Large Glazed Areas Research Articles

Structural assessment of translucent walls built with a novel type of insulating aerogel-filled glass bricks

Among a multitude of functions, the façade is responsible for providing sufficient thermal insulation and supplying the building interior with enough natural light. For the latter, transparent glazed areas are essential. However, compromises in terms of the glass-to-wall ratio are often necessary since large glazed areas lead to overheating in summer and heat loss in winter. A novel type of highly insulating translucent glass brick made from annealed glass and filled with aerogel granulate was developed recently as an alternative in this regard. The bricks are not supposed to replace the transparent glass areas, but to offer a translucent alternative for part of the otherwise opaque wall areas. This paper focuses on the structural behaviour of walls composed of such aerogel-filled glass bricks. The components of such a brick and their functions are described. Moreover, two prototype systems for supporting the bricks in translucent walls are introduced—one with interlocking connections and pre-stressed wires, the other with interlocking connections and edge clamping. Both systems are analysed in finite element simulations from a structural point of view under out-of-plane loading. The resulting global deformations as well as occurring stresses in different components are analysed. Based on the findings, advantages and limitations of the different systems are highlighted and suggestions for improved alternative systems for translucent walls with insulating aerogel-filled glass bricks are made.

Radiant capillary heat exchangers – power calculation for optimal heating and cooling

The issue of switching to renewable energy sources becomes very actual and it is important not only to change the energy source, but also the reduce the final energy needs by improving the energy efficiency of buildings and usage of efficient heating systems. Heat pumps as the most popular renewable energy source are widely used, but their energy efficiency is depending on temperature of the supplied energy carrier. The most efficient are radiant capillary heat exchangers with a large surface area and a low temperature, which typically does not exceed 30°C. Another advantage of radiant capillary heat exchangers is the possibility to operate them in both - heating and cooling modes. Unlike the underfloor heating solution, where the role of thermal convection is very important, the built-in radiant capillary heat exchanger systems provide the energy mainly due to thermal radiation. This study explores two modelling approaches for determination of required power and corresponding area of radiant capillary heat exchangers to be installed in a room to provide heating and cooling: simplified approach, which allows to create the heat balance with a minimum amount of input data and a precise standard-based approach. Calculations were made for three different rooms with variable glazing area and spatial orientation using both approaches. Analysis of the calculation results shows the limits of the simplified method, which overestimates heating need and underestimates cooling need, and the main reason for such differences is simplification of room orientation and subsequent solar heat gains. As the calculated cooling power is less than heating power, therefore the heating estimation is sufficient to estimate the amount of radiant capillary heat exchangers in small/medium rooms for providing both heating and cooling in the climatic conditions of Riga. The use of complex, comprehensive modelling approaches is necessary for rooms with large glazed areas, where the simplified method gives incorrect estimations.

Solar and thermo-technical properties of glazing with external blinds: Experimental analysis in a pavilion laboratory

The current trend in architecture is associated with the use of increasingly large glazed areas in the building envelope, leading to significant problems with high solar and heat gains that negatively affect the overall energy consumption of buildings. Several sources of current research indicate that shading systems significantly impact the indoor microclimate and overall energy consumption of a building. From this point of view, this paper deals with the analysis of the thermal and solar properties of glazing in a test laboratory with several positions of the external blind system arrangement. The pavilion-type test laboratory contains three window constructions of different material bases (wood, plastic, and aluminium) with triple glazing, in front of which exterior blinds for manual control were installed. The indoor environment of the laboratory is conditioned by an air-conditioning unit to the calculation standard values of a living room. During the measurements, the position of the blinds was periodically adjusted to quantify the effect of the different slat positions on the thermal-technical and solar properties of the glazing and their effect on the indoor environment of the living room. The results show that the different positions of the blind slats significantly affect the thermal and lighting performance indoors. The paper will present the values of surface temperatures, heat flux density, glazing U-value and total solar transmittance that are affected by the shading system.

