Glazed Facades Research Articles

Numerical Studies on Effects of Cavity Width on Smoke Spread in Double-skin Facade

Double-skin façade is more and more popular in modern buildings in recently years due to it can provide the building with improved thermal and sound insulation compared with a traditional glazed facade. But fire safety is a problem, the inner glass wall broken during a fire would lead to the smoke and flame spread to the adjacent levels, this might be dangerous for the occupants in those areas. Many such projects failed to comply with the fire safety codes at present. Engineering approach similar to performance-based fire codes practicing in some countries was applied to demonstrate the design is safe. Fire hazard assessment should be supported by the further investigations on the smoke and fire spread in DSF. Cavity depth effects, one of the key factors which can influence the smoke flow in DSF would be studied by numerical method in this paper. By examining the results for cavity depth of 0.5, 1.0 and 1.5 m, it is found that a wider cavity might give better fire safety under the scenarios studied. The outer glass panel would be broken rapidly for the cavity of 0.5m deep. a Cavity depth of 1.0 m might be the most risky design comparing with the other two cavity depths studied, the inner glass panel might be broken before the outer panel, this might lead to the fire spread to the adjacent upper levels, high strength glasses should be used or other protection measures should be taken for the DSF design under this condition. Further studied should be required for an in-depth understanding the smoke and fire spread in DSF in the further.

Experimental estimation of the solar properties of a switchable liquid shading system for glazed facades

As solar gains often constitute a high fraction of the overall cooling and heating loads in buildings, dynamically and adaptively controlled fenestration may be an important strategy for energy efficient buildings. The higher the variability in climatic conditions over the seasons, the longer is the list of benefits deriving from the adoption of this type of technology. This paper reports the experimental evaluation performed on a dynamic shading system based on a liquid layer sliding within a dedicated glass stratification. The advantages connected with the adoption of the described technology derive from its easy adaptability to almost every fenestration, its reversible switching between high and low solar transmittance configurations in a short time and its capability to maintain transparency in both operating modes. The summer outdoor experimental campaign, reported in this paper, allowed the solar factor of the liquid-shaded stratification to be estimated and compared with a reference low-emission double stratification, where one of the panes was treated with a magnetronic coating. The results showed not only that the shading provided by the dynamic liquid layer is more effective than its benchmark, but also that its dynamic capabilities have been preserved after a summer-long exposure to solar radiation.

Murrah Building Collapse: Reassessment of the Transfer Girder

The bombing of the Alfred P. Murrah Federal Building caused a progressive collapse that consumed nearly one-half of the building, killing 168 people. The use of a transfer girder along the front face of the building is often cited as the prime reason for the severity of the incident, although this paper provides evidence that suggests the transfer girder may not have been responsible. A method of predicting column failures attributable to blast is introduced and used to accurately predict the column failure pattern observed during the forensic investigation. The frame was adjusted with the transfer girder replaced with a conventional beam column arrangement. The failure pattern of the reconfigured building indicates that the extent of the collapse would be largely unchanged. This finding has important implications for the design of buildings that may be subjected to accidental or malicious damage. It is argued that the other buildings have demonstrated an ability to survive similar incidents and that the Murrah Building was vulnerable because it combined a glazed facade with open-plan architecture, in addition to lacking alternative load paths capable of redistributing loads after multiple column failures.

THE ANALYSIS OF NEEDS FOR HEATING AND COOLING ENERGY IN THE ADMINISTRATIVE BUILDING WITH BIG GLAZING FACADES

The article discusses the influence of big glazing facades on the needs for heating and cooling energy. Three ways of modelling the needs for energy were chosen. The influence of the orientation of the glazing facade and different heat – optical features of glazing on energy needs was established. The paper analyzed the influence of the measures of passive energy saving on the needs for heating and cooling. A comparison of calculation results applying two methods suggesting the needs for cooling energy was made and energy costs of actual and normal heating were examined.

