scholarly journals The influence of moisture on the energy performance of retrofitted walls

2020 ◽  
Vol 322 ◽  
pp. 01035
Author(s):  
Mafalda Amorim ◽  
Vasco Peixoto de Freitas ◽  
Isabel Torres ◽  
Tomasz Kisilewicz ◽  
Umberto Berardi

The renovation of old building facades should be performed mainly considering the building energy demand reduction. For this purpose, it is necessary to select retrofitted solutions that should be able of minimizing heat losses through walls. However, it is not only the nominal thermal transmittance that influences the amount of heat transported through the wall, but also the moisture content within the walls under in- service conditions. The main objective of this paper is the evaluation of the influence of the moisture content on the energy performance of retrofitted walls. A numerical study using the software WUFI Pro was carried out to quantify the influence of wind driven rain on the thermal transmittance of different wall assemblies exposed to different climates and orientations. This study reports the transient thermal transmittance of different retrofitted wall solutions as a function of moisture content.

2015 ◽  
Vol 737 ◽  
pp. 154-158
Author(s):  
Claudia Guattari ◽  
Gabriele Battista ◽  
Luca Evangelisti ◽  
Aldo Fanchiotti ◽  
Luciano Santarpia

The study of the building energy performance is based on simplified procedures that estimates the energy demand using monthly values of environmental parameters. It is well known that it is possible to use advanced dynamic softwares able to analyze the real building’s behavior along time. For this reason in this study a historical building energy retrofit has been performed through a dynamic software considering the influence of different kind of windowed elements on the annual energy demand. Four simulations, taking into account transparent elements characterized by progressively improved properties of thermal transmittance and solar gain factor, have been performed. The results obtained have been analyzed and compared.


Author(s):  
Zhiqiang Zhai

Natural ventilation is one of the primary strategies for buildings in hot and mild climatic regions to reduce building cooling energy requirement. This paper uses a building energy simulation program and a computational fluid dynamics program to investigate the influence of building scales on building cooling energy consumption with and without natural ventilation. The study examines the energy performance of buildings with different L/W and H/W ratios in both Miami, FL and Los Angeles, CA. The simulation results show the varying trends of natural ventilation potential with increased building scale ratio of L/W and H/W. The comparison of the predicted energy consumptions for twenty buildings discloses the most energy-efficient building scales for rectangular-shape buildings in both hot and mild climates with and without natural ventilation. The study indicates that natural ventilation is more effective in mild climates than in hot climates, which may save cooling energy by 50% and vent fan energy by 70%. The paper analyzes the most suitable seasons for natural ventilation in Miami and Los Angeles. Further simulations indicate that extra cooling benefits associated with more natural ventilation cannot compensate additional heat gains through larger windows.


2020 ◽  
Vol 10 (7) ◽  
pp. 2233
Author(s):  
Antón Cacabelos-Reyes ◽  
José Luis López-González ◽  
Arturo González-Gil ◽  
Lara Febrero-Garrido ◽  
Pablo Eguía-Oller ◽  
...  

Hospital surgical suites are high consumers of energy due to the strict indoor air quality (IAQ) conditions. However, by varying the ventilation strategies, the potential for energy savings is great, particularly during periods without activity. In addition, there is no international consensus on the ventilation and hygrothermal requirements for surgical areas. In this work, a dynamic energy model of a surgical suite of a Spanish hospital is developed. This energy model is calibrated and validated with experimental data collected during real operation. The model is used to simulate the yearly energy performance of the surgical suite under different ventilation scenarios. The common issue in the studied ventilation strategies is that the hygrothermal conditions ranges are extended during off-use hours. The maximum savings obtained are around 70% of the energy demand without compromising the safety and health of patients and medical staff, as the study complies with current heating, ventilation and air conditioning (HVAC) regulations.


Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4954
Author(s):  
Mohammad AlHashmi ◽  
Gyan Chhipi-Shrestha ◽  
Kh Md. Nahiduzzaman ◽  
Kasun Hewage ◽  
Rehan Sadiq

Rapid population growth has led to significant demand for residential buildings around the world. Consequently, there is a growing energy demand associated with increased greenhouse gas (GHG) emissions. The residential building energy demand in arid countries such as Saudi Arabia is supplied with fossil fuel. The existing consumption pattern of fossil fuels in Saudi Arabia is less sustainable due to the depletion of fossil fuel resources and resulting environmental impacts. Buildings built in hot and arid climatic conditions demand high energy for creating habitable indoor environments. Enormous energy is required to maintain a cool temperature in hot regions. Moreover, climate change may have different impacts on hot climatic regions and affect building energy use differently. This means that different building interventions may be required to improve the performance of building energy performance in these geographical regions, thereby reducing the emissions of GHGs. In this study, this framework has been applied to Saudi Arabia, a hot and arid country. This research proposes a community–government partnership framework for developing low-carbon energy in residential buildings. This study focuses on both the operational energy demand and a cost-benefit analysis of energy use in the selected geographical regions for the next 30 years (i.e., 2050). The proposed framework primarily consists of four stages: (1) data collection on energy use (2020 to 2050); (2) setting a GHG emissions reduction target; (3) a building intervention approach by the community by considering cost, energy, and GHG emissions using the Technique for Order of Performance by Similarity to the Ideal Solution (TOPSIS) to select the best combinations in each geographical region conducting 180 simulations; and (4) a clean energy approach by the government using grey relational analysis (GRA) to select the best clean energy system on the grid. The clean energy approach selected six different renewable power generation systems (i.e., PV array, wind turbine, hybrid system) with two storage systems (i.e., battery bank and a combination of electrolyte, fuel cell, and hydrogen tank storage). This approach is designed to identify the best clean energy systems in five geographical regions with thirty scenario analyses to define renewable energy-economy benefits. This framework informs through many engineering tools such as residential building energy analysis, renewable energy analysis, multi-criteria decision analysis (MCDA) techniques, and cost-benefit analysis. Integration between these engineering tools with the set of energy policies and public initiatives is designed to achieve further directives in the effort to reach greater efficiency while downsizing residential energy demands. The results of this paper propose that a certain level of cooperation is required between the community and the government in terms of financial investments and the best combinations of retrofits and clean energy measures. Thus, retrofits and clean energy measures can help save carbon emissions (enhancing the energy performance of buildings) and decrease associated GHG emissions, which can help policy makers to achieve low-carbon emission communities.


2021 ◽  
Author(s):  
Patrick Ritsma

Building energy models are an effective tool for evaluating energy reduction opportunities in both design phase and post-occupancy scenarios. By merging building energy models with city scale building stock data, it is possible to analyze energy performance at a greater breadth, providing more informed policy decisions and solutions to energy demand asymmetries in urban metropolises. This study examines the energy reduction potential for office buildings in the Toronto 2030 District, by testing individual and bundled energy conservation measures and greenhouse gas reduction strategies using a reference building energy model. When extrapolated across Toronto’s urban core, simulation results determined that standard interventions on the existing office building stock have the potential to reduce greenhouse gas emissions by as much as 91.5%, in line with 2030 District initiatives.


2016 ◽  
Vol 38 (1) ◽  
pp. 64-88 ◽  
Author(s):  
N Belkacem ◽  
L Loukarfi ◽  
M Missoum ◽  
H Naji ◽  
A Khelil ◽  
...  

Bioclimatic architecture strategies and solar active systems contribute strongly to the reduction of building energy demand and achieving thermal comfort for its occupants over the whole year. This paper deals with the study of the energy performance improvement of a pilot bioclimatic house located in Algiers (Algeria). First, a series of experimental measures are conducted during cold period to show the effect of passive and active solar gains on the improvement of the indoor air temperature of the house. Then, a dynamic model of a solar heating system coupled with a bioclimatic house has been developed using TRNSYS software and validated with experimental data. The validated model has been used to establish the energy balance of the pilot bioclimatic house without solar heating system and to compare them to those of a conventional house. Finally, the improvement of the energy balance of the pilot bioclimatic house has been done by passive and active ways. The passive one includes the increase of south facing windows size and the use of night cooling with the use of shading device in summer. The active one consists of the integration of a solar heating system. Furthermore, an environmental study has been performed. The experimental results show that the energy requirements of a pilot bioclimatic house are very low which is suitable for the use of solar heating system in building. The simulation results show that the application of bioclimatic strategies is a better way to provide thermal comfort in summer and decrease the space heating energy demand of the house with 48.70%. The active solar system will cover 67.74% of the energy demand for heating of the house. These energy savings generate a significant reduction in CO2 emissions. Practical application: This work will enable engineers and designers of modern buildings of buildings in a Mediterranean climate to improve building energy efficiency and reduce CO2 emissions by a conjunction of different passive heating and cooling techniques such as insulation, thermal mass, window shades, night ventilation, and the solar heating system. The paper provides designers an effective strategy in terms of energy savings and indoor thermal comfort while reducing CO2 emissions.


