Energy Efficiency Retrofit Research Articles

Positive Energy District: A Model for Historic Districts to Address Energy Poverty

The Positive Energy District (PED) concept has been pointed out as key for cities' energy system transformation toward carbon neutrality. The PED may be defined as an energy-efficient and flexible urban area with net-zero energy import and greenhouse gas emissions, aiming toward annual local surplus of renewable energy. Most of the studies and practical experiences about PEDs are based on newly built districts, where the planning and integration of innovative solutions are less complex and more cost-effective. However, to achieve Europe Union's 2050 carbon-neutral ambition, we argue that the transformation of the settled districts is essential, including historic districts, which present common challenges across European cities, such as degraded dwellings, low-income families, and gentrification processes due to massive tourism flows. This paper aims to discuss how the PED model can be an opportunity for historic districts to reduce their emissions and mitigate energy poverty. The historic district of Alfama, in the city of Lisbon (Portugal), is used as a case study to show the potential of energy renovation measures and solar PV production in households, cornerstones of a PED. The annual energy needs potential reduction due to building retrofit is 84 and 19% for space heating and cooling, respectively, while the integration of building-integrated PV technologies in rooftops and windows potentially generates up to 60 GWh/year. At the district scale, these two components of the PED concept could require an investment of 60M€ to 81M€ depending on the PV technologies in the rooftops, a sensitive aspect in historical districts. Unlike other mechanisms to tackle energy poverty, like the social tariffs, the adoption of structural measures like building energy efficiency retrofit and renewable energy integration will contribute to solve the energy poverty problem, which is significant in Alfama, in both the winter and summer. The highlighted investments require an innovative financial scheme to support not only buildings' owners but also tenants, as these are among the most vulnerable to energy poverty. However, the social benefits of that investment, on the health system, air quality, climate resilience, labor productivity, and social integration, would be invaluable.

Energy and CO2 emission reduction potential from investment in energy efficiency building retrofits in Bangkok, Thailand

ABSTRACT A major barrier to the widespread adoption of energy efficiency is the lack of understanding of the benefits - the investment opportunity (the returns), the cost savings, and environmental. We assess the potential of retrofits in commercial buildings in Bangkok using case studies and existing property information. The aim is to provide insights for policy makers, building owners, and investors on the potential to reduce energy consumption and costs, and greenhouse gas emissions. Our findings suggest that by undertaking energy efficiency retrofits in Bangkok, there is the potential to reduce energy costs by approximately US123 million and reduce over 500,000 tons of CO2 emissions per year, presenting an investment opportunity of approximately US300 million, with a payback of 3.49 years.

Assessing electricity and CO2 emission savings through energy efficiency measures in shopping malls in India: a feasibility study of appliance retrofit

Purpose Energy-efficient retrofitting of existing buildings is an inexpensive way of reducing energy consumption and mitigating climate change impacts. The purpose of this study is to examine electricity savings and carbon dioxide (CO2) emission reduction potentials of energy-efficient retrofit measures for surveyed two large shopping malls in India. Design/methodology/approach A techno-economic model was developed to estimate the electricity savings achieved due to energy-efficient retrofit measures in shopping malls that were surveyed in 2017. Alternative scenarios were constructed based on capital cost and cost of conserved energy (CCE) value for retrofit measures: cheapest replacement, best available technology and best value for money. The life-cycle electricity and CO2 emission savings and payback period for end-use retrofit measures were evaluated. Findings The estimated average electricity savings were around 39–56% for various retrofit measures across all three scenarios while the average CO2 emission reductions were around 50–125 kt-CO2. Retrofits to light-emitting diode lights and air conditioners with inverter technology offered more life-cycle electricity savings. Paybacks for most lighting end-use measures were estimated to be within 1.5 years while for most space conditioning end-use measures were between 1 and 4 years. Originality/value The primary survey-based comprehensive research makes an exclusive contribution by estimating life-cycle electricity savings and CO2 emission reductions for energy-efficient retrofit measures of lighting and space cooling end-use appliances for existing shopping malls. The present research methodology can also be deployed in other types of commercial buildings and in residential buildings to estimate electricity savings from energy-efficient retrofit measures.

