Heat Consumption In Buildings Research Articles

Determining the efficiency of local heat recycling wastewater based on a heat exchanger

RELEVANCE. The authors research the potential energy, economic and environmental effects of using local heat recovery from wastewater generated in showers. At the moment in Russia, almost all household wastewater is disposed of in sewer networks without the beneficial use of the heat that they possess. It is important to determine the effect of implementing this method of heat recovery, to identify and analyze the problems that prevent this from being done.THE PURPOSE. The purpose of the work is to determine the potential effect of using local heat recovery from wastewater generated in showers.METHODS. Based on a verified mathematical model of the heat exchanger, the energy effect from the individual use of the shower room is determined. A number of assumptions are applied to the heat consumption structure of an individual building and, based on available data on the average annual heat consumption of residential buildings in Moscow, the economic and environmental effect of energy-saving measures is calculated.RESULTS. Relative savings within the annual heat consumption of a building with a decentralized and centralized hot water supply system were 5,3% and 3,1%, respectively (64 and 37 GCal). Fuel economy amounted to: 9145 toe and 5227 toe for a building with a decentralized and centralized hot water supply system, respectively (14,5 and 8,5 thousand tons of CO2-eq). The payback period for energy-saving measures for the case of a decentralized hot water system based on an instantaneous electric water heater was 1,5 years.CONCLUSION. Local waste heat recovery makes it possible to obtain a significant energy and environmental effect within any locality, but at the moment there are no measures to support consumers implementing energy-saving measures. Currently, this method of heat recovery is of interest only to those consumers whose source of thermal energy for the needs of hot water supply is electricity.

System for monitoring building heat consumption

Relevance. Energy consumption and efficient use of district heating networks affect the environment, society and the economy. Solutions are needed that can significantly reduce specific thermal energy losses. Using a technically and economically feasible way to assess energy efficiency allows these decisions to be made. Currently, assessing the energy efficiency of buildings raises significant questions among specialists. There is not much modern specialized literature in this area. The problem of energy efficiency requires more rigorous attention to urban planning issues. Thus, refined methods for assessing the energy efficiency of buildings make it possible to simultaneously save capital investments and ensure efficient consumption of thermal energy. Aim. To develop a system for assessing the real heat consumption of buildings to ensure optimization of dispatching of centralized heat supply systems in real time. Methods. Computer modeling of the state of heat consumption of buildings with various characteristics and schemes for their connection to centralized heat supply networks; methods of geographic information analysis. Results. The authors have proposed the system for monitoring the heat consumption of buildings. This system allows assessing the energy efficiency of buildings through the maximum use of computer and software technologies. It is shown that the calculated heat flows of buildings used to predict savings when modernizing buildings do not always correspond to the actual heat loads, which can lead to an incorrect assessment of investment projects. The authors obtained graphical dependences of the quantities influencing specific heat losses on various primary independent factors. Conclusions. The constructed system for monitoring the heat consumption of buildings allows, together with the use of geoinformation analysis methods, obtaining a fairly complete picture of the state of heat consumption for city areas and an assessment of the energy characteristics of buildings.

Data-Driven Estimation of Time-Varying Stochastic Effects on Building Heat Consumption Related to Human Interactions

Within the field of statistical modelling and data-driven characterisation of buildings’ energy performance, the focus is typically on parameter estimation of the building envelope and the energy systems. Less focus has been put on the stochastic human effect on energy consumption. We propose a new method for estimating the thermal building properties while, in parallel, estimating time-varying effects caused by the humans’ interactions with the building. We do that by combining a smooth, non-linear formulation of the energy signature method known from the literature with a hidden state formulated as a random walk to describe the human interactions with the building. The method is demonstrated on data obtained from autumn 2019 to late spring 2021 from a 900 m2 newly built school building located south of Oslo, Norway. The demonstration case has shown that the model accuracy increases and the model bias decrease when cross-validated. The estimated hidden state has also been shown to resemble the estimated combined mechanical and natural ventilation pattern controlled by the building users and operational staff. These human interactions have increased the total heat loss expressed in kilowatts per kelvin by around 50% over the course of one year from before the COVID-19 pandemic to after its outbreak.

