Worldwide, the residential buildings are consuming a considerable amount of energy. The high potential of buildings towards energy efficiency has drawn special attention to the passive design ...parameters. A comprehensive study on optimal passive design for residential buildings is presented in this paper. Twenty-five different climates are simulated with the aim to produce best practices to reduce building energy demands (for cooling and heating) in addition to the life-cycle cost (LCC). The occupants' adaptive thermal comfort is also improved by implementing the appropriate passive cooling strategies such as blinds and natural ventilation. In this respect, the implemented methodology is composed of four phases: building energy simulation, optimization, Multi-criteria Decision Making (MCDM), sensitivity study, and finally an adaptive comfort analysis. An optimal passive solution of the studied building indicates the potential to save up to 54%, 87% and 52% of the cooling demands (Qcool), heating demands (Qheat) and LCC respectively with respect to the initial configuration. The obtained optimal passive parameters are validated with the National Renewable Energy Laboratory NREL benchmark for low energy building's envelope. Additionally, the integrated passive cooling strategies have demonstrated its competency since it leads to a significant overheating decrease.
•Residential building's passive design parameters are optimized.•Effect of different climates of Köppen Geiger classification is studied.•Thermal comfort and energy performance of the case-studies are significantly enhanced.•Passive cooling strategies lead to adequate thermal comfort and fewer cooling systems.
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•Heating system is the most crucial parameter for renovation.•Deep renovation is neither cost-effective nor climate-friendly considering future uncertainties.•Heating system ...replacement alone has lower overall emissions than solely envelope renovation.
Buildings are responsible for a large share of CO2 emissions in the world. Building renovation is crucial to decrease the environmental impact and meet the United Nations climate action goals. However, due to buildings’ long service lives, there are many uncertainties that might cause a deviation in the results of a predicted retrofit outcome. In this paper, we determine climate-friendly and cost-effective renovation scenarios for two typical buildings with low and high energy performance in Switzerland using a methodology of robust optmization. First, we create an integrated model for life cycle assessment (LCA) and life cycle cost analysis (LCCA). Second, we define possible renovation measures and possible levels of renovation. Third, we identify and describe the uncertain parameters related to the production, replacement and dismantling of building elements as well as the operational energy use in LCCA and LCA. Afterwards, we carry out a robust multi-objective optimization to identify optimal renovation solutions. The results show that the replacement of the heating system in the building retrofit process is crucial to decrease the environmental impact. They also show that for a building with already good energy performance, the investments are not paid off by the operational savings. The optimal solution for the building with low energy performance includes the building envelope renovation in combination with the heating system replacement. For both buildings, the optimal robust cost-effective and climate-friendly solution is different from the deep renovation practice promoted to decrease the energy consumption of a building.
The aim of this article is to report a comprehensive review of life cycle assessment (LCA) and life cycle cost (LCC) implication on residential buildings. It discusses the contemporary issues, and ...its relationship and significance of system boundary, assumptions, and reports how it effects on economic and environmental impacts. The tools, frameworks and processes of LCA and LCC of buildings are also discussed. It critically illustrates the existing LCA and LCC studies on residential house designs to determine the causes for the widely varying results of numerous previous studies. It evaluates life cycle cost and life cycle environmental impacts of a case study building, and compares with very similar LCA and LCC studies. Finally, it reports the implications and perspectives of LCA and LCC studies on building designs.
Nowadays, to protect the interests of customers, many warranty policies take into account the limit of repair time and the limit of repair number. Under a rebate warranty policy, the seller has to ...give a refund to the customer according to the rebate warranty contract if the number of product failures or a single repair time for failure exceeds some certain limits. Minimal repair is conducted when the product fails, and the repair cost is charged to seller during the warranty period. After warranty expires, the product continues operating for a period of time before being replaced. The repair cost during the post-warranty period is undertaken by the customer. From the customer’s perspective, the expected life cycle cost rate of the warranty product is derived. By minimizing the expected cost rate, the existence and uniqueness of the optimal maintenance strategy for the warranty product are proven theoretically. Finally, as an example, the warranty car under the protection of “lemon laws” is studied to illustrate the proposed rebate warranty model.
•The warranty product has a repair time limit and a repair number limit.•The refund amount is related to the working time of the product.•The constraint that the repair time of the product is far shorter than its working time is removed.•The repair cost of the product is based on its repair time rather than being constant.•The unique optimal maintenance strategy is proven theoretically.
The present study aims to assess the possibility of achieving net zero energy building in the Moroccan housing stock by combining architectural energy efficiency practices and renewable energies for ...hot water and electricity productions. The impacts of retrofitting an existing residential building to meet zero energy balance in the six Moroccan climatic zones have been investigated. The design features considered include building orientation, windows type and Window-to-Wall Ratio, wall and roof insulation and infiltration rate. A multi-objective optimization has been carried out in order to find the best solution which will allow a compromise between the building life cycle cost, energy saving and thermal comfort through the optimization of the aforementioned design parameters as passive energy efficiency measures. The obtained results show that the application of the multi-objective study conclusions combined with an efficient use of renewable energies makes it possible to achieve zero energy building throughout all Moroccan housing stock. More than 21% of energy saving can be achieved, 28% in heating load and 40% in cooling. Moreover, 45% of building energy load can be covered instantly by renewable energy systems in all Moroccan climatic zones. On the other hand, the comparison of levelized cost of energy shows that Tangier is the city with the greatest potential for wind energy system and other cities are expected to present a challenge since the areas for efficient on-site generation of photovoltaic and solar thermal collectors are limited.
•Various scenarios for achieving net zero energy building have been discussed.•A multi-objective optimization approach has been carried out to find the best solution.•The building life cycle cost, energy saving and thermal comfort have been considered.•More than 21% of energy saving can be achieved, 28% in heating load and 40% in cooling.
