Vertical Louvers Research Articles

Multi-objective optimization of energy and daylight performance for school envelopes in desert, semi-arid, and mediterranean climates of Iran

Considering global warming as a critical challenge to human life, performance optimization of the building envelope can play a noticeable role to reduce a building's environmental footprint. Meanwhile, shading systems are considered as sustainable passive solutions to contribute to building energy efficiency, and daylight control in early-stage design. Nonetheless, a paucity of research has examined the various shading strategies in diverse climates, particularly arid desert and steppe regions, in conjunction with educational buildings. The present study aims to evaluate the role of fixed exterior shading systems (FESSs), and window-to-wall ratio (WWR) on building’ thermal and daylight performance in Iran with desert, semi-arid, and Mediterranean climates. Pareto Frontier and weighted-sum method for multi-objective optimization, and sensitivity analysis were used to study the optimum solutions, and the relationship between the design variables and the performance metrics. Three objective metrics including Spatial Daylight Autonomy (sDA), Annual Sunlight Exposure (ASE), and Energy Use Intensity (EUI), were defined as performance metrics. Shadings include vertical louver, horizontal louver, light shelf, overhang, and egg-crate. The results showed that EUI was reduced via FESS-integrated façade by 25.22%, 20.84%, 19.14%, 14.06%, and 13.47%, in Yazd, Bushehr, Kerman, Rasht, and Mashhad as selected studied cities, respectively. Based on ASE, the horizontal louver surpasses the other systems by 100% ASE value reduction in all climate zones except for Rasht. sDA level is reduced in all climate zones considering five studied FESSs excluding horizontal louver in Yazd and Rasht and overhang in Mashhad by 100% sDA level. Building energy performance simulation is validated by ASHRAE140-2020.

Daylighting performance of an innovative Prismatic Vertical Louvers (PVLs) shading system incorporating Prismatic Materials (PMs)

Daylight has a decisive role in buildings to provide visual comfort, and human health and well-being as well as energy saving potential in buildings; thereby, to benefit from daylighting advantages, it needs to be delivered indoors properly through designing decent daylighting systems. This paper aims to investigate the operational mechanism of an innovative daylighting system, prismatic vertical louvers (PVL), incorporating a microstructure prismatic material (PM), through a comparative study. The PVL shading system continuously rejects the direct radiation of sunlight while it transmits the diffuse scattered skylight resulting in creating a significant potential to improve visual comfort and energy saving in buildings. Through developing a parametric iterative algorithm to simulate the unique optical behavior of the proposed PVL system, the authors evaluated the ability of this innovative system in improving daylight distribution uniformity, and glare occurrence in the space compared to two state-of-the-art shading systems: mesh roller shade (MRS) system, and conventional vertical louvers (CVL). The comparison result of the study reveals the robust capability of the PVL system in enhancing the uniformity distribution of natural light across the work plane as well as removing glare occurrence for occupants.

Impacts of horizontal and vertical louvers on the natural cross-ventilation performance of a generic building

Wind-based natural cross-ventilation is defined as a process in which fresh air is injected into a building via a high-pressure windward window and exhausts into the atmosphere through a low-pressure leeward window. There are several parameters that affect the natural ventilation performance, which should be considered in detail to reach the maximum air quality inside the buildings. In the present study, the effects of horizontal and vertical louvers on the wind-driven natural cross-ventilation performance of a generic building are assessed using computational fluid dynamics. In this regard, horizontal and vertical louvers with installation louver angles of 15°, 30°, and 45° are compared with each other and corresponding non-louver cases. Computations are carried out for three different free-wind speeds of 1, 2, and 3 m/s to show the impact of the external conditions on the natural ventilation of louvered cases. The obtained results revealed that under a low free-wind speed of 1 m/s, the minimum age of air and maximum air exchange efficiency occur for vertical louvers with an installation angle of 15°, while at moderate and high free-wind speeds of 2 and 3 m/s, the horizontal louvers with an installation angle of 15° provide the best condition for a generic building. Highlights Effects of horizontal and vertical louvers on the wind-driven cross-ventilation were studied. At a free-wind speed of 1 m/s, the minimum age of air and maximum air exchange efficiency occur for vertical louver with α = 15°. At U H = 2 and 3 m/s, horizontal louver with α = 15° provides the best condition for a generic 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.

