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•ETFE cushions were employed in a double-skin façade for energy retrofitting of office buildings.•Virtual Reality was used to investigate the user acceptance of ETFE in building ...envelopes.•View perception and emotional response was measured in an immersive environment.•Design criteria for second-generation ETFE climate adaptive building façades were derived.
Equipping building envelopes with an additional layer is an effective measure for improving the overall thermal and daylighting performance and reducing the energy consumption of buildings. This study investigated the user acceptance of energy-saving retrofitting measures in office buildings, reporting on the view perception and emotional response towards ETFE double-skin façades (DSF). Virtual Reality (VR) and physics-based imaging techniques were used to evaluate the user experience of a window view in an office space equipped with a pneumatic ETFE cushion as a second building skin. Three DSF scenarios with different ETFE cushions, including a clear, fritted and switchable sample, were evaluated and compared to the original single-skin façade with double-glazed windows. The physical and luminous conditions of the office space were replicated in a virtual environment with a validated physically-based imaging technique and presented to a group of volunteers (N = 22) using a virtual reality headset. While immersed in the virtual environment, participants responded to a questionnaire enquiring into their view perception and emotional states. The results revealed a preference for view clarity of clear ETFE in double-skin façades (Mdn = 5) and less satisfaction for fritted (Mdn = 4) and switchable foil cushions (Mdn = 1.75), yet double glazing was preferred in all measured parameters (Mdn = 6). Statistical significance was found for fritted in comparison to switchable ETFE in terms of spatial pleasure and control. The highest ratings were given to clear glazing across all investigated parameters of view perception and emotional response. The lowest ranking in all questions was given to the sample with the switchable ETFE cushion. The study concluded that view clarity is a major aspect for the user acceptance of ETFE double-skin façades. Overall, this study provides a better understanding of the visual and emotional implications of viewing through ETFE foil and contributes to forming criteria for the design of next-generation ETFE building envelopes.
•CFD model is applied to analyse the performance of single-phase ejectors with R134a.•A multi-objective optimisation algorithm is used to improve the ejector performance.•Four ejector cooling cycles ...are compared against the basic cycle through the SEPR.•Geometrically optimised ejectors are a must to achieve the desired performance.•A thermally-driven sub-cooler with ejector improved the SEPR up to 23%.
Global energy consumption for cooling applications is increasing every year, accelerating the fossil fuels consumption and the CO2 emissions. To improve the performance of the vapour compression cycles, ejectors can use the low grade wasted energy as a means of heat recovery. Several proposals have been studied to improve the global Coefficient Of Performance of the ejector cycles. However, very few optimised the ejector geometry to obtain the maximum performance. A CFD-based multi-objective optimization of the ejector geometry and a thermodynamic model of the cooling cycle have been coupled to obtain the best performance of four types of thermally-driven ejector cycles. The results predicted improvements of up to 13% and 23% in the rated Coefficient Of Performance and the Seasonal Energy Performance Ratio, respectively, compared with the basic vapour compression cycle. Using geometrically optimised ejectors makes it possible to achieve a high level of performance that justifies the use of this technology.
•An ejector cooling cycle model has been implemented to study the performance of the cycles.•Comparison between different typologies of ejector cooling cycles and refrigerants has been assessed.•A ...good agreement between experimental data found in literature and the ejector model has been obtained.•A new ejector efficiency has been proposed as a function of the area ratio and the entrainment ratio.•The results show a methodology which makes easier the simulation of the working conditions of an ejector cooling cycle.•Thanks to the model proposed, the best combination between the cycle configuration, the refrigerant and the working conditions has been found.
Most of the energy consumed in cooling cycles comes from fossil fuels, whose reserves are becoming depleted. The aim of this article is to show the potential benefits of using ejectors in cooling systems to improve its energetic efficiency. A review of different configurations of ejector cooling systems has been carried out for being compared against a conventional compressor cycle. The same cooling capacity and working conditions were imposed by using refrigerants R134a, R1234yf and R600a. The results showed that the Coefficient of Performance could increase up to 26%. Ejectors have been characterised by correlations of entrainment ratio and a new definition of ejector compression efficiency. Those correlations have been obtained by means of a pseudo-one dimensional method of ejector analysis. Ejector cooling systems were proven to be a potential alternative to conventional vapour compression cycles.