Progress in silica aerogel-containing materials for buildings’ thermal insulation

Silica aerogels hold remarkable properties, particularly their translucence/transparency and extremely low thermal conductivity and density, for buildings thermal insulation purpose. Incorporated in composites or framing systems, they reduce the overall weight of the building envelope while increasing its thermal resistance, being especially valuable for energy-efficient retrofitting solutions, spanning from covering façades to window panes. This review presents the production process of silica aerogels in brief, their relevant properties regarding building’s needs, and a full survey of last years’ scientific achievements on silica aerogel-containing materials for buildings, such as panels, blankets, cement, mortars, concrete, glazing systems, solar collector covers, among others.

Active–passive combined energy-efficient retrofit of rural residence with non-benchmarked construction: A case study in Shandong province, China

Unlike standard-restricted and well-equipped urban residential buildings, a large portion of rural buildings sacrifice indoor comfort and energy efficiency to reduce the initial investment. Therefore, cost-effective retrofit strategies for rural buildings are urgently needed to better living conditions and create higher energy efficiency. This study developed a framework to choose the optimal economical retrofitting strategies for existing rural buildings by taking both active and passive approaches into consideration. The building retrofitting measurements were a combination of thermal performance improvement for external walls and a solar photovoltaic generation system for the rooftop. With the case of a rural dwelling in Shandong province, this study first assessed the thermal transmittance of the external walls and collected geometry and operational schedules to create a building model for the later energy simulation. Environmental monitoring was also conducted for two months – in February for winter and August for summer – to obtain actual indoor temperatures, which were used to calibrate the energy model within a 10% error rate. In total, 17 retrofitting plans were then set up and analyzed in this study. The results showed that when applying the cost-optimal retrofit plan, there is the great potential to reduce energy use by 20.5% and to balance the annual building energy consumption with a payback period of 10.7 years. Finally, the proposed framework was proven to be accurate and feasible and was expected to be widely used in the improvement of living conditions in Chinese rural areas.

Homeowners’ Willingness to Make Investment in Energy Efficiency Retrofit of Residential Buildings in China and Its Influencing Factors

In China, energy efficiency retrofit of residential buildings is entering a new stage in which homeowners are the main subject. In order to investigate homeowners’ willingness to invest and to analyze its influencing factors, interviews and a questionnaire survey were conducted in central Tianjin, China. The results show that homeowners have a certain willingness to invest in energy efficiency retrofit but that their willingness to pay (WTP) is far from enough to cover the total cost. Among the influencing factors, the homeowner’s age, education level, and retrofit experience as well as the age and floor area of their home are significantly related to their WTP. The reasons for the impact of these factors are further discussed, including the influences of China’s previous housing policies and retrofit policies. Policy recommendations to promote investment by homeowners are suggested based on the findings.

Factors influencing radon concentration during energy retrofitting in domestic buildings: A computational evaluation

The findings of recent research signalled increased radon levels following energy retrofitting of dwellings but to date, there have been limited quantitative data to support this observation. A modelling framework was developed that incorporates a dynamic radon entry rate, capturing changes in pressure differentials, to investigate changes in radon concentration following different energy-efficient retrofit measures in naturally-ventilated dwellings. Simulations examined a range of input criteria: dwelling type, air permeabilities, radon flow exponents, pre and post thermal retrofit characteristics, outdoor weather locations and corresponding wind profiles, as well as different ventilation guidelines. A total of 3,780 simulations were carried out. The air permeability of the building had the greatest impact on radon concentration with increases of up to 107%. Non-linear increases were observed arising from the impacts on pressure differentials due to changes in air permeability. The application of representative weather profiles associated with different locations (e.g. coastal, inland) resulted in differences of up to 37%. To a lesser extent, increased indoor temperature due to thermally retrofitting the building fabric, without changes in air permeability, resulted in radon levels increasing by 7%. Additionally, it was shown that the radon flow exponent was not a significant influence on radon concentrations following a retrofit. The addition of ventilation measures means that it is possible to achieve increased airtightness without impacting on the radon concentration. Overall, the simulations provide quantitative information that explains increased airtightness and elevated radon levels, highlighting the potential for radon concentrations to either increase or decrease following an energy retrofit.

