Retrofit Measures Research Articles

Sustainable Retrofit of Existing Buildings: Impact Assessment of Residual Fluorocarbons through Uncertainty and Sensitivity Analyses

Fluorocarbons are an important category of greenhouse gas emissions, and currently, their use is prohibited due to their significant contribution to the global ozone depletion potential (ODP). During this century, they will continue to emit greenhouse gases into the environment since they are present in the thermal insulation foam and HVAC systems in existing buildings; however, proper disposal of these banks of CFCs/HFCs from existing buildings can limit their effects on the environment. However, there are no studies that have investigated quantifying the achievable environmental savings in this case. In this study, a comparative life cycle assessment (LCA) is conducted to evaluate, for the first time in the literature, the environmental savings achievable through the removal and disposal of CFC/HFC banks from buildings including damage-related emissions. To cope with the scarcity of data, uncertainty and sensitivity analysis techniques are applied. The results show that, for the selected archetype building, the largest annual emissions of CFCs/HFCs come from the external thermal insulation of the envelope. The removal of this material can lead to an additional significant reduction in the GWP (up to 569 kgCO2eq/m2) and the ODP (up to 117 × 10−3 kgCFC-11eq/m2), i.e., higher than that achievable by reducing energy consumption through energy retrofit measures (276 and 0, respectively). Thus, CFC/HFC banks should not be neglected in LCA studies of existing buildings due to their possible significant impact on a building’s ecoprofile.

A French Residential Retrofit toward Achieving Net-Zero Energy Target in a Mediterranean Climate

Cities are paying more attention to building energy use and carbon footprint for attaining sustainability. Within this building sector, there is a growing attention toward development and adoption of energy efficient retrofit strategies. Plagued by the lack of efforts in achieving comprehensive energy efficient retrofit solution sets (passive, active, and renewable energy systems), the authors acknowledge the concept of NZEB toward achieving energy efficiency by 2050. Toward this end, a numerical energy simulation modeling is carried out to retrofit an existing French “Puccini house” using ‘passive, energy efficient building systems and renewable energy’ strategies toward an NZEB target in the Mediterranean climate of Nice. Using Design builder 7.0, the simulated baseline energy model (Case A) is retrofitted through variations in the proposed energy efficient retrofit measures using two case scenarios (Case B: passive retrofit; Case C: energy-efficient building) to achieve NZEB (Case D). Assessing the performance of energy efficient retrofits using % energy reduction, the implementation of a high-performance building envelope is achieved using a thermally insulated external wall (46.82%), upgraded airtightness (20.39%), thermally insulated pitched roof component (33.03%), and high-performance window type—a glazing system (3.35%) with maximized window-to-wall ratio (5.53%). The maximum energy-saving retrofit solutions provide an ambitious reduction in energy consumption by approximately 90% from the baseline. A deep retrofitting of the French house meets the NZEB targets, as it reduces the baseline energy consumption from 194.37 kWh/m2/year to 23.98 kWh/m2/year using both passive and active strategies. The remaining energy demand is met by the integration of on-site PV panels (EUI= −27.71 kWh/m2/year), which achieve an increase in energy production by 15.5%, while returning energy back to the grid (−3.73 kWh/m2/year). Findings of this study serve as a guideline for retrofitting traditional French single-family residences, while contributing toward the NZEB goal.

Net-zero energy optimization of solar greenhouses in severe cold climate using passive insulation and photovoltaic

