Study on the Optimum Roof Type with 30° Roof Angle to Enhance Natural Ventilation and Air Circulation of a Passive Design

Ibrahim, Siti Halipah; Roslan, Qairuniza; Affandi, Rohaida; Razali, Abdul Wafi; Samat, Yon Syafni; Nawi, Mohd Nasrun Mohd

doi:10.14716/ijtech.v9i8.2759

Cited by 10 publications

(8 citation statements)

References 7 publications

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“…A study found 73% of the heat absorption rate of solar radiation is contributed by the facade of the building (U. S. DoE 2011), it is absorbed by the surface of the wall components and roof when exposed directly to the sun (Ralegaonkar & Gupta 2010). The effects of being exposed to solar radiation for more than 10 hours a day throughout the year will spread the heat of solar radiation into the interior space through the facade of the building in various directions (Ibrahim et al 2014). R. Daghigh's study found that daytime temperatures can reach 24 ºC to 34 ºC and relative humidity between 70% to 90% can occur throughout the year (Daghigh 2015).…”

Section: General Overview On Green Roof Conceptmentioning

confidence: 99%

Assessment of Economic Worth of Green Roof: A Case Study in Putrajaya

Hamzah

Sulaiman

Harun

et al. 2023

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The current global temperature rise has affected local climate change issues and increased the energy usage for the building cooling process. Following this, the roof components have been identified to contribute the building heating effect due to exposure for more than 10 hours a day which at the same time secretes 70% of the sun's radiation. As an alternative, the green roof concept approach potentially reduces the effects of internal heat and operating costs of cooling the building while providing an investment return for the desired period. This study aims to measure the level of effectiveness of the building green roof concept on the building cooling rate and its profitability implications. Two objectives have been set. First, to compare the effects of concrete and green roof applications on energy consumption and operating costs for the cooling effects of air-conditioned buildings (active systems). Second, to evaluate the maintenance cost and profitability of applying the green-roofed building concept in terms of periodic return on investment. The findings of this study are seen to help the government and relevant agencies consider using the green roof concept in the physical construction of buildings in the future.

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Section: General Overview On Green Roof Conceptmentioning

confidence: 99%

Assessment of Economic Worth of Green Roof: A Case Study in Putrajaya

Hamzah

Sulaiman

Harun

et al. 2023

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“…A lack of natural ventilation can cause an increase in indoor temperatures attributed to ineffective passive design in modern houses. In the design of a home, the roofing system is crucial because the roof accounts for 70% of the overall heat gain [3]. One of the common passive designs used to increase natural ventilation is through roof configuration as roof configurations and shapes can change pressure distribution and flowrate through the building [4].…”

Section: Effect Of Roof Design Configurations On Natural Ventilation ...mentioning

confidence: 99%

Effect of Roof Design Configurations onNatural Ventilation with an Obstacle Inside the Building Model

