Annual Heating Energy Demand Research Articles

Climate change mitigation and adaptation in Spanish office stock through cool roofs

In a context of climate change, the cooling period of buildings is increasing every year in Mediterranean countries. This will become a relevant issue when existing buildings are retrofitted. Cool roofs have a passive cooling effect on a building and can contribute to decreasing the annual cooling demand. In office buildings, thermal comfort has a considerable influence on workers’ performance. In these buildings cooling energy demands tend to be high due to the high internal thermal loads. This paper describes annual energy simulations of Spanish office stock to evaluate the potential energy savings of cool roofs within the context of building retrofitting. The energy demand and thermal comfort of representative office buildings is compared before and after the application of a cool roof coating, in the present time and in the year 2050, for all climate areas of Spain, under the most optimistic and most pessimistic future weather scenarios. Results showed that the cooling energy demand of Spanish office stock can be potentially reduced by 25 % when a cool roof is applied, and the annual energy demand for heating and cooling can be cut by 6 %, 11 % and 12 % in the present, the optimistic future scenario and the pessimistic future scenario, respectively.

The Impact of the Location of a Passive Frame House on Its Energy Demand for the Purpose of Heating—A Case Study

The reduction of energy demand in buildings is one of the key challenges in contemporary construction. To this end, the application of structural and material partitioning solutions that provide a high level of thermal insulation and the employment of technical installations with high energy performance have become widespread. However, there are a number of other factors that can reduce energy demand. These include the optimal use of heat gains from solar radiation. An aspect that is often discussed in the literature is the overheating of buildings due to excessive heat gains from solar radiation. This article is a case study showing the impact of the orientation of a single-family passive house on its heating energy demand. The building under consideration is located in Central Europe. External climate parameters measured directly at the site during experimental examinations were used for the calculations. This paper adopts six calculation options, considering the different orientations of the glazed façade. As the simulations showed, the effect of solar radiation on the energy demand between two extreme options of glazing orientation, that is south and north-facing orientation, reached 4.7% of the annual energy demand for heating, while for the option corresponding to the actual location of the building and the option involving south-facing windows, the difference was 0.3%, respectively.

On the effect of pressure coefficient source on the energy demand of an isolated cross-ventilated building

Natural ventilation is a simple and effective measure to both reduce the cooling demand of buildings and improve the indoor air quality. In the prediction of heating and cooling demands by means of building energy simulations (BES), the use of pressure coefficients (Cp) from databases as input for the airflow network model is the common approach. Cp values for the same building typology may differ according to the adopted database and are generally unavailable for buildings with complex geometry. Employed Cp values may lead to differences in BES results. This manuscript presents a comparison, for different wind directions, between the Cp distributions and mean values on the facades of a detached building obtained with full-scale CFD – Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) – simulations, from a database and from wind-tunnel experiments. The obtained pressure coefficients are used in the BES of a naturally ventilated building and the energy demand difference between the four approaches is quantified. Four climate zones (tropical, dry/desertic, temperate, continental) are considered. Although, in terms of accuracy of Cp prediction, LES outperforms RANS for all the wind directions considered, annual cooling energy demand is found to be relatively insensitive to the source of Cp for the current case study, while predicted peak cooling values differ up to 10.8%. On the other hand, the prediction of annual heating energy demand in cold climates varies up to 3% depending on the Cp source employed for BES simulations.

Evaluation of the Impact of Window Parameters on Energy Demand and CO2 Emission Reduction for a Single-Family House

This article deals with the determination of the impact of selected parameters on energy consumption for heating and cooling purposes and CO2 emissions. Mathematical modelling combined with planning a computational experiment was adopted as the research method. The database for creating the models was developed using building energy simulations performed with DesignBuilder software. A single-family house with an area of 101 m2 was the subject of this study. Four deterministic mathematical models for the estimation of annual energy demand for heating, cooling, total final energy demand, and CO2 emissions were developed. Four parameters affecting the energy balance of the house: the area of the glazing system (three levels), U-value of windows (two-, three- and four-pane), U-value of external walls (0.1, 0.15, 0.2 W/m2K) and location (Warsaw, Berlin, Paris) were considered. The article discusses in detail the influence of individual factors on the energy demand and their common interactions. It was found that the level of thermal insulation of the glazing system plays the most important role in saving energy. This factor was the only one to show a stable and significant reduction in house energy demand, and thus a reduction in CO2 emissions for all four objective functions.

