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The majority of the population in Indonesia lives in naturally ventilated and unconditioned residential buildings because they cannot afford energy services. This situation is common in many countries in tropical regions, negatively affecting the occupants’ health due to overheating. Therefore, housing types that can cool down indoor temperatures to the extent possible using a passive approach, rather than an active approach, should be developed. This study aims to improve naturally ventilated houses by considering the louver area and insulation of houses. First, we employ an on-site measurement for collecting data such as the indoor/outdoor temperature and relative humidity in an Indonesian city, Lhokseumawe. In addition, the experimental data are used to validate a numerical simulation model. Second, the numerical simulation is utilized to establish energy-efficient design solutions for houses in 14 Indonesian locations. The results show that, compared with the insulation cases, different louver areas insignificantly change indoor air conditions by approximately 0.3 to 1 °C. Additionally, the application of a combined performance improvement for both louver areas and building envelope insulation levels can reduce the indoor air temperature and relative humidity by 2.2 °C and 8%, respectively. Moreover, the daily cooling demand for the proposed improvement plan is reduced by 18.90% compared with that for the existing case. Furthermore, the annual cooling loads for the entire simulated regions are reduced by 46.63 GJ/year (23.09%). This study is a potential starting point for achieving zero-energy housing and occupants’ sufficient thermal comfort in unconditioned and naturally ventilated houses in Indonesia.

•Optimized surrounding shades can improve energy savings and visual comfort.•Prefabricated buildings are specifically suitable for warm climate zones.•Proposed hybrid shadings achieved a higher reduction in energy consumption.•The hybrid louvers can replace horizontal, vertical, and egg-crate shadings. Reusing shipping containers for residential purposes offers a promising approach to address global energy consumption challenges from economic and environmental perspectives. This study parametrically designed hybrid louver shadings by combining fixed vertical triangular slats with variable-depth horizontal rectangular slats, offering a novel approach to shading prefabricated buildings. The energy consumption, daylighting performance, and visual comfort were assessed for various shading configurations. Results indicated that implementing the proposed hybrid louvers, featuring fixed vertical triangular slats and variable-depth horizontal rectangular slats, significantly reduced Energy Use Intensity (EUI) to 133.95 kWh/m2. Moreover, Useful daylight illuminance (UDI), Daylight Autonomy (DA), and Glare Autonomy (GA) values improved to 95.38%, 89.97%, and 91.16%, respectively. The study highlighted the potential of the proposed shading system to significantly reduce overall energy consumption across various ASHRAE climate zones, including Miami (1A), Guangzhou (2A), Melbourne (3C), Esperance (3C), San Diego (3A), and Milan (4A). Notably, energy reductions of up to 50.2% were projected for climates such as Miami (1A) and San Diego (3A). Furthermore, container buildings in warm climate zones exhibited a significantly lower EUI range of 76.58 to 91.95 kWh/m². This study underscores the transformative potential of hybrid louver systems in promoting the widespread adoption of sustainable residential architecture, contributing to global sustainability efforts. [Display omitted]

•Split louvers improve daylighting performance and reduce lighting energy use.•Optimal positioning ensures well-distributed daylight with parametric control.•Parametric split louvers outperform conventional ones in daylight distribution.•Significant energy savings: 69.9 % (March), 43.6 % (June), 63.5 % (December). The incorporation of split louvers into building systems provides substantial potential for enhancing daylighting performance and, consequently, reducing lighting energy consumption. This study focuses on the critical aspect of determining the optimal positioning of split louver sections to ensure well-distributed daylight in indoor spaces and adding parametric control as a daylight redirection system. This research aims to investigate indoor daylight environments by modifying the relationships and configurations of split louver sections and enhancing the efficiency of daylighting performance through the parametric control of the split louver. In addition, it investigates the energy-saving potentials of using the parametric split louver through the reduction of electric lighting consumption. The study demonstrates that the daylighting performance of the split louver depends upon the status of each section. Specifically, the effects of the upper section of the split louver are predominantly apparent in the rear area of the room, whereas the lower section markedly enhances illumination in the frontal area near windows, particularly during winter months when the lower solar angles. Secondly, the daylighting efficiency of the parametric split louver outperforms that of the conventional single louver in terms of daylight distribution and availability. The efficient daylight performance is evident in the uniform distribution of illuminance within the useful daylight illuminance (UDI) range of 300–500 lux on all typical dates, reaching 44 % and 55 % during the morning and noon, respectively, on March 21st Additionally, the electric lighting efficiency of the parametric split louver surpasses conventional louver throughout the day for all typical dates, resulting in notable lighting energy savings, with average percentages 69.9 % and 63.5 % on March 21st and December 21st, respectively, while June 21st shows lower efficiency with 43.63 % savings. This study contributes valuable insights for architects and designers seeking to create energy-efficient and well-illuminated indoor environments through the integration of parametric split louver. [Display omitted]

