Present Worth Factor Research Articles

Thermal insulation performance curves for exterior walls in heating and cooling seasons

Determination of thermal insulation performance (i.e. optimum insulation thickness, energy saving and payback period) is a tedious and time-consuming task that requires a thorough knowledge in thermal insulation engineering and economics. The main goal of this paper is to make the determination of insulation performance simple and timesaving by introduc-ing thermal insulation performance curves (TIPCs) from which the insulation performance can easily be found for any climate condition and all economic factors related to energy and insulation. These curves were generated based on a life-cycle cost analysis (LCCA) method. The curves can be easily read based on a single factor, called the f-factor, which comprises the number of degree-day, coefficient of performance, present worth factor, energy cost, and insu-lation cost. With the gain of heating and cooling degree days (i.e. HDD and CDD), TIPCs can be used for both heating and cooling loads. TIPCs cover commonly used insulation materials for building walls with thermal conductivities range from 0.020 to 0.055 W/m K. TIPCs were validated against published data.

Optimum insulation thickness design of exterior walls and overhauling cost to enhance the energy efficiency of Albanian's buildings stock

In the present climate, thermal insulation is crucial for reducing energy consumption for heating or cooling in buildings, increasing the lifespan of structures, and building elements, and improving human comfort. The wall's composition layer has advanced regularly since the building regulations and established norms. However, calculation methods have remained quite the same, governed by Fourier's law. Therefore, to address this gap, a linearization process, and a correction factor of the optimized insulation thickness for four different insulation materials (i.e., EPS Graphite, EPS, GW, and RW) and five energy carriers (i.e., electricity, diesel, natural gas, liquefied petroleum gas, and biomass) by removing the boundaries of heating degree days by using Mathcad software is proposed. Other financial parameters (i.e., inflation rate, interest rate, lifespan, and present worth factor) and heating system features that lead to the optimized insulation thickness are considered. The RETScreen Expert model was coupled with a Mathcad script to compute a standardized corrected optimized insulation thickness (COIT) value by applying sensitivity analyses at ±35% of the most influencing parameters to calculate the total overhauling cost for different building types in Albania. A correction of the existing window's heat transfer coefficient for a different glass-to-wall ratio is proposed. Our findings suggest that the overall heat transfer value (U) should be equal to or less than 0.30 (W/m2•K), leading to a range of corrected optimized insulation thickness (COIT) from 0.03 m up to 0.11 m. Moreover, results exhibited encouraging economic and environmental values concerning the unrenovated buildings leading to annual net savings of 23.50–84.50 €/m2, CO2 reduction up to 39.10 kgCO2/m2, and a simple payback period (SPP) of 0.30 maximum up to 1.20 years. The outputs of this study can bring benefits in terms of reduced energy consumption and CO2 footprint, and the proposed COIT value can be applied not only in Albania but in other regions that exhibit similar climate conditions.

Energy, economic and environmental analysis of fuzzy logic controllers used in smart buildings

This article is divided into three parts: the first presents a simulation study of the effect of occupancy level on energy usage pattern of Engineering building of Applied Science Private university, Amman, Jordan. The simulation was created on simulation mechanism by means of EnergyPlus software and improved by using the building’s data such as building’s as built plan, occupant’s density level based on data about who utilize the building throughout operational hours, energy usage level, Heating Ventilating and air conditioning (HVAC) system, lighting and its control systems and etc. Data regarding occupancy density level estimation is used to provide the proposed controller with random number of users grounded on report were arranged by the university’s facilities operational team. The other division of this paper shows the estimated saved energy by the means of suggested advanced add-on, FUZZY-PID controlling system. The energy savings were divided into summer savings and winter savings. The third division presents economic and environmental analysis of the proposed advanced fuzzy logic controllers of smart buildings in Subtropical Jordan. The economic parameters that were used to evaluate the system economy performance are life-cycle analysis, present worth factor and system payback period. The system economic analysis was done using MATLAB software

Optimization of planning cost of radial distribution networks at different loads with the optimal placement of distribution STATCOM using differential evolution algorithm

This paper presents an optimization of planning of distribution systems with the allocation of DSTATCOM based on maximization of a net cost profit/savings analysis approach by using the differential evolution algorithm. In the proposed approach, the optimal placement of DSTATCOM, and reactive power compensation at a certain location, and the improvement of voltage profile are obtained by three objective functions: (1) minimization of the size of DSTATCOM, (2) minimization of network power loss, and (3) maximization of net cost profit/savings by minimizing the total planning cost of DSTATCOM installation scheme. Present worth factor is adopted to evaluate the net cost profit/savings of the DSTATCOM installation scheme for a certain planning horizon. The appropriate mathematical modeling of DSTATCOM is used to incorporate it suitably in the forward–backward sweep load flow algorithm of radial distribution networks to provide the reactive power compensation. The recommended method is validated on the IEEE 30-bus, 33-bus and 69-bus distribution networks.

