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Toward Building Sector Energy Transition
Published in Muhammad Asif, Handbook of Energy Transitions, 2023
Niccolò Aste, Claudio Del Pero, Fabrizio Leonforte
Generally speaking, passive solutions in buildings are technologies that are able to provide the required performance without the use of technical systems. All the passive technologies and design strategies aimed to reduce the thermal energy demand due to the building envelope for heating and cooling in buildings have to be put into practice before any other measure, ensuring comfort conditions with the minimum possible amount of energy. In detail, in countries with large heating loads, advanced insulation and proper architectural choices are pivotal to reduce thermal losses. In hot climates, where cooling loads are set to increase substantially, the reduction of the loads can be done through many low-cost and local components, such as cool roofs, shading systems, and high thermal inertia materials (e.g. stone or bricks). Heat flows can be better managed, preferably through natural ventilation or with mechanical ventilation systems that manage airflow and reduce unnecessary cooling energy demand. In mixed climates with both space heating and cooling loads, the multiplicity of seasonal constraints requires solutions to address both. For example, low-emissivity windows can reflect solar radiation during the summer to minimize heat gain as well as reflect radiative heat from the inside during winter to minimize heat loss.
Energy Basics
Published in Stan Harbuck, Donna Harbuck, Residential Energy Auditing and Improvement, 2021
Remember that metals are good conductors of heat. They have a high K-value and a low R-value, and cannot be used as insulators. For instance, if you grab a hot piece of metal, the heat from the metal easily transfers to your hand. It feels hot, and you pull your hand away to avoid being burned. In the case of radiation, metals, especially shiny ones, tend to be poor emitters of radiation energy. They can also reflect solar rays well and that is why some of the best roof coatings are made of aluminum or other appropriate metals. Metals have a low emissivity coefficient. This is the reason a thin metal layer can be on the underside of roof decking to help keep heat from the shingles from transferring into the attic space as easily, as long as no insulation is touching the barrier. Metals are some of the few common substances that reflect both visible and infrared radiation back away from the building. However, nothing can touch that thin metal layer where it faces the inside, or the benefit of being a poor radiation emitter is lost by allowing its high conductivity to transfer heat to whatever it is touching.
Thermal radiation
Published in Tariq Muneer, Jorge Kubie, Thomas Grassie, Heat Transfer, 2012
Tariq Muneer, Jorge Kubie, Thomas Grassie
If we wish to reduce the radiation heat loss from a surface to its surroundings, such as, for example, from the outer walls of a furnace, (surface 1), to those of the building in which it is housed (surface 2) we can place a low emissivity (high reflectivity) material between them. Such a material is termed a radiation shield. If the radiation shield is placed adjacent to the furnace outer wall, and is of the same area, the view factor will effectively be equal to one. Without a shield, the net radiative heat transfer rate between the furnace and building walls is given by qfS=A1(Eb1-Eb2)1/ε1+1/ε2-1
Additive manufacturing process monitoring and control by non-destructive testing techniques: challenges and in-process monitoring
Published in Virtual and Physical Prototyping, 2018
Emissivity is the most important calibration parameter for quantitative measurement of temperature using infrared radiation. It can be interpreted as the ratio of the radiance of a body at a particular temperature to the corresponding radiance of a black body at the same temperature (Raj et al. 2002). The emissivity of a black body is 1.0. In reality, objects rarely have emissivity of 1.0. High-emissivity materials emit more infrared radiation than materials with low-emissivity at the same temperature (Usamentiaga et al. 2014).
Application of passive measures for energy conservation in buildings – a review
Published in Advances in Building Energy Research, 2019
Farhad Amirifard, Seyed Amirhosain Sharif, Fuzhan Nasiri
The most important part of a fenestration system is the glazing as it has the largest area of the constituent parts. Thus, its U-value impacts the overall U-value of a window (Jelle et al., 2012). Recently glazing technologies have progressed tremendously. Glazing materials are presented in different forms such as multilayer glazing, suspended films, vacuum glazing, smart windows, solar cell glazing, self-cleaning glazing solar control glasses, insulating glass units, low emissivity (Low-E) coatings, evacuated glazing, aerogels and glazing cavity gas fills, just to name a few. Additional to glazing materials developments, many studies focus on improvements in frame and spacer designs (Quesada, Rousse, Dutil, Badache, & Hallé, 2012b). Both glass and plastic are common glazing material and can be clear, tinted, coated, laminated and obscured. There is a wide variety of tinted glass such as blue, grey, green and bronze. The high absorption rate of solar radiation by tinted glass can lead to reduction of the solar heat gain, visible transmittance, and glare. Coating of glasses is another method to improve the performance of glazed coating, which is typically applied in one or two surfaces of a glazing unit. The coating can be categorized in Low-Emissivity Coatings, Reflective Coatings, and Spectrally Selective Coatings. Laminated glass is made by sticking two panes of glass together, with a layer of clear, tinted or coated plastic placed in between. Obscured glass is used mostly for privacy and is translucent or decorative (ASHRAE, 2013). Sadineni et al. (2011) categorized glazing material based on their functions that include high performance insulation (HPI), solar gain control (SC), daylighting (DL), or a combination of these functions. They applied the above categorization to aerogel glazing, vacuum glazing, switchable reflective glazing, suspended particle devices (SPD) film and holographic optical elements.
Coupled transparent insulation system with low emissivity solar absorber: An experimentally validated building energy simulation study
Published in Science and Technology for the Built Environment, 2020
Miroslav Čekon, Jakub Čurpek, Richard Slávik, OndŘej Šikula
Basically, there are many building applications where the energy contributions and the climatic conditions are strongly influenced by the thermal radiation exchange with the ambient environment (Ibrahim et al. 2018). In BES approaches, most of them attempt to employ this phenomenon to obtain a model which is as simple as possible. Several of them are also being implemented in energy simulations at the present time, their utilization has a specific validity and so mechanisms in which validation methods are combined have their legitimate place. The aim of this research is to identify the overall thermal and energy performance of the proposed TIF prototypes based on solar wall concepts. The objective is to analyze the effect of different absorber emissivity behind a transparent insulation system. The improved thermal performance offered by incorporating low emissivity surfaces can basically influence the overall thermal efficiency of building components. Another aspect of its incorporation represents a key absorbing factor that may be used to influence overheating in summer. An assumption can be made, that this can be properly predicted through the use of the adequate theoretical models. However, simulation algorithms (mathematical representations of physical processes) and derivative code implementations may be erroneous (Mahdavi 2020). Therefore, the comparability between both measured and simulated results are studied to prove these fundamental assumptions. Experimental measurements were conducted using dynamic outdoor methods with the aim of verifying a BES model. Two different test cases and operation modes were observed. First represents the heating season test with aim to obtain a temperature response of tested components. The effect on the internal air temperature was primarily observed. However the second is focused on the cooling season, where internal air temperature is controlled at a constant level and the effect on dynamic heat flows, energy performance, is observed as a key indicator. It also corresponds to the more complex data obtained during these measurements based on energy balance parameters. Therefore, a simulation model was created to simulate the effect on the thermal and energy performance of the TIM-based façade prototype in the EnergyPlus computational engine. This was primarily focused on the capability of the thermo-optical properties (dynamic values of solar transmittance and heat transfer) of the proposed prototype to respond in an adequate way under different transient boundary and operation conditions, for both heating and cooling modes.