Applicability of Multivariate Linear Regression in Building Energy Demand Estimation

The vision of the research project is to find an energy optimal building configuration, suitable for specified requirements and restrictions. The first step on this way is to create a measure to compare building configurations, faster than explicit energetic simulations. The current study examines the applicability of multivariate linear regression to support the solution of building optimization problems. During the study, multivariate linear regression models were created to estimate the expected annual heating energy demand of building configurations and examined their accuracy Between examinations, the models were modified so that the complexity was increased only to such an extent that the approximation was still sufficiently accurate. The result was a multivariate linear model that estimated the expected output for unknown descriptive variables with a 0% relative error and a 1.6% standard deviation. The R2 point of the estimates was 0.9884. Based on these, the model was considered applicable in the search space defined by the training patterns.

Optimization of the Selected Parameters of Single-Family House Components with the Estimation of Their Contribution to Energy Saving

Knowledge of the influence of factors determining energy consumption in buildings is very important for the possibility of effective energy saving. This article describes the results of an original study on the analysis of the annual energy demand for heating (QH;nd), cooling (QC;nd), and annual usable energy demand (QH/C;nd = QH;nd + QC;nd) assumed as objective functions of a designed single-family building, which can be classified as a typical representative of currently built houses in Poland. It was assumed that the object of study was located in the climatic conditions of north-eastern Poland. The study takes into consideration three groups of selected parameters: architectural/spatial, structural, and physical properties of windows. The research was carried out in a single-family building, as energy consumption in residential buildings accounts for a significant part of the total energy consumption in buildings. In the group of architectural/spatial parameters, the height of rooms in the building (h) and the window area change coefficient (k) were taken into consideration. The design parameters pertained to the solutions of building components: the density of the material of the inner layer of the external walls (ρ1), the density of the material of internal walls (ρ2), and the thickness of internal walls (d). In the third group of parameters, the heat transfer coefficient of the glazing (Ug) and the total solar transmittance of the glazing (g) were considered. Deterministic mathematical models of these dependencies were developed on the basis of the results of a computational experiment, obtained by performing a simulation with the use of the DesignBuilder software, based on the EnergyPlus computational engine. The models allowed the authors to estimate the degree and nature of the influence of the examined factors on the building’s energy demand. As a result of the optimization of parameters according to the energy criterion, the contribution of each of the three groups of parameters to energy saving was determined. Deterministic numerical optimization using MATLAB was applied. It turned out that the factors from the first group played the most important role in energy savings (40.0%), and the factors from the third group contributed slightly less (25.7%). The contribution of the characteristics from the second group was 4.2% of the total value of energy saving. This information can be useful to scientists, as well as engineers and policymakers, in making correct decisions when designing new residential buildings.

Mapping the Potential of High-Reflective Roof Coverings in Residential Buildings in Italy

The current warming trend of the earth’s climate is making it increasingly necessary to focus on solutions to improve indoor comfort while reducing energy demand for buildings during the hot season. The use of high-reflective products on the building envelope, and particularly on the roof, has been suggested as a potential solution. The overall impact of using high-reflective products on roofs largely depends on the local climatic conditions and on the characteristics of the building, making it difficult to determine whether the use of these products is beneficial without the use of detailed modelling approaches. In this context, this study aims to propose a method to provide indications for designers and policymakers to make early decisions on the potential benefits of the use of high-reflective products on residential buildings, based on simple and readily-available climatic data of the location. The approach, based on the use of state-of-the-art simulation software, allows researchers to obtain a multi-linear regression of the effect of high-reflective products on roofs as a function of the heating degree days and of the local value of the climate vector. The approach is applied to the case of the Italian territory, where a block-of-flats is selected as the reference building, with features common to a significant part of the national residential stock. The proposed approach allows for the provision of a quantitative estimate of the expected impact of high-reflective roof coverings on the energy performance of residential buildings in all Italian municipalities. The analysis shows that high-reflective products on roofs are likely to reduce the building annual energy demand for heating and cooling in 9% to 25% of Italian municipalities, depending on the building energy renovation state. The proposed approach, whose results are expressed also by means of thematic maps, can be replicated to other geographic areas and can be extended to different energy saving technologies.

