The Qinghai-Tibet Plateau is rich in solar energy resources (SER), and the operation conditions of office buildings are consistent with the daily fluctuations in solar radiation. Solar heating for ...office buildings on the plateau has great potential. To obtain the optimal capacity ratio of solar heating system (SHS) for office buildings in plateau area, an optimization model of SHS capacity matching was established. The minimum life cycle cost (LCC) was taken as the objective function, and collector area, tank volume and auxiliary heat source (AHS) power as the decision variables in the model. The Qinghai-Tibet plateau was divided into five typical regions, and optimization was carried out for each region. The results show that the system LCC optimized by the intermittent heating load is 12% lower than that calculated by the average intermittent heating load and 44% lower than that calculated by the average parameter method for Lhasa. From an economic perspective, the AHS is suitable for electric boilers or gas boilers in regions with rich or general SER and cold regions with abundant SER. The AHS is suitable for electric boilers, air source heat pumps, or gas boilers in severely cold regions with abundant SER.
•The economic analysis of office building solar heating system was studied.•An optimization model of solar heating system capacity matching was established.•The suitability of auxiliary heat source in Qinghai-Tibet Plateau was analyzed.•The office building solar heating system on the plateau had a high solar fraction.•The optimized system had good energy saving and environmental protection.
•Optimising insulation thickness for the building’s envelope.•Eco-efficiency analysis of life cycle and cost assessment.•Sensitivity analysis by varying the building’s energy demand ...scenarios.•Emerging naturally-based insulation materials were the most eco-efficient.
Thermal insulation materials play an important role in the challenge of nearly zero-energy buildings thanks to their potential in reducing building’s energy demand and carbon emissions. However, increasing the thickness of the insulation material in the building’s envelope has implications from the energy, environmental and economic viewpoints. In this context, efforts should be made to optimise insulation thickness to balance all these aspects.
This study presents a methodology to analyse optimum insulation material for the building’s envelope (roof, façade and floor) and its thickness to achieve energy demand reductions in the operation phase of the building, which is based on the Life Cycle Assessment and Life Cycle Costing methodologies to integrate both environmental and economic aspects, respectively. The system boundary includes the life cycle stages of product and use defined by recent European standards. A selection of eleven alternative insulation materials, both conventional and emerging ones based on natural products, were chosen to conduct the study. After applying the methodology to a single-family house in Spain and performing a sensitivity analysis, the results revealed that sheep wool and recycled cotton, jointly with traditionally used mineral and glass wool, should be promoted in the construction industry as they offer the highest eco-efficient performance among the analysed insulation materials. Reductions of up to 40% in energy demand compared to regulations standards can be achieved in theeco-efficiency context.
•4E analysis of a building integrated photovoltaic thermal system is investigated.•The scenario is based on the variation via glass windows and PV module surface area on the outer façade.•A scenario ...with the highest PV module surface area with a payback time of 1.58 (years) has been suggested.•The life cycle revenue of 55,157 ($) is suggested as a feasible retrofit measure as a result of the (4E) analysis.
In this research paper, energy, exergy, economic and environmental analysis of a building integrated photovoltaic thermal system is investigated. To cover the aim of the research, the impact of a system as a retrofit solution for the existing office building has been evaluated in different scenarios through various key performance indicators including generated electricity, energy and exergy efficiency, greenhouse gas emission reduction and life cycle cost. The scenario development for the analysis is based on the variation between glass windows and photovoltaic module surface area on the outer façade. According to the results of the study, a scenario with the lowest photovoltaic module and highest glass windows surface area has been suggested due to the highest energy efficiency, lowest initial investment, lowest energy consumption and emission for manufacturing. Besides, a scenario with the highest photovoltaic module and zero glass windows surface area has been suggested because of the highest lifetime generated and avoided energy and emission reduction, lowest payback time and greenhouse gas rate as well as highest life cycle revenue. In conclusion, a scenario with the highest photovoltaic module surface area with a payback time of 1.58 years and a life cycle revenue of 55,157 (USD) has been suggested as a feasible retrofit measure as a result of the energy, exergy, economic and environmental analysis.
