Overall Thermal Transfer Value Research Articles

Analysis of cooling loads and air circulation in the passenger compartment of the CR400AF fast train trailer car

The air conditioning system is a system that regulates air circulation and air temperature on the train. The temperature standard for fast train passengers is in accordance with Permen No. 7th year 2022 is 22°C - 26°C. To achieve this temperature, a cooling system is needed that is suitable for the cooling load. This research was conducted on the CR400AF fast train trailer car with the aim of knowing the factors that influence cooling loads, calculating and analyzing cooling loads which are used as a reference in determining air conditioning technical specifications, as well as analyzing air circulation that affects air humidity. The data analysis method used is the quantitative data analysis method. This method is carried out by collecting primary and secondary data to be used as a basis for calculations in answering the problem formulation. Data analysis was carried out by calculating the OTTV (Overall Thermal Transfer Value) according to SNI 03-6389-2000, calculating the cooling load using the CLTD (Cooling Load Temperature Difference) method according to SNI 03-6572-2001, and carrying out an air circulation test referring to Permen No. . 7 of 2022. From the results of the analysis and calculations, the OTTV value is 15.6 Watt/m2. Room eligibility standards according to SNI 03-6389-2000 standards are OTTV values not greater than 45 Watt/m2. The internal cooling load is 15,010 W, the external load and ventilation is 22,688.92 W, the total cooling load is added 10% safety factor of 41.47 kW, the cooling capacity of the AC unit based on technical specifications is 45kW. The average value of air flow velocity during the air circulation test is 0.3 m/s. according to Ministerial Regulation No. 7 of 2022 maximum air circulation speed of 0.5 m/s. From several analysis and calculation results, it can be concluded that the passenger space of the CR400AF fast train trailer car is standard and feasible to operate

An Analysis of Energy Consumption In The Goverment Buildings’ In Indonesian Border

In this research, energy consumption analysis was conducted at the Main building regent’s office of nunukan. The analysis was conducted on the main variables of energy efficiency, namely: measurement of temperature and relative humidity, calculation of Overall Thermal Transfer Value (OTTV) and Roof Thermal Transfer Value (RTTV), calculation of Energy Consumption Intensity (IKE) in air-conditioned and non-air-conditioned rooms as well as an analysis of opportunities to increase the efficiency of energy consumption in the buildings.. Based on the calculation and result of IKE in both buildings, they are still considered in the category of EFFICIENT. However, based on the measurement of temperature and relative humidity, it shows that in both buildings air conditioning is still necessary to achieve the level of thermal comfort, therefore an increase of efficiency in the load is needed to avoid wastage.

Innovating building energy regulations enabled by radiative sky cooling: Enhanced code of practice for overall thermal transfer value (OTTV) of super-cool roofs

Radiative sky cooling, which utilizes outer space as the cooling source for heat dissipation, is attracting global interests for its ability to cool passively without using any energy. Considering the swift advancements in the production of cost-effective radiative sky cooling materials on a large scale, it is of practical significance to incorporate radiative sky cooling technology into buildings to improve energy efficiency, necessitating amendment of the corresponding regulations. With this objective, the present research particularly focuses on the impact of radiative sky cooling-based super-cool roof strategies on the code of practice for Overall Thermal Transfer Value (OTTV), which is a prescriptive building regulation introduced by the Hong Kong government for building design, aimed at providing correction factors for local typical roofs integrated with advanced radiative sky cooling materials. To achieve the purpose, a new model for predicting roof heat transfer based on radiative sky cooling was established. Scaled-down experiments were conducted to fully validate the developed model with sufficient accuracy. The findings indicate that the implementation of super-cool roof strategies through radiative cooling-based techniques can substantially decrease roof heat gains, with reductions ranging from 73.9 % to 90.7 %, yield considerable energy savings, averaging between 3.5 and 45.0 kWh/m2, as well as significant cost savings on cooling expenses, averaging from 5.8 to 74.2 HKD/m2. Moreover, the adoption of such strategies has the potential to reduce carbon emissions by 6.3 to 81.2 kg/m2 during the cooling season. These outcomes vary depending on factors like the coefficient of performance (COP), radiative cooling materials, and specific roof types. Correlations between roof heat gains and OTTVs are established with a high accuracy of fit, achieving a coefficient of determination as high as 0.978. The average correction factors of five cutting-edge radiative cooling materials range from −0.00563 to −0.01655 in response to different typical roof types. Utilizing these correction factors, incorporating radiative sky cooling materials results in the OTTV of super-cool roofs varying from −0.7216 to −0.239 W/m2, which are significantly below the prevailing OTTV limit of 21 W/m2 enforced for Hong Kong’s commercial buildings. The proposed approach in this study can provide a straightforward and practical approach to assess the OTTV of typical building roofs when integrated with cutting-edge radiative sky cooling materials. This research offers significant perspectives into evolution and innovation of building energy policies incorporating radiative sky cooling technology.