To take into account the crop growth of greenhouse and reduce energy consumption, this study investigated to optimize and retrofit a typical solar greenhouse in the severe cold climate of China into a net-zero energy solar greenhouse (NZESG). The envelope passive insulation measure and roof flexible photovoltaic (PV) technique are innovatively combined and some optimization cases were proposed based on simulation and analytical studies. The foamed cement insulation boards with different thicknesses and envelope positions were added as 11 passive insulation retrofit cases. The flexible PV panels in checkerboard (PV1), horizontal (PV2) and longitudinal (PV3) arrangements were positioned on the greenhouse roof and their electrical energy was estimated through PVsyst software. The optimal case was obtained based on the local technical standard for nearly zero energy consumption buildings and energy-saving, carbon reduction, payback period and cost multi-objective entropy weight method. The key finding is that passive energy-saving retrofit Case (a) & PV1 has the highest comprehensive score and is the optimal NZESG case. Its investment cost and payback period of Case (a) & PV1 are 45526.40 CNY and 5.23 years respectively. Case (a) adopts 50 mm foamed cement board with external insulation. Although the effect of energy-saving and CO2 reduction is poor, Case (a) has the shortest payback period and the lowest cost. PV1 has the lowest investment and higher power generation. It also shows that the investment payback period and cost weight are high, which are the key parameters for comprehensive evaluation of the retrofit cases; The entropy weight method is objective and scientific. The retrofit measures and optimization method can facilitate the promotion and application of NZESGs.

A cost-benefit analysis for the appraisal of social and market prices in the probabilistic seismic risk assessment of building portfolios: A methodology for the evaluation of disaster risk reduction programs

A cost-benefit analysis can be a milestone for the probabilistic seismic risk assessment of building portfolios. This approach appraises social, economic, and technical aspects as evaluation criteria, becoming a reliable method for more accurate feasibility evaluation of Disaster Risk Reduction (DRR) programs. This paper proposes a simplified methodological approach to estimate the feasibility of intervention campaigns directed to seismic retrofitting for building portfolios. Its feature is the number of variables it encompasses such as: multiple intervention levels, resource distribution, maximum repair time, direct and indirect losses, simplified seismic resilience, number of casualties, amount of replacement buildings, and expected service life. Then, all these factors are analyzed using a conventional probabilistic seismic risk assessment, followed by the estimation of net cash flows in terms of social and market prices. The final profitability and feasibility are determined based on investment indicators (Net Present Value, Internal Rate of Return, and Cost-Benefit ratio). In addition, plots of maximum repair time and simplified seismic resilience (as a function of the resource distribution) are proposed as novel decision-making tools. To illustrate the methodology, a case study of six building portfolios grouped into two categories is presented. The portfolios are conformed by a Peruvian school typology designated as 780-PRE, typically two-story high with reinforced concrete moment-resisting frames plus infill-walls and confined masonry walls. The demonstrative case included eleven target scenarios to assess the as-built and several intervention conditions, based on incremental seismic retrofitting measures. Results confirm that social prices influence the decision-making process, even making feasible projects that were initially unfeasible (when solely appraised under market prices). Finally, the authors propose further applications of this methodology as a tool to support the development of reliable DRR-programs.

A procedure set to construct the optimal energy saving retrofit strategy for old residential buildings in China

A key strategy for lowering emissions and reducing the effects of climate change is to execute energy-saving retrofits in residential buildings. Despite extensive research on different retrofit pathways for building energy efficiency, the current retrofitting of the aged housing stock in China is still constrained by several factors, including occupant willingness, government financial situation, and low energy prices, so retrofitting projects are almost entirely government-led and most of the solutions of existing studies are not applicable. Therefore, a comprehensive optimization framework for low-budget compliance retrofit strategies in the Chinese context is urgently needed. In order to fill this gap, this study established a set of procedures for developing an optimal energy-saving retrofit scheme in old residential buildings in Nanjing city. The results showed that the optimal scheme can reduce 18.52% of residential building energy consumption in five central districts of Nanjing City, and the total energy saving is about 260.43 GW h. The study also showed that improving wall insulation and heating, ventilation, and air conditioning systems were the most efficient retrofit measures but came at a high cost. Setting a reasonable air conditioning target temperature was further identified as the most cost-effective retrofit measure. This study provided a mechanism for district-level retrofit planners to formulate a strategy that may take the performance of retrofitting on the environment and the economy into account while still adhering to code requirements.