•The SEDICAE project applies a new methodology to optimize building design and cost.•Methodology based on a Tabu Search and a simplified method.•SEDICAE selects the construction elements that ...minimize the LCC and the demand of buildings.•The methodology reduces the development time requirements to make design decisions.•Economic scenarios can be studied with SEDICAE.
Designing a low energy building requires to evaluate a large number of parameters: design combinations, element thermal characteristics, HVAC systems efficiencies, etc. All of them determine the space heating and space cooling energy demands, energy consumptions, and life cycle cost over the lifetime of the building. This paper presents the achievements of SEDICAE research project consisting on a new methodology based on a tabu search and a simplified method to calculate energy consumptions. The methodology is designed to estimate the annual energy demand, life-cycle cost and energy rating. A second process is included to select the HVAC system is developed for the building designed with this methodology.
In general, builders should look for low energy, but investment in building design is a limiting factor. This paper show the relationship between energy efficiency index and investment in optimized residential building. Furthermore, the best energy rate is obtained applying the HVAC systems in the integrated optimization method for residential buildings. This methodology reduces investment, reduce the energy demand and selects the best construction materials, allowing to study the cost in different economic scenarios. In this paper, a building design case study is studied in 2028 scenarios in 12 climatic zone in Spain.
This paper presents new correlations to calculate natural convection heat transfer coefficients (CHTC) in enclosures for building performance simulation. Current work related to the development of ...correlations is not oriented to building enclosures, and the influence of high numbers of Rayleigh (Ra) and aspect ratio on the CHTC has not been studied in detail. In this work, two new correlations have been developed for a vertical wall, one in laminar regime (Ra < 10
7
) and another one in turbulent regime (10
7
<Ra<10
11
). Moreover, two new correlations have been developed for floor and ceiling, one in laminar regime (Ra < 10
6
) and another one in turbulent regime (Ra > 10
6
). All correlations have been developed as function of the aspect ratio (H/L) and Ra numbers calculated from the enclosure average air temperature and wall surface temperature. By contrast, in previous works the Ra numbers have been calculated from the temperature difference of opposite walls. Computer Fluid Dynamics (CFD) simulations for different aspect ratios (H/L = 0.5-1-2) and Ra numbers (10
3
-10
11
) have been carried out in order to obtain these correlations. The SIMPLE algorithm has been used for the solution of the Navier-Stokes equations and the realizable turbulence k-
model with an enhanced wall-function treatment has been used. The correlations developed follow the expected trend for the low number of Ra in comparison with the expressions developed by other authors. For a high number of Ra, our correlations improve the previous correlations, because it is a function of the aspect ratio of the enclosure and the average air temperature of the enclosure. This approach is simple to implement in the construction of thermal simulation programs with low computational cost.
Abstract
This study builds on the ways design modifications can improve the integration of solar electric generation in Malaysian educational buildings. The study suggests the benefit of a solar ...installation at a standard school as both an educational and economic opportunity for a photovoltaic (PV) system can bring together classroom learning and energy supply. In analysing the existing design details of selected case study schools, this study aims to determine how the integration of this technology in the building design can be applied to the most basic education buildings in Malaysia. The existing design patterns of school classrooms with and without PV systems were logged and examined through a series of post-occupancy evaluation studies on selected schools. Basic energy requirements were summarized, and specific design modifications for the existing case study schools were proposed to adapt to the newer, modern classrooms. The results of this conceptual evaluation, coupled with energy simulations to model a reference case energy usage, provided the basis to predict PV outputs and future energy use for a modified classroom. Positive results from the solar analysis provided additional evidence about how alternative energy sources are beneficial in long term future-proofing schools.