SIMULATION BASED COMPLEX ENERGY ASSESSMENT OF OFFICE BUILDING FENESTRATION

The number of office buildings with highly fenestrated facades is currently increasing in Lithuania and neighboring countries. Highly fenestrated facades reduce energy consumption for lighting and simultaneously increase energy consumption for heating, cooling, air conveying and may cause thermal and visual discomfort. Pursuing to reduce negative effects of the highly glazed facade, special glasses are frequently used. However, such windows usually increase demand for lighting energy. Therefore, when making early decisions about glazing the building, it is important to have a complex evaluation of energy demand related to the specific case. The paper presents the results of analysis made using energy simulation tools. The obtained results have shown that when shading is not applied, the north is the most energy efficient orientation to glazing for an air conditioned office building in cool climate zones like Lithuania. The most energy efficient window‐to‐wall ratios (WWR) for the south, east and west oriented façade are 20%, whereas for the north it makes 20–40%. However, such WWR values do not satisfy standard requirements for day lighting. Santrauka Pastaraisiais metais Lietuvoje ir kaimyninese šalyse daugeja administracines paskirties pastatu, kuriu dauguma išoriniu atitvaru yra skaidrios. Didesnis istiklinimo plotas lemia mažesnius energijos poreikius apšvietimui, tačiau didina šildymo ir vesinimo sistemu energijos poreikius, sukelia šilumini bei vizualini diskomforta. Neigiamai dideliu skaidriu atitvaru itakai sumažinti naudojami tamsinti ir kitu specialiu charakteristiku stiklai, tačiau tai savo ruožtu didina energijos poreiki apšvietimui. Todel, priimant sprendimus del pastato istiklinimo, svarbu prieš tai kompleksiškai išnagrineti konkretaus sprendimo itaka pastato energijos poreikiams. Straipsnyje pateikiama modeliuojant gautu rezultatu analize. Rezultatai parode, kad vesaus klimato šalyse, kurioms priklauso ir Lietuva, kondicionuojamu administraciniu pastatu fasadu, kai nenaudojamos apsaugos nuo saules priemones, energiškai efektyviausias istiklinimas yra i šiaures puse. Energiškai efektyviausias santykinis fasado istiklinimo plotas pietines, rytines ir vakarines orientacijos fasadams yra 20 %, o šiaurines ‐ 20–40 %. Tačiau tokie istiklinimo plotai neatitinka norminiu natūralaus apšvietimo reikalavimu.

Solar Control Glass

Solar control glass has applications for windows and glazed facades in order to modify indoor visual and thermal comfort in buildings. The article presents the results of evaluation study of optical properties of selected types of solar control glasses and foils. The spectral transmittance measurements were used as input data for daylight comparative studies, and the consideration of convenience of selected solar control glasses and foils for windows are summarised on the basis of analysis of optical properties.

Thermal behaviour of a ventilated double skin facade in hot arid climate

Modern Movement in architecture has resulted in a large number of high-rise buildings with glazed facades which increase the energy load of the buildings. To combat this phenomenon in colder climates, architects have turned to using double skin facades. These facades comprise of: a completely transparent external facade; an internal skin; and an air layer between the two. Research on the performance of double skin facades mostly considers cold and moderate climates. In addition, data collection is normally based on simulations, rather than actual field measurements. In this paper a building with double skin facade was monitored for 2 weeks in summer and 2 weeks in winter in the hot arid climate of Iran, in order to observe the behaviour of the facade both in hot and cold conditions. Additionally, simulations were performed on the case study building with and without double skin facade, to assess the effectiveness of the facade. The results revealed that the temperature difference between the outer skin, the inner skin and the cavity can significantly save heating energy in winter. To reduce the cooling loads in summer it is essential to introduce additional techniques such as night ventilation and installation of shading devices for the cavity.