Due to low efficiency of a basic CO2 transcritical cycle, the feasible system scheme of CO2 is studied to replace R134a for heat pump heating. Three modified CO2 systems are discussed for home ...heating, in which a transcritical CO2 cycle system combining technologies of two-stage compression, vapor injection and inter-stage cooling (CO2 HPTSC, VI, ISC) is proposed based on the other two modified CO2 systems. Meanwhile, they are evaluated with two basic systems of CO2 and R134a in energy, environment and economy. All modified CO2 systems in terms of energy efficiency are better than R134a base heat pump system (R134a HPbase). In particular, CO2 HPTSC, VI, ISC is the optimal system. By combining typical meteorological parameters of different regions in China, the seasonal performance factor (SPF), gases emissions and costs are studied. The annual gas emissions of modified CO2 heat pump systems are all lower than those of R134a HPbase. If the compressor cost could be decreased by 67.66%, the life cycle cost (LCC) of CO2 HPTSC, VI, ISC will rival that of R134a HPbase in Beijing area. It can be predicted that the modified CO2 heat pump systems will be more competitive in the future.
•CO2 two-stage compression system with vapor injection and inter-stage cooling is proposed.•Potential of CO2 heat pump systems to replace R134a system is analyzed.•Evaluations from energetic, environmental and economic performances are conduced.•New proposed system is the best heat pump system in energy efficiency and emissions.•Modified CO2 systems would have broader prospects.
Recently, due to the ever-increasing global warming effect, the proportion of renewable energy sources in the electric power industry has increased significantly. With the increase in distributed ...power sources with adjustable outputs, such as energy storage systems (ESSs), it is necessary to define ESS usage standards for an adaptive power transaction plan. However, the life-cycle cost is generally defined in a quadratic formula without considering various factors. In this study, the life-cycle cost for an ESS is defined in detail based on a life assessment model and used for scheduling. The life-cycle cost is affected by four factors: temperature, average state-of-charge (SOC), depth-of-discharge (DOD), and time. In the case of the DOD stress model, the life-cycle cost is expressed as a function of the cycle depth, whose exact value can be determined based on fatigue analysis techniques such as the Rainflow counting algorithm. The optimal scheduling of the ESS is constructed considering the life-cycle cost using a tool based on reinforcement learning. Since the life assessment cannot apply the analytical technique due to the temperature characteristics and time-dependent characteristics of the ESS SOC, the reinforcement learning that derives optimal scheduling is used. The results show that the SOC curve changes with respect to weight. As the weight of life-cycle cost increases, the ESS output and charge/discharge frequency decrease.
Paris Agreement has influenced a higher generation of renewable systems that impact energy balancing costs and question future energy supply stability. Energy storage could be the key component for ...efficient power systems transition from fossil fuels to renewable sources. The core objective of this paper is to investigate the cost-effectiveness of pumped hydro storage and large-scale battery storage systems. This paper provides prospects for pumped hydro storage installation in comparison to battery storage with an overview of installed capacities in the Western Balkan countries due to renewed interest in already installed pumped hydro plants. The method of approach is based on an economic assessment of the different types of storage depending on capital-recovery-factors for the capital costs, life cycle costs, full load hours, the price spread of electricity in the day-ahead markets, and Levelized costs of energy storage. Sensitivity analysis of the market prices is conducted. The major results of these investigations show the economic justification of pumped hydro storage systems implementation, their role in grid flexibility, and their influence on electricity market competitiveness. Levelized storage costs of 339 €/MWh for sodium-sulfur batteries show considerable potential for new installations, as compared to 125 €/MWh for pumped hydro storage.
•State of the art of technology and application of pumped hydro and battery storage systems.•Overview of the installed electricity storage capacities in Western Balkans.•Method for cost calculation of electric energy storage.•Economic analysis of reviewed pumped hydro and battery storage technologies.•Comparison and prospects for storage installation.
Piping layout, material, and dimension choices are essential in determining the initial capital costs and full operating costs of a district heating and cooling (DHC) network. While common practice ...aims to minimize initial capital costs or, in some cases, operational costs, this paper introduces a novel method for designing DHC network layouts for minimum total life-cycle cost by introducing additional engineering design parameters related to pipe sizing, heat losses, and pumping energy. The proposed mixed-integer linear programming solution satisfies the thermal and hydraulic constraints on the network while minimizing the objective function of total cost over the lifetime of the network. The method is tested with three case studies. Results show improvement in reducing total life-cycle costs of the network compared to approaches that consider only capital or operating costs and exclude network dimensioning.
•A novel optimization method for district heating and cooling pipe layout is presented.•Unlike common practice, pipe sizing and annual energy cost drive network design.•Pumping energy and heat loss are linearized to create mixed-integer linear problem.•Method improves design approaches that consider only capital or operating cost.•Method improves solutions from prior life-cycle cost optimization approaches.