Retrofit Proposals for Energy Efficiency and Thermal Comfort in Historic Public Buildings: The Case of the Engineering Faculty’s Seat of Sapienza University

The building sector greatly contributes to energy consumption and Greenhouse Gas emissions, relating to the whole building life cycle. Boasting a huge building heritage of historical and architectural value, Europe faces challenging retrofit perspectives, as the potential for high energy efficiency has to be exploited while preserving the buildings’ original characteristics. The present work aims to feature the influence of a passive strategy on a heritage building in a mild climate. As historical its façade cannot be modified, its large glazing areas involve multiple issues, such as an increase in the heating (QH) and cooling (QC) energy demands and the risk of thermal discomfort. Thus, window replacement was proposed for retrofitting. A dynamic simulation model in TRNSYS was validated with experimental data collected by the continuous monitoring of walls of different thicknesses and orientations. Solutions from replacement with Double Glazing Units (DGUs) with improved thermal insulation, to internal shading activation were applied. All configurations were compared in terms of QH, QC, thermal performance of the building and user comfort (Fanger). Low-e DGU enabled the saving of up to 14% of the annual energy demand, and shading also offered good results in summer, reducing QC by 19%. In summer, DGU involved a maximum PPD reduction of 10 units.

Solar Radiation in Architectural Projects as a Key Design Factor for the Well-Being of Persons with Alzheimer’s Disease

The beneficial effects of solar radiation on human health are well documented. One necessary mechanism triggers the production of vitamin D, whose insufficiency has been linked to a variety of disorders such as diabetes; hypertension; and, more recently, amyloidosis and Alzheimer’s disease. However, there are few architectural designs capable of ensuring the adequate provision of solar radiation inside buildings. Conventional fenestration is not sufficient to provide for significant doses of sunlight, even to prevent seasonal affective disorder (SAD). In this paper, we discuss the effect of new design alternatives for skylights, especially in the refurbishment of obsolete facilities. Based on the authors’ previous studies, we defined a theoretical model that was subsequently adapted to a real building that was to be retrofitted in an area near Sevilla. After such complex refurbishment was executed, we analyzed the performance of buildings in warm and sunny climates, as is the case of southern Spain, where cloudiness is very scarce and available simulation models are not useful. The study of the factors that relate to sunlight; UV reception and energy; and, to a certain extent, other aspects such as ventilation and insulation has been considered a priority. Many architectural designs are presented as correct if the thermal requirements alone are met, even at the risk of later energy waste in lighting devices and visual or physical discomfort. On the other hand, large glazed areas allow for more daylight and UV radiation into a space if properly treated, but they may also produce excessive heat gains or losses, which increase the air-conditioning cooling or heating load, respectively. The uncontrolled increase in temperature can have negative effects on the well-being of a person with Alzheimer’s dementia. To avoid these problems, we have considered the combined effect of daylight and energy from the beginning of the skylight design-process. Daylighting software, based on configuration factors that we have applied in studies of the complex problem of there being direct sunlight over architectural structures, has been used. This question cannot be treated adequately with conventional programs for overcast skies. The skylights have already been constructed, with special UV increasing glazing and on-site measurements in the offices to complement the computer simulation data. The results show that it is possible to achieve energy saving and high radiation levels in winter without increasing heat loads during the summer. Ventilation is also improved through the aerodynamic design of the clerestories. All this is considered beneficial to improve the condition of users with cognitive diseases as Alzheimer’s disease, by virtue of adapted spaces.