Experimental analysis of low-cost energy retrofit strategies for residential buildings to overcome energy poverty

Various policies for carbon reduction are being promoted due to the increase in energy consumption and changes in the global environment. However, the low-income household of South Korea are still living in old houses with poor energy performance; thus, they require a lot of money for heating. In response, the government is subsidizing the cost of remodeling houses as an energy welfare project. From the 2020 low-income household energy welfare project, out of approximately 30,000 households, 24 households were selected based on factors such as the construction method, region, year of construction, and floor area. These houses were visited before and after modification to measure and analyze heat loss and airtight performance. Instead of diagnosing with simple drawings or dimensions, the accuracy of the results was improved by placing the numerical values obtained before and after energy retrofit of the actual house into the simulation. Retrofit cases consist of three types of modifications: insulation wall construction, window replacement, and both. With a budget of about $2,500, we analyzed the heating energy savings of 24 households and the cost before and after the retrofit through three retrofit cases. The average annual heating energy demand of 24 households was reduced by 22.61%, and the average budget was supported by $2314.14. In addition, the retrofit cost required to reduce the heating energy demand of 24 households by 1 kWh/m2·a was $ 37.09 on average.

Modelling the Heat Loss of a Building

The aim of this paper is to calculate the heat loss and annual energy demand for heating of an administrative building for three variants of thermal-technical design and their evaluation. The heat losses were determined according to the legislation in force and in accordance with the normative requirements. The calculations made can be used in the next phase for the design of the heat source and heating system for heating and for the design of forced ventilation with heat recovery. Based on the optimum choice of technical equipment, it is also possible to evaluate the investment and operating costs for the installation of the different heating and ventilation concepts. Given the current significant increase in energy prices, the present topic is very topical.

Predicting energy demand of residential buildings: A linear regression-based approach for a small sample size

Abstract The key design strategies that reduce the energy demand of buildings are not present in most thermal codes in many countries. Therefore, modeling techniques offer an alternative to combine the architects' modus operandi with the energy efficiency in the early stages of architectural design and with higher speed and precision. However, a review of the scientific literature using modeling techniques shows that most researchers use a relatively large sample of thermal simulations. This paper proposes a simplified method based on the linear regression modeling technique and considers a relatively smaller sample of thermal simulations. A total of 6 key building design strategies were identified, related to the urban context, building envelope, and shape factor. A simulation protocol containing 60 possible combinations was designed by random selection. In the present study, the Pleiades software was used to estimate the annual energy demand for heating and cooling for a typical dwelling in a humid climate zone. A parametric study and sensitivity analysis to identify the most efficient parameters was performed in SPSS 21. The resulting model predicts the annual energy demand with an accuracy of 93.7%, a root mean square error (RMSE) of 5.88, and a scatter index (SI) of 8.59%. The models performed could efficiently and quickly assist architects while designing the buildings in the architectural practice.

Life Cycle Assessment with BIM Towards Sustainable Energy Policy-Making: The Case of Urban Transformation in Istanbul

Buildings are responsible for almost forty percent of global energy. Due to their high consumption of energy, buildings are on the front line of sustainability researches. In Turkey, six million out of twenty-two million buildings need to be demolished and rebuilt to meet seismic standards. These buildings are also far below the standards in terms of energy efficiency. Therefore, urban transformation can be thought of as a great opportunity for energy efficiency. This study investigates four things: (i) the energy-efficient urban transformation strategy in Gaziosmanpaşa-Istanbul region, which is selected as a case study; (ii) the effect of energy efficiency in this market; (iii) the adequacy of energy standards of Turkey; and (iv) contribution of digitalization in construction to sustainability with Building Information Modelling (BIM) and energy analysis. According to the energy efficiency scenarios, energy analyses were carried out on the BIM model. The most cost-effective strategy was determined with the Life Cycle Cost method. When compared with the current situation, it is possible to save energy up to 227 GWh a year, which is equal to the annual heating energy demand of approximately 30,000 housing, in the case study area with the most efficient scenario to be realized.

Optimization of Modernization of a Single-Family Building in Poland Including Thermal Comfort

The impact of thermal comfort demand on the renovation process was carried out on an optimization basis for the thermo-modernization process of an exemplary single-family home located in Warsaw. The verified TRNSYS simulation program was used to generate a set of variants of building modernization solutions. This variants set was used afterwards as a database for optimization. The analysis performed includes the internal air temperature, indicators of thermal comfort (PPD), and annual energy demand for heating and cooling, and investment costs of modernization building. The results indicated the importance of analyzing various variants of building modernization solutions. Performing modernization without analyzing its effects can have positive as well as negative consequences, e.g., achieving a significant reduction in the primary energy demands at the expense of the deteriorated thermal comfort of users. It was shown that separate analysis of indicators leads to completely different solutions and should not be recommended during modernization of single-family buildings.

