Energy Efficiency Retrofit Measures Research Articles

Multi-objective optimization of energy-efficient retrofitting strategies for single-family residential homes: Minimizing energy consumption, CO2 emissions and retrofit costs

The retrofitting of buildings for improved energy efficiency has been recognized as crucial for achieving climate mitigation goals in Bosnia and Herzegovina (B&H). However, performing multi-objective optimizations for retrofitting existing buildings poses challenges, as it requires balancing conflicting objectives such as retrofit costs, energy savings, and CO2 reduction. To tackle this challenge, we employed a multi-objective analysis approach that aims to identify Pareto-optimal solutions for retrofitting, striking a balance between energy consumption, CO2 emissions, and retrofit costs. In this study, we utilized a combination of Full Factorial Design (FFD) and the state-of-the-art NSGA-III framework to evaluate energy-efficient (EE) retrofit strategies for residential buildings in B&H. The analysis was based on the existing building database from the national TABULA study, serving as a fundamental reference. By analyzing this data, we aimed to determine the optimal approach for EE retrofitting in single-family homes (SFH). Key results indicate that upgrading external walls and improving heating system efficiency are the most effective measures for reducing energy consumption and CO2 emissions. However, these measures come with higher retrofit costs. A multi-objective optimization approach identifies a set of non-dominated solutions representing energy efficiency retrofit measures with the lowest specific final energy for heating, specific CO2 emissions, and overall retrofit costs. The top-ranked set of measures achieves a Simple Payback Period (SPP) of 19.9 years. The insights gained from this study are intended to provide valuable guidance to decision-makers in formulating cost-effective and energy-efficient retrofitting strategies that simultaneously minimize annual energy consumption, CO2 emissions, and retrofit costs.

Decision-making method for building energy efficiency retrofit measures based on an improved analytic hierarchy process

A large number of building energy efficiency retrofit measures (EERMs) are currently available; however, the ultimate choice of which retrofit measures should be performed is determined by many factors. The aim of this paper is to explore an application of the analytic hierarchy process (AHP) to the selection of EERMs. However, some of the limitations in the current AHP model include a large computational comparison matrix, an incomplete evaluation system, and the difficulty of integrating multidimensional factors. This paper proposes an improved AHP method to overcome these shortcomings. The improvements to the AHP focus on the normalization of the data and the influence of subjective opinions. An evaluation system was built in combination with a life cycle cost analysis. Moreover, a judgment matrix was built from multiple experts through questionnaires and the distributions of the weight factors were calculated. Furthermore, the advantages are discussed through a case study, and the results are compared with other decision-making methods. It was found that the top ranking and less desirable EERMs showed little change when using multicriteria weighted decision-making, but some policy-oriented EERM rankings showed significant changes. The case study indicated that the presented approach significantly simplified complicated multicriteria decision-making problems.

Investment decision-making optimization of energy efficiency retrofit measures in multiple buildings under financing budgetary restraint

Regarding to energy efficiency retrofit investment to numerous buildings, which buildings should be invested and which of the retrofit measures should be implemented for investable buildings are challenging tasks. The current literature have studied on choosing energy efficiency retrofit measures in single building, relatively little attention has been paid to the retrofit investment decision-making in multiple buildings. In addition, the existing studies almost put the retrofit cost as an objective that need to be minimized, and the retrofit capital budget is not taken into consideration. This paper proposes a decision-making optimization framework for energy efficiency retrofit investment in numerous buildings under financing budgetary restraint. A multi-objective optimization model with the economic goals being the net present value and time of return, and the environmental goals being the energy saving and emission reduction is presented, and then the intelligent optimization method combing particle swarm optimization and genetic algorithm is designed to search the retrofit investment strategy. The obtained investment strategy could determine which of the buildings should be invested to retrofit, and the combination of retrofitting measures for every investable building. An empirical study is conducted on 27 buildings of non-governmental organization in the state of Delaware in the United States, and the results indicate that the validity of the proposed framework. The findings indicate that the framework is an effective approach to assist the sustainability goal at regional level.

Exploring the range of energy savings likely from energy efficiency retrofit measures in Ireland's residential sector

This paper estimates the potential energy savings in the Irish residential sector by 2020 due to the introduction of an ambitious retrofit programme. We estimate the technical energy savings potential of retrofit measures targeting energy efficiency of the space and water heating end uses of the 2011 stock of residential dwellings between 2012 and 2020. We build eight separate scenarios, varying the number of dwellings retrofitted and the depth of retrofit carried out in order to investigate the range of energy savings possible. In 2020 the estimated technical savings potential lies in the range from 1713 GWh to 10,817 GWh, but is more likely to fall within the lower end of this range, i.e. between 1700 and 4360 GWh. When rebound effects are taken into account this reduces further to 1100 GWh and 2800 GWh per annum. The purpose of this paper was to test the robustness of the NEEAP target savings for residential retrofit, i.e. 3000 GWh by 2020. We conclude that this target is technically feasible but very challenging and unlikely to be achieved based on progress to date. It will require a significant shift towards deeper retrofit measures compared to what has been achieved by previous schemes.