What motivates building repair-maintenance practitioners to include or avoid energy efficiency measures? Evidence from three studies in the United Kingdom

Domestic energy-efficiency retrofit is an essential component of achievement of UK decarbonisation policy targets. UK policy strategy however has tended to focus on technology and new-build, with the implication of inadequate engagement with issues relating to the practitioners in the repair-maintenance-improvement (RMI) sector who work on energy-efficiency retrofit of the existing building stock. Addressing a gap in the literature on deep understanding of what is important to these practitioners, the study offers a novel application of a theoretical framework of behaviour change. Three datasets were aggregated, of semi-structured interviews with RMI practitioners around the UK. Template analysis was applied to the 31 transcripts. Focusing on motivation, evidence was found for motivations including pride in work, variety and challenge, working independently, maintaining a viable business, positive working relationships and customer satisfaction. Personal commitment to energy efficiency and co-benefits such as reduced condensation were additional motivating factors. Demotivations, which encouraged behaviour away from greater energy efficiency, included perceptions of increased cost, lack of confidence in technical standards, habit, and perceived burden of compliance. Implications for policy are proposed, including a reminder that profit is not necessarily a primary motivator for micro-enterprises, that changing attitudes is as important as providing information, and that all aspects of the context in which RMI practitioners operate must be considered in order to formulate effective policy.

The greater the investment, the greater the loss? – Resource traps in Building energy efficiency retrofit (BEER) market

Building Energy Efficiency Retrofitting (BEER) is an important measure to relieve energy pressure, conserve natural resources and promote urban low-carbon transformation . Governments of various countries have invested huge resources to promote the rapid development of BEER market. However, when the amount of resource input exceeds a certain threshold, the market will deviate from the desired state, falling into a resource trap and cutting consumer welfare. This is due to the fact that BEER service providers take advantage of their dominant position in the market and increase their own revenues by enhancing product heterogeneity. To make matters worse, the greater the government's effort, the earlier the resource trap appears and the more resource loss it causes. Incentives and penalties for service providers became necessary to guide the market to cross resource trap. The research in this paper is conducive to promoting the healthy development of the BEER market, conserving natural resources and promoting urban low-carbon transformation.

Developing a Calcium Silicate Prefabricated Board Ventilated Wall for Building Energy Efficiency Retrofit in Hot-Humid Areas

Ventilated wall is considered as an effective technique for building energy efficiency retrofit in hot-humid areas, and the heat exchange inside the ventilated layer blocks the heat gain into the wall. Most current researches focus on the performance assessment of the wall system but lack the optimize design of the external board. Here we demonstrated a new type of ventilated wall, using the calcium silicate material as the cladding panel for its excellent physical properties and easy installation and maintenance. In particular, the aluminum foil was attached to the interior side of the board to further lower the emissivity for achieving a better insulation effect. Based on the field experiment in summer days, the thermal performance of the new type of ventilation wall was obtained and further compared with the conventional wall. Moreover, the equivalent thermal resistance of this novel ventilated wall was also calculated. The results revealed that: the interior wall surface temperature and energy consumption of the new ventilated wall proposed was about 3-5°C and 39.2% lower than those of the conventional wall, respectively. The low emissivity significantly insulated the heat transfer inside the cavity. In parallel, the calculated equivalent thermal resistance of the ventilation wall (0.971m2⋅K/W) was also 2.07 higher than that of the conventional wall.

