Building Heat Loss Research Articles

An energy analysis methodology for residential heat pump retrofits

The government has targets to upscale domestic heat pump retrofit as part of the strategy to decarbonise heat. There are significant barriers to uptake including installation cost together with a lack of expertise in predicting and reporting energy and carbon performance. As a result, end user confidence in heat pumps can be low. This paper presents analysis of two monitored domestic properties using high resolution data. The aim is to develop reliable prediction and in-use diagnostic tools to improve transparency and reliability of heat pump performance. This paper focuses on a method drawn from theory as set out in CIBSE TM41, and shows how real building heat loss coefficients can be determined from regression analysis over different time frame resolutions. Practical application This research aims to provide residential heat pump retrofit providers with cost effective methods for assessing the suitability of dwellings to accept heat pump retrofit solutions, and to extend these techniques for the effective monitoring and performance evaluation of heat pumps post installation.

Impact of glazing type, window-to-wall ratio, and orientation on building energy savings quality: A parametric analysis in Algerian climatic conditions

Opaque surfaces, such as walls, are well-known for their significant contributions to heat loss and energy demands in buildings. However, transparent surfaces, such as windows, are equally critical to a building's energy performance. The design of these transparent elements requires a careful balance of various factors, including window size, glazing type, and orientation, each of which plays a pivotal role in enhancing energy efficiency. This study explores the optimization of these factors during the design process, emphasizing their impact on the overall building performance.This research evaluates the potential energy savings in a building archetype representative of the Algerian building stock. Utilizing the EnergyPlus simulation tool, the study conducted 1152 simulations on a baseline model to generate a comprehensive dataset detailing the building's energy demands for heating and cooling across various climatic conditions. The findings reveal that annual energy savings for this type of housing essentially depend on its climatic zone and can range from 6.92 % for a hot semi-arid climate (Bsh) to reach a maximum of 9.75 % in a cold semi-arid climate (Bsk), a window-to-wall ratio (WWR) of 60 % typically maximizes energy efficiency, low-E glazing proved most effective in most cases, although regions needing significant solar protection favored alternative glazing types. Optimal window orientation generally trends Eastward, except in regions where southern exposure better supports solar management, highlighting the complex relationship between architectural design choices and energy efficiency.

Structural analysis for a slab-on-grade cellular concrete foundation to reduce heat losses in temperate climate residential buildings

Reducing the energy requirements of buildings is imperative in the face of global warming and the imminent need to build low or zero-carbon housing in the following decades. This research proposes the design of a structural foundation to reduce heat transfer between the ground and the house to improve thermal comfort, thus reducing the incidence of low interior temperatures and lower energy requirements. The proposed foundation consists of a waffle slab system incorporating on-site cellular concrete fabrication for a residential home. The foundation proposal was evaluated over a year through simulation to quantify the heating demand reduction for four cities with temperate semi-arid and temperate sub-humid climates. The analysis shows that the prevalence of low temperatures is reduced when applying any of the proposed foundations. However, the benefits must be weighed for cities like Durango and Puebla since the reduction of hours with low temperatures is minimal, and they show an increase in energy for cooling. The city with the most significant benefit in reducing the incidence of low temperatures and the heating demand is Toluca, followed by Zacatecas, which are cities showing prevalent heating demands. Based on the results, it is observed that it is viable to apply foundations with a lower overall heat transfer coefficient, with the addition of lightened materials produced on-site. However, it is still necessary to conduct more experimental studies on these prefabricated systems applied to foundation slabs and care for their implementation in mixed climates.

УЧЕТ ВЛАЖНОСТИ В ПОВЫШЕНИИ ТОЧНОСТИ РАСЧЕТА ТЕПЛОВЫХ ПОТЕРЬ ЗДАНИЯ

A discrete-continuous approach was applied to the moisture transfer equation, which made it possible to obtain an analytical solution for the moisture potential. The new method was applied to study the unsteady-state moisture regime of the facade heat-insulating composite system with expanded polystyrene insulation and aerated concrete base. It was found that the mass moisture content of building materials achieved in the walls during the period of operation is lower than the mass moisture content used in construction regulations, which makes it possible to increase the accuracy of calculating the transmission heat losses of the building. Calculations of heat losses of a two-storey building in the climatic conditions of Moscow (Russia) showed a decrease in the heating system load by 5 %, and the reduction in heat losses for specific premises of the building ranged from 3.6 to 7 %.