2020 ◽  
Vol 10 (12) ◽  
pp. 4188 ◽  
Author(s):  
Chuan-Rui Yu ◽  
Han-Sen Guo ◽  
Qian-Cheng Wang ◽  
Rui-Dong Chang

Environmental concerns and growing energy costs raise the importance of sustainable development and energy conservation. The building sector accounts for a significant portion of total energy consumption. Passive cooling techniques provide a promising and cost-efficient solution to reducing the energy demand of buildings. Based on a typical residential case in Hong Kong, this study aims to analyze the integration of various passive cooling techniques on annual and hourly building energy demand with whole building simulation. The results indicate that infiltration and insulation improvement are effective in regard to energy conservation in buildings, while the effectiveness of variations in building orientation, increasing natural ventilation rate, and phase change materials (PCM) are less significant. The findings will be helpful in the passive house standard development in Hong Kong and contribute to the further optimization work to realize both energy efficiency and favorably built environments in residential buildings.


2016 ◽  
Vol 2 (1) ◽  
pp. 49 ◽  
Author(s):  
Miguel Núñez Peiró ◽  
Emilia Román López ◽  
Carmen Sánchez-Guevara Sánchez ◽  
Francisco Javier Neila González

Resumen Esta investigación se enmarca dentro del proyecto MODIFICA (modelo predictivo - Edificios - Isla de Calor Urbano), financiado por el Programa de I + D + i Orientada a los Retos de la sociedad 'Retos Investigación' de 2013. Está dirigido a desarrollar un modelo predictivo de eficiencia energética para viviendas, bajo el efecto de isla de calor urbano (AUS) con el fin de ponerla en práctica en la evaluación de la demanda de energía real y el consumo en las viviendas. A pesar de los grandes avances que se han logrado durante los últimos años en el rendimiento energético de edificios, los archivos de tiempo utilizados en la construcción de simulaciones de energía se derivan generalmente de estaciones meteorológicas situadas en las afueras de la ciudad. Por lo tanto, el efecto de la Isla de Calor Urbano (ICU) no se considera en estos cálculos, lo que implica una importante falta de precisión. Centrado en explorar cómo incluir los fenómenos ICU, el presente trabajo recopila y analiza la dinámica por hora de la temperatura en diferentes lugares dentro de la ciudad de Madrid. Abstract This research is framed within the project MODIFICA (Predictive model - Buildings - Urban Heat Island), funded by Programa de I+D+i orientada a los retos de la sociedad 'Retos Investigación' 2013. It is aimed at developing a predictive model for dwelling energy performance under the Urban Heat Island (UHI) effect in order to implement it in the evaluation of real energy demand and consumption in dwellings. Despite great advances on building energy performance have been achieved during the last years, weather files used in building energy simulations are usually derived from weather stations placed in the outskirts of the city. Hence, Urban Heat Island (UHI) effect is not considered in this calculations, which implies an important lack of accuracy. Focused on exploring how to include the UHI phenomena, the present paper compiles and analyses the hourly dynamics of temperature in different locations within the city of Madrid. 


2020 ◽  
Vol 330 ◽  
pp. 01028
Author(s):  
Mohamed Elamine GHEDHAB ◽  
Ikram EL ABBASSI ◽  
Rafik ABSI ◽  
Yannick MELINGE

This paper represents a numerical study of mixed convection conduction in enclosed two- dimensional square cavity differentially heated. Complex geometries are designed on a vertical partitioned wall, those geometries are applied to building facades aiming to improve the overall energy performance of the building. Our numerical results are based on the resolution of coupled momentum and energy equations using Ansys Fluent. Numerical study has been performed for different values of the Rayleigh number. Triangular geometry element will be considered in the middle wall. Finally, temperature profile and streamlines will be analyzed to examine the influence of this studied shape.


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