Building Thermal Energy Consumption Research Articles

A detailed investigation on thermal performance and energy savings of cool roof systems for composite climates of India

ABSTRACT The rising worldwide temperatures leading to a spike in air conditioning to ensure thermal comfort in buildings is the root cause of the increase in energy demand in India's building sector. The roof of a building significantly adds to the heat gained on the top floor, accounting for 50–60% of the total heat gain. One sustainable way to reduce this heat gain is via cool roofing technology. Through examination and dynamic simulations with the Energy-Plus-based Design Builder software tool, this study explores different cool roof solutions. An experimental setup of a Reinforced Cement Concrete (RCC) roof with cement plaster, solar reflective paint, solar reflective tiles, and earthen pots have been created on the institute campus. Recordings were taken during the peak summer days and peak winter days, alongside simulations carried out to determine various factors such as Albedo, Surface Temperatures, Air Temperatures, Diurnal Heat Ingress, and the Building's Thermal Energy Consumption. The experiments have demonstrated that cool roof layers can considerably improve interior thermal comfort by minimizing heat transfer, which maintains a constant temperature over the bottom surface of the roof. By reducing heat gain by 33–71%, they can save energy by 21-26% compared to traditional RCC roof slab.

Evaluating Reduction in Thermal Energy Consumption across Renovated Buildings in Latvia and Lithuania

Currently, the optimization of thermal energy consumption in buildings is considered a suitable alternative in the construction of new buildings, as a result of which the overall energy efficiency of the building increases. Thus, this study examined the efficiency and efficacy of different building renovation packages conducted across several buildings in Latvia and in Lithuania (across a larger building stock). In the first section of this study, 13 multi-apartment residential houses with 3 building renovation packages have been investigated in the city of Daugavpils, Latvia, in order to determine the actual reduction in heat energy consumption across each of the renovation implementation packages. The study findings indicate that changes in Latvian building regulations regarding insulation thickness did not significantly impact thermal energy consumption in fully renovated buildings. However, the combination of facade renovations, upgraded heating systems, and improved ventilation systems resulted in substantial energy savings, with an average reduction of 50.59% in thermal energy consumption for space heating across the reviewed multi-apartment residential building stock. In the following section of this study, the impact of the Energy Performance of Buildings Directive (EPBD) on building energy efficiency in Lithuania has been examined. The results show that over a 10-year period in the 2000s, Lithuanian building stock experienced a 20% increase in energy efficiency, followed by an additional 6.3% increase between 2010 and 2016. The mandatory requirement for renovated buildings to achieve a minimum energy efficiency class has resulted in significant reductions in energy consumption for heating purposes. The findings underscore the effectiveness of building renovation packages and the EPBD regulations in enhancing energy efficiency and promoting sustainable building practices. The importance of heat metering, consideration of indoor air temperature, and the need to address indoor air quality during renovations were also highlighted.

Calculation and evaluation of building thermal energy consumption and carbon emissions based on BIM technology

In order to calculate the carbon emissions in the construction process to achieve low-carbon buildings and low-carbon construction, the author puts forward the calculation and evaluation of building thermal energy consumption and carbon emissions based on building information modeling (BIM) technology. The author first proposed the important value and application of BIM technology in energy consumption evaluation of green buildings, taking a gymnasium as an example, a carbon emission accounting system for building construction and installation process is established based on BIM technology, and the carbon emissions in building construction and installation process are calculated and analyzed. The results show that the carbon emission during the construction and installation of a gymnasium is 766300 tons, of which the carbon emission caused by building materials is 737200 tons, the carbon emission caused by mechanical equipment is 4500 tons, and that caused by office and living is 34500 tons, accounting for 94.90%, 0.59%, and 4.51%, respectively. In conclusion through data analysis, determine the largest carbon emission source in the construction process, and then propose targeted carbon emission reduction measures in the construction process of the construction industry.