Evaluating the Impact of Biocomposite Brick Materials on The OTTV and Diverse Thermal Characteristics of Rooms in Residential Buildings

The development of biocomposite materials for building purposes, including their incorporation in bricks, has gained momentum. Bricks are extensively utilized in residential buildings in Indonesia, making their performance a critical factor. To ensure building performance meets certain standards, Indonesia adheres to SNI 6389:2011, which mandates compliance with the Overall Thermal Transfer Value (OTTV) before construction commences. This study aims to examine the impact of using biocomposite bricks on the OTTV value. Additionally, it investigates the effects on various thermal properties of the room, such as humidity, air temperature, operative temperature, and Mean Radiant Temperature (MRT), which serve as indicators for assessing thermal comfort. The findings demonstrate that the use of biocomposite bricks can reduce the OTTV value by approximately 7.9% - 10.2%. However, there is no significant alteration observed in the physical properties of the room when compared to conventional bricks. As a result, it can be inferred that the use of biocomposite bricks holds promise for further progress in enhancing energy efficiency and addressing environmental concerns.

Towards Energy Analysis and Efficiency for Sustainable Buildings

Energy analysis that leads to energy efficiency becomes one of the most important factors in the building design process, especially considering the current energy crisis and the effects of global warming. Building designers greatly benefited from the review and analysis to optimize energy usage for the building in the design stage. While the current design approach is mostly done manually, this paper presents the automated version using the developed BIM plugin. It eases the designer’s choice of alternative plans that yield an effectively designed building. The development of energy analysis in the application aims to promote energy efficiency by calculating the energy consumption estimation based on energy codes MS2680 and MS1525. This application is improved by a simulation that uses the Building Information Modeling (BIM) platform and extracts the necessary parameters from the BIM model with the aid of the created plugins. This study measured energy consumption and efficiency using the two primary parameters of Overall Thermal Transfer Value (OTTV) and Roof Thermal Transfer Value (RTTV). According to the results, OTTV reaches 42.72% and RTTV reaches 8.02%, both of which respectively meet Malaysian Energy Code limits of less than 50% and 25%. Doi: 10.28991/ESJ-2023-07-06-022 Full Text: PDF

Analisis Konservasi Energi Pada Dinding Kaca Ruang Tunggu Bandara Ahmad Yani Semarang

The implementation of green building principles in building structures in Indonesia has a positive impact on reducing the effects of global climate change. In this regard, several airports in Indonesia have adopted the green building concept. One example of an airport that has been implemented this approach is Ahmad Yani International Airport, located in Semarang City, Central Java, Indonesia. In this study, an exploratory quantitative approach was used to analyze thermal comfort in buildings using the overall thermal transfer value (OTTV) formula according to SNI 03-6389-2020 guidelines, and utilizing data collected in the field. Furthermore, this study only focuses on the type of glass wall material and certain orientations. Based on the analysis result, it was found that the OTTV value for glass walls reached 54,98 W/m². However, it should be remembered that these result actually exceeds the set standard. However, these result do not actually cover the entire context of OTTV values as a whole, because this study considers one type of material and a certain orientation.