Investigation of parameters affecting the optimum thermal insulation thickness for buildings in hot and cold climates

This paper investigates the factors affecting the optimum insulation thickness and its pay-back period, such as heating and cooling energy requirements of building, lifetime, present worth factor, costs of insulation material and installation, costs of energy sources for heating and cooling, heating and cooling system efficiencies, and solar radiation. For this purpose, by considering two cities characterizing the hot and cold climatic conditions, the optimum insulation thickness and its pay-back period have been calculated and a detailed parametric analysis has been carried out. To achieve practical results, the ranges of the parameters considered in the study include the values typically reported in the literature. The variations in the optimum insulation thickness and the pay-back period with all parameters are presented in graphical form. Finally, order of importance and contribution ratios of the examined parameters on the optimum insulation thickness are determined with the help of Taguchi method. It is found that heating degree-days is the most efficient parameter on the optimum insulation thickness with an impact ratio of 27.33% of the total effect while the least efficient parameter is the efficiency of heating system with an impact ratio of 3.21%.

Optimization of Energy Loss Cost of Distribution Networks with the Optimal Placement and Sizing of DSTATCOM Using Differential Evolution Algorithm

This paper presents an optimization of energy loss cost (ELC) of distribution networks (DN) with the optimal allocation and sizing of DSTATCOM to maximizing the total net profit (TNP)/cost savings by using the differential evolution algorithm per annum and planning horizon of DSTATCOM installation scheme. In this approach, the optimal reactive power compensation is the main vital role in solving the objective function. The optimal reactive power compensation with the optimal placement and sizing of DSTATCOM and the improvement in voltage profile of the DN are obtained based on certain objectives such as best reduction in network power loss and the total ELC and the maximization of TNP. The modeling on the size of DSTATCOM is used and was incorporated in DN through the forward–backward sweep load flow technique to evaluate the parameters of load flows in DN. Present worth factor is instigated to evaluate the TNP of the DSTATCOM installation scheme. The proposed method is validated on the 30, 33, and 69-bus DN.

Insulation of Ceiling with Different Insulation Materials and its Effect on Energy Saving

The aim of this paper is to investigate the effect of ceiling insulation with different insulation material on energy saving. The values of the optimum insulation thickness, the payback periods (PP), and the life-cycle savings (LCS) for three different types of insulation materials (expanded polystyrene, glass wool, and rock wool) were calculated. In calculations, life cycle cost analysis (LCCA) was applied. In the analysis, the present-worth factor (PWF) technique was used for evaluating systems and annual interest and inflation rates were taken 8% and 0%, respectively. The best solution was obtained when the expanded polystyrene was used. The optimum insulation thickness, PP, and LCS were computed as 0.0901m, 1.615years, and 9.643 $/m2, respectively.

Economic optimization of PCM and insulation layer thickness in residential buildings

As suggested by previous studies, in economic optimization of buildings equipped with phase change materials, insulation layer and PCM highly affect each other’s performance. To consider these effects, in the present study, the thickness of the insulation and PCM layer of a residential building are optimized simultaneously. Coupled with EnergyPlus as the thermal simulation tool, genetic algorithm is applied to optimize the thicknesses for different climatic regions of Iran. Tehran, Isfahan, Shiraz, Bandar Abbas, Yazd, and Tabriz were selected for optimization. The fitness function is the total cost of the building throughout its operation years. In each city, the optimum PCM and insulation layer thicknesses are obtained with different present worth factors each accounting for a different scenario regarding the economic outlook of the country. Results show that the optimum PCM thickness is zero for all cases. On the other hand, the optimum insulation thickness varies significantly by region and PWF. While in southern parts of the country it was approximately zero, in cold regions, the optimum thickness was more than 6cm. Moreover, results show that with current economic situation of the country, insulation layers are far more cost effective than phase change materials.

Building envelope with a new aerogel-based insulating rendering: Experimental and numerical study, cost analysis, and thickness optimization

In France, renovation of existing buildings has a high priority. The thickness of insulation layers becomes a major issue of concern especially in cities. In this study, we present a recently developed insulating rendering based on silica aerogels that can be applied to new buildings and to retrofit existing ones. A full scale experimental house is built near Chambery in France, with the rendering applied on its external facades. The results of a numerical model developed in EnergyPlus are compared to the on-site measurements. After validating the numerical model, the thickness of the rendering is optimized based on a cost analysis for different climates for the case of retrofitting an old building. Then, a sensitivity analysis is carried out to determine the thickness dependency on annual heating load, present worth factor, rendering’s cost, and heating set-point. Results show that the optimum rendering thickness is in the range of 1.7–4.4cm and the payback period in the range of 1.4–2.7years depending on the climate. The optimum thickness increases with the increasing heating set-point and increasing present worth factor; however, it decreases with the increasing rendering cost.