Correlations for forced convective heat transfer coefficients at the windward building façade with vertical louvers

Vertical louvers are a widely used external shading system to control natural lighting and solar heat gain for buildings. However, when installed on a building façade, they can disrupt the flow field around the façade and affect the external convective heat transfer process of building's exterior surfaces. To this end, this paper conducted CFD simulations to clarify the forced convective heat transfer patterns in a vertical louver-facade system based on the k-ω SST model with a detailed verification. The extended Newton's cooling equation is used to describe the heat exchange process between louvers, building façade, and air, which generates four heat transfer coefficients: hwa, hwb, hba, and hbw. Then the impacts of dimensionless temperature difference (θ), louver angle (φ), louver slat width (B), and installation distance (W) on the heat transfer coefficients are investigated. The results show that θ does not affect the average heat transfer coefficients. hwa reaches a minimum value and hba reaches a maximum value when φ = 75o. In addition, hwa increases by 55.3% and hba decreases by 21.9% as B increases from 0.3 m to 1 m. When W increases from 0.25 m to 1 m, hwa decreases by 5.6% and hba increases by 39.6%. The variation in the heat transfer coefficients (hwb and hbw) between the louvers and building façade is also explained. Finally, new correlations of paired heat transfer coefficients are established as a function of φ, B, W, and wind velocity (U10). The accuracy of these correlations is evaluated by comparing calculated values with simulated results.

THE OPERATIONAL CHARACTERISTICS AND THE UNWRITTEN DESIGN MANNERS OF THE DESIGN MANAGEMENT SYSTEM WITHOUT GUIDELINE BY FIXED MEMBERS

I clarify the operational characteristics of the Nagasaki Urban Design System and the unwritten design manners in this report. I can point out as operational characteristics that the fixed members give advice while long-term, that it is applied to both of public and private projects, that it has no guideline, that they advise after watching the site and the actual product, and that the planners who can understand this system are chosen. vertical louvers of buildings, white tones, rooftop greening and voluminous green, hiding fences, reuse of historic materials, and similar designing are unwritten design manners.

Comparison of Daylight Performance in Three Different Sky Conditions for Various Window Shading Types

Building sector contributes 40% of total energy consumption. In line with this, passive design strategy should be taken as an essential consideration to bring occupants comfort both thermally and visually. Besides, related to human health, one of the factors that the designer is encouraged to fulfill is the proportional amount of daylight that penetrates the building’s room. The passive strategy to optimize the daylight performance can be approached both from the building orientation and the shading system. This paper will computationally compare the different shading systems from vertical and horizontal louver, perforated metal sheets, and expanded metal shading, aiming to investigate the desirable shading-related design solution for the given condition. The simulated room is virtually situated in three different sun positions: Birmingham, United Kingdom, Jakarta, Indonesia, and Sydney, Australia. The metrics used in this experiment are Useful Daylight Illuminance (UDI). The Rhinoceros and Grasshopper were used to model the intended simulated room, while Ladybug and Honeybee were used to undergo environmental analysis. The results show that the vertical louver LV performs better in the three regions than the rest three compared shading. The experiment results are expected to give an overview which of which is fit for the situation.

PARAMETRIC DESIGN STUDY OF A PROPOSED PHOTOBIOREACTOR-INTEGRATED VERTICAL LOUVER SYSTEM FOR ENERGY-EFFICIENT BUILDINGS

ABSTRACT In recent years, researchers have been actively attempting to integrate biological materials into static building envelope systems. One promising approach is the integration of flat panel photobioreactors into building envelope systems and the BIQ (Bio-Intelligent Quotient) house is the state-of-the-art case building; however, the additional costs for glazing systems to contain photobioreactors, complexity of controlling cultures for microalgae growth, and difficulty of providing indoor environmental quality have kept flat panel photobioreactor systems from being applied widely. If we are able to bring about pleasant physical comforts for occupants through the use of shading devices capable of functioning as the photobioreactors, we can not only grow microalgae but also use less operational energy input to provide better IEQ for occupants. To this end, this study has explored a way to optimize the physical and functional properties of photobioreactor (for Chlorella sp.)-integrated shading devices (specifically vertical louvers). To find the optimal shape for static vertical louvers to be positioned on the west-facing facade, parametric design studies were conducted. To find the optimal vertical louver geometry among numerous alternatives, computer simulations were conducted in terms of three performance criteria (thermal balance by solar radiation, Daylight Autonomy, and microalgae growth rate) and an optimal option was found with the genetic algorithm optimization solver. To ensure reliability of the computer simulation (including numerical model) results, a series of experiments was conducted under the analogous climatic conditions; the computer simulation results were validated with the experimental data. When it comes to hourly indoor illuminance performance, the error between experimental data and computer simulation results was within a range of 5–20%; for average microalgae growth rate, the error was up to 19.9%. Despite the relatively high error between the simulation results and measurements, considering ever-changing light intensity conditions in our measurement compared to that of the computer simulation, it was justifiable to utilize the computer simulation results for the current parametric design study. Finally, the biofuel energy production from the proposed static envelope system was estimated to be 16.5 kWh/m2yr, which is smaller than the state-of-the-art annual biofuel energy production (30.0 kWh/m2yr) from the BIQ house. Nevertheless, the results are promising, given that we used the worst cultivation conditions for the microalgae in the current study.