Building Envelope Performance to Achievement of Energy-Efficient Buildings : a case study analysis in Ulil Albab Mosque Yogyakarta

The performance of the building envelope is one of the most important in energy-efficient buildings. As the outermost layer, the building envelope will be very decisive for heat transfer from outside to inside the building. The performance of the building envelope in heat transfer refers to as the Overall Thermal Transfer Value (OTTV). OTTV measures the average heat gain into the building through the building envelope. It is a measure widely adopted in many countries to improve the design of energy-efficient buildings. The OTTV value strongly influences the ratio of transparent openings on the building facade. The size of the transparent opening will affect the inclusion of natural lighting in the building. This study aims to see how closely the relationship between the OTTV value and the achievement of natural lighting in buildings according to standards. The values used as success standards are the GBCI and SNI parameters. This research expects to provide a reference for existing buildings to improve building performance, especially for energy efficiency. This study uses a simulation method with OTTV worksheets and DIAlux Evo calculations. The mosque chooses to be a case study because the mosque is a building that has a distinctive orientation. In this research, Ulil Albab mosque, Yogyakarta, for the case study. For the location of Yogyakarta, the Qibla direction is azimuth direction 294° 42′ 39.894″ (Northwest) from Yogyakarta, where the radiation factor value is the largest. The results of this study indicate that the OTTV value can follow the standard by lowering the percentage of WWR in a facade with a high radiation factor value. Still, a WWR that is too small can result in natural lighting being unable to enter the room. In this building, the most efficient thing to do is replace the transparent material with one with better thermal properties.

Analisa Nilai OTTV (Overall Thermal Transfer Value) pada Bangunan Pemerintahan di Kota Lhokseumawe

Global warming and the energy crisis are the biggest problems in the world today, many efforts must be made to avoid them. One of them is by continuing to increase the implementation of energy efficient buildings. In Indonesia, energy-efficient buildings must meet the requirements set out in SNI 03-6389-2020 where the maximum limit for the OTTV (Overall Thermal Transfer Value) value is 35 Watt/m² and has been enforced by the Government from now on. However, these requirements have not been fully fulfilled by investors, as well as planning agencies or consulting units. There are still many buildings whose OTTV value is not yet known. As is the case with the object of this research, namely the Lhokseumawe Mayor's Office building. This research aims to calculate and determine the OTTV value for the research object of the Lhokseumawe Mayor's Office building, so that later it will be known whether the building is categorized as an energy efficient building or not. The research method used is an experimental quantitative method using the OTTV Microsoft Excel spreadsheet calculator from the Ministry of Public Works and Public Housing (BGH-PUPR). The results of this research analysis show that the Lhokseumawe Mayor's Office building has many large openings and has sunlight fenestration, so that the overall OTTV value on the building envelope is below the SNI standard threshold of 35 Watt/m² and can be categorized as an energy efficient building.

Development of Vertical Shading Parameter Model for Reducing Energy Consumption in Tall Building based on Overall Thermal Transfer Value -A Case Study

In tall building, shading design is a configuration that includes geometry, material, and the system. Currently, the design of the shade found for building’s envelope is not only used to improve the thermal performance, but is also required to provide aesthetic value to the appearance of a building. The use of shading design in the form of vertical shade at certain places will provide differences in the acquisition of sunlight for interior spaces. Therefore, by shading design the appearance will certainly affect the thermal performance of the building envelope. This study aims to develop and propose a model that can be used as parameter measuresof the effect of shading design variations on the thermal performance of the building envelope. This variation will include shading design concept which applies different vertical shading that covers glass material, the shading width, and the shading angle. This research design includes the calculation of the shade coefficient (SC) and overall thermal transfer value (OTTV) of each variant, followed by using multiple linear regression (MLR) analysis with manufacturer’s SC glass, shading width, and shading angle as the predictor variables. The study is conducted by two parts: designing of vertical shading parameters that affect the value of the SC and determining the thermal performance of the building. The MLR analysis is carried out to obtain a linear equation showing the effect of shading design on thermal performance of the building envelope. Based on the regression analysis result, it can be seen that the manufacturer’s SC of glass has the biggest impact on the OTTV value, while the shading angle has the lowest. With 95.2%-98% of the predictors data can explain the value of OTTV, the model can be used as the tool for designing vertical shading for reducing the energy consumption in the building.