Evaluating the time lag and decrement factor of mortar and concrete containing OPBC as an agricultural by-product lightweight aggregate

Replace the normal weight aggregate with wastes or by-products materials is an appropriate method for producing a sustainable cement-based material. The replacement helps to have an energy-efficient component that reduces environmental impact. Time lag and decrement factors are vital wall system variables to evaluate thermal energy consumption in buildings. Thus, this study investigates the thermophysical properties of an innovative sustainable mortar and concrete containing oil palm boiler clinker (OPBC) as fine and coarse aggregate through an experimental approach. Then, time lag and decrement factor in different wall systems are calculated based on EN ISO 13786 through Python 3.7 (NumPy and math modules) and optimized using the response surface methodology (RSM). The results indicated mortar with OPBC has a slightly reduced decrement factor and increased time lag compared to a typical mortar. More significantly, the decrement factor of OPBC concrete was reduced by 34%, and its time lag increased up to 58% compared to conventional concrete.

Impact of thermal renovation on selected characteristics of partition walls and the consumption of heat energy

Renovation of multi-family residentials, including mainly thermal renovation, which includes adding thermal insulation, contributes to the improvement of living conditions. Above all, it reduces the operating costs of renovated buildings by reducing the consumption of heat energy for central heating. This article discusses the impact of light wet thermal renovation on the temperature distribution in the vertical cross-section of the partition wall and the calculation value of the temperature on the inner surface of the partition wall, as well as on the reduction of thermal energy consumption in buildings. The subject of the research was residentials erected in the large-panel, large-block, and traditional technology between 1984 and 1994, managed by Łomża Housing Cooperative (ŁSM).

Intelligent Monitoring System for Thermal Energy Consumption of Buildings under the IoT Technology

In view of the poor accuracy of single value of heat energy consumption and the weak real-time monitoring of energy consumption in buildings, an intelligent monitoring system for thermal energy consumption of buildings under the internet of things (IoT) technology is designed. The overall structure of the intelligent monitoring system for thermal energy consumption of buildings is constructed. The DSP integrated signal processor is used for data acquisition and real-time information processing of thermal energy of buildings. A wireless intelligent gateway for building thermal energy consumption monitoring is designed by using internet of things technology, a wireless sensor network model is constructed. The VME bus is used as information transmission channel to realise intelligent monitoring for thermal energy consumption. The test results show that the real-time monitoring accuracy of the system is better than that of the traditional method and it has a good application prospect in all aspects.

Development of an Improved Model to Predict Building Thermal Energy Consumption by Utilizing Feature Selection

Humans spend approximately 90% of the daytime in buildings, and greenhouse gases (GHGs) emitted by buildings account for approximately 20% of total GHG emissions. As the energy consumed during building operation from a building life-cycle perspective amounts to approximately 70–90% of the total energy, it is essential to accurately predict the energy consumption of buildings for their efficient operation. This study aims to optimize a model for predicting the thermal energy consumption of buildings by (i) first extracting major variables through feature selection and deriving significant variables in addition to the collected data and (ii) predicting the thermal energy consumption using a machine learning model. Feature selection using random forest was performed, and 11 out of 17 available data were selected. The accuracy of the prediction model was significantly improved when the hour of day variable was added. The prediction model was constructed using an artificial neural network (ANN), and the improvement in the prediction accuracy was analyzed by comparing different cases of variable combinations. The ANN prediction accuracy was improved by 15% using the feature selection process compared to when all data were used as input data, and 25% coefficient of variation of the root mean square error (CVRMSE) accuracy was achieved.

Identifying key variables and interactions that explain hydraulic imbalance - application of regularization-based variable selection methods

Heating systems must be subjected to hydraulic balancing in order to ensure proper operation. When the heating system is hydraulically imbalanced, heat is unevenly distributed across dwellings resulting in a large temperature spread, overheating, and consequently, waste of energy. In this study, we investigate the extent to which hydraulic imbalance affects the thermal energy consumption in buildings. Furthermore, key variables and interactions that influence the thermal performance in buildings are identified. Results show that higher variation in indoor temperature lead to higher energy consumption. Compared to new buildings, old buildings that have large boiler capacity and small heated floor area are more likely to be hydraulically imbalanced and to consume more energy.