A study of Indoor Environment of Large Glazed Office Building in Semi Arid Climate

In recent years the rate of buildings with large glazed facades is rapidly increasing, particularly in office buildings. Where, the creation of a suitable thermal and visual comfort is a significant factor affecting productivity. The use of large glazed facades without adapted shading measure generates thermal and visual discomfort, wich ranges from uncomfortable environment conditions to serious health effects. Specialized work and literature about performance evaluation of large glazed office buildings in relation to their environment are lacking in semi arid climates, characterized by significant intensity of solar radiations in the summer period of the year. This study investigates the impact of large glazing areas on thermal and visual comfort in a sample of naturally ventilated office building located in the semi arid climate of Algeria (36°, 17 N and 7°, 23’ E). A Post Occupancy Evaluation technique (POE), being a mainstream activity in the process of building operation phase is used for this purpose. The main objective is to stress practitioners, specifically architects, to take conscious decisions in an early phase of design process. The study clearly highlighted discomfort in the studied office building. It included unacceptable temperature arising from glazed facade; overheating due to excessive solar gains; insufficient ventilation and poor daylighting. The results indicate that such large fenestration system is not recommended in summer time. However, a judicious choice of the glazing size and type by simulation tools must balance lighting and thermal needs.

Zero Energy Building Economic and Energetic Assessment with Simulated and Real Data Using Photovoltaics and Water Flow Glazing

The new paradigm of Net Zero Energy buildings is a challenge for architects and engineers, especially in buildings with large glazing areas. Water Flow Glazing (WFG) is a dynamic façade technology shown to reduce heating and cooling loads for buildings significantly. Photovoltaic panels placed on building roofs can generate enough electricity from solar energy without generating greenhouse gases in operation or taking up other building footprints. This paper investigates the techno-economic viability of a grid-connected solar photovoltaic system combined with water flow glazing. An accurate assessment of the economic and energetic feasibility is carried out through simulation software and on-site tests on an actual prototype. The assessment also includes the analysis of global warming potential reduction. A prototype with WFG envelope has been tested. The WFG prototype actual data reported primary energy savings of 62% and 60% CO2 equivalent emission reduction when comparing WFG to a reference triple glazing. Finally, an economic report of the Photovoltaic array showed the Yield Factor and the Levelized Cost of Energy of the system. Savings over the operating lifetime can compensate for the high initial investment that these two technologies require.

Heat transfer model for energy-active windows – An evaluation of efficient reuse of waste heat in buildings

Minimizing thermal losses through windows and maintaining large glazing areas to provide adequate natural lighting in residential buildings are essential considerations for modern architecture, sustainability, and indoor comfort. In this study, a detailed heat transfer model for a novel energy-active window (EAW) is developed and validated to rate its thermal performance. An EAW utilizes low-grade heat to reduce building heat losses during the winter season. A thorough literature review was conducted to select the correct heat-transfer correlations for the investigated configuration. A two-dimensional finite differencing scheme was applied to approximate the vertical and horizontal temperature distribution across the EAW. Detailed temperature gradients, across the height and width of the window, were obtained. Thorough sensitivity analyses of the governing parameters were conducted to evaluate the windows’ thermal performance. The results indicate that EAWs have the potential to reduce heating power demand by approximately 2.2 W/m2floor area and 1.3 W/m2floor area at outdoor temperatures of −20 °C and −5 °C, respectively, for buildings with a window-to-floor area ratio of 10%. This potential increases proportionally with the ratio. The highest thermal efficiency of EAW is achieved when the temperature of the supplied air inside the EAW is equal to or above room temperature.

Thermal Comfort Aspects of Solar Gains during the Heating Season

Glazing plays a key role in the energy balance of buildings. The aim of this paper is to enlighten the thermal discomfort caused by large glazed areas in the heating season and to point out a possible solution that can provide proper thermal comfort with low energy use. It is unusual to discuss the negative effects of solar gains on thermal comfort during the heating season. However, there are cases when glazing may lead to unforeseen indoor thermal discomfort conditions. Laboratory and on site measurements were performed in order to assess thermal discomfort caused by direct and diffuse radiation. It was shown that the WBGT (Wet Bulb Globe Temperature) index may exceed even 30 °C in the winter season in a room having large glazed area oriented to east. Laboratory tests performed in climate chamber have shown that the high PMV values cannot be reduced below 1.0, increasing the air change rate in the room. Using opaque drapes, the WBGT index was reduced by 2 °C, but the daylighting decreased substantially. It was demonstrated that by using advanced personalized ventilation systems, the appropriate thermal comfort can be provided avoiding the reduction of daylighting.