The promotion strategies of heat metering and charging in China’s heating region based on complex network evolutionary game model

Abstract Heat metering and charging can help raise residents’ awareness of energy conservation and save heat consumption in buildings. The heat metering and charging in China, however, was promoted insignificantly. To explore the behavior mechanism of heat-supply enterprises implementing heat metering and charging under the background of complex network in China’s heating region, and put forward the promotion strategies of heat metering and charging, this paper uses the heat-supply enterprises as the sample, improves the utility function of heat-supply enterprises by considering their difference aversion preference and altruistic preference at the same time based on the Difference Averse Surplus Maximizer Model. Then, we establish a complex network evolutionary game model among different heat-supply enterprises, and an empirical analysis is conducted to examine the impact of different factor on heat-supply enterprises in China’s heating region to implement heat metering and charging. The conclusions are as follows: (1) With the current heating cost and income, even if the government subsidizes all environmental benefit generated by heat metering and charging to heat-supply enterprises, the heat metering and charging could not be promoted in different scales of networks. (2) Increasing metering heat price, government fine, environmental protection tax and carbon emission trading price have positive effects on the promotion of heat metering and charging in different scales of networks. (3) The value of metering heat price, government fine, environmental protection tax and carbon emission trading price have no significant impacts on the evolutionary speeds of different scales of networks.

Comparison of empirical modal decomposition class techniques applied in noise cancellation for building heating consumption prediction based on time-frequency analysis

Empirical Modal Decomposition (EMD), and improved or modified techniques derived from EMD, collectively referred to as Empirical Modal Decomposition class (EMDC) techniques. EMDC techniques have a wide range of applications in building energy analysis, especially time–frequency analysis based noise cancellation in data-driven building energy prediction. However, there is a gap in the literature related to the choice of EMDC techniques in data-driven models. This paper provides a framework for a comprehensive comparison of EMD, Ensemble Empirical Mode Decomposition (EEMD), Variational Mode Decomposition (VMD) and Empirical Wavelet Transform (EWT) techniques for building heat consumption prediction modeling. A real building is used as an example to compare the noise cancellation potential of these techniques and the prediction accuracy under various data-driven models. The results demonstrated that noise cancellation using the EMDC techniques significantly improves Signal-Noise Ratio, regularity, and consistency with the original signal trend. The prediction models trained using the noise-cancelled data have the Root Mean Squared Error and the Mean Absolute Error reductions of 22.5 % and 31.3 % on average, respectively. Meanwhile, the predicted signals of the models inherit the noise cancellation benefits of the noise-cancelled training data.

ANALYSIS OF THE EFFECTIVENESS OF SOLAR SYSTEMS USE IN THE UNIVERSITY CENTRALIZED HEAT SUPPLY SYSTEMS

The paper analyzes the current state of solar energy for communal needs and the possibility of using it as part of centralized heat supply systems. Helio systems are widely used in the southern region for a number of reasons. The use of solar collectors allows you to significantly reduce the heat consumption of buildings in the summer, and sometimes to reduce the use of traditional energy sources to zero. However, in other periods of the year, the share of replacement by traditional solar energy is much lower. In such cases, the question arises as to which heat supply load the system will be designed for - for summer, winter or demi-season. To fulfill the main tasks of the research, an analysis of the main operating methods and software complexes for calculating the operation of the solar system as part of combined heat supply systems was carried out. The main indicators that affect the efficiency of the solar system and recommendations for their selection when calculating the annual heat output are also given. For the centralized heat supply system of the university's buildings, a simulation of the operation of the solar plant throughout the year was carried out. For buildings of different types, storeys, area, purpose, an analysis of the effectiveness of solar systems using different types of solar collectors was carried out with the help of a specialized software complex. The share of heat replacement by solar collectors is shown, which shows the expediency of using solar collectors on a number of buildings.