Recent Advances in the Application of Agricultural Waste in Construction

On a global scale, millions of tons of diverse agricultural residues are generated annually. Most of these wastes are burned or dumped in landfills, which causes environmental pollution. Addressing environmental issues arising from agricultural waste materials, in addition to mitigating heating and cooling expenses in the construction sector, is an interesting challenge for researchers. The utilization of agricultural wastes in different parts of construction is producing positive findings day by day, and investigating research in this field is a curiosity for researchers. This short study reviewed the most recent achievements in using agricultural wastes as a substitute or additive material for construction. Using these wastes as aggregate, ash (as a supplementary for cement), or fibers for foam concrete, insulation materials, etc. has been reviewed. This review has focused on very recent published papers. Several studies have demonstrated the effective influences of agro-waste materials in construction, like retaining the compressive strength (155 MPa) of concrete at standard levels and reducing heat losses in buildings (69% energy savings for brick insulated using wheat straw), as well as sound insulation. The use of agro-waste materials for insulation positively improved thermal conductivity, costs, and energy savings. However, some wastes did not provide a high added value, which shows that more investigations still need be performed to fill this gap in the research. Considering the global scale of agricultural waste generation and the potential benefits to both the environment and construction industry, continued research in this area is essential.

УПРАВЛЕНИЕ ЖИЗНЕННЫМ ЦИКЛОМ ЗДАНИЯ НА ЭТАПЕ ЭКСПЛУАТАЦИИ С ИСПОЛЬЗОВАНИЕМ МОДЕЛЕЙ ИСКУССТВЕННЫХ НЕЙРОННЫХ СЕТЕЙ И МАШИННОГО ОБУЧЕНИЯ

The use of artificial neural networks and machine learning methods for the analysis of heat loss in buildings is of significant relevance in modern construction. These technologies are highly accurate and efficient in data processing. Artificial neural networks have the ability to analyze vast amounts of information and identify complex patterns, which significantly increases the accuracy of determining heat loss in buildings. In turn, machine learning methods make it possible to take into account various influencing factors, such as geographic location and meteorological conditions, thereby making a significant contribution to improving the quality of analytical results. Such approaches provide more reliable and accurate conclusions, which is critical for effective energy management and reducing heat loss in buildings. In this article, the authors conducted a study of heat losses of buildings and their prediction at the operational stage using artificial neural networks and machine learning methods. The technique is based on the analysis of data on heat loss and their relationship with various building parameters. Forecasting was carried out using artificial neural networks in the Statistica software package and the machine learning method based on the scikit-learn library. The proposed approach allows you to effectively manage the energy consumption of a building, optimizing its energy efficiency and improving the life cycle management of a capital construction project. The results demonstrate the high accuracy and convergence of the model with actual values, as well as its ability to predict performance.

Experimental analysis of insulating materials using Guarded Hot Box - Preliminary results

The containment of energy consumption in the construction sector strongly depends on the envelope, which is mainly responsible for heat loss in buildings. Thus, great attention should be paid to the selection of thermally-performing materials. In this work, preliminary results of three different configurations of walls in real size have been compared, conducting the analyses with the heat flow meter method inside the Guarded Hot Box apparatus, capable of guaranteeing repeatable and controlled conditions. The analyses were carried out with two types of heat flow meters, characterized by different sensitivity. The side of the wall facing the hot chamber has been insulated with rock wool for all the experiments, while the other side has been insulated first with expanded polystyrene (EPS) with graphite, then with hemp, and finally with cork. The results showed that the sample with the best thermal behaviour is the first one, i.e., the wall with EPS with graphite, characterized by a transmittance value between 0.148 W/m2K and 0.153 W/m2K. The other two configurations, characterized by the use of natural materials, showed worse performance with conductance values about 20% higher than EPS. The percentage differences between the two heat flux sensors for the experimental campaigns ranged from 2.8% to 4.4%.