The Effect of Shading Devices on OTTV (Overall Thermal Transfer Value) Value of Office Buildings: Case Study of PT Industri Kapal Indonesia (IKI) Building

One of the passive design strategies that effectively reduce the heat load on the building envelope, especially in areas with a large surface area of glass shading Device. The research aims to measure the design influence of shading devices against the value of Overall Thermal Transfer Value (OTTV) buildings. Research using quantitative methods, research done by trying Shading devices with Vertical Models, Horizontal multiple fins, and Egg crates, which have the length and slope provided by the Indonesian National Standard SNI. It tests each design shading measured on an impairment basis OTTV the best and best under 45 Watt/m². The results of the study show that shading devices affect the impairment of OTTV. The longer the shading device and the higher the slope, the more effective it is in blocking incoming radiation through the glass surface. Impairment OTTV existing buildings without a shading device have an initial value of 69.572 W/m2, decreased by 55% to 31.57 W/m2. Shading an egg crate with length120 cm with a slope of 40° is the best shading based on a comparative analysis between vertical louver shading and horizontal multiple fin shading. This is due to shading egg crates being able to respond to the sun in incoming low and high altitude angles to minimize or block radiation that enters through the glass surface.

A Study on Transparent Type Envelope Material in Terms of Overall Thermal Transfer, Energy, and Economy for an Office Building Based on the Thai Building Energy Code

Energy consumption in buildings has increased significantly as population and economic activities are concentrated in urban areas. Air conditioning accounts for a significant percentage of energy consumption in buildings, especially in tropical climates. The main area where heat can be transferred into the building is through glass windows. Thus, this study aims to evaluate feasibility in terms of overall thermal transfer value (OTTV), energy, and economics for retrofitting different glass materials in an office building in Thailand by using building energy code (BEC) software. The software uses Thailand’s building energy code as the standard to evaluate the energy performance of the case study building in comparison with different glass types used in retrofitted cases. From an economic perspective, the internal rate of return (IRR) and discounted payback periods (DPP) were used as determining indexes. The results demonstrated that retrofitted windows with the best energy-efficient glass might achieve energy performance, but installation cost can reduce economic feasibility, while the glass with the second lowest heat transfer coefficient can reduce the OTTV by 68.89% and building energy consumption by 16.87%. However, it can achieve the highest economic performance with 10.70% IRR and DPP at 11.83 years. Therefore, the balance between energy and economic factors must be considered to provide energy-efficient and investment-friendly glass materials for retrofit projects. In addition, the study focuses specifically on tropical climates. Thus, the finding may not be reflected similarly for buildings located in different regions.

Lighting Energy Reduction by Optimizing Daylight while Maintaining Cooling Load in Tropical Educational Building, Depok, Indonesia

This study aims to reduce the lighting energy consumption in educational buildings while avoiding an increase in cooling load. The Faculty of Engineering building in Universitas Indonesia, Depok, West Java, Indonesia is used as a case study. Daylight optimization can have an impact on lighting energy, which is the largest energy consumer in educational buildings. However, given Indonesia’s tropical climate, daylight leading to heat gain is a concern. Current passive design interventions for controlling daylight and heat gain include light shelves, clerestories, and glazing materials. Daylighting performance is simulated using DIALux software. Results of each intervention are analyzed quantitatively and qualitatively by theories and parameters, namely illuminance level, light uniformity, and overall thermal transfer value (OTTV). Light shelves result in increased uniformity and lower OTTV. Clerestories result in increased average illuminance but higher OTTV. Active intervention with a dimming and grouping system is applied after daylight increases. The combination of passive design interventions and active dimming of electric lights reduces lighting energy with the same OTTV as existing. This study recommends the use of passive and active daylighting strategies considering their effect on the cooling load of buildings.

Developing The Building Envelope Thermal Transfer Value Calculator Based on BIM-VPL Framework

The use of formula to calculate OTTV (Overall Thermal Transfer Value) for buildings in Indonesia is written in the SNI (Indonesia National Standard) 6389:2020 document. There are at least 3 equations and 7 tables that require to refer for calculating the thermal transfer value of the building envelope. The series of formulas is quite time consuming and prone to human error if it is done repeatedly at the building design stage. This study aims to develop an OTTV formula based on the SNI 6389:2020 so that the OTTV calculation process can be carried out more effectively. The formula development process has done using the Autodesk Revit 2019 and Autodesk Dynamo 2.2 applications. From the studies that have been conducted, 11 scripts were written to calculate OTTV semi-automatically.

