO 13788 steady-state analysis, and dynamic simulations by WUFI were used to analyze the risk of interstitial condensation in the exterior wall, according to the initial moisture content of concrete wall and whether the vapor retarder had been installed. For modern heritage buildings with fully dry concrete walls, the mock-up test verified that the risk of interstitial condensation between the concrete and insulation is low, regardless of whether the vapor retarder had been installed. Per ISO 13788 steady-state analysis and WUFI transient simulation, if PF board was used as the internal insulation for concrete exterior wall, the chance of interstitial condensation was also low, regardless of the initial moisture content and the use of a vapor retarder.

Optimizing the energy saving potential of public hospital through a systematic approach for green building certification in Malaysia

Hospital buildings are the main energy users among government facilities which require substantial energy reduction to save its annual operational costs. At the same time, the Ministry of Health Malaysia has set a policy for all hospitals to achieve green building certification, which in line with its global commitment to conserve the environment. Energy efficiency is an important component in every green building rating tool because of its high potential on point scoring. Thus, there is a need to find the most appropriate method to explore energy saving opportunities as much as possible. The overall aim of this article is to evaluate the potential for energy saving in public hospital using a systematic approach. Three methods are applied in this approach which involved energy audit, empirical evidence and simulation works. Energy audit predicts that the chiller system provides the highest energy saving amount of 1,535,175.40 kWh/year (45.54 %) with discounted payback period of 7.15 years. A chiller retrofit measure was implemented as pilot project and the predicted energy savings were validated by empirical evidence. The actual energy saving of 1,688,347.02 kWh/year (50.08 %) was obtained from the chiller system retrofit and slightly higher than what was predicted with discounted payback period of 6.29 years. Apart from active measures, many more energy saving potentials can still be explored through passive strategies. Simulation method is used to establish energy baseline as the basis for predicting energy saving potential for passive strategies that cannot not be measured through energy audit. The combination of these methods is essential to optimize the potential of energy saving through active and passive strategies that have so far has never been implemented in any public hospital in Malaysia.

Fire safety evaluation of different internal insulation measures in European and Danish context

In about the last 10 years there has been an increased focus on energy upgrading the existing building stock. This have included several international and national projects dealing with internal insulation. Many of the studies have considered the internal insulation as a measure to achieve a specific energy consumption of buildings. Later, the focus has been on the durability of the ‘new’ structure with additional insulation on the internal side of walls, i.e. if the measure is moisture safe. These measures have been applied in both theoretical studies, laboratory and real buildings. None of the studies have reported whether or not the suggested retrofit measures fulfil respective fire regulations. The height of the building is also considered in fire regulations, and therefore, measures that are applicable in e.g. single-family houses might not be applicable in apartment buildings. This study includes a review of a number of different insulation materials and – systems used for internal insulation. These measures are evaluated against the EU-harmonized and Danish fire regulations, as many countries might have adapted national requirements. The study evaluates, whether the measure is applicable at all floor levels or not.

Cost optimal energy retrofit strategies for public administrative buildings: A Cairo case study

The Egyptian government is currently constructing a new governmental quarter in the New Administrative Capital City, located east of Cairo. A planned relocation for all ministerial authorities to the New Capital City will leave a vacant governmental estate in Cairo. The study of the energy retrofit options provides a unique opportunity to reduce energy use and maximize the benefit from the anticipated investment in the re-use to be implemented within this stock. However, energy retrofit was found to be under-researched in the Egyptian context. This paper presents a pilot study that aims to identify cost optimal retrofit strategies for one of the soon to be vacated buildings, the Central Agency for Public Mobilization and Statistics (CAPMAS). Using DesignBuilder, an energy modelling study was implemented to estimate the existing performance of the building, assess the projected performance after a change of use (to an office building), and evaluate the cost optimality and the savings associated with the application of retrofit measures. The study found that the feasibility of implementing retrofit can be significantly offset by the discount rates in Egypt. As such, maintaining economic stability and considering non-economic incentives can be key drivers to increasing the energy retrofit uptake in Egypt.

Impact of seismic retrofitting on progressive collapse resistance of RC frame structures

Most of the existing buildings in seismic prone regions have been built before the publication of modern design provisions against earthquakes, resulting in the need for structural retrofitting. Furthermore, some of those buildings are also subjected to additional hazards that may be either triggered by earthquakes (e.g., landslides, soil liquefaction, tsunamis) or associated with other natural or anthropogenic events, such as floods, vehicle collision, blast, and fire. A multi-hazard performance assessment of building structures is thus of paramount importance to implement integrated retrofit strategies, which otherwise would not be economically sustainable if oriented to structural risk mitigation against a single hazard. While retrofit strategies to improve the seismic performance of reinforced concrete (RC) structures have been widely investigated, structural retrofitting against progressive collapse has received very little attention. Within this context, the present paper illustrates a numerical investigation on the influence of seismic retrofitting on structural robustness of a four-storey, five-bay, RC frame building designed only to gravity loads. Seismic performance and structural robustness were respectively evaluated in OpenSees through pushover and pushdown analyses of a fibre-based finite element model. Structural robustness was evaluated under two relevant column-removal scenarios, i.e., the sudden loss of a central and a corner column, whereas earthquake resistance was assessed according to the N2 method, evidencing the need for seismic retrofitting. A retrofit measure based on carbon fibre reinforced polymers was then considered to avoid premature brittle failures. Analysis results show that this retrofit strategy was able to increase both seismic safety and structural robustness. Subsequently, a parametric analysis was carried out in order to evaluate the impact of beam span length and shear strength of the retrofitting system.

A parallel computing simulation-based multi-objective optimization framework for economic analysis of building energy retrofit: A case study in Iran

The building sector represents a large share of rising global energy demand. Improving energy efficiency in existing building stock is a crucial strategy. Adopting the best energy retrofitting strategy in a specific building is a challenging task due to a plethora of possible combinations of retrofit measures and mutually contrasting objective functions. In addition, peculiar conditions of Iran, such as extremely subsidized energy prices, and step utility tariffs, escalate the challenges of building energy retrofit. Accordingly, the current study presents a simulation-based multi-objective optimization framework characterized by parallel processing structure and results-saving archive. The framework is implemented by integrating MATLAB® as an optimization engine with EnergyPlus as a dynamic energy simulator to minimize primary energy consumption and discounted payback period while maximizing the net present value. The algorithm explores a vast domain of possible solutions including, building envelope, cooling and heating systems, and renewable energy sources. The framework is applied to a single-family residence located in Iran. Three different scenarios are examined with reference to prospective energy pricing policies to evaluate their effect on the attractiveness of energy retrofit projects. For each scenario, final solutions are selected from respective Pareto fronts according to cost-optimality and energy-efficiency criteria and considering budget constraints. The results indicate that even though significant reductions in primary energy consumption can be achieved, implementing energy retrofit under the current energy pricing policy in Iran would not yield economic benefits. However, the elimination of subsidies along with offering incentives for building energy retrofits presents promising outcomes.