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

Improving the energy efficiency of buildings is among the most urgent social development tasks due to the scale of energy consumption in this industry. At the same time, it is essential to meet high requirements for indoor environmental quality and thermal comfort. The issue of overheating is most often analysed in summer but it also occurs in transition seasons, when the cooling systems do not operate. The paper attempts to evaluate the effectiveness of external mobile shading elements on the microclimate of rooms with large glazed areas in the transition season. Passive solutions, such as shading elements, which limit the increase of indoor temperature, do not always allow the acquisition and maintenance of comfortable solutions for the duration of the season, as demonstrated by the authors. Temporary cooling of the rooms may be necessary to maintain comfortable conditions for the users, or other solutions should be devised to improve comfort (e.g., reduction of clothing insulation characteristics). The novelty of the study consists in the analysis of comfort in a “nearly zero energy consumption” building (NZEB) during a period not analyzed by other scientists. This is a transition period during which heating/cooling systems do not operate. The research task set by the authors involved the assessment of the possibility to reduce office space overheating in the transition season (spring) by using external shading equipment in rooms with large glazed areas. An additional research task aimed at checking the extent to which user behaviour, such as reduction in clothing insulation characteristics, can improve comfort in overheated rooms. The results of the tests reveal that the difference in the ambient air temperature between a room with external venetian blinds and an identical room with no venetian blinds in the transition season, i.e., from 27 March to 6 April 2017, ranged from 12.3 to 2.1 °C. The use of a shading system (external venetian blinds positioned at an angle of 45°) reduced the number of discomfort hours by 92% (during working hours) compared to the room without external venetian blinds. A reduction in the thermal insulation of the clothes worn by people working in the room with no venetian blinds helped to reduce the number of discomfort hours by 31%.

Parametric synergy of passive design elements in cold-cloudy climate zones of north-east India

Boundaries of nations and states are not demarcated base on climate characteristics, but the generic application of design elements and materials in contiguous regions with antagonistic climates increase energy needs. Assam-type houses designed for warm-humid climate zones increases heating needs in cold-cloudy zones of North-East India. So, the intuitive and rational analysis of critical building elements parametric synergy is a prescient passive design. The method includes survey and analysis of climate and architectural thermal environment, parametric simulations, and synergy analysis. The studies show the evolution of similar design patterns in antagonistic climate zones. Simulation results shows that the integration of direct passive solar heat gain from moderate glazing area on South and West and indoor heat sources with moderate thermal mass heat storage and high envelope insulation are synergetic while the individual effects of only large glazing areas or only high thermal mass aren’t. The process for finding optimum parameters may be further iterated. Passive design entails intuitive architectural ingenuity base on climate and rational parametric synergy to straddle differences between climate and design elements to improve the design process and energy efficiency.

A method to evaluate glare risk from operable fenestration systems throughout a year

Nowadays buildings are being designed with large glazed areas mainly due to aesthetics considerations but also to achieve daylit spaces. However, large glazed facades are prone to cause glare problems for building users. To mitigate this risk, it is important to predict existing glare metrics dynamically and reliably in the early stages of the design of a facade. Current evaluation methods for dynamic glare are either computationally too expensive or not suitable for operable façade systems. In this study, a new method is proposed to calculate the Daylight Glare Probability (DGP) index in a computationally efficient fashion, while allowing the fenestration system to switch states during the annual simulation. The method is based on a matrix formalism to calculate the vertical illuminance at a view position, and also on the calculation of a luminance map of the field of view solely from the direct component of the light sources. A first validation of the proposed method is presented. An office setup in Freiburg is monitored with a luminance camera for different weather conditions and different façade systems. Additionally, the calculation of the DGP index by the proposed method is compared with the calculation of the DGP by backward raytracing with high rendering parameters. The proposed method has been implemented in a building simulation program, called Fener. A case study is presented to illustrate the new possibilities offered by the Fener tool. The glare risk of three different textile roller blinds, with similar visible transmittance but different openness coefficient, is assessed.

