Energy Retrofitting Of Residential Buildings Research Articles

Energy savings potential and life cycle costs of deep energy retrofits in buildings with and without habitable style loft attic conversions: A case study of Irelands residential sector

This paper evaluated the potential energy and life cycle cost (LCC) savings arising from the deep energy retrofit of residential buildings. The cost optimal model was determined for material upgrades and the addition of an air-to-water heat pump, where the household level of savings at 2023 energy prices will be dependent on the typical housing characteristics and weather conditions. LCC savings post retrofit for a detached dwelling insulated at the ceiling/rafter including installation of a heat pump amount to a €20,031-€21,370 for an uninsulated dwelling pre-retrofit, rising to €38,448 for dwellings with a habitable loft conversion. Partially insulated dwellings, pre-retrofit did not all incur favourable returns in investment, and in some cases were unviable. Although, the application of a 50% grant results in a viable return on investment for home owners. A sensitivity analysis found high discount rates, fuel prices and increasing capital costs can negate positive returns on investment. Finally, at a national level energy saving of 7.72 TWh by 2030 could be realised if the Irish Climate Action Plan 2023 retrofit targets are adhered to. In addition, total LCC savings could be valued at €1.4 billion. Where only material upgrade are pursued a loss occurs of €0.56 billion.

Assessing energy efficiency at urban scale through the use of energy performance certificates: An application in the Emilia-Romagna region, Italy

Energy retrofitting of residential buildings is considered a challenge to be tackled not only at building level, but also at urban scale, to give a stronger impulse for a concrete transition towards climate neutrality. This paper presents an easy-to-use analysis method based on the elaboration and scaling-up of data collected through the energy performance certificates (EPCs) to identify different urban energy zones distinguished by their energy performance index. This method is therefore conceived for better informing urban planning decisions, thus boosting more effective energy-sensitive urban planning strategies and eventually to foresee dedicated financial instruments to act in the more energy demanding areas of the city, establishing priorities for integrated strategies. This analytical method has been applied and tested in one municipality in the Emilia-Romagna region, Italy, where the recent urban planning law is pushing municipalities towards the development of urban planning strategies oriented to drastically improve the energy efficiency of the existing building stock. Results show that only a small number of areas manage to reach a good performance with fairly low levels of energy performance index, with the most critical situation found in the most central areas of the capital and in the hamlets.

Assessment of operational and embodied energy in passive residential retrofitting strategies for the Mediterranean climate

This study contributes to the research of lifecycle environmental impact in buildings’ passive strategies, specifically passive strategies incorporated during the energy retrofitting of residential buildings in the Mediterranean climate. With a simplified lifecycle methodology, this research considers operational and embodied energy and CO2 emissions calculations to compare the results of the two passive strategies and the existing dwelling. In a 50-year reference period, results show that the operational improvement gained with the passive strategy can be reduced or cancelled due to the consideration of the embodied energy and CO2 emissions attributed to the additional materials.

Multi-Criteria Decision Analysis for Energy Retrofit of Residential Buildings: Methodology and Feedback from Real Application

Decision-making in energy retrofit of existing buildings needs to consider the economic and technical criteria, as well as social and environmental ones. The main problems are to define and to aggregate these contradicting issues to support a measurable and verifiable decision process. The working hypothesis of this paper is that the ELECTRE Tri method would respond to the problem. The paper proposes and tests in a real professional environment the ELECTRE Tri method to help choose a retrofit program for collective residential buildings. The evaluation criteria used as performance indicators are defined in consultation with the decision maker and weighted by using the revised Simos’ cards method. The paper proposes to construct the renovation scenarios by combining individual actions that are mutually compatible. The methodology, the proposed criteria and the scenarios were successfully applied on a renovation project of a residential assembly composed of three buildings (67 apartments). A new solution to the problem of defining reference scenarios specific to the ELECTRE Tri method is also proposed. The main advantages of the proposed methodology are the formalization of the decision-making process within the framework of energy renovation strategies and the application of a robust multi-criteria analysis method, considering the complexity of the problem. The main drawbacks are the cost (in time and resources) for obtaining the information needed to construct the decision matrix and the precision of the weights of the criteria. The methodology implemented in Python is available in open source.

