Analysis of the Effect of Using External Venetian Blinds on the Thermal Comfort of Users of Highly Glazed Office Rooms in a Transition Season of Temperate Climate—Case Study (original) (raw)
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In this study a thermal analysis during a year period for a Double Skin Façade corporative office building in Barcelona was carried out, by using TAS simulation software. The climate in this specific area of Spain is representative of the Mediterranean region, while several special characteristics appear. The investigation concerns a typical office building with an extended working hours schedule for cooling or heating. Two different double skin façade assemblies were simulated. These are: (a) a Corridor Façade and (b) a Multi-Storey Façade. Shading devices in the interior of the cavity and the control of the external and internal openings for both typologies were examined. The simulations have revealed that cooling loads are significantly higher than heating loads on a double glazed skin façade building south oriented in Barcelona. Moreover, the use of shading elements and the control of the internal openings of the façade can save up to 13% on energy demands for cooling loads.
Although the presence of large window surfaces could be preferable during the heating season when solar gains through the glazed components can overcome heating losses from the same surfaces, during the cooling season more attention has to be paid in order to limit the inlet of solar radiation which causes the increment of cooling load. Generally the optimal tradeoff for energy optimization, as already underlined in a previous paper by the authors, is using low thermal transmittance and high solar factor glazing, even if higher solar transmittance considerably worsens the cooling performance. However, the choice of glazing type and the design of windows on a façade may depend on comfort consideration besides energetic evaluations. Thermal sensation of an individual is mainly related to the whole thermal balance of the human body. Comfort limits can in this case be expressed by two indexes proposed by Fanger in 1970: the Predicted Mean Vote, PMV, and the correlated Predicted Percenta...
The role of shading devices to improve thermal and visual comfort in existing glazed buildings
Energy Procedia, 2017
Buildings with large glazed surfaces may show severe thermal and visual discomfort issues, as an effect of the large incoming direct solar radiation. In order to avoid excessive solar gains and glare issues to the occupants, it is necessary to adopt suitable solutions that limit the incoming solar radiation, such as highly reflective coatings or movable shading devices. However, such devices must be accurately selected, according to the building location and to the exposure of the glazed façades, while also taking into account possible regulatory measures. This paper evaluates the effectiveness of a series of shading devices applied to an existing office building in Southern Italy. The building shows large glazed surfaces and has no overhangs, thus significant thermal discomfort is perceived in summer by the occupants. The aim is to identify those solutions that allow to improve thermal comfort while also keeping a sufficient illuminance level indoors, without disregarding the compliance with Italian regulations about the installation of shading devices and, of course, the need to keep costs on a reasonable level. The analyses are repeated for different building orientations, in order to provide general information.
Building and Environment, 2010
This paper presents an experimental study of indoor thermal environment near a full-scale glass facade with different types of shading devices under varying climatic conditions in winter. Interior glazing and shading temperature, operative temperature and radiant temperature asymmetry were measured for façade sections with roller shades and venetian blinds at different positions. Interior glass surface temperatures can be high during sunny days with low outdoor temperature. Shading systems significantly improved operative temperature and radiant temperature asymmetry during cold sunny days, depending on their properties and tilt angle. During cloudy days the impact was smaller, however the shading layers could still decrease the amount of heat loss through the façade. A transient building thermal model, which also calculates indoor environmental indices under the presence of solar radiation, was developed and compared with the experimental measurements. Part II of this paper uses this validated model with a transient, two-node thermal comfort model (including transmitted solar radiation) for assessment of indoor environmental conditions with different building envelope and shading properties, façade location and orientation.
A Viennese apartment building, KAM, was built in 2007 to minimum passive house requirements primarily designed to perform for heat conservation in winter. Less emphasis was placed on cooling in the warm months when planning the building due to the temperate continental climate of Vienna, Austria. Due to apartment owner complaints of overheating, exterior blinds were installed on apartment windows and doors on the topmost floor. Indoor temperature and humidity in four apartments have been monitored over three summer periods. The monitoring results are presented where mechanical ventilation with heat recovery is used in combination with exterior sun shading. The users in the case studies prefer using natural window ventilation to changing ventilation system settings. Indoor daily temperatures remain constant when windows are left closed and shading is used. Results from monitoring and interviews indicate the importance of considering summer cooling strategies in combination with user behavior in highly insulated buildings to control overheating in summer.
A simplified method for modelling the effect of blinds on window thermal performance
International Journal of Energy Research, 2006
An approximate method is presented for predicting the effect of a louvered blind on the centre-glass thermal performance of a fenestration. The method combines a one-dimensional heat transfer model with data from a numerical simulation of the window and blind. Sample results for a blind mounted on the indoor surface of a window show the effect of blind slat angle on heat transmission. Both summer and winter conditions are considered. The results show that a louvered blind can improve the U-value of a standard double-glazed window by up to 37%. Also, the radiation heat exchange with the room can be dramatically reduced (by up to 60%), which will improve the level of occupant comfort. However, there was found to be a trade-off between U-value and occupant comfort; placing the blind closer to the window improves the U-value, but increases the radiation heat exchange with the room. The predictions from the present simplified method compare well with results from a full two-dimensional computational fluid dynamics solution of the conjugate blind/window interaction.
Migration Letters, 2023
This paper addresses the significance of natural lighting and solar control in building design, mainly focusing on housing buildings at the University of Mosul. The effective utilization of natural lighting is crucial for achieving optimal thermal performance and environmentally successful buildings. Various design and natural factors influence the lighting levels within interior spaces, necessitating the critical process of controlling natural lighting aspects and providing appropriate shading based on space requirements. Among the factors that pose environmental and thermal challenges for buildings are the direction, area, and shape of windows. Utilizing solar control and shading methods becomes imperative to mitigate these challenges and enhance energy efficiency. Shading plays a vital role in building cooling systems, as it helps reduce direct solar heat gain and prevents excessive solar radiation from entering the building during different seasons. Additionally, it offers the potential for harnessing natural light to achieve self-heating benefits during colder seasons. Hence, this research focuses on developing a simple and effective solar control mechanism using solar shades for university buildings within the University of Mosul. By employing qualitative analysis and simulations, the study explores the optimal design and physical characteristics of solar shades to ensure suitable thermal comfort and address the facade treatment of university buildings. The research findings highlight that models 1 and 2 of louvre designs demonstrate the most effective performance, providing comfortable thermal conditions and optimal lighting and significantly reducing energy consumption by 65%. This study underscores the importance of natural lighting and solar control strategies in building design and offers practical solutions for improving thermal comfort and energy efficiency.
Influence of Control and Finishing of Internal Blinds on the Cooling Energy Consumption of Buildings
2020
This study presents a simulation-based approach to investigate the influence of control and finishing of internal blinds on building performance. Three control patterns were combined with two finishings of internal blinds in spaces with different solar orientations, windowto-wall ratios and width-to-depth ratios. Building performance simulations were conducted using the EnergyPlus computer programme. Results showed that both control and finishing of internal blinds impact the performance of buildings. This outcome supports the belief that both designers and occupants must know how systems affect the energy consumption of buildings to boost their performance throughout the life cycle.
Building and Environment, 2021
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