scholarly journals Outer wall with thermal barrier. Impact of the barrier on heat losses and CO2 emissions

2020 ◽  
Vol 29 (2) ◽  
pp. 223-233
Author(s):  
Ewa Figiel ◽  
Dorota Leciej-Pirczewska

New demands for lowering energy consumption of buildings lead to many new solutions including, amongst others, the introduction of an outer wall thermal barrier for both heating and cooling effect. The analysed thermo-active-wall-barrier is a water-based system, where the pipes are embedded in the wall construction. It enables the use of a low-temperature barrier medium for space heating, thereby increasing the efficiency of all potential energy supply systems using renewable energy sources. The pipes form an active thermal barrier for heat transfer between the outer and the heated space. There are many possibilities to place the pipes in the wall for example in the case of energetic thermo-modernisation. Our research and calculations have shown that thermo-active-wall-barrier is sensitive to the location of pipes. The following paper also provides a study of the impact of thermal barrier on a building’s energy performance. The analysis was conducted for a single-family house in a temperate climate based on parameters taken from one of the Polish meteorological data-bases. Calculations using current procedure of evaluating building energy performance show, that the thermal barrier can contribute to signifi cant reduction of transmission energy loss thus lowering the environmental impact.

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 761 ◽  
Author(s):  
Jagoda Błotny ◽  
Magdalena Nemś

Changes in climate, which in recent years have become more and more visible all over the world, have forced scientists to think about technologies that use renewable energy sources. This paper proposes a passive solar heating and cooling system, which is a Trombe wall located on the southern facade of a room measuring 4.2 m × 5.2 m × 2.6 m in Wrocław, Poland. The studies were carried out by conducting a series of numerical simulations in the Ansys Fluent 16.0 environment in order to examine the temperature distribution and air circulation in the room for two representative days during the heating and cooling period, i.e., 16 January and 15 August (for a Typical Meteorological Year). A temperature increase of 1.11 °C and a temperature decrease in the morning and afternoon hours of 2.27 °C was obtained. Two options for optimizing the passive heating system were also considered. The first involved the use of triple glazing filled with argon in order to reduce heat losses to the environment, and for this solution, a temperature level that was higher by 8.50 °C next to the storage layer and an increase in the average room temperature by 1.52 °C were achieved. In turn, the second solution involved changing the wall material from concrete to brick, which resulted in a temperature increase of 0.40 °C next to the storage layer.


2020 ◽  
Vol 307 ◽  
pp. 01028
Author(s):  
Mohammed Cherif LEKHAL ◽  
Abderahmane Mejedoub MOKHTARI ◽  
Rafik BELARBI

The Earth-Air Heat Exchanger (EAHE) system was used for many years for both primary heating and cooling applications, especially in the building sector. Its energy performance can be influenced by three principal factors: the EAHE pipe material, the airflow rate, the soil characteristics and the moisture content. The state of the art shows a divergence about the effect of the pipe material on the performance of the EAHE. The aim of this study is to provide an adequate response to this problematic based on experimental analysis. In this regard, we tested two EAHEX of different materials: PVC and Zinc. The comparative study was conducted under a warm temperate climate in the north of Algeria. The data analyses showed that the pipe material can significantly affect the EAHE performance during periods when the EAHE passes from heating to cooling mode. Furthermore, the air outlet temperature differences provided by EAHE Zinc and those of PVC up to about 7.5°C.


Author(s):  
John Igo ◽  
Charles E. Andraka

Dish Stirling power generation systems have been identified by DOE, Sandia National Laboratories, and Stirling Energy Systems (SES) as having the capability of delivering utility-scale renewable energy to the nation’s electrical grid. SES has proposed large plants, 20,000 units or more (0.5 GW rated power) in one place, in order to rapidly ramp up production automation. With the large capital investment needed in such a plant it becomes critical to optimize the system at the field level, as well as at the individual unit level. In this new software model, we provide a tool that predicts the annual and monthly energy performance of a field of dishes, in particular taking into account the impact of dish-to-dish shading on the energy and revenue streams. The Excel-based model goes beyond prior models in that it incorporates the true dish shape (flexible to accommodate many dish designs), multiple-row shading, and a revenue stream model that incorporates time-of-day and time-of-year pricing. This last feature is critical to understanding key shading tradeoffs on a financial basis. The model uses TMY or 15-minute meteorological data for the selected location. It can incorporate local ground slope across the plant, as well as stagger between the rows of dish systems. It also incorporates field-edge effects, which can be significant on smaller plants. It also incorporates factors for measured degraded performance due to shading. This tool provides one aspect of the decision process for fielding many systems, and must be combined with land costs, copper layout and costs, and O&M predictions (driving distance issues) in order to optimize the loss of power due to shading against the added expense of a larger spatial array. Considering only the energy and revenue stream, the model indicates that a rectangular, unstaggered field layout maximizes field performance. We also found that recognizing and accounting for true performance degradation due to shading significantly impacts plant production, compared with prior modeling attempts.


Urban Science ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 82
Author(s):  
Maria Rosaria Guarini ◽  
Francesco Sica ◽  
Pierluigi Morano ◽  
Josè Antonio Vadalà

The International Energy Agency (2019) states 40% of CO2 emissions in cities are linked to the buildings stock, in particular to heating and cooling systems, material types and users’ performance. According to Green New Deal, the energy transition of buildings is becoming a priority. This is via investments with low environmental impacts through renewable energy sources. The paper describes an integrated economic-energy-environmental framework (IE3F), i.e., an economic evaluation protocol for new constructions and/or existing renewal projects aimed at supporting the choice phase between alternative technological solutions based on biocompatible materials. The IE3F borrows the logical-operative flow of the life cycle assessment multi-criteria approach. The value aspects translated into monetary terms that characterize the project life cycle are taken into account. The protocol was tested on an emergency project in Italy, namely in Messina City. The results obtained provide evidence of the versatile use of IE3F and its practical utility to guide economic convenience judgements on building investments and choice problems between alternatives in sustainable perspective. The research deepening will be about keeping track of multiple performance levels of the construction, not only the energy performance, and attempting to estimate the corresponding economic value in terms of increase/decrease of construction cost value.


