Thermal performance of two building envelope elements: glazing surfaces and shading devices (original) (raw)
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Thermal performance of different glazing surfaces in a hot climate
2005
ABSTRACT This paper describes an experimental study about thermal performance of different glazing materials in prototypes. In Brazil, due to its low latitudes and predominantly hot and humid climate, high solar radiation provokes strong heat gain in almost all the regions of the country. The worst building exposure conditions are on north and west façades.
2009
This study presents the results of a monitoring study carried out in residential buildings with considerable glazing areas (more than 70% of the façade) with different solar exposures in Lisbon The monitoring was performed during the summer and winter months in 2007-2008 (first phase) and 2008-2009 (second phase). Temperature and relative humidity sensors were installed in 23 units (45 compartments) with different solar dispositions and localizations in several buildings with specific relevant characteristics for study.
Rapid growing of energy use has raised critical concerns over energy supply difficulties and negative environmental impacts globally and among ASEAN countries. Malaysia is experiencing a high average annual energy demand growth rate of approximately 2.3% which large portion of that energy is used by office buildings. Under the hot-humid climatic conditions in Malaysia, high-rise office buildings with large or fully glazed façades are facing a major problem of overheating due to high solar radiation through the glazed façades. This has caused high cooling energy requirements. The aim of this study is to investigate the potential of three types of shading devices on cooling energy savings when applied at different façade orientations. The aim also extends to investigations on different cooling energy savings when shading devices are applied on façade glazing with different configurations and thermal performances. This was done through a case study of a high-rise office building in Kuala Lumpur, Malaysia using IES (VE) building thermal simulation software. Twenty simulation building models were applied with different shading devices at different façade orientations and with high and low performance façade glazing. The simulation results indicate that high-rise office buildings in Malaysia use approximately 45.9% of total building energy for cooling purposes. The results also suggest that use of various shading devices on low-e double glazed façades will result between 1.0% and 3.4% annual cooling energy savings, depending on the types of shading devices and façade orientations. The estimated annual cooling energy savings increase to between 5.0% and 9.9% when the shading devices are applied to all orientations of low-e double glazed façades. The estimated annual cooling energy savings further increase to between 5.6% and 10.4% when the façade glazing is replaced by single clear glazing. This study recommends prioritizing shading devices on the East and West façades for optimized annual cooling energy savings. The simulation results show that egg-crate shadings are able to produce the highest annual cooling energy savings compared to vertical shadings and horizontal shadings. It is recommended to use shading devices on low performance glazing compared to high performance glazing since the energy savings are more significant when shading devices are used on low performance glazing. In conclusion, the use of shading devices is more effective in achieving cooling energy savings compared to the use of high performance glazing under the hot-humid climate of Malaysia.
Indoor and Built Environment, 2014
The need to reduce energy consumption in buildings leads to the development of new facade systems that can be energy efficient; thus, contributing significantly to heat transfer between outdoor and indoor spaces. Here, the versatility and flexibility of the modules are key attributes. For this purpose, this study focused on the thermal performance of Trombe walls and glazings and the glazing daylighting performance of a modular fac¸ade system in four different Portuguese cities. Computational simulations for the thermal performance of different arrangements of the modules were accomplished with the DesignBuilder software, while the glazing daylighting performance was studied by means of Ecotect and Desktop Radiance software, and compared with the transmittance curves of glazings. Occupancy profile and internal gains were fixed according to the Portuguese reality for both studies. The main characteristics considered in this research were the use of two double glazings, four different Portuguese climates and one or two Trombe walls in the facade. According to results, the use of Trombe walls and double self-cleaning glazing in the fac¸ade showed an important reduction in the energy consumption as well as better daylighting performance.
Procedia Engineering, 2011
The present study focuses on the effect of shading devices on the indoor temperature of high-rise residential buildings in the hot-humid climate of Malaysia. Several methods can be employed to improve indoor thermal environment, including using a reflective glazing system, using light colors for external surfaces, and using the appropriate thermal properties of external walls and roofs. However, before using any of these methods, it is important to have an optimum shading device to reduce the solar radiation absorption that leads to an overheated indoor environment and an increase in cooling energy loads. Therefore, the main objective of the current paper is to find the extent of a building's solar heat gain and, consequently, the indoor air temperature that is influenced by the external shading devices. A computerized simulation tool (IES) is used to carry out the investigation, taking Penang as the empirical background of the hot-humid climate. The results indicate that egg-crate shading has a significant impact on decreasing discomfort hours compared with other shading types.
