Optimization of insulation thickness for different glazing areas in buildings for various climatic regions in Turkey

Insulation is one of the most effective methods intended for reducing energy consumption in both heating and cooling of buildings. Selecting the right materials and determining the optimum insulation thickness in building insulation application is an important issue. In 2000, the “Thermal Insulation Requirements for Buildings” was enacted in Turkey, energy saving by limiting the energy amount used for heating in buildings being the target. In this study, the effect of the alteration of windows and exterior wall areas on the heating energy requirement of the building and on the optimum insulation thickness has been examined by using P₁–P₂ method. The study has been carried out for four degree-day regions of Turkey for various insulation materials, glazing areas, and fuel types; the results have been presented in charts. In the rest of this study, effects of different insulation thicknesses and fuel on fuel consumption and thereby on emissions of pollutants such as CO₂ and SO₂ are evaluated. For example, in the building where XPS (extruded polystyrene foam) insulation material and natural gas are used and where the ratio of glazing area to exterior wall area is 0.2 (glazing area percentage), energy saving for the four regions has been found to be 13.996, 31.680, 46.613, and 63.071 $/m², respectively, and the payback period of investment has been found to be 2.023, 1.836, 1.498, and 1.346 years, respectively. The emissions of CO₂ are decreased by 50.91% for the cases in which optimum insulation material (XPS) and natural gas are used. The emissions of CO₂ and SO₂ are decreased by 54.67% for the cases in which optimum insulation material (XPS) and fuel oil are used.     

Adaptive thermal comfort model for different climatic zones of North-East India

Thermal comfort standards ISO 7730 and ASHRAE 55-2004 are based on the experimental results conducted in climatic chambers and the adaptive opportunities are usually limited in these experiments. However, in naturally ventilated buildings, adaptive opportunities are not fixed and occupants always have the liberty to modify the opportunities in order to feel comfortable. A comfort survey has been carried out in three different climatic zones of North-East India in four different seasons of a year. Climatic parameters corresponding to actual mean vote (AMV) are recorded during the survey and the values are used to calculate the predicted mean vote (PMV) using ISO 7730 calculation procedures. Results show that the PMV deviates from AMV values. A corrective term ‘adaptive coefficient’ is calculated based on PMV and AMV values and least square method to assess the different adaption used for thermal comfort. Theoretical adaptive models of thermal comfort have been developed based on these adaptive coefficients for the region. The adaptive coefficient values are varying for different seasons and also for different climatic zones. This reflects the various levels of adaptation in different seasons in a particular climatic zone. This adaptive coefficient can be used as a reference to thermal comfort assessment of the buildings and also can be used as dynamic control of the set temperature in the air conditioning system, which will results enormous energy saving. Result of this study also contributes towards the debate over the applicability of PMV model to naturally ventilated building.     

Comparative resource analyses for ethanol produced from corn and sugarcane in different climatic zones

Comparative analysis of resource input for ethanol produced from corn and sugarcane in temperate, dry, and tropical climate zones was conducted. Parameters such as the Net Energy Value (NEV), water requirement, land requirement, carbon dioxide emission with and without impact of changes in land use, and fertilizer released to the environment—as surface runoff for nitrogen and phosphate, were compared for corn and sugarcane ethanol production. The estimates of NEV for corn ethanol varied from ?462 to 1757 kJ l^?1, while those of sugarcane ethanol were between 16 057 and 17 092 kJ l^?1 for the three climatic zones considered in this study. The results of the study also indicate that ethanol produced from sugarcane uses less or comparable amount of resources in contrast to ethanol produced from corn. Copyright © 2011 John Wiley & Sons, Ltd.     

Stability of antireflection coatings for large area glazing

We draw attention to the excellent stability of the antireflection (AR) coatings on glass prepared by liquid-phase etching in a silica supersaturated flousilicic acid in comparison to dipping in a teflon sol. Both methods resulted in both sides of the glass being coated with antireflection films. For the best samples the transmission of the original glass was increased by as much as 5.5%. The samples have then been exposed to weathering for about seven years to test their durability, after which their optical properties were measured again. Even after this long period of outdoor exposure, the acid-etched samples show remarkable stability in their antireflection properties. After cleaning, their transmittance is restored to almost pre-exposure levels.     