К РЕШЕНИЮ ЗАДАЧИ КОЛИЧЕСТВЕННОГО РЕГУЛИРОВАНИЯ В СИСТЕМАХ ТЕПЛОСНАБЖЕНИЯ

The quantitative regulation of the heat supply process has a number of significant advantages and is widely used abroad. This method of regulation is also used in the Russian Federation. At the same time, the algorithmization of quantitative regulation is currently still quite problematic and requires further development. For example, the literature data on the algorithm proposed by E.Ya. Sokolov are characterized by the “omission” of the procedures of inference and justification, which is particularly undesirable for educational applications. In addition, the algorithm does not work across the entire range of thermal loads (outside temperatures). Purpose of the study. To develop an algorithm for quantitative regulation in terms of its subsequent use as part of the algorithmic support of an automated control system (ACS) for heat supply. Materials and methods. Literature data on the issue under consideration was analyzed. Using models of heating systems and heat losses of buildings, we compiled a balance equation that makes it possible to find the necessary coolant flow for heating. Results. A detailed substantiation and derivation of the algorithm for quantitative regulation of heat supply according to the heating load is proposed, and its characteristics were analyzed. The conditions for the physical feasibility of heating are taken into account. The algorithm as a whole is represented by a two-interval formula; in the second range of outdoor temperatures, the heat carrier flow rate is calculated based on the condition that the return water temperature should be noticeably higher than the indoor air temperature of the heated premises. However, when regulating the heat carrier flow in the second interval, an overestimated power of the heating system will be observed, i. e. some overshoot is possible. It is shown that with an increase in the minimum allowable value of the return water temperature, the range of outdoor temperatures in which regulation is possible in the first interval (ideal regulation without overflow) noticeably narrows, and when the water temperature in the supply line decreases, conversely, it expands. Conclusion. The results of the work can be used to develop algorithmic support for automated control systems for heat supply.

Enhancement Techniques for the Reduction of Heating and Cooling Loads in Buildings: A Review

The building sector is rated as a big consumer of electric energy and emissions, responsible for about 40% of final electric energy consumption. As a result, the Paris Agreement 2015 set a goal for buildings and the construction sector to reach a nearly zero-carbon stage by 2050. This urged most countries to create regulations for the construction sector and invest in energy efficiency programs. The present paper aims to present an updated review of building energy-saving solutions and techniques to contribute to carbon emission mitigation in the building sector. The high energy consumption of a building is mainly due to heating and cooling, which is directly related to the thermal properties of the materials used. Natural ventilation and illumination are other aspects that contribute to the high energy consumption. Considering these issues, the review covers energy-efficient construction materials such as mortars, concrete with PCM, new construction materials with PCM such as 3d printing concrete and geopolymer concrete, and bricks usually used in buildings. Also, the review covers the methods and solutions for energy saving for building heating and cooling. Since transparent windows and façades are essential for structures, their thermal and visual performance is crucial. Established and under-development techniques for windows and façades are presented and discussed. Walls and roofs are usually rated at the top of the weak barriers against a building's heat losses and energy gains. The present paper reviews existing and still under research and development techniques to improve the thermal performance of walls and roofs, such as cool roof and cool walls, walls and roofs with phase change materials (PCM), and ventilated walls and ceilings.Some authors’ comments are presented at the end of each topic. Some possible opportunities for future research and developments are also presented.

The impact of thermal insulating materials in heat loss control in smart green buildings using experimental and swarm intelligent analysis.