EVALUATION OF ENERGY-EFFICIENT RETROFIT POTENTIAL FOR GOVERNMENT OFFICES IN INDIA

Introduction: High energy consumption by buildings is a great threat to the environment and one of the major causes of climate change. With a population of 1.4 billion people and one of the fastest-growing economies in the world, India is extremely vital for the future of global energy markets. The energy demand for construction activities continues to rise and it is responsible for over one-third of global final energy consumption. Currently, buildings in India account for 35% of total energy consumption and the value is growing by 8% annually. Around 11% of total energy consumption are attributed to the commercial sector. Energy-efficient retrofitting of the built environments created in recent decades is a pressing urban challenge. Presently, most energy-efficient retrofit projects focus mainly on the engineering aspects. In this paper, we evaluate various retrofitting options, such as passive architectural interventions, active technological interventions, or a combination of both, to create the optimum result for the selected building. Methods: Based on a literature study and case examples, we identified various energy-efficient retrofit measures, and then examined and evaluated those as applied to the case study of Awas Bhawan (Rajasthan Housing Board Headquarters), Jaipur, India. For the evaluation, we developed a simulation model using EQuest for each energy measure and calculated the resultant energy savings. Then, based on the cost of implementation and the cost of energy saved, we calculated the payback period. Finally, an optimum retrofit solution was formulated with account for the payback period and ease of installation. Results and discussion: The detailed analysis of various energy-efficient retrofit measures as applied to the case study indicates that the most feasible options for retrofit resulting in optimum energy savings with short payback periods include passive architecture measures and equipment upgrades.

Life Cycle Carbon Emission Analyzing of Rural Residential Energy Efficiency Retrofit-A Case Study of Gansu province

Objective To study and analyze the life-cycle carbon emissions of existing rural residential energy retrofit projects to provide theoretical and data support for local rural green development and sustainable construction. Methods Life cycle analysis (LCA) was used to analyze and compare the life cycle carbon emissions (LCE) of a rural residential envelope energy efficiency retrofitting project in central Gansu. Results It was found that rural dwellings have a very high potential for energy efficiency retrofitting, and the contribution of retrofitted homes to CO2 emissions reduction can reach more than 30% over the whole life cycle. Secondly, during the retrofitting process, neglected in previous studies, carbon emissions account for about a quarter of the LCE. It is concluded that introducing LCA into evaluating rural residential energy retrofit projects' energy-saving and emission reduction benefits is more scientific, reasonable, and necessary.

Novel Data-Driven Building Electricity Consumption Prediction Method for Public Buildings Based on Historical Data and K-Nearest Neighbor-Matrix Algorithm

The energy crisis is one of the most serious crises in modern society. In this context, building energy prediction is more and more important, as it can guide energy management and efficiency retrofitting, especially for public buildings that often have more energy-using equipment and larger numbers of users. However, existing physical modeling methods and data-driven methods are difficult to predict suitably and accurately. Therefore, the KNN-Matrix algorithm method is developed. It introduces the concept of fuzzy quantification levels for electricity intensity, and uses historical data (after screening and processing) as the prediction data. The validation results on nine buildings with different functions and climate zones show that the average of hourly prediction error is 13.1%. This algorithm relies only on historical data without simulation software and unpredictable parameters as the initial conditions. Moreover, this algorithm can better address noise data, allowing for better accuracy and less data volume.