不同气候区高校用能用水特征分析研究

通过对我国部分高校的总体用电用水情况进行统计分析,发现我国节约型校园建设工作正有序进行,高校单位建筑面积电耗和生均水耗稳步下降.通过对各高校所处的不同气候区进行分类,旨在寻找严寒地区、寒冷地区、夏热冬冷及夏热冬暖地区各高校的用电用水特点和各高校用能及其结构的不同.发现夏热冬冷和夏热冬暖地区的高校电耗相对较多;在总能耗方...     

Spectral effects on the transmittance, solar heat gain, and performance rating of glazing systems

This study investigates the potential changes in Solar Heat Gain Coefficient (SHGC) and Visible Transmittance (VT) ratings of vertical or tilted glazing systems that would result from a deliberate change in the reference spectrum used as Spectral Weighting Function (SWF). This SWF is necessary to evaluate broadband-average optical properties from their spectral values, and obtain the desired rating of such bulk properties. The SWFs currently specified by rating institutions in Europe and North America for SHGC and VT are now outdated, and their inadequacies are discussed. Six potential replacements, which have been recently adopted by ASTM are described, including three direct irradiance spectra and three global irradiance spectrum incident on tilted surfaces of various tilts (20°, 37° and 90°). Some of these spectra have been tailored for use in building energy applications, including Building-Integrated Photovoltaics (BIPV). The effect of tilt on the U-factor and hence SHGC of glazing systems used for skylights on roofs is discussed, using a representative dataset of 37 glazing system specimens. The spectral effects on SHGC induced by a change in the current North American SWF are also obtained for this dataset, and show small to moderate deviations from current ratings (−2% to +7% for windows, and −3% to +11% for skylights). The variations in VT are within ±2% for most glazing systems. To remove the current inconsistency in the SWFs used for SHGC and VT, it is recommended that a single SWF be used for both properties. For improved accuracy and reliance on active standards, it is also recommended that the SWF for SHGC and VT be either one of the two recent ASTM G197-08 global irradiance spectra, depending on application (incidence on a vertical surface for window applications, and incidence on a 20°-tilted surface for skylight applications). No change in colorimetric calculations (based on the D65 illuminant) is recommended, however.     

Assessing the overall performance of advanced glazing systems

This paper describes the approach taken within the European Community's IMAGE (IMplementation of Advanced Glazing in Europe) 97 project to apply combined thermal/daylight simulations to existing and proposed building designs incorporating advanced glazing systems. The application of the approach to a live design project is described to exemplify the process and the outcome.     

Techno-economic viability of three different energy-supplying options for remote area electrification in India

Distributed power generation based on renewable energy sources brings new life and hope to electrify remote villagers. The proposed work suggests the techno-economic feasibility of three different energy-supplying alternatives namely the solar photovoltaic (SPV) system, diesel generator system and extending the grid connection for energy supply to a remote village located around 15 km away from the place where grid supply is available. Design of all the above three systems along with their economic analysis is carried out in this paper. A comparison on the basis of economic indicators like unit cost of electricity, net present value and payback period among the three systems is also discussed. The results show that the SPV system is economically more viable among the three options apart from environment benefits. This study may provide a new direction for energy planners to supply energy in remote non-electrified areas of India through SPV systems.     

Comparative study of three different catalyst coating methods for direct methanol fuel cells

The performance of direct methanol fuel cells (DMFCs) with membrane–electrode assemblies (MEAs) made separately by three different catalyst coating methods, namely, air-spray, electro-spray and dual-mode spray, is evaluated. Platinum–ruthenium (PtRu) is incorporated as a catalyst for the anode. Several techniques (XRD, FE-SEM, and TEM) are used to examine whether the coating method affects the morphological features of the PtRu catalyst, whereas cyclic voltammetry is used to evaluate the active surface area. The cell polarization curves attained for the three coating methods that use different methanol concentrations are compared to determine the best method. It is found that the PtRu catalyst coated by the dual-mode spray shows the most uniform nanoparticle distribution and the highest active surface area. The DMFC performance is best when the dual-mode spray is employed (165 mW cm⁻² at 2 M methanol).     

Multi-criteria analysis of combined cooling,heating and power systems in different climate zones in China

The design and operation of combined cooling, heating and power (CCHP) systems are greatly dependent upon the seasonal atmospheric conditions, which determine thermal and power demands of buildings. This paper presents a mathematical analysis of CCHP system in comparison to separate system. The corresponding primary energy consumption in thermal demand management (TDM) and electrical demand management (EDM) operation modes are deduced. Three relative criteria, primary energy saving (PES), CO₂ emission reduction (CO₂ER), and annual total cost saving (ATCS) are employed to evaluate the respective performances of CCHP systems for a hypothetical building in five different climate zones from the technical, environmental and economic aspects. The results indicate that CCHP system in TDM mode in the cold area, where the building requires more heating during the year, achieves more benefit over separate system while CCHP system in EDM mode suits the building having stable thermal demand in mild climate zone.     