Indoor thermal environmental conditions near glazed facades with shading devices – Part II: Thermal comfort simulation and impact of glazing and shading properties

This second part of the study uses a validated dynamic building thermal model for perimeter zones with glass facades (described in Part I) and combines it with a transient two-node thermal comfort model. The objective is to investigate the impact of varying exterior climatic conditions, glazing properties and shading properties on indoor thermal comfort and heating demand in such spaces under the presence of transmitted solar radiation. It is evident that selecting appropriate fenestration components becomes a trade-off between energy, thermal comfort, and lighting needs. Facades with insulating and low transmittance glass create more comfortable and stable conditions; however, there is a relationship between lower transmittance of the glazing and increased demand of primary heating needed, as well as with lighting energy use. Regardless of glazing type, shading can improve comfort conditions by decreasing radiant temperature asymmetry and extremes in operative temperature. The results show that perimeter building zones with high-performance facades (glazing and shading) can maintain comfortable conditions and even eliminate the need for secondary perimeter heating in cold climates.

Indoor thermal environmental conditions near glazed facades with shading devices – Part I: Experiments and building thermal model

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.

The effects of explosive blast load variability on safety hazard and damage risks for monolithic window glazing

Although the modelling of built infrastructure subject to blast loading has been well developed, considerable uncertainty remains with respect to explosive loading parameters and structural response. This paper focuses on facade glazing – as this poses significant safety hazards when affected by explosive blast loads. A structural reliability analysis is used to calculate probabilities of glazing damage and safety hazards conditional on given threat scenarios. The analysis considers the variability of explosive blast loading; in particular, from variations in explosive weight, explosion effects in terms of pressure, stand-off distance, inherent blast load variability and model error. Uncertainties in structural response (including the variability in glazing stress limits, situational geometry, fragment drag coefficients and modelling error) are then considered in the analysis. This allows the prediction of likelihood and extent of damage and casualties. It was found that damage and safety hazard risks are very sensitive to the accuracy of the blast loading prediction model and the inherent variability of blast loading.

Risk acceptability and cost-effectiveness of protective measures against terrorist threats to built infrastructure considering multiple threat scenarios

Decisions are often needed about the need and/or extent of protective measures against explosive blast loads on built infrastructure. A decision support analysis considers fatality risks and cost-effectiveness of protective measures expressed in terms of expected cost spent on risk reduction per life saved for terrorist threats to infrastructure. The analysis is applicable to any item of infrastructure, but in this paper is applied to casualties arising from building facade glazing damage. Risks may be compared with risk acceptance criteria in the form of quantitative safety goals. The risk acceptability and cost-effectiveness of protective measures includes cost of the protective measures, attack probability, reduction in risk due to protective measures, probability of fatality conditional on successful terrorist attack and number of exposed individuals.

An internal assessment of the thermal comfort and daylighting conditions of a naturally ventilated building with an active glazed facade in a temperate climate

An active facade is often used to promote the flow of air through a building, however in order to ensure that this process is effective the facade should face a southerly orientation. This means that not only solar energy is transferred across the glazing but in sunny periods shading is needed to prevent excess brightness levels occurring on the working areas where it may result in the luminance distributions not complying with current lighting requirements. The building investigated is located in Sheffield, England and is one of the University of Sheffield's recently built green buildings. It has a high thermal mass which is used to promote the use of night cooling. This paper reports the initial findings of an internal assessment of the thermal comfort and daylighting conditions in such a building. The results have indicated that such designs are to be commended for their passive use of solar energy and can provide a high quality working environment.