OTTV'S Assessment on Thermal Performance of High-Rise Apartment Buildings in Penang

This study evaluates the envelope thermal performance of high-rise apartment buildings in Malaysia, which are being largely dominated due to the high economic development and increased population. The evaluation was conducted using the Overall Thermal Transfer Value (OTTV), which is the key tool used in the Green Building Index to assess the Energy Efficiency of buildings. Different high-rise apartment buildings were selected with different architecture styles, to account for several periods of building construction. The OTTV value was calculated for the west-oriented façade of the selected buildings, which is considered as a critical orientation that receives high solar radiation. The results showed that four out of the five investigated buildings achieved the minimum requirements for the OTTV, i.e., less than 50 W/m². The maximum and minimum OTTV values with the buildings’ original design were 82.60 W/m² and 41.54 W/m², respectively. However, one of the buildings achieved a lower OTTV value with the installation of shading devices by the owners, i.e., decreased from 48.39 W/m² to 37.60 W/m². The solar radiation penetration through the fenestration was found to be the major contributor to the total OTTV, while it can be controlled by the shading devices. Besides, using dark paints increased the heat conduction through the opaque walls by more than double compared to light paints. This study shows that some design considerations, such as paint colour, shading devices, and glazing material, can have a great influence on the heat gain in buildings.

Retrofitting of a High-Rise Residential Building for Energy Efficiency with OTTV as an Assessment Tool

Buildings account for nearly 50% of the total energy consumption. The use of air-conditioning is one of the major influencers to the high energy consumption in buildings. To tackle this high energy consumption, buildings are required to be more energy efficient. This study aimed to investigate the retrofitting of existing residential building for energy efficiency by using the Overall Thermal Transfer Value (OTTV) as an assessment tool. Various retrofitting measures were involved, including varying the colour of the opaque wall with different solar absorptivity, the U-value and shading coefficient of the Glazing system, and the type and projection of the external shading. The results showed that applying the retrofitting measures individually (i.e., using light colour with low solar absorptivity, replacing the glazing system to have lower shading coefficient and U-value, and the installation of external shading systems with low shading coefficient) can decrease the OTTV by 26% to 33.4%. However, combining these measures managed to decrease the OTTV by up to 75.6% (i.e., the OTTV decreased from 82.87 W/m² to 20.19 W/m²). This can improve the building energy efficiency as it contributes to less cooling load for the air-conditioned buildings, while it provides a better indoor environment in non-air-conditioned buildings.

Analysis of Hotel Façade Thermal Performance with a Special Reference to the City Hotels in George Town, Penang

The present study identifies issues pertaining energy efficiency of high-rise city hotels in Malaysia and aims to examine the thermal performance of high-rise hotels with different façade design configurations. Large hotels in the tropics of Malaysia are found to be energy intensive among commercial building categories. The present study proposes two case studies of high-rise city hotels in George Town, Penang, with different façade configurations to determine their capability to comply the Overall Thermal Transfer Value (OTTV) requirements set by the Malaysian Standards MS 1525;14 and the Green Building Index (GBI). Utilizing the OTTV formula as stipulated in the MS 1525:14, the OTTV of each case study was manually calculated using the identified façade design parameters. Comparative analysis of the results indicate that each of the cases garnered OTTV which exceeded the recommended value of 50 Wm-2. General guidelines and recommendations for improvement in the hotel façade design in the tropics are also included in the discussion.

Thermal transfer and temperature reductions from shading systems on opaque facades: Quantifying the impacts of influential factors

In recent years, with the rapid development of cities across the globe and global warming, Urban Heat Island (UHI) and building cooling energy consumption have reached a point of perilous concern. The use of shading systems on building fenestrations has long been known as an effective strategy to minimise façade heat gain as well as glare, resulting in lower cooling energy consumption and indoor comfort. Expending the potentials of shading systems beyond conventional use, the present paper focuses on the effects of shading systems on opaque facades that is currently unaccounted for in simplified Overall Thermal Transfer Value (OTTV) calculations in standards adopted by many countries. A field study was first conducted to compare the effects of various shading configurations on an opaque façade. Subsequently, a simulation study was then conducted to quantify the effects of shading systems on opaque facades with varying thermal transmittance value (U-Value). The results of this study revealed numerous benefits for the deployment of shading systems on opaque building facades, which includes, reduction to building conductive heat gain, building cooling loads, microclimate temperature near the façade, as well as potential reduction to carbon emissions over the building lifecycle. Moreover, the paper also provides considerations for the selection shading configurations, as well as the considerations that would be required for the formulation of a more accurate simplified OTTV equation that would take into account the effects of shading systems on opaque facades.