Effects of non-heating users in heating residential buildings on heat consumption

Building heat consumption is affected by factors such as building characteristics, surrounding non-heating users, and outdoor temperature. Therefore, in order to achieve precise and efficient heating, it is of great importance to study the effects of building characteristics and the existence of non-heating users on the building heat consumption. This paper proposed two factors to evaluate the influences of the building characteristics and the non-heating users on heat consumption in a multi-storey heating residential building. Based on the heat consumption without non-heating adjacent users, the top-side users, top-middle users, middle-side users, middle-middle users, bottom-side users and bottom-middle users are identified as six types of typical-location users. Taking the heat consumption of middle-middle users as the benchmark, location factors (LFs) are introduced to consider the influence of building characteristics on the heat consumption of different typical-location users. For each typical-location user, non-heating user factors (NHFs) are introduced to consider the influences of different distributed non-heating adjacent users on the heat consumption of each typical-location user. The results show that, for low-temperature hot water floor radiant heating system, the impact of upstairs adjacent non-heating users is greater than that of same-floor adjacent non-heating users, and the impact of downstairs adjacent non-heating users is minimal. Besides, it can be considered the non-heating user factors vary slightly with the outdoor temperature when the outdoor temperature is below 0 °C. The results provide a guide for heating operation regulation of residential buildings with non-heating users.

Data-Driven Approach to Forecast Heat Consumption of Buildings with High-Priority Weather Data

By increasing the penetration of renewable energies in district heating (DH), the intermittency of the supply-side increases for heating service providers. Therefore, forecasting the energy consumption of buildings is needed in order to hedge against renewable power intermittency. This paper investigates the application of data-driven approaches to forecast the heat consumption of buildings in the winter, using high-priority weather data. The residential buildings are connected to mixing loops of DH to supply space heating and hot water. The heating consumption of the building is calculated using sensor data, including inflow/outflow temperature and mass flow. Principal component analysis (PCA) is applied to determine the key weather data affecting heat energy consumption. Then, the study compares the competences of artificial neural networks (ANNs), linear regression models (LRM), and k-nearest neighbors (k-NN) in forecasting heat consumption, using informative data. Based on the PCA analysis, ambient temperature and solar irradiation are shown to be the highest priority weather data, contributing to 40.6% and 29.2% of heat energy forecasting, respectively. Furthermore, the ANN exhibits a forecasting accuracy of more than 50% higher than LRM and k-NN.

Smart sensors network for accurate indirect heat accounting in apartment buildings

A new method for accurate indirect heat accounting in apartment buildings has been recently developed by the Centre Suisse d’Electronique et de Microtechnique (CSEM). It is based on a data driven approach aimed to the smart networking of any type of indirect heat allocation devices, which can provide, for each heat delivery point of an apartment building, measurements or estimations of the temperature difference between the heat transfer fluid and the indoor environment. The analysis of the data gathered from the devices installed on the heating bodies, together with the measurements of the overall building heat consumption provided by direct heat metering, allows the evaluation of the characteristic thermal model parameters of heating bodies at actual installation and working conditions. Thus overcoming the negative impact on accuracy of conventional indirect heat accounting due to off-design operation, in which these measurement systems normally operate. The method has been tested on conventional heat cost allocators (HCA), and on innovative smart radiator thermostatic valves developed by CSEM. The evaluations were carried out at the centralized heating system mock-up of the Istituto Nazionale di Ricerca Metrologica (INRIM), and also in a real building in Neuchatel, Switzerland. The method has proven to be an effective tool to improve the accuracy of indirect heat metering systems; compared to conventional HCA systems, the error on the individual heating bill is reduced by 20%–50%.