CFD PREDICTIONS OF INDOOR AIR MOVEMENT INDUCED BY COLD WINDOW SURFACES/VĖSIŲ LANGŲ PAVIRŠIŲ SUKELIAMO ORO JUDĖJIMO TYRIMAI PASITELKIANT KOMPIUTERINIO MODELIAVIMO METODUS

During the past decades, large windows and glazed façades have become an important part of modern architecture and they are designed frequently in both public and residential buildings. However, besides the positive effect of such a design on building occupants, large windows may cause thermal discomfort. Cold inner window surface may generate draught in the occupied zone. Thermal comfort in rooms is usually assessed by measuring air temperature, relative humidity, air velocity and heat transfer due to radiation. In this study computational fluid dynamics (CFD) methods have been used to investigate these phenomena. Air movement caused by cold vertical window surfaces was evaluated and its impact on thermal comfort conditions in rooms have been outlined. Windows of different constructions and having different heat transmission coefficients were modelled (2.4, 1.6 and 1.0 W/m2K). CFD predictions showed that even in cases of low window thermal transmittance coefficient (U value), thermal discomfort conditions may appear in the room if the height of the window is more than 2.0 meters. Santrauka Dideli langai ir stiklo fasadai tapo neatsiejama šiuolaikiškos architektūros dalis. Jie projektuojami ne tik visuomeniniuose, bet ir individualiuose namuose. Nekalbant apie teigiamus tokios architektūros aspektus, didelių matmenų langai gali tapti šiluminio diskomforto priežastis. Už patalpos orą vėsesnis vidinis stiklo paviršius sukelia žemyn nukreiptą oro srautą, kuris tam tikru greičiu patenka į žmonių gyvenamąją arba darbo zoną. Vėsių stiklo paviršių sukeltų oro srovių intensyvumas priklauso nuo lango šiluminių savybių, jo konstrukcijos bei šildymo prietaisų įrengimo vietų. Dažniausiai mikroklimato sąlygos patalpose vertinamos matuojant oro temperatūrą, santykinį drėgnį, oro judrumą ir šilumos mainus spinduliavimu. Straipsnyje pristatomas tyrimas, kuriam buvo pasitelktas kompiuterinis oro judėjimo modeliavimas (skaitiniai skysčių ir dujų dinamikos metodai). Buvo tiriama oro judėjimo patalpose priklausomybė nuo langų bei stiklo fasadų konstrukcijų ir šiluminių savybių. Modeliuojant įvertinti trys langų tipai, kurių šilumos perdavimo koeficientų vertės: 2,4; 1,6 ir 1,0 W/m²K. Rezultatai parodė, kad net ir mažiausiai šilumai laidūs langai gali sukelti neleistiną oro judėjimą patalpose, jei jų aukštis viršija 2 metrus.

The most efficient position of shading devices in a double-skin facade

In recent years, there has been a great deal of interest in double-skin facades due to the advantages claimed for this technology in terms of energy saving in the cold season, protection from external noise and wind loads and their high-tech image. The advent of computers and other office equipment has increased the internal heat gains in most offices. Highly glazed facades, together with the extra heat gains from the electric lighting made necessary by deep floor plans and the wider use of false ceilings, have increased the risk of overheating. To preserve comfort and reduce cooling loads, it is important to apply natural cooling strategies, including solar protections use. External solar protections are more effective than internal shading devices. In the case of the double-skin facade, the blinds can be integrated in the cavity. It is thus protected from the bad weather and pollution. Solar protection can remain in place even in the event of important wind, which represents an undeniable advantage for the buildings with great height. This article examines the influence of the position and the colour of the blinds on the cooling consumption of an office building with a double-skin facade.

Feasibility analysis of an active technology to improve acoustic comfort in buildings