Rethinking decision‐making about home improvements

Rethinking decision‐making about home improvements

How does future climatic uncertainty affect multi-objective building energy retrofit decisions? Evidence from residential buildings in subtropical Hong Kong

Energy consumption of and carbon emissions from buildings, which substantially depend on outdoor climate conditions, may be susceptible to future climate change. However, how future climatic uncertainties affect decision-making regarding building energy retrofits is unclear from the life-cycle analysis perspective. This study used typical high-rise public rental housing buildings in subtropical Hong Kong as a case study to consider future climatic uncertainties under representative concentration pathway scenarios and in different general circulation models to estimate their effect on multi-objective building retrofit decisions considering trade-offs among different objectives, namely, life-cycle economics, life-cycle carbon emissions, and operational energy use impacts. The results indicate the significant influence of future climatic uncertainties on the optimal values of building energy retrofit measures. The passive house infiltration standard and thick (0.06–0.1 m) polyurethane foam insulation can be recommended for long-term future climatic conditions (RCP8.5–2065s). By contrast, optimal values of glazing materials, horizontal shading projection factors, and window-to-wall ratio are not susceptible to future climatic uncertainties. Uncertainties from different general circulation models are another notable factor affecting optimal values and retrofit options. This study reveals the importance of considering future climatic uncertainties when deciding optimal values and selecting building energy retrofit options.

Retrofitting Historic Buildings for Future Climatic Conditions and Consequences in Terms of Artifacts Conservation Using Hygrothermal Building Simulation

Climate change will greatly influence the world at several levels and will have consequences on the interior climate of historic buildings and artifacts conservation. Buildings are responsible for a large slice of the overall emissions, which is due both to the greenhouse gases that are released during their construction as well as the activities that are performed therewithin. One way of counteracting this trend is to design more efficient retrofit buildings and predict their behavior using simulation software, which can thoroughly assess the performance of new buildings or the impact of each retrofit measure for existing buildings. In this study, a calibrated computational model of high thermal inertia building was used to assess the performance of passive retrofits in mitigating the effects of climate change concerning artifact decay mechanisms. In addition, a methodology that aims to reduce the amount of time spent to perform these studies is also presented, in which time savings reach up to 63%.

Potential impact of work from home jobs on residential energy bills: A case study in phoenix, AZ, USA

Nearly one-third of U.S. households face challenges paying energy bills. During the day, many residents have routine access to cooled environments provided by others—employers, shopping centers, and other public buildings. The COVID-19 pandemic, however, has significantly shifted the cost burden of air conditioning in hot cities. Specifically, during the pandemic, many companies either laid off employees or put them in work-from-home (WFH) assignments. Large tech companies are already promoting WFH as a long-term option for their employees, even after the pandemic. This change in the nature of the workforce might reduce daily travel expenses for workers, but could also significantly increase residential energy bills, particularly during summer in very hot climates. This study uses building energy simulations to quantify the potential residential energy bill penalties resulting from WFH for typical residences in Phoenix. Four building archetypes are used in this study to represent variations in building vintage, occupancy, and characteristics. The results show that, for some single-family residences in Phoenix, WFH can increase annual energy bills by more than $1100 (up to a 70% increase). The study also demonstrates that building performance enhancement retrofit measures have the potential to reduce this WFH energy bill penalty for the existing buildings substantially.

Energy futures of representative Swiss communities under the influence of urban development, building retrofit, and climate change

Reducing energy demand in buildings is an integral part of many climate change mitigation strategies. Yet, the prospected development of communities is often overlooked when estimating future energy demand. Here, we investigate the future energy demand in representative Swiss communities, considering climate change projections, building retrofit and urban development. Following a scenario-based approach we model urban, suburban and rural community archetypes under changing boundary conditions and different time scales using the City Energy Analyst an open-source computational framework. The results demonstrate that the future energy demand of Swiss communities is highly dependant on their development trajectories regarding population growth, occupant density and building use-types. For the urban archetype, the most significant result is the increase of annual space cooling which by 2060 could be comparable to space heating. For the sub-urban, increases in energy demand due to urban development were observed despite retrofit measures, whereas the rural archetype displays high space heating demand across all scenarios. Consequently, predictions for future energy demand at the community scale without considering urban development trajectories are likely to be incomplete. The results demonstrate the relevance of increasing the modelling scale from national to community scale to support decision making on different levels of governance.