Analysis of influencing factors on heat consumption of large residential buildings with different occupancy rates-Tianjin case study

In-depth studies on the supply-side and demand-side are required to realize the on-demand heating of the heating system. At present, a lot of researches have conducted on the supply-side for obtaining the accurate heat consumption prediction, and researches on the demand-side are mainly concentrated on the single-family. For the large residential buildings, occupancy rate is an important factor affecting building heat consumption, but it is often ignored. In this paper, taking buildings in Tianjin as an example, the heat transfer relationship between households was analyzed firstly, and obtained that the heating condition of up household had a greater influence on object household than left, right and down households. Secondly, the influencing factors of heat consumption of household in different locations were analyzed, the number of classes for households in buildings with and without basement were determined, and the numerical relationship of heat consumption of classes for building with different energy-saving standard were further determined. Finally, the building heat consumption calculation method and household heat consumption distribution method with different occupancy rates were determined, and the correctness and necessity of their application in practical engineering were verified, that will provide theoretical guidance for refined heating.

Optimizing building heat consumption: Weekday and weekend profiles

Paper’s objective is to save time for district heating (DH) companies, which are new to the Geographic Information Systems-supported (GIS) modelling and optimizing heat consumption profiles; also to suggest specific guidelines for the system operation within a residential area. A specific case of the real DH network was simulated. A two-stage programming model combining the optimal design and operation of a DH pipe network was developed. We designed an aerial image of the testing area (modified from Google Map by means of QGIS) and to forecast the building thermal energy consumption, we used a pre-collected data set representing the heating season in Omsk, Russia. Weekday and weekend day were taken as the periods for forecasting. Actual profiles and the simulated data were compared. The error differs slightly for both forecasts regardless of a weekday or a weekend day it is. The obtained results are important because the simulation allows to cut off the peaks at 2:00 and 7:00. The error increases when the optimized values differ greater from the heat consumption basic profiles and vice versa. There are clearly visible local peaks induced by the domestic hot water (DHW) use and a manual temperature setting through a weekday. This leads to a larger inconsistency in relation to a weekend day. It is proposed to optimize the system operation, its objective is to minimize the daily heat energy consumption, annual total fuel demand consumption and the annualized cost of the network.

Study of stand-alone building heating system operating with renewable energy sources under moderate continental climate conditions

The climatic conditions in Moscow limit to a certain extent the utilization of renewable energy sources for heat supply. Long heating period, relatively low average daily sunshine hours during heating period, and low outside temperatures act as barriers to realising the full potential of renewable energy sources. The paper presents an evaluation of feasibility and effectiveness of using various renewable energy sources in the heat supply system of Block 23 of the National research university «MPEI». The system arrangement for heat supply of the building with renewable energy sources is described. Experimental data have been obtained on the basis of this system. The calculated time dependences of building heat consumption and heat pump system (HPS) outputs are given. In addition, for the air-source heat pump system, the dependence on the outdoor temperature is given. Values of HPS efficiency indices are also presented. A comparative analysis of the efficiency of air-source HPS and liquid-to-liquid HPS with a geothermal circuit in winter conditions is carried out.

THE STUDY OF PLATE HEAT EXCHANGER THERMAL INERTIAL PROPERTIES AS OBJECT OF CONTROL IN CLOSED-LOOP RADIATOR HEATING SYSTEM

The development of central heating systems for buildings was analyzed. Heating systems take the significant place on energy consumption of Ukrainian economic, so the improvement of energy efficiency is of great importance because it defines the consumption of hydrocarbon fuel resources and pollutions into environment. Heating systems energy consumption depends on construction of consumers thermal substations. The most efficient construction is independent radiator heating system of building through intermediate heat exchange apparatus. The efficiency of heat exchanger determines the quality of radiator heating service. Very important is the heat supply control from district heating supply system depending on ambient air temperature Both these factors define the building heat consumption. Plate heat exchangers now are widely used in independent radiator heating systems.In this paper the results of thermal inertial characteristics investigation for plate heat exchanger installed in existing heat substation of academic building are presented. The heat substation includes also control system that lets to regulate the heat consumption for building radiator heating. The comparison with thermal inertial characteristics of shell-and-tube heat exchanger was carried out. The much better heat transfer in plate heat exchanger pattern causes the better thermal inertial properties of this unit.