太阳能光热与光电/光热系统在中国不同建筑气候带下的性能研究

文章利用TRNSYS动态模拟软件研究了在我国不同建筑气候带条件下,不同类型的太阳能PV/T集热系统和普通太阳能PT集热系统的各项性能.其中,太阳能PV/T集热系统分为基于普通玻璃型太阳能PV/T集热系统和基于Low-e型太阳能PV/T集热系统.文章探究了基于普通玻璃型太阳能PV/T集热系统和基于Low-e型太阳能PV/...     

Prediction of direct gain solar heating sytem performance

General design methods for building-integrated (passive) solar heating systems are needed to evaluate the effects of design parameters on building energy needs. The solar Load Ratio Method[1] for direct gain systems is limited in the scope of system parameters which can be considered; it does not allow an examination of the effects of house capacitance, allowable room temperature swing, or alternative high and low room thermostat set point temperatures. In this paper, we present a more general design method for direct gain systems.     

An empirical validation of modeling solar gain through a glazing unit with external and internal shading screens

Empirical validations are integral components in assessing the overall accuracies of building energy simulation programs. Two test cell experiments were performed at the Swiss Federal Laboratories for Material Testing and Research’s (EMPA) campus in Duebendorf, Switzerland to evaluate the solar gain models with external and internal shading screens in four building energy simulation programs including: (1) EnergyPlus, (2) DOE-2.1E, (3) TRNSYS-TUD, and (4) ESP-r. Detailed information about the shading screen properties, modeling procedures, and thorough statistical and sensitivity analyses of simulation results are provided. For the external shading screen experiment, the mean percentage of the absolute difference between measured and simulated cooling power to maintain a near-constant cell air temperature for EnergyPlus, DOE-2.1E, TRNSYS-TUD and ESP-r were 3.7%, 5.5%, 10.6%, and 7.5%, respectively. EnergyPlus and DOE-2.1E were considered validated within 95% credible limits. For the internal shading screen experiment, the mean percentage of the absolute mean differences for EnergyPlus, DOE-2.1E, TRNSYS-TUD, and ESP-r were 6.7%. 13.8%, 5.7%, and 4.3%, respectively; only ESP-r was considered validated within 95% credible limits.     

Silicone glazing for solar applications in rural areas

Silicone glazing is a translucent glass fabric reinforced material which was produced by coating silicone resin 1-2577 on an open weave leno fabric in a coating tower constructed in Basaisa village, Al Sharkiya Governorate, Egypt. The unique feature of the tower used in this work is the utilization of solar energy for both powering its coating mechanism through the use of a photovoltaic module, and also heating its curing chamber. The optical and mechanical properties of silicone glazing were studied. Silicone glazing is found to have a solar transmission of 90%, an ultraviolet cut-off at 270 nm, and an infrared cut-off at 8.0 μm. The material has a high tensile strength, particularly along the fill and the wrap directions of the reinforcing fabric. The tensile strength tested at 0.8 strain rate is 50, and 80 pli (pounds per lineal inch) at the fill and the wrap directions, respectively. Silicone glazing was found suitable for many solar applications such as greenhouse screen, space solar heating, solar food driers, and skylights in buildings, especially in rural areas.     

Development and validation of a condenser three zones model

A general and simple “deterministic” model of a refrigeration condenser is presented. The model assumes that the condenser can be divided into three distinct zones on the refrigerant side: the vapour de-superheating zone, the two-phase zone and the sub-cooled liquid zone.The model inputs are the air supply temperature, the air mass flow rate, the refrigerant supply temperature (or the over-heating), the exhaust sub-cooling and the refrigerant mass flow rate. The model is able to identify the pressures and temperatures in each zone and the corresponding heat flows. The model also gives the geometrical repartition among the zones and the pressure drop on air-side.The condenser model is validated with a total of 183 tests. Testing conditions cover a very wide domain, including pressures up to 40 bars with refrigerant R134a. The model is able to predict with a probability of 95% the condenser supply pressure within a confidence interval of +0.5 and −0.1 bar. This means a condenser power confidence interval within −200 and +100 W, which is considered here as acceptable. Refrigerant pressure drop is predicted with a higher error, but it is attributed to measuring uncertainty. On the other hand, air pressure drop is predicted with a very poor accuracy. Undoubtedly, this is due to the friction factor correlation used in this study which is not the most adequate. Here a difference of 40% is obtained.     