In buildings, windows and glazed facades are often the preferred noise path for exterior disturbing noise towards the interior. Since passive means for improving sound transmission loss (STL) of glazed facades are very expensive and are effective only at high frequencies, an active controller that increases the STL in the low-frequency range is an attractive approach for reducing the noise level in buildings with glazed facades, guaranteeing the performance required by the 89/106/CEE European Directive, which made protection against noise a compulsory requirement for buildings. As buildings are often inserted in highly inhabited urban areas, near infrastructures and plants radiating high noise levels, the strategic importance of this task is increasing, together with the importance of acoustic comfort inside buildings.This paper concerns a feasibility study on the implementation of an active structural control system for glazed facades, in order to improve their STL at low frequencies. At present, applications for the reduction of noise level inside cars and planes are known. Relative to the use of active structural acoustic control (ASAC) systems, these systems are based on the reduction of structural vibrations through the use of actuators bonded on the vibrating surfaces, driven by an automated control system, whose task is minimizing those vibrations, and the radiated sound as a consequence. In this work, it is shown that actuators bonded on the vibrating surfaces, driven by an automated control system, are able to dramatically reduce those vibrations and, consequently, the radiated sound. The proposed technology is tested through experiments and numerical simulations, in order to compute the reduction of interior noise that could be pursued through the use of piezoelectric stack actuators.

Guidelines for improving natural daytime ventilation in an office building with a double-skin facade

In recent years, there has been a great deal of interest in double-skin facades due to the advantages claimed for this technology in terms of energy saving in the cold season, protection from external noise and wind loads and their high-tech image. The advent of computers and other office equipment has increased the internal heat gains in most offices. Highly glazed facades, together with the extra heat gains from the electric lighting made necessary by deep floor plans and the wider use of false ceilings, have increased the risk of overheating. To preserve comfort and reduce cooling loads, it is important to apply natural cooling strategies, including natural ventilation. Some argue that double-skin facades are designed to improve natural ventilation in buildings by the stack effect, and to allow this even in situation in which it is generally not possible due to high outdoor noise levels and/or high wind speeds. But poor operation of the double-skin facade openings can generate disastrous scenarios such as the injection of hot air from the double-skin facade into the offices and the contamination of offices on the upper floors by used air from the offices on the lower floors. This article examines how natural ventilation can be utilised in an office building with a double-skin facade during a sunny summer’s day. It mainly considers natural daytime ventilation in relation to the orientation of the double skin and the speed and direction of the wind.

06/00834 Effects of double glazed facade on energy consumption, thermal comfort and condensation for a typical office building in Singapore: Wong, N. H. et al. Energy and Buildings, 2005, 37, (6), 563–572.

06/00834 Effects of double glazed facade on energy consumption, thermal comfort and condensation for a typical office building in Singapore: Wong, N. H. et al. Energy and Buildings, 2005, 37, (6), 563–572.

06/00318 Effects of double glazed facade on energy consumption, thermal comfort and condensation for a typical office building in Singapore: Wong, N. H. et al. Energy and Buildings, 2005, 37, (6), 563–572

06/00318 Effects of double glazed facade on energy consumption, thermal comfort and condensation for a typical office building in Singapore: Wong, N. H. et al. Energy and Buildings, 2005, 37, (6), 563–572

Effects of double glazed facade on energy consumption, thermal comfort and condensation for a typical office building in Singapore

Fully glazed facade that has been increasingly used in Singapore causes higher energy consumption and thermal discomfort due to higher solar gain. The use of double glazed facade system with ventilation system is one way to solve these problems. The objective of this paper is to investigate the effects of double glazed facade with ventilation system on the energy consumption, thermal comfort and condensation and compare to single glazed facade system. TAS and CFD software were utilized to calculate energy consumption, thermal comfort and condensation for single glazed facade building as well as double glazed facade building. The simulation results showed double glazed facade with natural ventilation were able to minimize energy consumption as well as to enhance the thermal comfort. Turning the mechanical fans on could also solve the condensation problem due to high humidity.

04/02151 Numerical analysis of the thermal behaviour of ventilated glazed facades in Mediterranean climates. Part I: development and validation of a numerical model: FAggembauu, D. et al. Solar Energy, 2003, 75, (3), 217–228

04/02151 Numerical analysis of the thermal behaviour of ventilated glazed facades in Mediterranean climates. Part I: development and validation of a numerical model: FAggembauu, D. et al. Solar Energy, 2003, 75, (3), 217–228