The effects of shading devices on office building energy performance in Mediterranean climate regions

Fixed shading devices (SDs) are still used as an essential and useful element in architectural design. Even with minor changes to be made when designing these devices, the energy performance of a building, especially in hot climate regions, can be significantly increased. In contrast to studies using one or a few parameters, this study aimed to make a comprehensive evaluation by considering more parameters simultaneously to determine energy-efficient fixed external SD scenarios that can be used in office buildings. This approach increases the accuracy of the results in terms of providing trade-offs. This study also aims to fill the gap of the research on SD strategies in Turkey. A total of 1485 scenarios were created with fixed external SDs (overhangs, horizontal and vertical louvers, and egg-crate variations) using the parameters of direction, glazing type, window-to-wall ratio (WWR), SD depth, and slope. Primary energy consumption values of all scenarios were calculated with the DesignBuilder software. Results were discussed according to the impact of each parameter on energy consumption and evaluated through descriptive statistical analysis. As a result, energy-efficient scenarios were determined. The best scenarios obtained for each SD type reduced the cooling energy consumption by between 37% and 49% compared to the no shading scenario using high-performance glazing type and by between 73% and 78% compared to the no shading scenario using low-performance glazing type. The total annual energy consumption was reduced by approximately 33% and 70%, respectively.

Application of double glazed façades with horizontal and vertical louvers to increase natural air flow in office buildings

The results of previous researches clearly indicate that the main concern in applying double skin façades (DSF) is overheating of the cavity and increasing the cooling energy consumption in warm seasons. The present study intends to consider the excessive heat trapped between two skins of double glazed façades in hot arid climates as a driving force to reinforce the natural airflow across the floors of an office building. To meet this purpose, numerical simulation of airflow and heat transfer inside the cavity of the double glazed façades and the adjacent floors, as well as the effect of different types of solar shading systems in horizontal and vertical modes on the airflow has been investigated using the CFD technique. The results show that the stack effect formed inside the cavity has enough power for air suction from the floors of the building and reinforcement of the natural airflow. The type of shading device has a significant effect on the airflow behavior and the heat transfer rate in the facade. In double skin facades with horizontal louvers, the buoyancy forces inside the cavity are stronger and the ventilation rate in the building floors is higher than the model with vertical louvers. On the other hand, due to the stronger convective flow in the cavity with horizontal louvers, the heat flux on the interior glass is higher than the cavity with vertical louvers and part of the heat inside the cavity is transmitted through the interior skin to the occupied spaces.

The Impact of Shading Type and Azimuth Orientation on the Daylighting in a Classroom–Focusing on Effectiveness of Façade Shading, Comparing the Results of DA and UDI

There are many kinds of façade shading designs which provide optimal indoor daylighting conditions. Thus, considering combinations of different types of façade shading systems is an essential aspect in the optimization of daylighting in the building design process. This study explores (1) how the pattern and different characteristics are evaluated by varying façade shading types and considering their impact on daylighting metrics; and (2) the relative relationships between Daylight Autonomy (DA) and Useful Daylight Illuminance (UDI) with changes of the façade shading types, input parameters, and azimuth orientations. A typical high-school classroom has been chosen as a base model, and seven different façade shading types: vertical louver, horizontal louver, eggcrate louver, overhang, vertical slat, horizontal slat, and light shelf have been applied to eight azimuth orientations for the building. As tools for parametric design and indoor lighting analysis, Design Iterate Validate Adapt (DIVA)-for-Grasshopper has been used to obtain DA and UDI for comparison. Based on the simulation, (1) the effectiveness of the installation of façade shading compared to a non-shading case; and (2) design considerations for façade shading are presented. The result shows that there are some meaningful differences in DA and UDI metrics with the variation of orientation and façade shading types, although all cases of façade shading show some degree of decrease in DA and increase in UDI values. The types of shading devices which produce a dramatic decrease in DA values are the light shelf, horizontal slats, horizontal louvers, and eggcrate louvers. On the contrary, the types of shading devices which produce a dramatic increase in UDI values are the light shelf, horizontal slats, horizontal louvers, and eggcrate louvers. In the case of the vertical and vertical slat shading, the improvements of UDI values are significant in the east and west orientations. This demonstrates that the application and design of shading devices in certain façade orientations should be carefully considered for daylight control. Also, the results show that UDI explains relatively well the daylight performance in the case of the installation of a shading device.