Exploring key risks of energy retrofit of residential buildings in China with transaction cost considerations

Energy retrofit of residential buildings is an approach to reduce worldwide energy consumption. Residential energy retrofitting in China mostly focuses on multi-owner residential buildings with composite ownership that dozens of private homeowners own their apartment and jointly own the common parts of a building. The implementation of residential energy retrofit faces many risks, causing the slow retrofit process in the hot summer and cold winter (HSCW) zone of China. Transaction cost theory (TCT) is conducive to enrich an in-depth understanding of risk inventories in the energy retrofitting context. This paper aims to explore the key risks in retrofit projects of residential buildings in the HSCW zone with transaction costs (TCs) considerations, in order to provide the direction for effective risk management. First, based on the theoretical risks with TCs considerations, interviews were conducted to adjust the risk list and to connect these risks with stakeholders and stages. Second, a questionnaire survey was made based on two parameters of risk probability and severity, and then ten top risks were chosen as key risks through both a risk matrix and Borda count. The results show that most of the key risks are associated with homeowners and contractors, involving retrofit awareness, cooperation performance, opportunism, professional expertise, construction management, safety management, and maintenance, of which most occur at the stage of on-site construction. Information cost is the largest source of TCs relevant to these key risks and is mainly borne by the government and homeowners. TCs can also provide a lens for the retrofitting in other countries to understand risks, and the decrease in information costs contributes to effective risk management both in China and in the international context.

Techno-Economic Assessment of Energy Retrofitting Educational Buildings: A Case Study in Saudi Arabia

The buildings and construction sector accounts for the majority of the energy consumption in the Kingdom of Saudi Arabia (KSA). For a sustainable future, energy consumption in the sector should be reduced and existing buildings need to be energy retrofitted. A number of studies present energy retrofitting of residential buildings in KSA; however, there is a lack of studies presenting retrofitting of educational buildings. Thus, the aim of this study is to adopt a BIM-based approach to assess Energy Conservation Measures (ECMs) in a prototypical Government-built educational building in Dammam, KSA. The methodology consists of six prime steps, (1) case study data collection, (2) energy auditing, (3) proposing ECMs, (4) BIM model development, (5) energy assessment, and (6) economic assessment. The energy audit revealed several inefficiencies in the building construction and operation and four ECMs were proposed and simulated. It was found that annual energy consumption can be reduced by 22.7% in the educational building, and the investment for the four ECMs is paid back in 2.7 years only. Therefore, implementing the proposed ECMs is a viable option to energy retrofit such educational buildings in the country, and the presented BIM-based approach can be adopted to efficiently conduct the energy retrofitting process.

LEARNING FROM THE PAST TOWARD ENERGY RESILIENT STRATEGIES IN HISTORIC DISTRICTS. A CASE STUDY IN APULIA REGION (ITALY)

Abstract. The high exposure of future changes in temperature trends in the southern part of Mediterranean area encouraged scientific community in defining strategies aiming at the reduction of cooling needs as short and long-term goals. Furthermore, local urban properties and their transformation contribute in altering microclimate at the micro-scale. Focus on a specific part of urban built stock, historic districts represent an exception in managing processes of recovery and energy retrofit strategies due to their landscape values; moreover, these districts show their recent transformations caused by the previous abandonment phase and, often, consequent loss of blocks. In that context, the paper shows the representative case study of historic district of Molfetta, in Apulia region (Italy): here, the energy assessment takes into account the effect of the abandonment of the district during 60s on the in use residential built stock in a temporal-climate prediction. As it was well demonstrated in previous experiences, strategies for the energy retrofit of residential buildings in historic district should allow to identify their inherent bioclimatic behaviours according with the genius loci evidences; furthermore, recognize and correct previous failures represent the opportunity to “learn from the past” in the “resilient thinking” process, above all after traumatic events.