Investigation of Thermal Comfort Responses with Fuzzy Logic

In order to reduce the energy consumption of buildings a series of new heating, ventilation and air conditioning strategies, methods, and equipment are developed. The architectural trends show that office and educational buildings have large glazed areas, so the thermal comfort is influenced both by internal and external factors and discomfort parameters may affect the overall thermal sensation of occupants. Different studies have shown that the predictive mean vote (PMV)—predictive percentage of dissatisfied (PPD) model poorly evaluates the thermal comfort in real buildings. At the University of Debrecen a new personalized ventilation system (ALTAIR) was developed. A series of measurements were carried out in order to test ALTAIR involving 40 subjects, out of which 20 female (10 young and 10 elderly) and 20 male (10 young and 10 elderly) persons. Based on the responses of subjects related to indoor environment quality, a new comfort index was determined using fuzzy logic. Taking into consideration the responses related to thermal comfort sensation and perception of odor intensity a new the fuzzy comfort index was 5.85 on a scale from 1–10.

A study of the passive cooling potential in simulated building in Latvian climate conditions

In this paper authors point out that overheating in buildings during summer season is a major problem in moderate and cold climates, not only in warm climate zones. Mostly caused by solar heat gains, especially in buildings with large glazed areas overheating is a common problem in recently constructed low-energy buildings.At the same time, comfort demands are increasing. While heating loads can be decreased by improving the insulation of the building envelope, cooling loads are also affecting total energy demand. Passive cooling solutions allow reduction of heat gains, and thus reducing the cooling loads. There is a significant night cooling potential with low temperatures at night during summer in moderate and cold climates. Night cooling is based on cooling of buildings thermal mass during the night and heat accumulation during the day. This approach allows to provide thermal comfort, reducing cooling loads during the day. Authors investigate thermal comfort requirements and causes for discomfort. Passive cooling methods are described. The simulation modeling is carried out to analyze impact of constructions and building orientation on energy consumption for cooling using the IDA-ICE software. Main criteria for simulation analysis are energy consumption for cooling and thermal comfort.

Comfort Study of Office Buildings with Large Glazed Areas

In the buildings with large glazed areas the biggest problem is the space overheating during the warm season. This causes increased energy demand for cooling. The survey was carried out during the warm and cold seasons in two office buildings with large glazed areas. The methodology was prepared for evaluating indoor climate parameters using objective and subjective evaluation. The measurements have shown that there are problems with lighting in workplaces of both buildings during both the warm and cold seasons. The biggest problem is too dry air during the cold period, an acceptable temperature is also not always in the building No. 2. The survey has shown that some employees are dissatisfied with the indoor climate in the workplace, the bigger dissatisfaction is in building No. 2. Assessing according to the O. Fanger methodology was obtained that the number of PPD is in the normal range during the cold period, whereas close to the limit when the building can not be operated in the warm period.

Thermal Comfort and HVAC Systems Operation Challenges in a Modern Office Building – Case Study

Abstract The aim of the study is to evaluate the indoor environment conditions in the new-built office building, Energetikum, and consequently suggest the control strategies, which can lead to determination of critical areas and elimination of thermal discomfort. Representative offices have been selected and equipped with portable sensor groups for monitoring of the indoor environment parameters. Contribution is presenting the data obtained from 6 selected rooms during 3 reference weeks - heating, transition and cooling period. The measured results indicate overheating of the rooms, particularly in the ones with the large glazed areas with higher solar gains. The values of indoor air temperature during heating and transition period could not meet the normative criteria according to standard EN 15251:2007 (the cat. II.) during 13 % - 49 % of evaluated time intervals. Consequently, the simulation model of the selected office was created and is pointing to the possibilities of the control system improvement, which can lead to an elimination of the problem with overheating.