Affordability assessment of passive retrofitting measures for residential buildings using life cycle assessment

Climate change impacts have been increasingly noticeable worldwide, especially as energy concerns have increased. Because buildings consume significant amounts of energy, sustainably retrofitting existing buildings has become essential. However, several countries are pretty concerned about the affordability of retrofitting and energy conservation measures. Therefore, this research assesses the affordability of selected passive heating and cooling retrofitting strategies using the residual approach methodology. Specifically, this work studies the effects and efficiency of retrofitting the residential buildings in Irbid, Jordan, through life cycle analysis, where dynamic thermal simulation (IES-VE) is employed. This strategy determines the required heating and cooling loads, the life cycle carbon dioxide emissions, and the economic feasibility of retrofitting using the Net Present Value methodology. The results show that passive building retrofitting can generate considerable economic and environmental benefits. Additionally, the affordability assessment reveals that retrofitting measures are affordable for 73–78% of Jordanian households. Furthermore, retrofitting makes the energy required for building conditioning affordable for 82.8–85.8% of households. This affordability assessment proved that the initial investment cost of retrofitting is the major obstacle to implementing it, especially for low-income households, despite the long-term economic and environmental benefits of this process. Thus, governmental financial support for the retrofitting projects would support achieving the sustainable development goals and mitigating climate change impacts.

Performance-Based Retrofits of Long-Span Truss Bridges Based on the Alternate Load Path Redundancy Analysis

Existing long-span truss bridges typically undergo significant retrofits to improve their resistance against extreme load events, such as the seismic loads, for which the bridge may not have been designed or considered originally. However, the conventional seismic retrofit measures recommended in most existing codes and specifications may not be effective in providing sufficient alternative load path (ALP) redundancy to a bridge that is vulnerable to sudden member-loss scenarios because of the significantly different magnitude of demands. This paper proposed a performance-based retrofit (PBR) approach for long-span truss bridges that are vulnerable to sudden member-loss scenarios. The performance of the bridge has been evaluated by using the demand-to-capacity ratio (DCR) or strain ratio (SR) on the member/component level or the displacement factor on the bridge system level as indicators. Based on the analysis results, the argument is made that the proposed PBR approach allows bridge designers to meet the predetermined performance objectives for sudden member-loss loading conditions. Increase in weight of steel because of such the ALP retrofits is less than 10%. The retrofitted bridge would meet the desired performance levels in the event of sudden loss of any members on the primary trusses of the bridge.

A responsive double-skin façade for the retrofit of existing buildings: Analysis on an office building in a Mediterranean climate

The history of our planet has always been characterized by climate change, but the way in which this change has been taking place in recent decades puts us in front of a real climate crisis, for which man is primarily responsible. Among the sectors affected by the energy transition process, that of construction is in the foreground, especially with reference to existing buildings. This study proposes a dynamic envelope based on the double-skin façade (DSF) technology as retrofit measure for an existing building office located in a city with a Mediterranean climate. The methodology used is of an experimental type, using DesignBuilder® and EnergyPlus software, for the energy modeling and simulation phases respectively. The responsiveness of the proposed facade is obtained through the controlled opening of the windowed components of the internal and external surface of the DSF, which allows for the establishment of an airflow. Furthermore, for the summer season, a shading system with dynamic activation controlled by the temperature is proposed. Compared to the current state of the building, the impact on energy consumption for the thermal load is between −17.8 % and −37 %, while for the cooling load it is between +9 % and −3%, based on the configuration adopted. With the best solution, a total primary energy saving of 20 % is obtained.