Building heat consumption and heat demand assessment, characterization, and mapping on a regional scale: A case study of the Walloon building stock in Belgium

Energy consumption in buildings results in CO2 emissions and it is necessary to reduce energy consumption thus its related emissions. This research is included in the Wal-e-cities project, which is funded by the European Regional Development Fund (ERDF) and aims to create tools that facilitate the transition toward smart territory. The annual heat consumption (HC) and heat demand (HD) of Wallonia building stock of more than 1,700,000 buildings are assessed. Subsequently, the developed energy models are coupled with a geographic information system (GIS) to calculate and map the HC and HD. The HC and HD are calculated for each building and are represented by different levels of territorial aggregation, namely neighbourhood, municipality, and urban region scales. The highest HC values were observed in large cities and main industrial areas, whereas the lowest values were observed in rural areas. For residential sector, HC is mainly related to the number of dwellings, which differs from that of tertiary and industrial sectors where HC also depends on the nature and function of buildings. Based on mean values at the neighbourhood scale, the HD is 16.44% lower than the HC for the residential sector, 15.78% lower than the HC for the tertiary sector, and 9.26% lower than the HC for the industrial sector. The proposed energy models are validated. The relative differences between annual HC calculated in this study and that provided in the regional energy reports are −5.82% for the residential sector, −14.29% for the tertiary sector, and −2.02% for the industrial sector.

Quantitative Analysis and Multi-Index Evaluation of the Green Building Envelope Performance in the Cold Area of China

In China, relevant standards about building energy efficiency and green buildings have resulted in corresponding requirements for the envelope thermal performance. However, improvement of the thermal performance of the envelope is accompanied by an increase of the environmental impact and cost. This study quantitatively analyzed the thermal performance, environmental impact, and cost of the green building envelope in cold areas and established a common practice database, as well as a multi-index evaluation model. The results show that the best thermal performance improvements are 40% in residential buildings and 30% in public buildings, respectively, based on the relevant standards. The exterior walls and windows have the greatest impact on building heat consumption. There is no significant correlation between the heat consumption and the comprehensive heat transfer coefficient of 10 green buildings. Therefore, the comprehensive heat loss coefficient is corrected. The verification results show that all errors except project 10 are within 15%. Additionally, the projects with balanced thermal performance improvement of exterior walls and windows showed a better performance. Finally, the best combination of residential building envelopes in the cold area was selected, using the evaluation model and quantitative database to calculate the comprehensive score.

Heat consumption analysis and energy-saving renovation of building heating in high sunshine heating area

In order to explore the effect and influence of energy-saving renovation on buildings in high sunshine heating area, the method of visit survey is used. The main scope of reconstruction includes: building windows, walls, door joints, pipe net-work, insulation measures, etc. The heat consumption of buildings, the comprehensive effect of improvement, and the satisfaction of residents are studied. The results show that after the energy-saving renovation of buildings and equipment in the heating area, compared with before the renovation, the residents' awareness of saving heating has been greatly improved and the waste has been significantly reduced. With the decrease of heating economic expenditure, people are more satisfied with energy-saving renovation. Both heating companies and individual users have been relatively large expenditure reduction. To sum up, it is very important to improve the energy efficiency of buildings in high sunshine heating area. After the energy-saving renovation of the building, not only the awareness of saving is improved, but also the consumption of resources are reduced, so that more people can enjoy the warmth. A win-win situation in the cost of users and heating companies is achieved. This study has a positive effect on the follow-up research of building energy-saving renovation in heating area.

Field verification of thermal energy meters through ultrasonic clamp-on master meters

The measurement of heat consumption in buildings through thermal energy meters presents numerous metrological issues due, for example, to the installation and operational conditions (e.g. presence of plant constraints, low flow rates, low temperature differences between flow and return) leading often to unacceptable measurement errors and uncertainties. Therefore, in several EU countries, to guarantee consumer protection it is mandatory to carry out periodic inspection both in the laboratory and in the field to assess their accuracy, while in service. In this work, the authors present the results of experimental campaigns aimed at analysing the key metrological concerns for clamp-on master meters during in-field verification of thermal energy meters. The results showed that particular care should be paid to the meter configuration and installation of the transducer and that legal metrology statutes in terms of permissible error and uncertainty for fielded meters are often very difficult to comply with.