Windows, as transparent intermediaries between the indoors and outdoors, have a significant impact on building energy consumption and indoor visual and thermal comfort. With the recent development of dynamic window structures, especially various attachment technologies, the thermal, visual, and energy performances of windows have been significantly improved. In this research, a new dynamic transparent louver structure sandwiched within conventional double-pane windows is proposed, designed, optimized, and examined in terms of energy savings in different climates. The uniqueness of the proposed design is that it autonomously responds to the seasonal needs prompted by solar heat gain through the use of thermally deflected bimetallic elements. Moreover, by integrating spectral selective louvers into the system design, the dynamic structure enables strong solar infrared modulation with a little visible variation. The optical and thermal properties of the dynamic glazing structure support about 30% and 16% seasonal variations in solar heat gains and visible transmittance, respectively. Furthermore, the potential energy savings were explored via parametric energy simulations, which showed significant potential for heating and cooling energy savings. This proposed design demonstrates a simple smart dynamic glazing structure driven by seasonal temperature differences, with significant solar heat control capabilities and minor effects on the visible or visual quality of the glazing system.

Noticing the low efficiency caused by fluid flow retention phenomena and the high pressure loss in the shell-and-tube heat exchanger with common segmental baffle, an embedded louver shell-and-tube heat exchanger is designed, and numerical simulation of fluid heat transfer and flow characteristics of this novel heat exchanger is carried out. Results reflect that the structure with embedded louvers can significantly reduce the area of the flow retention zone and increase the fluid disturbance on the leeward side of the baffle, making the pressure drop of the shell side fluid 20.5–21.3% lower and the heat transfer coefficient 8.75–16.4% higher. At the shell side fluid inlet, outlet, and middle section of the heat exchanger, the average fluid temperatures are 0.34 °C, 2.12 °C, and 3.08 °C higher, respectively, compared to those in the common segmental baffle shell-and-tube heat exchanger. On this basis, the influence of the louver geometrical parameters, including louver angle and louver length, on the performance is also analyzed. The comprehensive evaluation factor is proposed and applied to evaluate the improvement of heat exchangers with different design parameters. The results showed that the evaluation factor is higher when the louver angle is 60°. However, when the louver length increases from 1/7 to 1/3 of the distance between adjacent baffles, the evaluation factor is almost unchanged.

The performance of heat exchangers is severely limited by airside thermal resistance. The effect of redirection louvers (RLs) on the airside thermal performance of a compact flat-tube louvered fin heat exchanger was investigated. A steady-state 3D numerical analysis was conducted for different fin configurations by varying the number of RLs (NRL = 1, 2, 3, and 5). Conjugate heat transfer analysis was performed at the low Re (50–450) for domestic and transport air-conditioning applications. Geometric parameters such as louver pitch, louver angle, fin pitch, and flow depth were set as 1.7 mm, 27°, 1.2 mm, and 20 mm, respectively. The effective heat transfer fin surface areas of different fin configurations were also kept identical for a comparative analysis. The influence of the RLs on the airside thermal–hydraulic performance was analysed by exploring the local and average Nusselt numbers, pressure drop, Colburn j factor, friction factor f, performance evaluation criteria (PEC), and flow efficiency of different fin configurations. The numerical results revealed that the asymmetric fin configuration with two RLs (NRL = 2) showed the best heat transfer performance for the entire Re range. It resulted in a 33% higher average Nusselt number, causing a 24% higher pressure drop compared to NRL=5. At low flow velocities (Re < 75), NRL = 3 showed better PEC; however, at high flow velocities (Re > 75), NRL = 1 outperformed other fin configurations. Finally, it was noted that increasing the number of RLs reduced the amplitude of the wavy-shaped flow formed between the neighbouring louvered fin, consequently deteriorating the flow efficiency.