Influence of Glazing Selection on Commercial Building Energy Performance in Hot and Humid Climates
1987
This paper presents a comparative study in which commercial building perimeter zone electric energy (cooling, lighting, fan) and peak electric demand are analyzed as a function of window glazing type, with a particular emphasis on the use of glazings with wavelength-selective solaroptical properties. The DOE-2 energy analysis simulation program was used to generate a data base of the electric energy requirements of a prototypical office building module located in Singapore. Algebraic expressions derived by multiple regression techniques permitted a direct comparison of those parameters that characterize window performance in hot and humid climates: orientation, size, and solar-optical properties. Also investigated were the effects of exterior and interior shading devices, as well as interior illuminance level, power density, and lighting controls to permit the use of daylighting. These regression equations were used to compare the energy implications of conventional window designs and newer designs in which the type of coating and substrate were varied. The analysis shows the potential for substantial savings through combined solar load control and lighting energy use reduction with daylighting.
External Sun shading strategy provide an opportunity for the architect to control natural lighting, ventilation, and solar gain, all of which provide a benefit to the overall building performance. The intensity of solar radiation on a building façade called for the use of strategies that will intercept its devastating effect before reaching the interior of the building. Due to some challenges encountered by some exterior shading devices, recessed window is confirmed to be one of the best form of shading as it is a form of self-shaded strategies. As the building's biggest heat directing surface, the façade which housed window has the greatest influence in minimizing the building's energy utilization. It is on this premise that this framework aimed at assessing the potentials of recessed window façade for heat gain reduction in the tropical buildings. The methodology used in this study focuses on an intensive review of previous studies and literatures. The paper verified from previous studies that the use of recessed window façade is preferred to other forms of external shading devices because of the problem of thermal bridges, thermal mass, e.t.c encouraged by most shading devices. It also finds out that, the dimensionless " depth " to which the window is recessed, R = r / L and is a very crucial formula amongst orders that determine the heat transfer rate in recessed window shadings.
International Journal of Performability Engineering
With the increasing awareness of sustainable development in the building construction the assessment of energy demands for heating/cooling under the influence of extended glazing façade, type of glazing, building orientation and energy control management strategies have become more important. In this study, focus is given on the energy performance assessment of a building zone with an entirely glazed façade, with four types of glazing at various orientations, by defining: (a) a desirable indoor zone temperature margin (ZTM) and (b) a desirable indoor minimum overnight temperature (MOT). Particular emphasis is given on the overheating during the summer season by introducing and evaluating the overheating temperature-index (OTI) for the examined glazing systems. The modeling and mathematical formulation is based on the thermal-network modeling approach with distribution of solar radiation on both the external and internal zone surfaces in 15 min time increments. Simulation results are...
The annual solar gains in public buildings with large percentage of glazing can be shaped by different kind of shading constructions and glazing with proper spectral radiative properties. These properties can be obtained by covering panes with special spectral selective covers or by colouring panes in mass. Spectral selective panes enable control of solar gains in summer, reduce heat loss in winter and reduce electric energy for cooling. These elements, except obvious influence on the annual heat balance of the building, have an impact on parameters of thermal and visual comfort. The paper presents selected results of the influence of horizontal overhangs and glazing with special spectral radiative properties on the annual thermal balance of analysed buildings (computer analysis) and on thermal comfort of users measurements). Microclimate measurements show that it’s impossible to maintain thermal comfort conditions during hot summer in natural ventilated buildings with high percenta...
2011
The study was developed after a two year monitoring campaign in a group of 23 building apartments (the units have more than 60% of the main façades in glazing). The main goal was to carry out a representative model that can be validated by the experimental results in order develop a set of parametric studies for the Lisbon Climate. Part of the modeling included the development of detailed and simplified geometrical models related to the units selected for the study. Different parametric variations were performed (summer and winter) using the detailed and simplified geometrical models. These took into account the characteristics of each housing unit and the conditions under which they were monitored in summer and winter. The thermal simulation software EnergyPlus (with the calculation model present in this software) was used to simulate all solutions and models. Thus, the study allows not only comparison but also the evaluation and validation of the models.