Optimalisasi Konservasi Energi Bangunan Bertingkat melalui Pilihan Material Kaca sebagai Fasad

<p><em>Box-shaped buildings covered by glass and minimal shading elements are increasingly common</em><em>, then</em><em> </em><em>causes </em><em>more</em><em> large building energy consumption. This </em><em>research</em><em> aims to analyze the selection of the most optimal glass material for the Undip Integrated Laboratory Building, so that the Overall Thermal Transfer Value (OTTV) of the building is expected to meet the SNI 6389:2020 standard. The research was conducted with an experimental quantitative approach using a spreadsheet calculator OTTV Microsoft Excel of the Ministry of Public Works and Housing. The simulation is divided into three treatment variations, namely variations in BNFL glass thickness; variations in the color of Panasap's glass; and various types of glass. The results show that glass materials with good thermal properties have low shading coefficient (SC), solar factor (SF), and U-value. In addition, the brighter and thicker the glass material, the better the thermal performance. The Undip Integrated Laboratory Building has a total OTTV that meets SNI 6389:2020 standards. However, if viewed partially, the OTTV of the east facade of the building needs to be retrofitted.</em></p>

VPL-based Code Compliance Checking for Building Envelope Design Using OTTV Calculation

Building Envelope plays a vital role in reducing thermal loads, minimizing energy consumption, and ensuring sustainability. The Overall Thermal Transfer Value (OTTV) is a recognized method to evaluate the thermal performance of buildings. Building Information Modelling (BIM) has added great value to the AEC industry as an efficient tool to facilitate the building design process. With the development of BIM, more properties and material characteristics are assigned to the project design and building model that are getting more complex. Meanwhile, performing OTTV assessment and checking compliance with the assigned values involving time-consuming calculations with the possibility of ambiguity. Hence, automation of the code compliance checking process has become on-demand within the BIM environment. The objective is to develop a Visual Programming Language (VPL)-based script for automating the OTTV rule-based code compliance checking process. The applied method is to integrate BIM, VPL, and OTTV requirements; and develop a visual script that is responsible for extracting parameters from the BIM model, performing OTTV calculation, comparing output with assigned standard values of OTTV aiming answering the research question whether automated code compliance checking process can contribute to code compliance facilitation effectively. The results indicate that integrating VPL into the code compliance checking process has promising signs in facilitating the compliance checking process, increasing the accuracy and reliability of outcomes.

Method of Calculating Solar Heat Transmitted Through Shaded Windows for OTTV in Consideration of Diffuse Radiation Diminished

The energy used in the buildings in hot climate conditions is mainly for the cooling load requirements for air conditioning in summer. To reduce the energy consumption for air conditioning, the threshold value for OTTV (Overall Thermal Transfer Value) is regulated in energy standards for air-conditioned buildings of some subtropical and tropical countries. To ensure a satisfactory OTTV value, the top priority of building envelope designing is reasonable Window to Wall Ratio (WWR) with appropriate sun shading devices to reduce the heat penetrated through window glass into the buildings. Therefore, the accurate calculation of solar radiation through window glass with shading devices is very important to properly determine the cooling load of the air conditioning system in the summer and the energy efficiency of the architectural facade solutions. The research aims to calibrate the reduced solar radiation coefficient of the shading device (β) from the original method of calculating the solar heat transmitted through window glass with sun-shading devices, thereby completing the OTTV evaluation method with high accuracy. The calculation is based on the sunlight projection to determine the window’s shaded area created by shading devices of any shapes with consideration of diffuse radiation diminished. The results of β calculated showed that in tropical climate, the total solar radiation transmitted through the window glass calculated by the proposed method is much lower than the previous method. A computer software built from the proposed theory helps the designer easily choose the optimal sun shading solutions. The research conducts the calculation as an example for horizontal-inclined and the combined of horizontal and left/right vertical shading devices (accepted as EKE).