Long-term carbon intensity reduction potential of K-12 school buildings in the United States

School buildings have a great potential for carbon emission reduction since their annual emission is about 72 million metric tons. Currently, more than 30 % of school buildings were built before 1960 and are underperforming. To effectively reduce carbon emissions via school building retrofits, it is critical for policymakers to understand the carbon intensity reduction potential of retrofitting school buildings in different regions. Hence, this study develops a method to comprehensively assess the long-term carbon intensity reduction potential of aggregated commercial buildings on a county-by-county basis in the continental U.S. We apply this method to the K-12 school buildings including primary and secondary school buildings. This paper predicts the carbon intensity reduction potential of K-12 school buildings with eight building retrofit measures from 2022 to 2050 in the continental U.S. The results reveal several interesting findings: (1) In the approximately 3,000 counties of the U.S. from 2022 to 2050, the carbon intensity reduction potential of retrofitting K-12 school buildings in each county ranges from 0.41 kg/m2 to 40.00 kg/m2. (2) Even in the same climate zone, the trends of carbon intensity reduction potential from 2022 to 2050 are different depending on their electricity sources. For example, in a hot and humid climate zone, the carbon intensity reduction potential in Florida will decrease from 2044 to 2048. However, in Mississippi, the carbon intensity reduction potential from 2044 to 2046 will increase due to the termination of the nuclear energy usage. (3) Generally, reducing lighting power density leads to more carbon intensity reduction in most states, but it might not be applicable for states with high clean energy penetration, such as Washington.

Review on Thermal Energy Audit of Pyro-Processing Unit of a Cement Plant

Energy consumption in cement factories is an important issue for the government as well as private organizations. The cement manufacturing industrial sector has become the worldwide energy consumer accounting for over 40% of overall energy consumption by the industrial sub-sector. Most of the thermal energy consumption by a cement manufacturing plant occurs in the Pyro-processing unit. Thus, the energy audit of the cement plant is an essential exercise to promote energy retrofitting measures. The aim of the energy audit is to reduce energy consumption in the plant, reduce energy costs and identify possible Energy Conservation and Management Opportunities (ECMOs). The aim of this study was to review the techniques of energy auditing which include Mass (Material) balance and Energy balance by considering energy conservation in the form of thermal energy that helps to fill the gap in energy efficiency improvement, policy development, and environmental analysis. Using the operational data of Kiln system of Messobo Cement obtained from the literature, the heat losses were quantified for major energy consuming components of the system using both the mass and thermal energy balance approach. The production line's capacity for clinker was 145.4 tons per hour, and both burners received a combined 25 tons of coal per hour. Energy balance tests were conducted in all areas of the pyro processing systems, and the findings revealed significant energy losses from the surface of the kiln systems, kiln exhaust, and cooler exhaust.

Seismic risk reduction through retrofitting of school masonry buildings from Romania

Retrofitting the existing building stock is needed since it can cause significant losses as in case of a damaging earthquake, particularly in structures used for public services, such as schools. Effective and optimal seismic retrofitting measures applied to existing masonry constructions should arise from a strong understanding of the vulnerabilities associated with each structural typology and construction practice. Using representative structural configurations of the masonry buildings used in the education sector from Romania, the paper aims to evaluate the seismic risk associated to the existing buildings and to support informed decision-making for seismic retrofitting measures. Starting from a broad database of school masonry buildings, potential losses were evaluated considering two seismic hazard scenarios. For an earthquake having a 63% exceedance probability in 50 years, losses estimated for the education sector comprising masonry structures reached almost 240 mil. € and 2,500 potential casualties. For highlighting that investments in retrofitting masonry structures from the education sector lead to significant reductions of potential losses, prioritization criteria were proposed and cost–benefit analysis was carried out for about 15,000 buildings. Results are presented through graphs and maps that illustrate the distribution of annual failure probabilities at the national level. Therefore, the methodology proposed and the results presented in this paper can represent a valuable tool for substantiating public policies aiming at reducing the seismic risk, in particular for existing masonry structures.