The efficacy of saving energy standards depends on the ability to anticipate the heat loss of buildings. Environmentally friendly materials, also known as eco-friendly or sustainable materials, have a minimal negative impact on the environment throughout their life cycle. These materials are designed to conserve resources, reduce pollution, and promote sustainability. The characteristics of non-stationary and non-linear heat loss through environmentally friendly materials make it challenging to anticipate accurately. At the same time, many of the industry's presently accessible computational models have been created with this in mind; the majority call for powerful computers and time-consuming computations. The artificial neural network (ANN) has been utilized for prediction, and ground-breaking research has shown the viability of this strategy. This research proposes an artificial neural network (ANN) prototype to estimate construction cooling load usage. ANN is integrated with the vortex search algorithm (VS), stochastic fractal search (SFS), and multi-verse optimizer (MVO) models to compare the three models' outcomes and suggest a more accurate strategy. These techniques make a linear mapping among the output and input parameters, often utilized for modeling and regression. The value of the multiple determination coefficient is also determined. The values of the training R2 (coefficient of multiple determination) are 0.9464, 0.99827, and 0.99522 for VS-MLP, SFS-MLP, and MVO-MLP, respectively, with an unknown dataset which is acceptable. The training RMSE amounts for VS-MLP, SFS-MLP, and MVO-MLP are 0.06433, 0.00619, and 0.01028 for the unknown dataset, which is acceptable. According to the MAE values of 0.0082902, 0.0047834, and 0.0076534 in the training phase for VS-MLP, SFS-MLP, and MVO-MLP approaches and the values of testing MAE error of 0.029107, 0.018167, and 0.029212 for VS-MLP, SFS-MLP, and MVO-MLP approaches, respectively, it is obtained that the SFS-MLP has a lower MAE value. The lowest RMSE value and the higher R2 value indicate the favorable accuracy of the SFS-MLP technique.

Investigating the reliability of estimating real-time air exchange rates in a building by using airborne particles, including PM1.0, PM2.5, and PM10: A case study in Suzhou, China

This study aimed to evaluate the reliability of using airborne particles to estimate the real-time Air Exchange Rate (AER) of buildings, considering particle size and outdoor conditions' impact on the AER estimation accuracy. The study utilized on-site data collection and numerical simulations to analyze the factors affecting the AER prediction accuracy. Results showed that the PM1.0- and PM2.5-based empirical correlation could predict the AER of buildings with a Normalized Mean Error (NME) of less than 10% and a correlation coefficient (r) of over 0.97, outperforming the pressurization method. Fine particles with a diameter under 2.5 μm were found to be a reliable tracer for AER prediction, with a negative correlation between particle size and AER prediction accuracy due to their higher penetration rate. The study also found that outdoor particle levels and pressure differentials positively impacted the accuracy of PM-based AER estimation. These findings have practical applications for maintaining Indoor Air Quality (IAQ) and accurately predicting a building's heat losses.

Assessment of the thermal resistance of novel roof structures incorporating nano-Phase Change Materials capsules under the influence of an external magnetic field

Controlling energy waste from different building bodies plays a key role in energy consumption management. Heat losses in buildings mostly occur through their envelopes and, more particularly, their roofs. Improving the thermal response of roofs is therefore an essential objective. In recent years, the incorporation of Phase Change Materials (PCM) into roof structures has proved to be an effective method in this regard, but still requires further optimization. Here, six different structures of a roof structure, in which PCM capsules have been placed in different positions and orientations, are considered to examine their role as a passive factor in controlling heat loss and increasing thermal resistance. Also, the effect of an external inclined magnetic field on the thermal behavior and energy loss is investigated. The thermal conditions in roofs are reproduced. Governing equations inside the solid parts and the PCM capsules are presented and solved numerically via the finite element method. Streamlines and isotherms, as well as plots of melted volume fraction and thermal resistance are presented. The main outcomes show that the magnetic field has a limited effect on thermal behavior due to the small size of the capsules. Orienting the capsules in the horizontal direction delays heat transmission, slows down the melting, and increases the thermal resistance of the roof structure. PCM melting can be further slowed down by moving the horizontal capsules down, close to the heated boundary. These results can be very useful for future roof designs in which capsules of PCM might be added.

Are the local sky temperature models and the global thermal standard model EN ISO 6946(2017) numerically compatible?