Optimizing insulation thickness and analysing environmental impacts of aerogel-based thermal superinsulation in buildings

Abstract Although commercialization is still challenging for superinsulation materials, intensive efforts are being made for cost reduction. They provide superior thermal performance and hence their future potential is notable. Optimizing insulation thickness of superinsulation materials can make a significant contribution to the energy saving in buildings and thus to greenhouse gas abatement. Therefore in this study, optimum thermal insulation thickness of aerogel and its environmental impacts are investigated for the climatic conditions of Nottingham, UK. Insulation thickness dependencies of annual energy cost and energy saving are determined for different energy sources. Degree-day and present worth factor effects on optimum aerogel thickness are investigated. The paper also covers the environmental aspects of aerogel-based retrofitting of buildings by analysing the potential fall in greenhouse gas concentrations. It is concluded from the results that aerogel-based thermal superinsulation provides remarkably slimmer constructions and larger living spaces in buildings compared to the conventional insulation materials. Aerogel insulation is found to be very appropriate as additional internal insulation for the non-insulated cavity walls. The reliability and the feasibility of the theoretical results are also verified by an experimental work carried out in a test house.

MODEL HUBUNGAN ANTARA VOLUME LALULINTAS DENGAN TARIF JALAN TOL

Indonesia has experienced increasing economic growth every year. This recent trend needs to be supported by adequate transportation infrastructures, especially roads. Since there is limited budget for infrastructure development, the government has invited private investors for toll road construction. Toll tariff and traffic volume are two main factors that affect toll road income and investment. A method based on financial approach needs to be developed to enhance the benefit cost analysis of toll road construction and furthermore to determine the toll tariff. Factors that affect toll tariff were analyzed based on vehicle number and vehicle growth rate. The elasticity theory was applied in this case study to identify the effects of toll tariff on traffic volume. A model of critical traffic volume was created based on the analysis of several factors such as construction cost, operation and maintenance cost, payback period, and internal rate of return. The results from Jia method and the Present Worth Factor (PWF) method show that the relationship between traffic volume and toll tariff is very sensitive, indicated by the elasticity value equal to 1. The difference between the two method is about 27% and is caused by the double counting on taxes on Jia method.

Analysis on Life Cycle Cost and Economic Benefits of Self-Thermal Insulation System of Three Different External Walls in Changsha in China

The mathematical analysis model of LCC of self-thermal insulation system of external wall that is applicable to Changsha region is established by using degree days and present worth factor. And the LCC of three commonly used self-thermal insulation systems in Changsha is analyzed by using this model. Analysis results have proven that self-thermal insulation system of external wall has very significant comprehensive economic benefits compared with the wall that energy-saving measures are not taken, and it has an important practical significance to promote the development of energy-saving building in Changsha, China．

Optimum insulation thickness of residential roof with respect to solar-air degree-hours in hot summer and cold winter zone of china

Thermal protection of building envelope is one of the most effective ways for building energy conservation. In this study, the determination of optimum insulation thickness for residential roof with different surface colors is studied based on life cycle cost analysis and solar-air degree-hours in four typical cities of hot summer and cold winter zone of China. Four insulation materials including expanded polystyrene, extruded polystyrene, foamed polyurethane and foamed polyvinyl chloride are analyzed. The solar-air degree-hours are calculated considering night time operation and 24-h operation of the cooling and heating equipments. Life cycle total costs (LCT), life cycle savings (LCS) and payback period resulting from the use of optimum insulation thickness are calculated. Depending on different cities, insulation materials and roof surface colors, optimum insulation thicknesses of a typical roof vary from 0.065 to 0.187 m and payback periods vary from 0.9 to 2.3 years for 24-h operation of cooling and heating equipments; optimum insulation thicknesses are between 0.051 and 0.149 m and the payback periods are between 1.1 and 2.8 years for night time operation. At last, the effects of present worth factor, thermal resistance and climate on the optimum thicknesses are studied which is very useful for practical use to estimate the optimum thickness of insulation material.