Contract decisions analysis of shared savings energy performance contracting based on Stackelberg game theory

Energy Performance Contracting is a contractual arrangement between energy users and Energy Service Companies (ESCOs) and is currently the main mechanism for implementing energy-saving retrofitting measures in existing buildings. The paper centers around the decision-making conundrum pertaining to the energy-saving sharing percentage and initial project investment within the realm of shared savings Energy Performance Contracting. By formulating a Stackelberg game-based decision-making game model, we examine the optimal contract decisions of both the energy user and the ESCO. The results of numerical experiments demonstrate that this method yields significant advantages for both energy users and ESCOs. Additionally, we observed that the employment of more sophisticated energy-saving technologies by the ESCO and a higher share of investment by the energy users result in superior energy-saving efficiency.

Understanding current retrofit practices to prevent the unintended consequences affecting IEQ and health

The climate crisis demands an urgent societal shift, and the UK government has responded with a strong policy targeting energy retrofit to improve the energy performance of homes to achieve the net zero target by 2050. However, research has shown that standard retrofit measures have resulted in undesirable unintended consequences. Incorrect interventions such as using incompatible materials can affect the equilibrium of the building, increasing the risk of surface and interstitial condensation due to excessive humidity levels. Mould growth may develop under high levels of humidity, damaging the building fabric but also posing a risk to the occupants; it has been linked to asthma exacerbation and other respiratory infections. Therefore, what is needed is a well-integrated retrofit approach that not only reduces energy use but protects the building and the health and well-being of its occupants. This paper discusses the retrofit practices, the main challenges that retrofit practitioners face in the UK, and which guidance and tools they work with through the lens of the impact on occupants. A deeper understanding of the current practices is needed if those unintended consequences are to be avoided. For instance, replacing a 'fabric-first' mindset with a 'people-first' approach that considers more factors like the causes of thermal discomfort, and the gains to be made from passive and adaptive comfort approaches, could contribute to deliverer energy and carbon savings and increased building's indoor environment quality and usability justified.

Application of McKinsey Curve in Building Emission Reduction Technology

In order to promote the application of McKinsey energy reduction cost curves in buildings, This paper introduces the concept of McKinsey abatement cost curves, the current application status of building abatement measures and abatement cost data, makes an analysis for the economic characteristics of different energy efficiency measures in retrofit projects, and presents the retrofit measures, annual energy savings and investment costs used in retrofit programs by taking the example of energy efficiency retrofits in office and commercial buildings in the past 2 years, discloses the data changes in abatement costs for some energysaving retrofit technologies contrastingly, and suggests that dates should be iterated based on McKinsey abatement cost curves. The McKinsey abatement cost ctuve is usefill for guiding the selection of building energy efficiency measures. The curve is economical and visualized compatibly and is a good reference for making abatement decisions through timely updating the data of retrofit technologies and influencing factors.

Energy performance assessment of a post-retrofit office building using measurement and verification protocol: A case study from KSA

Buildings account for over one third of the global energy consumption and greenhouse gas emissions. While new buildings are being sought to be more efficient, retrofitting of existing building is also critical to improve the energy and environmental sustainability of the building sector. Measurement and Verification (M&V) based energy retrofitting studies are becoming important in presenting the case for energy retrofit solutions. This work presents an energy performance assessment of a retrofitted office building using the International Performance Measurement and Verification Protocol (IPMVP) option B to conduct the M&V. The building, an office block with a built-up area of 7,500 m2, is in the Eastern Province of Saudi Arabia. The work carries out a detailed energy audit of the building to investigate the energy saving opportunities. Of the identified options, five energy efficiency measures (EEMs) are implemented. The energy performance of the building is also helped by the installation of a rooftop Photovoltaic (PV) system. The results indicate that retrofit measures helped reduce the Energy Use Index (EUI) from 458.9 kWh/m2/year to 361.4 kWh/m2/year. The economic analysis finds the compound payback period for the investments to be six years.