Field study of thermal comfort and occupant satisfaction in Canadian condominiums

ABSTRACTIn Canada and much of the world, high-rise residential buildings with large glazing areas are increasing in popularity. These buildings are associated with lower thermal resistance envelopes and higher solar gains than more traditional construction with smaller windows. This study explores the comfort implications and usability in condominiums by performing a field study of 20 units: 10 with large window areas (LW) and 10 with medium-sized window areas. Occupant comfort was assessed in summer and winter, through two open-ended surveys, infrared thermography, and recorded interior temperature and humidity. LW occupants more often report uneven interior temperature distributions and windows as a source of discomfort in winter. One quarter of condo units experience condensation on windows, indicating window and frame improvements may benefit both groups. This exploratory study identifies key issues and occupant preferences within condominiums to guide future research on this building type.

Exhibition Pavilions Car Showrooms Based on Translucent Structures: Providing Microclimatic Comfort for Clients

Transition to a new approach related to use of facades and roofs entirely made of glass in pavilions car showrooms construction called for an additional analysis to evaluate an issue of how to ensure an interior climate. There was a need to have solutions generalized and systematized with the aim to ensure human comfort in pavilions with large glazed areas in facades and roofs. Exhibition pavilions car showrooms based on translucent structures were taken for consideration. General data concerning temperature conditions for the rooms and internal glazing surfaces of pavilions car showrooms based on translucent structures are stated herein. Pertinent information for glazing design is given with due account for winter maintenance conditions in regard to the pavilions car showrooms having significant areas of façade or roof glazing.

Glazing Design for Exhibition Pavilions Based on Translucent Structures under Winter Conditions during Cold Periods

Transition to a new approach related to use of facades and roofs entirely made of glass in building construction called for an additional analysis to evaluate an issue of how to ensure an interior climate. In the article have been investigated the factors, which make people feel uncomfortable in the pavilions with large glazing areas: cold air flow near glazing area, which occurs on the cold surfaces of the windows, going down and along the floor, radiation heat exchange between human beings and building envelopes, condensation on internal glazing surfaces.

Modern insulation requirements change the rules of architectural design in low-energy homes

In the design of very well-insulated homes, there is a need for a more nuanced design that takes into account winter and summer conditions. In this paper, we compare a traditional design for a typical Danish single-family house with large glazing areas oriented towards the south and smaller glazing areas towards the north, and a design with an even window distribution where the glazing-to-floor ratio is the same for each room. We found that the use of solar gains through south-oriented windows is not as important as is traditionally believed because, in well-insulated homes, space heating demand is not reduced much by having larger south-facing windows. Furthermore, we found that there is a g-value above which the additional solar gains through south-oriented windows do not help reduce space heating demand, and it becomes important to use solar shading or glazing with solar-control coating as a cheaper alternative to reduce overheating. Maximum window sizes from an overheating perspective were identified that are larger than the optimal window sizes for space heating demand. However, we show that the difference in space heating demand with optimal window size and with larger window sizes is small, so it is up to the building owner to decide whether or not he wants larger glazing areas to allow for more daylight. And windows can be positioned in the façade with considerable architectural freedom. However, we do recommend an even distribution of the glazing-to-floor ratio, because this generally provides an improved thermal indoor environment in south-oriented rooms and will ensure a better daylight level especially in north-oriented rooms. We also show that the optimal window size is influenced by thermal zone configuration and that there is a need for models in which a difference is made between zones with direct and with non-direct solar gains.