Stakeholders’ Risk Perception: A Perspective for Proactive Risk Management in Residential Building Energy Retrofits in China

The implementation of energy retrofit of residential buildings faces many risks around the world, especially in China, leading to low retrofit progress. Stakeholders’ proactive risk management is the key to the smooth implementation of retrofit projects but is normally affected by risk perception. Perceived risks instead of real risks are the motivators of their proactive behaviours. This paper aims to understand and address the present risk perception of stakeholders in order to drive effective proactive risk mitigation practices. Based on a risk list identified through a literature review and interviews, a questionnaire survey was then made to analyse and compare different stakeholders’ perceptions of each risk by measuring the levels of their concern about risks. It is validated that all the stakeholder groups tend to mitigate risks perceived highly proactively. Proactive risk management of risk-source-related stakeholders deserves more attention and responsibility-sharing with transaction costs (TCs) considerations contribute to the enhancement of risk perception. More responsibilities of construction quality and maintenance is taken by the government and contractors should be clarified, and the government should also be responsible for assisting design work. Effective information is beneficial to the decrease in homeowners’ risk perception that can motivate their initiative of cooperation.

Potential for energy savings in Czech residential building stock by application of a prefabricated mass retrofitting system

Buildings are responsible for a significant share of EU energy consumption. To improve energy efficiency of the building stock, it is needed to significantly increase renovation rates. To overcome actual barriers related to this problem, such as partial and non-systematic renovations, lasting unrest during renovation or time-consuming wet processes, an industrialized construction system using prefabricated modular elements seems to be a possible way. Such system for mass energy retrofitting of residential buildings in Central Europe was developed in H2020 project MORE-CONNECT. The work presented in this article aimed to roughly estimate potential yearly energy savings by applying this new modular retrofitting system on one typology segment of the Czech residential building stock: non-renovated multifamily residential buildings built between 1946 and 1960 with total gross floor area covering over 7 million square meters. The main objective of the research presented in this paper was to make a hypothetic rough estimation of potential yearly energy savings by applying the new modular retrofitting system on a target typology of the Czech residential building stock. According to the calculations, application of proposed retrofitting system on the chosen building type would reduce the total energy consumption in Czech residential buildings by 2.9 % and by 1.8 % compared to energy consumption in all Czech buildings.

Lessons learnt from design, off-site construction and performance analysis of deep energy retrofit of residential buildings

The article introduces the process of deep energy retrofit carried out on a residential building in the UK, using a ‘TCosy’ approach in which the existing building is completely surrounded by a new thermal envelope. It reports on the entire process, from establishing the characteristics of the existing building, carrying out design simulations, documenting the off- site manufacture and on-site installation, and carrying out instrumental monitoring, occupant studies and performance evaluation. Multi-objective optimisation is used throughout the process, for establishing the characteristics of the building before the retrofit, conducting the design simulations, and evaluating the success of the completed retrofit. Building physics parameters before and after retrofit are evaluated in an innovative way through simulation of dynamic heating tests with calibrated models, and the method can be used as quality control measure in future retrofit programmes. New insights are provided into retrofit economics in the context of occupants’ health and wellbeing improvements. The wide scope of the lessons learnt can be instrumental in the creation of continuing professional development programmes, university courses, and public education that raises awareness and demand. These lessons can also be valuable for development of new funding schemes that address the outstanding challenges and the need for updating technical reference material, informing policy and building regulations.

MedZEB: a new holistic approach for the deep energy retrofitting of residential buildings

The MedZEB (Mediterranean Zero Energy Building) approach aims at stimulating the market uptake of energy deep and beyond retrofitting of existing buildings of the Mediterranean. Its holistic nature implies the evaluation and integration of a range of relevant factors and the effective support to the retrofitting supply chain, also with the help of an ICT platform. Main concern of the approach are residential buildings within a framework dealing with High TRL levels and with already on the market technologies to be combined to create Med-specific cost-optimal Packages of technical Solutions, linked to a Voluntary Certification Scheme. The triggered creation of trust and information exchange will pave the way to new investments and strengthen the Med deep and beyond retrofitting network.