On input parameters, methods and assumptions for energy balance and retrofit analyses for residential buildings

In this study we explore key parameter values, methods and assumptions used for energy balance modelling of residential buildings in the Swedish context and analyse their effects on calculated energy balance of a typical multi-storey building from 1970s and on energy savings of energy efficiency retrofit measures. The parameters studied are related to microclimate, building envelope, occupancy behaviour, ventilation, and heat gains from electric appliances and persons. Our study shows that assumed indoor air temperature, internal heat gains and efficiency of ventilation heat recovery units have significant effect on the simulated energy performance of the studied building and energy efficiency measures. Of the considered microclimate parameter values and assumptions, the outdoor temperature, ground solar reflection and window shading have significant impact on the simulated space heating and cooling demands. On the contrary, the simulated energy performances are less affected by the variations in air pressure outside and the percentage of wind load that hits the building. We found that input data and assumptions used for energy balance calculations and energy saving analyses vary significantly in the Swedish context. These result in significantly different calculated final energy performance of buildings and energy efficiency measures. To inform accurate analysis of energy performance of building and energy saving measures, input parameters used in simulation models need to be appropriate.

Energy retrofit of historic buildings: Environmental assessment of cost-optimal solutions

This paper describes the implementation of an integrated cost optimality and environmental assessment involving alternative energy efficiency retrofit packages for a building that dates from the beginning of the 20th century. A building typical of the building stock in the centre of Coimbra (located in the central region of Portugal and recently classified as a UNESCO World Heritage Site) was used to illustrate the methodology presented. The results were also analysed for the same building in two other locations. A life-cycle (LC) model was implemented to assess different energy efficiency measures for an apartment. The economic assessment complied with European Directive 2010/31/EU. The results show that the lowest life-cycle environmental impacts were obtained for insulation thicknesses between 50 and 120mm, which are also cost-optimal. It is also shown that insulation thicknesses of more than 80mm do not improve energy efficiency or global cost reduction. This paper shows that, even though historic buildings in Portugal do not have to comply with building energy codes, significant energy savings can be achieved for them without changing their historic character. It was also concluded that economic and environmental costs can both be minimised by choosing the most suitable energy efficiency retrofit measures.

Energy efficiency investments in Kraft pulp mills given uncertain climate policy

Energy efficiency measures in pulp mills can potentially reduce the consumption of biofuel, which can instead be exported and used elsewhere. In this paper a methodology is proposed for analysing the robustness of energy efficiency investments in Kraft pulp mills or other industrial process plants equipped with biofuelled combined heat and power units, given uncertain future climate policy. The outlook for biofuel and electricity prices is a key factor for deciding if energy efficiency measures are cost competitive. CO2 emission charges resulting from climate policy are internalized and thus included in electricity and biofuel prices. The proposed methodology includes a price-setting model for biofuel that assumes a constant price ratio between biofuel and electricity in the Nordic countries. Thirteen energy efficiency retrofit measures are analysed for an existing Swedish Kraft pulp mill. Special attention is paid to heatintegrated evaporation using excess process heat. Four possible energy market development paths are considered that reflect different climate policies. Pulp mill energy efficiency investments considered are shown to be robust with respect to uncertain climate policy. Copyright # 2006 John Wiley & Sons, Ltd.

The impact of energy efficient refurbishment on the space heating fuel consumption in English dwellings

The aim of this study is to examine the effect of a major domestic energy efficiency refurbishment programme on domestic space heating fuel consumption. The case study dwellings were monitored either before or after (or both) the introduction of energy efficiency retrofit measures such as cavity wall insulation, loft insulation, draught stripping and energy efficient heating system. Property and utility consumption data were collected and half-hourly living room and main bedroom temperatures were monitored for 2–4 week period over two winters from a total of 1372 households selected from five major urban areas in England. Space heating fuel consumption was normalized to account for variation in the indoor–outdoor temperature difference and the dwelling floor area. The findings show that cavity wall and loft insulation can reduce the space heating fuel consumption by 10% in centrally heated properties and 17% in non-centrally heated properties. However, the introduction of a gas central heating system, although theoretically more efficient, has no significant impact in reducing fuel consumption even after adjusting for increased internal temperature.