Exergoeconomic evaluation of electricity generation by the medium temperature geothermal resources, using a Kalina cycle: Simav case study

Recent technical developments have made it possible to generate electricity from geothermal resources with low and medium enthalpy. One of these technologies is the Kalina Cycle System (KCS-34). In this study, electricity generation from Simav geothermal field is investigated. The optimum operating conditions for the KCS-34 plant design are determined on the basis of the exergetic and life-cycle-cost concepts. With the best design, power generation of 41.2 MW and electricity production of 346.1 GWh/a can be obtained with an energetic efficiency of 14.9% and exergetic efficiency of 36.2%. It is shown that, with the currently prevailing interest and inflation rates, the plant designs considered are economically feasible for values of the present worth factor ( PWF) higher than 6.

Determining the best type of heat exchangers for heat recovery

It is a common problem to choose the most appropriate heat exchanger configuration for heat recovery. In this study, a new model has been developed for determining the area and type of the most appropriate waste heat recovery heat exchanger for maximum net gain. A non-dimensional E number has been defined based on known technical and economic parameters such as the life-time, unit area cost of the heat exchanger, lower heating value of the fuel, overall heat transfer coefficient of heat exchanger, boiler efficiency, operation time per year, heat exchanger effectiveness, ratio of heat capacities, annual variation of the temperature of fluids supplied to the heat exchanger and present worth factor. The non-dimensional E numbers has been demonstrated in graphical forms as a function of NTU and ratio of heat capacities and corresponding heat exchanger area giving maximum net gain can easily be obtained from these graphs. The best heat exchanger type and its area can be determined comparing net gains or effectiveness of heat exchangers at NTUmax. Application of the new method has been given with a case study as a sample calculation.

Selection of routes in a flexible manufacturing facility

Routeing flexibility is defined as the ability to manufacture a product via several alternate routes in the same facility. A route is defined as the set of work centers or machines through which a product is processed, and the processing times at these work centers. Routeing flexibility permits the facility to adjust to changes in the production ratio. Typically, with every change in the production ratio, the FMS scheduler will assign routes to each product, so as to achieve a close to perfect load balance between work centers while minimizing the interference or setups between processing routes. The assigned routes will belong to the set of routes that have been implemented, and hence are available for scheduling. A route is described as implemented when the instructions, skills, tools, handling needs, and other auxiliaries associated with it have been positioned in the facility. The ability to change routes and optimize performance is therefore dependent on the routes which have been implemented. In this paper we assume that several good and feasible routes are generated by the process planner for each product. Since it is economically possible to implement only a few routes per product, the route selection problem is described as identifying the set of routes which should be implemented so as to optimize routeing flexibility related costs. The problem is formulated as a mixed integer program and rules for deriving tight initial solutions are proposed. Tests with sample problems were conducted, and model sensitivity to the scenario change factor and present worth factor were studied.

On the Proper Use of Compound Interest Factors—A Technical Note

Five of the seven factors in most common use for compound interest calculations involve a uniform series of payments (or receipts). These interest factors, for use when interest is compounded at discrete points in time, are commonly referred to as the uniform series present worth factor, the uniform series compound amount factor, the capital recovery factor, the sinking fund factor and the uniform series gradient conversion factor. The proper use of these five factors requires that the period of time between the compoundings of interest coincide with the period of time between the uniform payments. If the interest is compounded more frequently (assume by an integer number of times) than the payments, then the best way to apply the compound interest factors is to determine the effective interest rate between payments. If interest is compounded less frequently than the payments (assume there are an integer number of payment periods within each compounding period), the correct solution procedure is not well ...

Optimal Control of Linked Reservoirs

Control rules for linked reservoirs meeting a common demand are evaluated for a two storage case. Draw‐off can be made from either of the reservoirs directly to supply, and transfers are permitted from the smaller to the larger reservoirs. Dynamic programming is effective in selecting the optimal control rules, for any stage of reservoir contents, given a defined objective of operation. The objective is expressed in monetary terms, relating to transmission, purification, or shortage costs, which are to be minimized in the long term. The case considered allows monthly inflows to the reservoirs to be treated as random variates; first order serial correlation of inflows is expressed by using ‘high’ or ‘low’ inflow distributions, according to whether the previous month's inflow was above or below its mean. Present worth factors, switch‐on costs, and costs of shortage that vary nonlinearly with total deficit can all be brought into the reckoning.The paper includes a numerical example of the dynamic programming calculation for a system of a finite surface reservoir and a full aquifer, the latter having limited pumpage. Also, the flow diagram for a computer program is given, which incorporates inflow, draw‐off, storage volumes, and operating costs as general parameters. Using this program, the convergence to optimal control rules has been obtained, for the most part within 5 years of iteration. Given the optimal control rules for an assumed reservoir system, it becomes possible to form transition matrices of contents, by an adaptation of Gould's method. The steady‐state solutions of the matrices show probabilities of each reservoir's contents in the long term. These lead to a long‐term operating cost for consideration at the design stage of the system.