Author(s):  
Sobhy Issam ◽  
Brakez Abderrahim ◽  
Brahim Benhamou

Abstract This paper aims at identifying the impact of three retrofit scenarios of a typical single family house on its energy performance and its indoor thermal comfort in several climates. Two of these scenarios are based on the Moroccan Thermal Regulation in Constructions (RTCM) while the third is the one proposed in this study. The climates, which range from group B to group C of the Köppen climate classification. The results show that the proposed renovation scenario allows reducing the heating load by 19-42% and the cooling load by 29-60% depending on the climate. Furthermore, the RTCM retrofit scenario leads to summer overheating in all climates. One of the main reason of this overheating is the insulation of the slab-on-grade floor as this insulation increases the annual heating/cooling energy needs of the house by 6%-10%. Moreover, the cavity wall technique was found to be the best option for external walls, instead of using high thermal insulting material, in the hot climates. The analysis of the energy performance, the thermal comfort indices and the payback periods for each retrofit scenario shows that the proposed scenario presents the best thermal performance, except for the Cold climate where the RTCM scenario is the most favorable.


2017 ◽  
Vol 39 (4) ◽  
pp. 492-500 ◽  
Author(s):  
Roger Hitchin

This Technical Note describes a framework for handling the inherent complexities of carbon emission and primary energy factors for networked electricity supply systems within building energy codes and similar policy instruments. The proposed framework reflects the main characteristics of carbon emissions from such networked supplies, while retaining a level of complexity (and simplification) comparable to that of procedures used in existing building energy codes. The main issues that are addressed are the time-varying nature of factors for networked supply, the impact of variability and curtailment for variable and intermittent renewable sources of electricity and relationship between “marginal” factors and “average” factors. These are important issues as the currently common use of annual system-average factors can result in misleading guidance as to the most effective ways of reducing carbon emissions or primary energy demand. The note first explains the relationship between building energy performance ratings and networked electric supplies. It then discusses the characteristics of electricity demand and the networked supply systems before proposing and discussing the framework. Practical application: A framework that can improve the reliability of building energy performance rating based on carbon emissions or primary energy factors.


2019 ◽  
Vol 11 (9) ◽  
pp. 2519 ◽  
Author(s):  
Tsoka ◽  
Tsikaloudaki ◽  
Theodosiou

Replacing conventional pavements with the corresponding high albedo ones constitutes a well-known technique to improve outdoor thermal environment of modern cites. Since most of the existing studies assess the impact of the high albedo pavements at the pedestrian’s height and with respect to thermal comfort, this study aims to examine the effect of the application of highly reflective pavements on the heating and cooling energy needs of a building unit, located inside a dense urban area. Aiming at a higher accuracy of the energy performance simulations, an integrated computational method between ENVI-met model, Meteonorm weather data generator and Energy Plus software is established, to consider the site-specific microclimatic characteristics of the urban areas. The analysis is performed both for the design and the aged albedo values as significant changes may occur due to aging process. The analysis revealed that the application of cool materials on the ground surfaces only marginally affects the energy performance of the examined building unit, both for the design and the aged albedo value; changes on the annual heating and cooling energy demand, for both albedo scenarios did not exceed 1.5% revealing the limited potential of cool pavements regarding the improvement of the energy performance of urban building units.


Solar Energy ◽  
2006 ◽  
Author(s):  
Kais Ouertani ◽  
Moncef Krarti

This paper investigates the impact of the architectural form on the energy performance of residential buildings in Tunisia. A relative compactness is defined as one indicator of a building shape. The results of the analysis indicate that a significant decrease in heating and cooling energy requirements can be obtained by minimizing the relative compactness of detached residential houses. A simplified analysis tool, suitable for early design process, is developed to assess the impact of building form on its energy performance for several cities in Tunisia.


Polygeneration systems refers to highly efficiency integrated systems characterized by the simultaneously production of different services (electricity, heating, cooling, water, etc) by means of several technologies using fossil and/or renewable energy sources. In many cases it is difficult to promote polygeneration projects due to its complexity. This complexity mainly comes from the high energy integration of the technologies involved in polygeneration plants and the high variability in the energy demand in many applications in the building sector that makes the design and optimal operation of these systems quite complex. The result is that without a very careful design and operation of these plants the economic viability is in many cases not clear. In this paper is presented an economic, energetic and environmental analysis of a polygeneration system in Cerdanyola del Vallès (Spain) built in the framework of the Polycity project of the European Concerto Program. This polygeneration system comprises three high efficient natural gas cogeneration engines with a total power capacity of about 10 MW with advanced thermal cooling facilities including a single effect hot water driven chiller and a double effect chiller of 5 MW driven directly by the exhaust gases of the engines. This plant provides electricity, heating and cooling to a new Science and Technological Park in development including a Synchrotron Light Facility through a district heating and cooling network with a total length of more than 30 km. The operational data for the energy performance analysis was taken using the plant SCADA system and a monitoring system specific for the cooling units in order to study in detail its performance. The results show that the polygeneration plant is an efficient way to reduce the primary energy consumption and CO2 emissions although it is not yet at its full capacity


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