Analytical model,sensitivity analysis,and algorithm for temperature swings in direct gain rooms

An analytical method is presented for determining the temperature swings in direct gain rooms for relatively clear days. Fundamental network concepts, such as the delta to star transformation and the Norton theorem, are used to obtain the solution for a representative room temperature and the storage mass front surface temperature, in the frequency domain. The storage mass is modelled as a two-port element, analogous to a transmission line, and thus no discretization is required. Heat sources representing the absorbed solar radiation and the ambient temperature source are modelled analytically by Fourier series. The results of a sensitivity analysis are given, illustrating the flexibility of the method in studying the effects of changing the values of room design variables and the daylength. The daylength is shown to determine the relative magnitude of the harmonics of the solar radiation absorbed in the room; the number of harmonics required in the analysis increases with decrease of the daylength and of the amount of storage mass. Comparison of results with a lumped parameter model shows a maximum difference of 12% in the storage mass surface temperature swings. It is useful to know how frequently the room is likely to overheat under real weather conditions. Thus, an algorithm implementing the method is also described, and it requires as input the daily clearness index and the daily ambient temperature range.     

Anaerobic digestion of grain stillage at high organic loading rates in three different reactor systems

In this study the anaerobic digestion of grain stillage in three different reactor systems (continuous stirred tank reactor, anaerobic sequencing batch reactor, fixed bed reactor) with and without immobilization of microorganisms was investigated to evaluate the performance during increase of the organic loading rate (OLR) from 1 to 10 g of volatile solids (VS) per liter reactor volume and day and decrease of the hydraulic retention time (HRT) from 40 to 6 days. No significant differences have been observed between the performances of the three examined reactor systems. The changes in OLR and HRT caused a reduction of the specific biogas production (SBP) of about 25% from about 650 to 550 L kg⁻¹ of VS but would also diminish the necessary digester volume and investment costs of about 75% compared to the state of the art.     

Solar assisted biogas plants IV: Optimum area for blackening and double glazing over a fixed-dome biogas plant

The paper presents the economic analysis of a fixed-dome biogas plant of rated capacity 8 m³, above which a part of the ground is blackened and doubly glazed in the cold climate of Srinagar. Blackening and glazing of the ground cannot alone maintain the slurry temperature at 35°C, which is the optimum temperature in the mesophilic range for the anaerobic digestion of cattle dung, and so a part of the biogas must be burnt. The electrical simulation experiments have been performed to determine the loss or gain of heat from the underground biodigestor to the ambient atmosphere through the ground if a part of the ground above is blackened and double glazed. Economic analysis of the system shows that the optimum area to be blackened and glazed would have a radius 1.5 times that of the biodigestor.     

Durability of polymeric glazing materials for solar applications

The economic viability of solar collector systems for domestic hot water (DHW) generation is strongly linked to the cost of such systems. Installation and hardware costs must be reduced by 50% to allow significant market penetration. An attractive approach to cost reduction is to replace glass and metal parts with less expensive, lighter weight polymeric components. Weight reduction decreases the cost of shipping, handling, and installation. The use of polymeric materials also allows the benefits and cost savings associated with well established manufacturing processes, along with savings associated with improved fastening, reduced part count, and overall assembly refinements. A key challenge is to maintain adequate system performance and assure requisite durability for extended lifetimes. Results of preliminary and ongoing screening tests for a large number of candidate polymeric glazing materials are presented. Based on these results, two specific glazings with moderate and poor weathering stability are selected to demonstrate how a service lifetime methodology can be applied to accurately predict the optical performance of these materials during in-service use. A summary is given for data obtained by outdoor exposure and indoor testing of polyvinyl chloride (PVC) and high temperature modified polycarbonate copolymer (coPC) materials, and an initial risk analysis is given for the two materials. Screening tests and analyses for service lifetime prediction are discussed. A methodology that provides a way to derive correlations between degradation experienced by materials exposed to controlled accelerated laboratory exposure conditions and materials exposed to in-service conditions is given, and a validation is presented for the methodology based upon durability test results for PVC and coPC.