•A multi-criteria methodology for the analysis of retrofitting solutions is proposed.•LCA and LCC are combined by expressing environmental impacts in monetary values.•A Pareto optimization is used to ...select the preferred strategies.•The methodology is illustrated by a case study in Madrid, Spain.•Business as usual scenario is far from being an optimal solution.
The building sector is well known to be one of the key energy consumers worldwide. The renovation of existing buildings provides excellent opportunities for an effective reduction of energy consumption and greenhouse gas emissions but it is essential to identify the optimal strategies. In this paper a multi-criteria methodology is proposed for the comparative analysis of retrofitting solutions. Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) are combined by expressing environmental impacts in monetary values. A Pareto optimization is used to select the preferred strategies. The methodology is exemplified by a case study: the renovation of a representative housing block from the 1960s located in Madrid. Eight scenarios have been proposed, from the Business as Usual scenario (BAU), through Spanish Building Regulation requirements (for new buildings) up to the Passive House standard. Results show how current renovation strategies that are being applied in Madrid are far from being optimal solutions. The required additional investment, which is needed to obtain an overall performance improvement of the envelope compared with the common practice to date, is relatively low (8%) considering the obtained life cycle environmental and financial savings (43% and 45%, respectively).
The life cycle cost and environmental impacts of electric vehicles are very uncertain, but extremely important for making policy decisions. This study presents a new model, called the Electric ...Vehicles Regional Optimizer, to model this uncertainty and predict the optimal combination of drivetrains in different U.S. regions for the year 2030. First, the life cycle cost and life cycle environmental emissions of internal combustion engine vehicles, gasoline hybrid electric vehicles, and three different Electric Vehicle types (gasoline plug-in hybrid electric vehicles, gasoline extended range electric vehicle, and all-electric vehicle) are evaluated considering their inherent uncertainties. Then, the environmental damage costs and the water footprint of the studied drivetrains are estimated. Additionally, using an Exploratory Modeling and Analysis method, the uncertainties in the life cycle cost, environmental damage cost, and water footprint of studied vehicle types are modeled for different U.S. electricity grid regions. Finally, an optimization model is coupled with Exploratory Modeling and Analysis to find the ideal combination of different vehicle types in each U.S. region for the year 2030. The findings of this research will help policy makers and transportation planners to prepare our nation's transportation system for the influx of electric vehicles.
•An electric vehicle regional optimization model is created to address uncertainty.•Life cycle cost, environmental cost, and water footprint range of vehicles are modeled.•Internal combustion vehicles have lowest cost, highest environmental impact.•Electric vehicles have relatively low cost and lowest environmental impact.•The optimal U.S. fleet mix in 2030 will consist of electric and gasoline vehicles.
Early design decisions made by architects have been shown to significantly impact the energy performance of buildings. However, designers often lack the resources or knowledge to take informed ...decisions that might improve building performance. The refurbishment of existing buildings is considered to significantly contribute to the reduction of the life cycle environmental impact of buildings. Building refurbishment is also seen as the most cost-effective way of achieving this goal. In assessing the life cycle impacts of constructing and usage processes of buildings, LCA (life cycle analysis) is often used.
In order to simplify the decision-making process in early design, this study uses MOGA (multi objective genetic algorithms) to find optimal designs for a refurbishment of a residential complex case study, in terms of LCCF (life cycle carbon footprint) and LCC (life cycle cost) over an assumed life span of 60 years.
Results show that utilizing MOGA has the potential to reduce the refurbishment LCCF and LCC. Findings emphasize the life-cycle impacts of insulating thermal bridges and the importance of using different heating systems and fuels. Finally, in comparing LCA with more commonly used performance-based decision-making design procedures, the study highlights that employing these distinctive methods can lead to different design solutions.
•We use Multi Objective Genetic Algorithms to optimise refurbishment designs.•We used Life Cycle Carbon Footprint and Life Cycle Cost as objective criteria.•MOGA chose a design with the thickest insulation and smallest available windows.•The utilization of MOGA has the potential to reduce LCCF and LCC.•Thermal bridge insulation and different fuel types can impact LCCF and LCC.
In the present work, water desalination by solar energy is investigated based on life cycle cost. In the first step, regions under consideration are prioritized for solar energy utilization applying ...an appropriate ranking method based on desalinated water demand, saline water availability, annual average solar irradiation, and local water tensions. TRNSYS software is used for simulation and a multi-stage flash desalination system is defined in this software as a new component type by employing the Fortran program. Solar troughs and natural gas are used for solar energy extraction and heater, respectively. The considered system is investigated in seven different cities with high solar potential from the economic point of view. Also, an economic comparison is conducted in order to assess the multi-stage flash desalination system utilizing solar collector, auxiliary heater, and the system using natural gas without solar system. In this regard, the life cycle cost method is applied. The results of the study showed that using solar energy is more economical in comparison with natural gas for all of the case studies and the highest saving is obtained for Port Hedland in Australia. The lowest cycle cost of the system, utilizing solar energy and natural gas, is observed in Hurghada. In Hurghada, 88% of the energy required by the system is supplied by sun, and this city benefits the most from solar energy compared to other cities. Los Angeles and Manzanillo had the lowest share of solar energy at 59% and 57%, respectively.
Abstract
A planning tool was developed which is able to integrate renovation strategies on district level as a combination of energy efficiency upgrades for buildings and the use of renewable energy ...deliver positive energy districts. It combines elements of energy master planning, district development and optimization in a Modelica environment by combining energy demand, circularity and stakeholder engagement on the demand side and life cycle costs in multi-objective optimisation on the supply side. Thus, the tool consists of six dedicated modules for optimizing positive energy districts (PED).
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