Moey,

Wan,

Tai

et al. 2023

IJIE

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Roof shape, roof angle, and internal obstacle are some of the factors that have a substantial impact on building's ventilation performance. However, previous roof ventilation studies have not considered the influence of internal obstacle which can affect the overall building’s ventilation performance. For this study, CFD was used to study the effect of roof design configurations on natural ventilation with an obstacle inside the building model. The numerical simulation was carried out by using steady RANS equation specifically the Standard k-ε with enhanced wall treatment. A total of 40 simulation cases were carried out. The study considered two roof shapes mainly the sawtooth roof and the saltbox roof with varying roof angle which were 10º, 20º, 30º, and 40º. Internal obstacles with various height were further added into the simulation cases. Next, grid sensitivity analysis was carried out using Grid Convergence Index (GCI) and Factor of two of observations (FAC2) analysis was carried out as model verification method to ensure a reliable simulation result. Based on the results, it is found that airflow characteristics such as wind speed, distribution of pressure coefficient, and flowrate of an isolated building are strongly dependent on the roof shape and roof angle. Next, the dimensionless flowrate (DFR) is measured to be highest with largest roof angle while lowest with smaller roof angle. Furthermore, the DFR of a building with internal obstacle is lower than that without an internal obstacle due to blockage of incoming air. Moreover, the results show that the sawtooth roof outperforms the saltbox roof in terms of measured parameter. Finally, the study concluded that an isolated building with higher roof angle and without an internal obstacle leads to the best dimensionless flowrate throughout the building.Roof shape, roof angle, and internal obstacle are some of the factors that have a substantial impact on building's ventilation performance. However, previous roof ventilation studies have not considered the influence of internal obstacle which can affect the overall building’s ventilation performance. For this study, CFD was used to study the effect of roof design configurations on natural ventilation with an obstacle inside the building model. The numerical simulation was carried out by using steady RANS equation specifically the Standard k-ε with enhanced wall treatment. A total of 40 simulation cases were carried out. The study considered two roof shapes mainly the sawtooth roof and the saltbox roof with varying roof angle which were 10º, 20º, 30º, and 40º. Internal obstacles with various height were further added into the simulation cases. Next, grid sensitivity analysis was carried out using Grid Convergence Index (GCI) and Factor of two of observations (FAC2) analysis was carried out as model verification method to ensure a reliable simulation result. Based on the results, it is found that airflow characteristics such as wind speed, distribution of pressure coefficient, and flowrate of an isolated building are strongly dependent on the roof shape and roof angle. Next, the dimensionless flowrate (DFR) is measured to be highest with largest roof angle while lowest with smaller roof angle. Furthermore, the DFR of a building with internal obstacle is lower than that without an internal obstacle due to blockage of incoming air. Moreover, the results show that the sawtooth roof outperforms the saltbox roof in terms of measured parameter. Finally, the study concluded that an isolated building with higher roof angle and without an internal obstacle leads to the best dimensionless flowrate throughout the building.

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“…The impact from different Heating, Ventilating, and Air Conditioning (HVAC) systems and controls are also explored, combined with the aforementioned items [23,24]. Some studies focused on improving natural ventilation, assessed different window positions, sizes, and shapes [25][26][27]; roof types [28]; and also testing ventilation controls to improve Phase Change Materials (PCM's) efficiency [29][30][31].…”

Section: Sensitivity Analyses and Optimizationmentioning

confidence: 99%

Building Optimization through a Parametric Design Platform: Using Sensitivity Analysis to Improve a Radial-Based Algorithm Performance

et al. 2021

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Performance-based design using computational and parametric optimization is an effective strategy to solve the multiobjective problems typical of building design. In this sense, this study investigates the developing process of parametric modeling and optimization of a naturally ventilated house located in a region with well-defined seasons. Its purpose is to improve its thermal comfort during the cooling period by maximizing Natural Ventilation Effectiveness (NVE) and diminishing annual building energy demand, namely Total Cooling Loads (TCL) and Total Heating Loads (THL). Following a structured workflow, divided into (i) model setting, (ii) Sensitivity Analyses (SA), and (iii) Multiobjective Optimization (MOO), the process is straightforwardly implemented through a 3D parametric modeling platform. After building set up, the input variables number is firstly reduced with SA, and the last step runs with an innovative model-based optimization algorithm (RBFOpt), particularly appropriate for time-intensive performance simulations. The impact of design variables on the three-performance metrics is comprehensively discussed, with a direct relationship between NVE and TCL. MOO results indicate a great potential for natural ventilation and heating energy savings for the residential building set as a reference, showing an improvement between 14–87% and 26–34% for NVE and THL, respectively. The approach meets the current environmental demands related to reducing energy consumption and CO2 emissions, which include passive design implementations, such as natural or hybrid ventilation. Moreover, the design solutions and building orientation, window-to-wall ratio, and envelope properties could be used as guidance in similar typologies and climates. Finally, the adopted framework configures a practical and replicable approach for studies aiming to develop high-performance buildings through MOO.

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Study on the Optimum Roof Type with 30° Roof Angle to Enhance Natural Ventilation and Air Circulation of a Passive Design

Cited by 10 publications

References 7 publications

Assessment of Economic Worth of Green Roof: A Case Study in Putrajaya

Assessment of Economic Worth of Green Roof: A Case Study in Putrajaya

Effect of Roof Design Configurations onNatural Ventilation with an Obstacle Inside the Building Model

Building Optimization through a Parametric Design Platform: Using Sensitivity Analysis to Improve a Radial-Based Algorithm Performance

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