This study performs a 3D turbulent flow numerical simulation to improve heat transfer characteristics of wavy fin-and-tube heat exchangers. A compound design encompassing louver, flat, and vortex generator onto wavy fins can significantly enhance the heat transfer performance of wavy fin-and-tube heat exchangers. Replacement of wavy fins around tubes with flat fins is not effective as far as the reduction of thermal resistance is concerned, although an appreciable pressure drop reduction can be achieved. Adding two louvers with a width of 8 mm to the flat portion can reduce thermal resistance up to 6% in comparison with the reference wavy fin. Increasing the louver number and width can further decrease the thermal resistance. Also, it is found that the optimum louver angle is equal to the wavy angle for offering the lowest thermal resistance. Therefore, compound geometry with three louvers, a width of 12 mm, and the louver angle being equal to wavy angle with waffle height to be the same as fin pitch of the reference wavy fin has the most reduction in thermal resistance of 16% for a pumping power of 0.001 W. Adding punching longitudinal vortex generators on this compound geometry can further decrease thermal resistance up to 18%.

Numerical studies of laminar forced convective heat transfer and fluid flow in a 2D louvered microchannel with Al 2 O 3 /water nanofluids are performed by the lattice Boltzmann method (LBM). Eight louvers are arranged in tandem within the single-pass microchannel. The Reynolds number based on channel hydraulic diameter and bulk mean velocity ranges from 100 to 400, where the Al 2 O 3 fraction varies from 0 to 4%. A double distribution function approach is adopted for modeling fluid flow and heat transfer. Code validations are performed by comparing the streamwise Nusselt number ( Nu ) profiles and Fanning friction factors of the present LBM and those of the analytical solutions. Good agreements are obtained. Simulated results show that the louver microstructure can disturb the core flow and guide coolant toward the heated walls, thus enhancing the heat transfer significantly. Furthermore, the addition of nanoparticles in microchannels can also augment the heat transfer, but it creates an unnoticeable pressure loss. With both the louver microstructure and nanofluid, a maximum overall Nu enhancement of 7.06 is found relative to that of the fully developed smooth channel.

In defining wind-driven natural ventilation in buildings, external louvers and slat angles are essential flow factors. Louvers are frequently used to minimize sunlight while enabling natural ventilation. Many studies on ventilated louvers have been conducted in the past, emphasizing the influence of louver opening positions and slat angles. External louvers, on the other hand, have received less attention. As a result, this research examines the impact of exterior louver slat angles on the key characteristics of natural cross-ventilation flow in a single-zone isolated structure, based on four main flow parameters: (i) air velocities, (ii) air age, (iii) volume flow rate, and (iv) air exchange efficiency. A model without louvers is simulated to provide a clearer understanding of the influence of louvers. The standard k- ε method is used to solve the isothermal 3D steady Reynolds-averaged Navier–Stokes (RANS) simulations. CFX software is used to validate the computational fluid dynamics (CFD) simulations using wind-tunnel experiments. The results show that the building without louvers has the greatest normalized volume flow rate (0.56). In contrast, the instance with exterior louvers with 45º slat angles has the highest air exchange efficiency (58.6%). This study can aid architects and academics in improving building design and sustainability.

This study evaluates the energy‐saving potential of hollow glass windows integrated with reflective aluminum foil louvers, tailored for hot‐summer, cold‐winter regions. The reflective integration minimizes solar absorption and bolsters insulation. Experimental results indicate a 14.9% reduction in heat transfer coefficient ( K ) (from 2.427 to 2.066 W/[m 2 ·K]) and a 20% decrease in shading coefficient (SC) (from 0.30 to 0.24) compared to standard louvers in the closed position. Furthermore, a coupled effect between air layer thickness ( δ ) and louver angle ( θ ) on K is observed, with smaller δ intensifying θ ’s influence. The reflective system demonstrates superior thermal performance at a modest cost increase of 3.4%, rendering it viable for energy‐efficient applications.