Local sky temperature models are often used by researchers to improve the estimation of building heat losses. Besides the local sky temperature models, there is a global temperature model implemented in EN ISO 6946(2017) that may also produce reasonable results if it is conveniently applied. To assess the competitiveness of global and local models, it is desirable to perform a direct numerical comparison of their results. Such a comparison has not been published so far. This study aims to analyze the computational differences between three models of sky temperature, namely, the Swinbank model, the universal model and the standard model implemented in EN ISO 6946(2017). The study verifies the robustness of the global thermal standard model to account for the acting of the cold sky on building envelopes compared to local sky models specially designed for this purpose. The quasi-nocturnal conditions are supposed to reveal the main features of the long-wave infrared interactions between the building facade and the sky. The study has proved the capability of the global standard model to successively compete with the local sky temperature models at least within the conditions of the quasi-nocturnal environment.

Integration of Daylight Use and Analysis in Double Skin Facades: A Literature Review

Double skin facades (DSF) aim to save energy reducing the heat losses in buildings. They are visually appeal while allowing to use daylight efficiently. Such facade systems can reduce glare and distribute daylight evenly in the interior when compared to conventional facade systems. That is a result of cavities between two glass facades and locating sunshading elements in them, although this system provides a high level of transparency. As their primary purpose of application is to ensure thermal performance and ventilation, most studies in literature have focused on these. However, to construct and maintain a holistic point of view in building performance, researchers and professionals need to take into account the integration of daylight use and analysis in such facades. This study aims to analyse daylight performance implemented studies in relation to these systems and presents a comprehensive and recent review on integration of daylight use and analysis. Recent studies are shown in tabulated form and interpreted in detail with graphics. considering their methodologies, daylight parameters and findings. Results show that the daylight parameter is one of the most important issues that architects or designers should consider from the moment they start the design, and they should make their designs based on the optimum penetration of daylight into the building. This review can contribute to literature in calling attention to daylight studies in DSF. It provides feedback information on how recent researches and technological developments in DSF can let them benefit from daylight more efficiently. That makes more and further improvements in such facade system design. Thus, DSF helps to build an integrated building performance approach in achieving sustainability.

Approximating heat loss in smart buildings through large scale experimental and computational intelligence solutions

The attainment of energy sustainability in the building sector can be realised by implementing a green building programme, which has grown significantly over the last thirty years. Green building is considered a technical and management strategy within the building and construction industries. Many different prediction methods, both complex and simple, have been put out in recent years and used to solve a wide variety of issues. Several case studies have highlighted factors that impede energy and resource usage in green buildings. The utilisation, trends, and consequences of wall and thermal insulation materials are examined. The main scope of this investigation is to predict buildings’ heat loss by applying artificial neural networks according to the heat transfer coefficients of walls and coating materials, as well as indoor, outdoor, and external surface temperatures. The data has been normalised and presented to two selected neural networks (Harmony search (HS) and particle swarm optimisation are used and contrasted (PSO)). For evaluating the accuracy of models, two statistical indexes are used (R2 and RMSE). Model performance of PSO-MLP is shown by R2 amounts of 0.97055 and 0.87381, respectively, and RMSE amounts of 0.02534 and 0.09685. Similarly, HS-MLP model accuracy is also indicated by R2 amounts of 0.93839 and 0.84176 and RMSE amounts of 0.03635 and 0.10753. The analysis in this paper shows that PSO-MLP predicts heat loss with higher accuracy and improved performance.

Comparison of Central and Individual Heating Systems Used for Heating Housings

Today, energy production based on fossil energy sources has become seriously questioned by societies due to both cost and environmental pollution. Fossil energy sources are mainly used for heating houses, which constitute a significant part of energy consumption. In this study, central heating systems, which are the most widely used methods to meet the heat energy needs of buildings, and individual heating systems are examined and compared. In the study, the heat loss and energy need of a 5-story building consisting of 10 flats in Kars Center with a total heated area of 1080 m2 were calculated using the TS 825 calculation method, accordingly, calculation of heater devices for both systems, determination of heating system elements, annual fuel consumption amount and cost calculation has been made. Natural gas was used as fuel in both systems to be compared for heating the building. According to the values obtained as a result of the study, it was seen that individual heating systems have higher costs than central heating systems in terms of both initial investment and heating cost. It has been determined that central heating systems are more advantageous in terms of initial investment cost, fuel consumption, and total cost. While the total cost was 441096 TL for the central heating system, it was 508825 TL for the individual heating system.