Environmental assessment at the urban level combining LCA-GIS methodologies: A case study of energy retrofits in the Barcelona metropolitan area

This study proposes a combined life cycle assessment (LCA) and Geographical Information Systems (GIS) methodology to develop complex LCA inventories for multiple applications. The study focusses on the environmental implications of buildings retrofits, especially in the European context, where the building sector is one of the largest energy consumers. In this context, a new and holistic perspective is needed that expands from the building scale to the urban scale.The combination of LCA and GIS methods includes the development of an urban characterization model based on bottom-up methodologies. The environmental implications associated with increasing the thermal insulation of existing buildings to the current standard are determined based on LCA methods. In this step, common construction systems for building retrofits are used, and insulation materials are compared. Then, absolute and relative extrapolations are performed considering different urban morphologies.The results confirm the importance of the energy retrofitting of residential buildings in large functional urban areas such as the Barcelona metropolitan area, which is examined as a case study. The LCA results indicate that the selection of proper construction systems and thermal insulation materials is important to the environmental performance of building retrofits, and these selections can lead to CO2 emission differences of up 16% in the region. The relative extrapolation results indicate significant environmental differences between urban morphologies. The LCA results show the potential strategic impacts of the inclusion of LCA methods in retrofit policies at the urban scale.

Energy retrofitting of residential buildings—How to couple Combined Heat and Power (CHP) and Heat Pump (HP) for thermal management and off-design operation

Cogeneration (CHP) and Heat Pump (HP) are playing a key role in energy systems due to their high efficiency, especially, in energy refurbishment of buildings and industrial processes. This paper explored the opportunity to couple those two well-established technologies for heating purposes. Basically, the coupling entails limitations and constraints consisting of the mismatch between the power sizes of merchandised machines as well as the deriving technical issues. The main aim of this paper is to analyse the coupling procedure to help HVAC specialists in their job. This paper deals with a simple model formulation, based on the First Law of thermodynamics, for CHP/HP systems rating and off-design operations. Indeed, an analytical method was designed along with the definition of a size factor. Then, a graphical method for coupling CHP and HP was presented so as to be an expeditious tool in designing phase. Finally, two numerical applications were illustrated highlighting the energy performance gains and the high level of operation flexibility.

Economic Evaluation of Financial Incentive Schemes for Energy Retrofit Projects in Residential Buildings

Even if the EU has made important progress towards meeting its climate and energy targets for 2020, the effects of financial instability due to the economic crisis are still apparent, especially in the southern European countries, acting as a great obstacle for residents to invest in energy retrofit projects in order to improve their house energy performance. EU Member States striving to limit the risks that such investments entail and to aid with high upfront costs, are using financial incentives in the form of funding schemes, grants, tax exemptions/reductions etc. as a way of spurring investments in energy efficient services and technologies. Within this framework, the current study deals with the financial attractiveness of incentive schemes for energy retrofitting of residential buildings that are set in three European countries (Cyprus, Greece and UK). The methodology followed uses, as a first step, three case studies of typical residential buildings, one for each country, for the computation of pre-retrofitting and post-retrofitting energy demands. Material and labor costs that apply in each country together with energy costs and economic parameters are taken into account in order to sum up the initial energy upgrade budget for each case. The second step regards the computation of investment criteria such as NPV and IRR and the analysis is formed for a 30-year period to account for the life-cycle of a building using economic parameters such as Discounting and Inflation Rates. Then, the particulars of each country’s funding scheme are incorporated into the economic model to reveal their benefits and evaluate their attractiveness. The final output of the study comprises a comparative analysis of the current funding schemes using Present Worth as an indicator for the evaluation of their application in each country. DOI: http://dx.doi.org/10.5755/j01.sace.16.3.16200