Comprehensive Benefits Evaluation of Solar Water Heating System Application in Energy Efficiency Retrofit of Existing Residential Buildings in Cold Climate Zone

The application of renewable energy in energy efficiency retrofit of existing residential buildings is very important for energy conservation and emission reduction. Promoting the application of solar water heating system is conducive to the construction of comprehensive technical system for energy efficiency retrofit of existing residential buildings. Based on the case study, this research uses the comprehensive benefits evaluation methods to evaluate solar water heating system application in energy efficiency retrofit of existing residential buildings in cold climate zone, and concludes that the payback period and internal rate of return are 13.5 years and 4.11% respectively. It is suggested that electricity should be chosen as the auxiliary energy of solar water heating system and the government should increase subsidies and develop incentive mechanisms to encourage the application of solar water heating system.

Data-driven correlation model between human behavior and energy consumption for college teaching buildings in cold regions of China

Correlation models between human behavior and energy consumption of teaching buildings are crucial for devising energy efficiency strategies. Especially in teaching buildings in campus, on one hand, the investment is limited and the level of operation and maintenance is low. On the other hand, the certain management system exists, and the flow of occupant in campus is also regular obviously. So, it is difficult for large-scale technical retrofits and possible for management retrofits. In order to the low-cost management retrofits, the model between human behavior and energy consumption are studied in this paper. According to the models, on the one hand, managers of campus can predict energy consumption based in historical, for matching energy consumption supply and demand each other. On the other hand, managers can judge future human behaviors based on historical energy consumption, for conducting management to reduce energy consumption. In this paper, first, correlation models between the energy consumption and human behavior are proposed and the lighting management level coefficient K is defined to evaluate the lighting management level. With the aid of the correlation models and K, managers can obtain management strategies to increase energy efficiency without large-scale technical retrofits. The verification results show that the proposed strategies could bring a 13.96% economic benefit ratio. Second, correlation models between human behavior and influencing factors of human behavior are proposed for predicting human behavior. Finally, a technical route of energy efficiency retrofit by management is suggested and validated. Although the energy-saving ratio is not conspicuous, the cost is low and the operation is easy. It means that the technical route is worthy for research and promotion.

Prioritizing Decision Factors of Energy Efficiency Retrofit for Facilities Portfolio Management

AbstractImprovements to building energy efficiency are critical to a more sustainable future. In this paper, an analytic hierarchy process method was applied to systematically highlight how experts...

Residential retrofit in the UK: The optimum retrofit measures necessary for effective heat pump use

The Department for Business, Energy & Industrial Strategy and the Committee on Climate Change place high dependency on the electrification of heat and use of heat pump systems to achieve net zero emissions by 2050. Energy efficient buildings are essential for effective heat pump operation. However, the UK’s housing stock is amongst the least energy efficient in Europe. Household electricity demand will increase with heat pump use, meaning reinforcement to infrastructure and generation capacity. This study uses dynamic simulation modelling to determine the optimum energy efficient retrofit required to minimise energy use and electrical demand for an average semi-detached dwelling using a heat pump. Solid wall insulation is found to be critical in energy abatement, although the heat pump operates at a high demand compared with low voltage network design. A whole house retrofit in-line with current Building Regulations reduces the heating demand and emissions by 65%, and lowers the input electrical demand for the heat pump to under 1 kW. Solid wall insulation and low U-value glazing are the cost-optimal solution, achieving similar abatement. Measures that exceed building regulations are shown to lower heat demand and carbon emissions by almost 80%, highlighting scope for improvement in retrofit standards. Practical application: At present, UK policy makers have a preferred alternative to high carbon fossil fuels that is a system heavily reliant on heat pumps powered by low carbon electricity. Heat pump systems require energy efficient buildings to operate effectively. A key factor when improving building efficiency is fabric standards, which can dramatically impact the heat transfer coefficient. Retrofit of energy efficiency measures is key to future net zero success and will have large implications to consumers and supply chains alike.