Mathematical Analysis of Optimal Operating Conditions in Heating Systems

With changes in the outdoor air temperature, the heat consumption of buildings also changes. Timely adjustment of the heating systems to ensure optimal operating conditions is extremely significant to save energy. In this study, the operation conditions of a heating system were analyzed numerically, and the existence, uniqueness, and stability of the optimal operation conditions of the heating system were proved. An operation optimization model that could obtain the optimal operation conditions was also established, and the correctness of the model was verified experimentally. Experimental results showed that when the flow rate was 0.606 m3/h, the supply water temperature was 67.13°C, water return temperature was 65.90°C, and the pump consumed the least amount of electricity. The experimental results and model calculation results showed that the operating cost is lower when the system flow rate is low and the supply water temperature is high under the same heat dissipation and indoor temperature.

MODELING ENERGY-EFFICIENT CONSUMPTION AT INDUSTRIAL ENTERPRISES

A possibility to reduce costs incurred in both product manufacturing and energy consumption constitutes energy-efficient consumption at industrial enterprises. Manufacturers operating in various economic sectors adopt similar conceptual models of energy consumption, which allows developing a universal solution for modeling such processes. The central problem of modeling lies in finding an adequate objective function based on a sufficient set of parameters and characteristics of the efficiency of an enterprise’s power circuit. The article justifies the performance indicators of industrial enterprises’ power supply systems. The literature review proves that economic feasibility of energy efficiency is especially obvious if a massive modernization program is implemented. The estimates produced indicate that the largest portion of the potential energy savings is attributed to implementation of energy-saving projects in industrial buildings and other structures. We present a mathematical model designed to perform a comparative analysis of technical and economic features of two modernization scenarios of the heat and power supply system of an industrial enterprise circuit. Performing a simulation calculation based on performance aspects of Russian companies, the paper outlines the advantages of integrated modernization and analyzes the influence of various factors. The results reveal that there is an inverse correlation between specific heat consumption of buildings under thermal modernization and the length of the thermal network. As specific energy consumption in the thermal modernization scenario increases, the payback period for capital investments decreases. The effect of this dynamics is virtually proportional. Compared with total costs for various heat sources, the share of capital costs differs significantly; however, the share of running costs is dominant for all types of units. At the same time, the length of an enterprise’s heat circuit weakly affects the payback period of capital costs.

Effect of the energy-saving retrofit on the existing residential buildings in the typical city in northern China

Since the last ten years, non-energy-saving residential buildings have been retrofitted in China. However, theoretical and practical effects did not match. Due to the lack of actual measurement, the effect of energy-saving retrofit is affected. This study emphasizes on heating energy consumption of the existing non-energy-saving residential buildings in typical cities in northern China and intends to measure them through a heat exchange station, a secondary network, and building during the heating season from 2015 to 2016 and from 2016 to 2017 (before and after retrofit). Comparing the actual measured energy consumption and the energy consumption boundary index of each nod, the energy consumption levels before and after retrofit of different links are analyzed. Comparing the measured energy consumption data of the typical projects at each node before and after the retrofit and using the data standardization method, the buildings before and after the retrofits are at the same boundary conditions. And the actual energy consumption levels and energy savings before and after the transformation of different nodes are analyzed. The main influence factors are determined in the retrofit process. The effect of heat exchange station's control strategies on heating energy consumption is studied. The change of heating radius before and after retrofit is explored. Moreover, the influence of energy-saving retrofit on the indoor temperature and excess heating were analyzed. Results show that the energy-saving rates of the heat supply for heat exchange stations and the heat consumption of buildings were 12.5% and 15.6%, respectively. The intermittent regulation of the heat exchange station, after the energy saving retrofit, saved 18.5% compared with before retrofit, when the heating was stopped. The range of heating radius was expanded by 25.5% after retrofit. There was an increase of 2° centigrade in the indoor temperature of the buildings. And the pass rate of indoor temperature increased by about 20%. Energy loss cannot be ignored and it was caused by 32.8% increase in the excess heating rate.