This study aims to compare two commonly used ASHP (air-source heat pump) and DX-GSHP (direct-expansion ground-source heat pump). There have been many debates on energy efficiency, system costs and ...relative payback period of DX-GSHP against ASHP systems over the past few years. In this context, and with the aim of enriching this debate, a detailed screening heat pump model previously developed is modified and used to compare the seasonal performance of ASHP vs DX-GSHP in a residential building in the cold climate city of Montreal. Further, a life cycle cost analysis is performed to account for the difference between initial and 10-year operating costs of the two systems based on the current prices in Quebec. The obtained results show that by proper sizing, energy consumption of the DX-GSHP system can be reduced by 50%. Moreover, with current borehole installation prices, the relative payback period of the GSHP (ground source heat pump) compared to ASHP is more than 15 years. However, if the borehole installation price reduced by 50% the payback period would be reduced to just a few years. Such results highlight the importance of further investigations in the area of DX-GSHPs, in order to reduce the borehole installation cost and increase its performance.
•A techno-economic comparison between DX-GSHP and ASHP is undertaken.•A detailed numerical modeling of both systems is performed.•The effect of heat pump capacity and borehole size on system costs is evaluated.•Under good design condition, DX-GSHPs offer some performance and cost advantages over ASHPs.
•Structured method for the evaluation of PV implementation for historical buildings.•PV integration including the aspects aesthetics, performance and added values.•Historical building renovation to ...Net Zero Energy Building (NetZEB).•Low prospects for financial viability of PV in combination with NetZEB.•Profitability of PV systems is highly dependent on the cost of capital.
Retrofitting historical buildings towards net zero energy building (NetZEB) in Northern countries is facing some issues confirmed in the literature review of this study. Following a holistic approach proposed by the authors, a 150-year old castle situated in Helsingborg, Sweden, was used to evaluate the potential of historical buildings in the Nordics to be turned into a NetZEB building. Following a retrofit tailored to achieve energy-savings in the historical building which was done in a previous study, the installation of a photovoltaic (PV) system, to cover the primary energy use of the building on a net annual basis was proposed. Building integration of the PV system was proven not to be realistic due to historical sensitivity as well as low irradiation due to overshadowing on the roofs of the historical buildings. Alternatively, the concept of landscape integrated PV was followed and the system covering the energy use of the castle was optimised in azimuth and tilt to provide the highest possible monetary results for electricity expenses for the castle weighed with the rate for feeding electricity to the grid. A second PV-system was optimised in azimuth and tilt, however, according to the maximum electricity generation. Life-cycle costing (LCC) calculations using the Net Present Value (NPV) method were used to determine the viability of both PV systems according to nine financial scenarios. A comparison of generated primary energy and primary energy use of the historical building was presented for two scenarios and it showed that reaching NetZEB was possible for the presented case study object.
The environmental emissions and energy from construction activity and building materials contributes significantly to a building's sustainability. Previous research dealing with wood or engineering ...wood's energy requirements compared to reinforced concrete and steel structures has shown that embodied energy and embodied carbon is significantly lower in wood-based construction. This study has assessed the environmental impact and costs of glued laminated timber (GLT) or cross-laminated timber (CLT). Hardwood and softwood variants of both GLT and CLT were considered. We compared the life cycle costs (LCC) of these alternatives to discover the lowest cost. The comparative results indicated that GLT has higher emissions in Global warming potential (GWP), Terrestrial Ecotoxicity (TE), Land Use (LUP), and Ozone layer depletion (OLD), while CLT has higher impact in Human-Toxicity Potential (HTP), Fossil Depletion Potential (FDP). The results indicated that using CLT significantly reduces embodied energy by 40%. However, a comparison of costs showed that CLT is 7% more expensive than GLT. Establishing which material performs best based on environmental and economic criteria thus required further analysis. Thus, the multi-criteria decision making (MCDM) method was applied. This showed that CLT manufactured with softwood is the most sustainable choice among the alternatives considered. This study's findings are important for aggregate level decision making of different wood materials for residential buildings.
•CLT and GLT have been assessed as manufactured from both hardwood and softwood.•GLT has higher emissions for global warming potential and ozone layer depletion.•CLT has higher emissions for human carcinogenic toxicity and fossil depletion.•Softwood has a lower environmental impact and embodied energy than hardwood.•Multi-criteria decision-making determined that CLT is the most sustainable option.
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