IEQ and energy effect analysis according to empirical Full Energy Efficiency Retrofit in South Korea

The purpose of this study was to analyze energy performance along with the effect on the improvement in the indoor environment and air quality through the empirical case of the Full Energy Efficiency Retrofit (EER) in Korea. To increase the improvement effect objectivity, changes before/after the Full EER were measured and compared through various special equipment. The Full EER implementation through energy diagnosis, indoor environment, and air quality measurement led to the derivation of seven areas of improvement. Considering the efficiency of energy cost, the optimal full EER model of alternatives based on the area was selected, and passive design techniques were applied to enhance improvement effect during design and construction.After building the Full EER, the Predicted Mean Vote (PMV)/Predicted Percentage of Dissatisfied (PPD) satisfied the criteria (before the Full EER: unsatisfied) regarding the indoor environment. Concerning indoor air quality, more than 30% improvement was observed in all the items except CO2, and criteria were met. Considering changing heat source equipment, improvement in energy performance was compared by converting the usage of energy into carbon emission; it was reduced by 5.9% and 2.7% on a cooling/heating basis, respectively, and by approximately 12% ($14,000) regarding annual energy consumption cost.This result is expected to facilitate future Full EER activation by mitigating uncertainty regarding energy consumption cost for the Full EER improvement effect and demonstrating additional improvements related to the indoor environment and air quality.

Social Versus Private Benefits of Energy Efficiency Under Time-of-Use and Increasing Block Pricing

Many energy policies are implemented to subsidize the adoption of energy efficiency. However, when private benefits from energy efficiency exceed the social benefits, there is an incentive for the consumers to over-invest in energy efficiency; otherwise, there is an incentive to under-invest. This study adds to this discussion by providing an empirical estimation of the electricity savings and social benefits after energy efficiency retrofits for consumers on time-of-use (TOU) and increasing block pricing, respectively. We aim to examine how social versus private savings from a given energy efficiency measure may be different depending on different pricing plans. This study applies hourly electricity data for about 16,000 residential consumers during 2013–2017 in Arizona. We show that for the TOU consumers, the private savings from energy-efficient AC retrofits are greater than the social savings by 61%, while the increasing block rate consumers’ private savings exceed the social savings by 46%, when other market failures are not considered (e.g., principal-agent problem and imperfect information). Different rate plans impose different marginal electricity prices which influence the incentives to invest in energy efficiency as well as electricity consumption behaviors that can influence both the private and social savings from energy efficiency. The result indicates that there should be potentially different levels of policy interventions towards energy efficiency for consumers on different pricing. Additionally, we also find that energy efficiency makes the electricity demand more elastic to price changes.

Performance evaluation and sustainable, cost-effective and energy-efficient process enhancement measures for Pagla sewage treatment plant, Bangladesh

At present, Pagla Sewage Treatment Plant (STP) is the only sewage treatment plant in Dhaka, the capital city of Bangladesh, with a capacity to treat 120 million litres per day (MLD) of sewage. Evidence suggests that the plant is overburdened and cannot by itself handle the wastewater generated in Dhaka. Furthermore, the treatment plant is hampered by a number of functional problems which limit both its capacity to treat wastewater, and the efficiency of the treatment process. Rectifying the functional problems of the plant and implementing enhancement measures would greatly improve the functionality of Pagla STP. A thorough evaluation was carried out on the performance of the plant and a detailed process flow diagram developed. Several functional problems were identified, mostly pertaining to the primary sedimentation tanks and the unused sludge lagoons. The influent and effluent characteristics of Pagla STP were also assessed using BOD5 values as the primary criteria. It was found that the influent BOD5 value was 832 mg/L and effluent BOD5 was 497.5 mg/L, against design values of 120 mg/L and 50 mg/L respectively. Based on the evaluation, theoretical analysis was done, and a sustainable, cost and energy efficient retrofit was proposed whereby the sludge lagoons would be converted to anaerobic lagoons to facilitate biological pretreatment. It is estimated that implementing such an enhancement would increase the treatment capacity of the plant beyond its original design. Furthermore, theoretical calculations show up to 5,000 m3 of methane gas can be generated daily from the plant, which is enough to power 6,000 homes with renewable energy.