Occupancy-based buildings-to-grid integration framework for smart and connected communities

Buildings-to-grid (BtG) integration simulations are becoming prevalent due to the development of smart buildings and smart grid. Buildings are the major energy consumers of the total electricity production worldwide. There is an urgent need to integrate buildings with smart grid operation to accommodate the needs of flexible load controls due to the increasing of renewable energy resources. In the imminent future, smart buildings can contribute to grid stability by changing their overall demand patterns in response to grid operations. Meanwhile, building thermal energy consumption is also maintained by building operators to satisfy occupants’ thermal comforts. However, explicit large-scale demonstrations based on a simulation platform that integrates building occupancy, building physics, and grid physics at community level have not been explored. This study develops an occupancy behavior driven BtG optimization platform that can simulate, predict and optimize indoor temperature and energy consumption of buildings, generator setpoint and deviation while maintaining acceptable grid frequency. Authors have tested the framework on two standard power networks. The results show that the integrated framework can provide potential cost savings up to 60% comparing with the decoupled operation.

Characterization of Building Thermal Energy Consumption at the Urban Scale

The ongoing urban transition toward decarbonized energy systems has raised the attention on local energy planning practices. Besides the multiple actors involved in the planning process, the complexity of the urban energy systems requires the elaboration of heterogeneous data. In such contest, the paper introduces and compares two GIS-based methodologies for supporting the spatial characterization of the local residential built environment in terms of building distribution and space heating energy consumption. Starting from the assessment of residential consumption, a third method for the characterization of non-residential building thermal energy consumption is proposed. From a bottom-up perspective, in both residential models all the buildings are geo-referenced and clustered according to their thermo-physical characteristics. From a top-down perspective, energy balance data are used to calibrate the bottom-up results and to match the total building loads. The procedure, tested on the city of Turin as case study, allows assessing the energy use of buildings and to create urban energy maps.The energy spatial characterization of a territory is the basis for performing short and long-term scenarios analysis. Results of this method can be useful to: i. decision maker to understand the current state of the territorial energy consumption to identify critical energy intense areas; ii. citizens for visualising their energy consumption and iii. researchers for setting up the basis of further urban analysis.

Experimental Study of a Small Scale Hydraulic System for Mechanical Wind Energy Conversion into Heat

Significant potential for reducing thermal energy consumption in buildings of moderate and cold climate countries lies within wind energy utilisation. Unlike solar irradiation, character of wind speeds in Central and Northern Europe correspond to the actual thermal energy demand in buildings. However, mechanical wind energy undergoes transformation into electrical energy before being actually used as thermal energy in most wind energy applications. The study presented in this paper deals with hydraulic systems, designed for small-scale applications to eliminate the intermediate energy transformation as it converts mechanical wind energy into heat directly. The prototype unit containing a pump, flow control valve, oil tank and piping was developed and tested under laboratory conditions. Results of the experiments showed that the prototype system is highly efficient and adjustable to a broad wind velocity range by modifying the definite hydraulic system resistance. Development of such small-scale replicable units has the potential to promote “bottom-up” solutions for the transition to a zero carbon society.

Economic and environmental benefits of thermal insulation of building external walls

Thermal modernization is viewed by its users in Poland mainly in terms of economic benefits. Nevertheless, it does not reduce the significant role of thermal modernization in lowering the environmental impact at the phase of a building use. The paper presents economic and environmental benefits due to thermal insulation of building external walls. Thermal insulation of building walls has a significant effect on the reduction of thermal energy consumption in buildings that leads to the reduction of CO 2 emissions. Making a thermal insulation of a building external wall can in terms of economic aspects be approached as an investment. In this investment the cost is related to the purchase, transport and laying the insulation, whereas the profits are linked to the reduction of thermal energy consumption necessary to heat a building. The author determines the optimum thickness of the insulating layer that gives the maximum net present value of thermal insulation investment. Several versions of thermal insulation are presented. The following criteria were taken into account: energy sources, wall constructional materials and insulating materials. Bearing the sustainable development paradigm in mind, the best possible thermal insulation versions were determined by means of a two-criteria optimization for the economic and environmental criterion.