Thermal and Lighting Performance of 5 Complex Fenestration Systems in a Semiarid Climate of Chile

Overheating, high cooling energy demand and glare are common concerns in office buildings in Santiago de Chile. Complex Fenestration Systems (CFS), which include an external shading device, represent a means to control these problems, reducing cooling energy demand and enhancing visual comfort. The present paper evaluates and compares the thermal and lighting performance of 5 different types of CFS (3 with horizontal louvers and 2 with vertical louvers) through laboratory experiments.Experiments were made using two calorimetric test-rooms emulating the size of a small office for three orientations: North, Northeast and Northwest. A Coefficient of Performance was calculated for each CFS by comparing the radiation entering the room in both test-rooms. A useful daylight illuminance factor was calculated to evaluate visual comfort.Horizontal louvers consistently performed better than vertical louvers for all orientations tested. Results for vertical louvers, clearly show which combination of louver alignment and façade orientation does not provide an effective solar protection. For horizontal louvers, although the ones that completely block the passage of direct light, not allowing an outside view, perform better than the ones permitting a view to the outside, the difference is not significant (less than 10%). So two cases of louvers allowing an outside view are recommended for office buildings. These results may help designers to make more informed decisions in the early building design stages.

THE EFFECTIVENESS OF DIFFERENT CONFIGURATIONS OF VERTICAL LOUVERS ON ENERGY PERFORMANCE IN OFFICE BUILDINGS IN CAIRO

This paper aims to identify the effect of solar control devices - vertical sun louvers - in an open-planoffice space with a western full glazing facade in order to test the optimization level of energyperformance within office buildings in Cairo through controlling the different configurations of thevertical louvers. An action experimental research is used to investigate annual cooling loads(representing energy performance).Environmental simulation software (Design Builder for thermal and energy + for analysis) are usedduring this testing research to investigate the effect of changing rotation angle of vertical louvers onannual cooling loads. It is concluded that energy performance can be enhanced while applying smalland large values of rotation angles of vertical louvers.

Solar Shading Performance of Different Louver Shading Materials in Hot Summer and Cold Winter Zone

The aim of this paper is to investigate the solar shading performance of louver shading materials. Regression analysis is used to compare the potential performance of horizontal and vertical louver shading materials. Results show that louver shading is not suitable for north facing windows and has little improvement of shading performance in south orientation. For east windows in the west orientation, horizontal louver shading performs well only in summer. Horizontal and vertical shading materials have similar shading performance in summer and winter.

Using simulation for studying the influence of vertical shading devices on the thermal performance of residential buildings (Case study: New Assiut City)

The building and spaces shape have a great impact on indoor temperature. Well-designed sun control and shading devices can dramatically affect indoor temperature. The thermal performance of interior spaces in hot arid desert is highly influenced by various passive design techniques, e.g. space dimensions, facade colors, fenestration ratio, glazing type; and vertical and horizontal shading devices. Simulation tools play an important role in taking decision during early design phase that could help in improving the thermal performance of buildings. The aim of this paper is to present the effect of vertical louvers length on the thermal performance of residential buildings in Egypt. To achieve this aim of the research, first, the climatic analysis of New Assiut City is introduced followed by identification for the prevailing residential patterns within the city and the selected residential model. Second, the role of the used simulation tool in enhancing the designs is highlighted. Finally, a simulation has been run for the selected residential model in New Assiut City over the four cardinal orientations. The results of the study showed that the vertical louvers with a protrusion of 38cm or more result in a decrease of 2°C in indoor temperature in all four orientation. However, for the northern façade it is noticed that any protrusion more than 38cm had only a slight effect on the indoor temperature.

Effect of louver shading devices on building energy requirements

External louvers are increasingly used to provide solar protection for building glazed surfaces. In this work, a general study of the effect of louver shading devices applied to different façades of a building is carried out, for different locations (latitudes). Building energy requirements for a building in the cooling and heating seasons is quantified for different window and louver areas, under climatic conditions of Mexico (Mexico), Cairo (Egypt), Lisbon (Portugal), Madrid (Spain) and London (UK). Also, operative and indoor temperatures were calculated through simulations using TRNSYS software, whereas the model for the shading geometry study was solved with EES software. Both horizontal and vertical louver layouts were considered. The results show that the integration of louver shading devices in the building leads to indoor comfortable thermal conditions and may lead to significant energy savings, by comparison to a building without shading devices.

General calculation method of illuminance from a vertical louver blind system

A general calculation method is described for determining of illuminance from a vertical louver blind system, which slats are of negligible thickness, uniformly diffusing surfaces and uniform reflectances. Available data in practice are also prepared for this method. First, configuration factors of arbitrary position on the working plane are analytically introduted for the sky to be viewed between louver slats and for these slats themselves. Next, a direct illuminance of this position is obtained by using these configuration factors and average luminances of the sky and slats. The luminance of slat is calculated in two cases, that the window faces to the uniform sky and gronnd, and the slats are uniformly illuminated by the direct sunlight on the critical condition of precisely shading it with slats. For an indirect illuminance a simple formula by author is effective in practice. Necessary transmittances of louver system in this formula are presented as useful data in above mentioned two cases. An overlapping of results calculated in the both cases is approximately applied to almost all weather conditions with or without the direct sunlight.