Climate-sensitive school buildings can enhance students’ learning performance and reduce the building’s overall energy consumption. This paper reports on a post-occupancy study of contemporary school ...buildings in Malaysia, assessing problems of solar heat gain. The research aims to propose retrofitting measures based on passive design principles adapted specifically for the Malaysian tropical climate to strengthen the resilience of local school buildings in a global climate emergency. On-site measurements in two different schools provided the empirical basis for the design modifications. The monitoring procedure included site observations, extended temperature and humidity measurements, and daylight analysis. A virtual classroom model was generated based on the on-site measurements, and a parametric simulation study was conducted to evaluate the proposed retrofit measures’ effectiveness. The model variables were evaluated and compared to identify the passive design elements that significantly impact heat gains and thermal comfort. The results showed that increasing roof overhangs to 1500 mm for additional shading, sensitive selection of roof materials and colours of white-painted zinc roof, and reduction of window-to-wall ratio by 30% to the operable windows helps to reduce solar gains by 6% to improve comfort conditions within the classrooms. Overall, the study provided evidence of how passive solar building design would benefit the climate resilience of Malaysian schools.
ETFE pneumatic foil constructions are used increasingly by designers and builders as an alternative to glass in state of the art building envelopes. Low weight, high transparency, mechanical ...resistance and self-cleaning properties of ETFE may contribute to the overall performance. However, reliable information on the thermal performance of ETFE cushions in building envelopes is scarce, limiting the performance prediction in energy simulations. The present study aims to investigate the thermal performance of air-inflated ETFE foil cushions and evaluates parameters of material properties and design which might affect the thermal transmittance. The paper reports on the experiments conducted to quantify the thermal performance using a climate chamber and full-size mock-ups. Based on available standards, tests were designed to compare the thermal performance of three different ETFE cushion designs, under changing climate conditions. The design variations, including frit prints and switchable shading mechanisms, were tested and compared at hot, temperate and cold weather scenarios. The test series provided detailed results on the thermal performance of ETFE cushions which may be of use for the comparison with the performance of other building components and materials, serve as input for energy simulations and provide a theoretical basis for future developments of novel building envelopes.
The paraventricular nucleus of the hypothalamus (PVN) contains heterogeneous populations of neurons involved in autonomic and neuroendocrine regulation. The PVN plays an important role in the ...sympathoexcitatory response to increasing circulating levels of angiotensin II (Ang-II), which activates AT1 receptors in the circumventricular organs (OCVs), mainly in the subfornical organ (SFO). Circulating Ang-II induces a de novo synthesis of Ang-II in SFO neurons projecting to pre-autonomic PVN neurons. Activation of AT1 receptors induces intracellular increases in reactive oxygen species (ROS), leading to increases in sympathetic nerve activity (SNA). Chronic sympathetic nerve activation promotes a series of metabolic disorders that characterizes the metabolic syndrome (MetS): dyslipidemia, hyperinsulinemia, glucose intolerance, hyperleptinemia and elevated plasma hormone levels, such as noradrenaline, glucocorticoids, leptin, insulin, and Ang-II. This review will discuss the contribution of our laboratory and others regarding the sympathoexcitation caused by peripheral Ang-II-induced reactive oxygen species along the subfornical organ and paraventricular nucleus of the hypothalamus. We hypothesize that this mechanism could be involved in metabolic disorders underlying MetS.
This study presents new correlations for internal forced convective heat-transfer coefficients (CHTCs) in buildings. CHTCs are used by building energy performance simulation (BES) tools to estimate ...the annual heating and cooling demands of buildings. Most programs use constant values or correlations but do not consider in detail the 3D geometry or the dimensions and positions of the inlet and outlet openings. The correlations developed here take into account 3D geometry and the dimensions and positions of the inlet/outlet openings in opposite walls. A new methodology has been developed for the calculation of CHTCs in 3D enclosures from two 2D planes, one with a horizontal orientation and another with a vertical orientation. Comparing the results from correlations with those from computational fluid dynamics (CFD) simulations, the errors found are less than 15%. These correlations are easy to use in BES.
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