In-situ assessment of the thermal performance of earth masonry construction

The interest in traditional earth constructions has grown in Europe since a few years. This growing interest can be attributed to the fact that earth has among other qualities a good capacity for the hygrothermal regulation inside a building. This well-established ability of earth to store and manage heat and moisture has been extensively studied in the past at the material scale. However, the evaluation of the building envelop performance is rarely achieved in practice. This study presents an evaluation of the thermal performance of earth masonry construction based on in-situ measurements under real conditions of exposure. The construction consists of a single unoccupied room with habitable surface area of 12.9 m2 located in Canohès in the Southern France. Firstly, the airtightness of the envelop was quantified with the blower door test. The air permeability results indicated a very good level of airtightness. Then the thermal insulation of the envelop was measured according to the ISABELE method (In Situ Assessment of the Building EnveLope pErformances). The latter is a method developed by the CSTB to deduce the transmission heat transfer coefficient of the building with its uncertainty within short unoccupied period (few days). The results of the different ISABELE tests demonstrated that the total thermal insulation level of the tested envelop could be classified as good to average according to the scale of the building heat loss coefficient (Ubat) of the French Energy Performance Diagnosis. The results of the ISABELE tests were confirmed by the outcomes of a Coheating test conducted during a long period of 3 months. This study gives encouraging results on the application of the ISABELE method on earth masonry buildings to deduce the thermal performance of their envelope quickly, instead of a complete Coheating test which can be too long to apply in practice.

Empirical Relationship Describing Total Convective and Radiative Heat Loss in Buildings

Empirical Relationship Describing Total Convective and Radiative Heat Loss in Buildings

Appraisal of energy loss reduction in green buildings using large-scale experiments compiled with swarm intelligent solutions

Today, the issue of energy efficiency is a major one in global politics. The external environment, particularly the wind speed and outside air temperature, determines the thermal burden the cold outside air places on a building's interior. The heat load of a building is influenced by several factors, including the wall’s heat transfer coefficients (W/mK), the coating material (W/mK), the inside temperature (°C), and the outside temperature (°C), and the temperature of external surface (°C). In this investigation, we undertake a comprehensive assessment, evaluation, and comparing the performance of two unique artificial approaches (BSA and COA) utilized for anticipating heat loss in green buildings; the optimum way is then identified depending on the R2 and RMSE criteria. The outcomes demonstrate that BSA and COA have R2 values of (0.97038 and 0.90158) and (0.9919 and 0.94239) in the training and testing phases. Additionally, the RMSE values for BSA and COA in the training and testing stages are (0.02541 and 0.08616) and (0.01336 and 0.06662), correspondingly. Also, the estimated MAEs (0.019055 and 0.0097193) denote a low level of training error for both methods. Regarding R2, RMSE and MAE values, the COA predicts energy loss more accurately.

Optimal Location of the Active Thermal Insulation Layer in the Building Envelope

One of the modern methods of protecting against building heat losses is active thermal insulation (ATI). In winter conditions, ATI works by supplying heat into the envelope, which increases the temperature in the ATI layer. A low-temperature renewable energy medium feeds the active insulation layer directly, e.g., through solar or geothermal energy. A model for heat transfer through the building envelope with an ATI layer was developed. The numerical simulations verified the simplifying assumptions in the model. A relationship was derived to determine the optimal location of the ATI layer in the envelope. The objective function of the summed costs of the thermal energy supplied to the internal space and the envelope was assumed. We took into account the fact that the unit price of energy supplied to the ATI layer is lower than the price of the energy supplied to the internal space. Based on the results of the measurements carried out in a building facility with the ATI layer installed, the actual savings effects due to the ATI layer were compared to the calculated values.