Energy loads, CO2 emissions and building stocks: morphologies, typologies, energy systems and behaviour

Today's existing building stocks are major energy consumers and CO2 emitters, depending on various factors including urban morphology, architectural archetypes, construction technologies, energy systems, and inhabitant behaviour. A large case study based on 96 000 buildings in Paris, France, is the subject of detailed analysis of the existing residential building stock by comparing some environmental metrics of Paris's urban fabric with thermal energy consumption in buildings. The environmental metrics, such as building shape factor and passive volume (for natural ventilation and daylighting), are functions of urban morphology. This comparison of urban forms and heating energy consumption reveals some impacts of urban morphology and building typology on the energy efficiency in the different zones of Paris. The energy efficiency and CO2 emissions related to heating mode and inhabitant behaviour are separated from those linked to urban form and construction technology. Thus, a balanced view of the complex impacts of morphologies, typologies, energy systems, and inhabitant behaviour on energy loads and CO2 emissions is presented, which allows for the optimization of urban form in terms of density, building configuration, and morphology. Similar large-scale simulations can analyse urban form and the mix of building stock as well as the interaction of increased equipment efficiency, alternative energy mix, and inhabitant behaviour. Les parcs bâtis existant aujourd'hui sont d'importants consommateurs d'énergie et émetteurs de CO2, qui dépendent de divers facteurs tels que la morphologie urbaine, les archétypes architecturaux, les technologies de construction, les systèmes énergétiques et le comportement des habitants. Une grande étude de cas basée sur 96 000 immeubles de Paris, en France, fait l'objet d'une analyse détaillée du parc bâti résidentiel existant en comparant certaines métriques environnementales du tissu urbain de Paris à la consommation énergétique thermique des immeubles. Les métriques environnementales, telles que le facteur de forme des bâtiments et le volume passif (pour la ventilation naturelle et l'éclairage du jour), sont des fonctions de la morphologie urbaine. Cette comparaison des formes urbaines et de la consommation énergétique de chauffage révèle certaines incidences de la morphologie urbaine et de la typologie des bâtiments sur le rendement énergétique dans les différents secteurs de Paris. Le rendement énergétique et les émissions de CO2 en rapport avec le mode de chauffage et le comportement des habitants sont distincts du rendement et des émissions liés à la forme urbaine et aux technologies de construction. Est ainsi présentée une vision équilibrée des incidences complexes des morphologies, des typologies, des systèmes énergétiques et des comportements des habitants sur les taux d'utilisation d'énergie et les émissions de CO2, qui autorise l'optimisation de la forme urbaine en termes de densité, de configuration des bâtiments et de morphologie. Des simulations similaires à grande échelle peuvent analyser la forme urbaine et la diversité du parc bâti, mais également les interactions résultant du rendement accru des équipements, des diverses sources d'énergie alternatives utilisées et du comportement des habitants. Mots clés: géométrie des bâtiments, parcs bâtis, forme bâtie, émissions de CO2, coefficient de profondeur, consommation énergétique, performances environnementales, comportement des habitants, typologie, morphologie urbaine

Influence of glass curtain walls on the building thermal energy consumption under Tunisian climatic conditions: The case of administrative buildings

The glass curtain walls have been recently introduced in Tunisia; they are seen as a new fashion and are highly appreciated by some for their pleasing aesthetics. The objective of this paper is to investigate whether the glass curtain walls are appropriate for the Tunisian local climate and context and if it is so, to give recommendations concerning the kind of glass to be used. A TRNSYS [Klein SA. TRNSYS a transient system simulation Program V5 14.2. Solar Energy Laboratory, University of Wisconsin Madison, July 1996] simulation was conducted on a typical administrative building. The investigation concerns only the building heating and cooling load. The building was split in five thermal zones; for each thermal zone, all the windows have the same orientation. The single zone model TYPE19 of TRNSYS [Klein, 1996] was used to model each thermal zone. An additional convection heat transfer between the different thermal zones of the building was modelled according to the Brown and Solvason law [Brown WG, Solvason KR. Natural convection through rectangular openings in partitions, Part 1: vertical partitions. Int. J. Heat Mass Transfer 1962; 5: 859–68]. This particular law was used because it has been validated in the Tunisian context by Bouden [Bouden C. Analyse du suivi thermique d’un pavillon solaire expérimental en région Tunisoise, Thèse de doctorat, Université de Paris 7, 1989]. We assume that the glass curtain wall will be implemented only on the main building facade; this is why it was simulated with different glazing sizes and glass types. The other facades remain unchanged. The results of this simulation have shown that, in relation to space heating, the glass curtain wall can be very interesting in the Tunisian context if the orientation as well as the kind of glazing are carefully selected.