Influence of Thermal Retrofitting on Annual Energy Demand for Heating in Multi-Family Buildings

The paper presented the analysis of heat consumption for heating in multi-family residential buildings before and after thermal retrofitting. The analysis involved four groups of buildings, i.e., 43 buildings in total, located in various localities, belonging to one weather station. The predicted level of energy savings resulting from thermal retrofitting was achieved from the energy audits. The actual heat consumption, following the calculation into so-called external standard conditions, was obtained based on the readouts from heat-meters. For each building, the values of heat consumption over the periods of 6–10 years were read. The performance measurements involved the periods before, during, and after thermal retrofitting. The following statistical tests were used for data analysis: Wilcoxon–Mann–Whitney, Shapiro–Wilk, Bartlett, ANOVA, Kruskal–Wallis, Dunn and Holm post-hoc. The performed analyses showed that the mean value of energy savings predicted by audits reached 38.5% when the real mean value of savings, achieved from heat-meters, equaled 30.3%. The annual energy demand factors for heating were calculated for final energy and non-renewable primary energy factors. It was established that most of the analyzed objects fulfilled the primary energy factor requirements found in the Polish technical and construction regulations, which were valid at the time of investment.

Analysis of Thermal Performance Improvement of Residential Building: A Case Study in an Urban Bhutan

This paper presents an estimate of the level of energy efficiency that could be achieved through improvement in building envelope. A residential flat in Thimphu, Bhutan was simulated in transient simulation software TRNSYS with measured weather data. From the simulation, it was observed that the thermal energy demand of the flat could be reduced between 11-64% by insulating the building envelopes under various scenarios. The simulation result suggests that attic insulation must be the first method to look into while deciding for retrofitting a poorly performing building as it could result in a high reduction of annual heating energy demand. The simulation shows that maximum heating energy demand reduction (64%) could be achieved when attic and wall insulation was used. Keywords- Building thermal performance, TRNSYS, energy analysis, energy savings, thermal energy DOI: 10.7176/JEP/11-27-14 Publication date: September 30 th 2020

Sustainable energy saving alternatives in small buildings

Day lighting significance in architectural designs is well established for enhancing visual comfort, energy-efficiency and low carbon buildings development. Practising the atrium element in the modern architectures has been increasingly popular in recent years because of the fact that the transitional space with good environmental elements can improve the quality of the buildings and reduce extra energy utilisation. The present study explores the advantages and effectiveness of the atrium on the energy performance of small buildings, a case study of ‘The Azuma Row House’. Based on local micro-climate data Autodesk Ecotect Analysis was performed to calculate the daylight factors and the energy demand of the building. A comparison was made with atrium and without atrium in the building to evaluate overall energy savings. The results show a higher annual heating energy demand with atrium 3443 kWh compared without atrium 2526 kWh. The annual cooling energy demand without atrium 2516 kWh is significantly greater than with atrium 912 kWh. The total energy requirements under no atrium case is about 5042 kWh which is considerably higher than the total annual energy demand with atrium 4355 kWh. The total amount of energy saved is about 15.7% per year by introducing the sunlight through the atrium. Along with the increasing issue of the energy crisis, environmental problem and the beautiful design of atrium, the development of atrium in modern architecture designing is feasible to have a good future.

Parametric simulation study for green roof retrofit over high performance solar house prototype “EFdeN Signature”

The advantages of green roofs are well documented, ranging from heat island reduction, thermal comfort, air quality, stormwater management and energy savings for buildings. However, it has been shown that green roof retrofits are more effective in old, low efficiency buildings. This paper studies the possibility of retrofitting a high efficiency solar house with a green roof system being partially shaded, optimising its characteristics by means of parametric simulation. The input variables of the green roof system are: growth medium thickness, LAI (leaf area index) and height of plants. The output variables by which the different green roof systems are compared are: annual energy demand for heating and for cooling. The study concluded that the average reductions of energy consumption when retrofitting an efficient building with an extensive green roof are of 1.01% for heating and 4.61% for cooling, but optimising parameters (low LAI in winter, high LAI and height of plants in summer) can get reductions to 1.55% for cooling and 5.95% for cooling.

Interlinking the effect of thermal mass and temperature control strategies in dwellings

Exposed heavyweight constructions with a high specific heat capacity can dampen and delay transient heat flows in buildings. This paper explores the dynamic effects of various construction assemblies and explores the effect of different temperature control strategies in relation to the thermal mass. The thermal inertia of a building not only affects the pace of heating up a thermal zone, but also the temperature set-back that can be attained with an intermittent heating regime, and thus the setpoints of control regimes. Based on a simulation study, it is demonstrated that the impact of the thermal mass on the heating demand of dwellings is rather limited in a temperate climate. Lightweight timber frame construction can display an annual heating energy demand of up to 6.6% higher compared to a heavy mass concrete and limestone construction in case of fixed thermostat setpoints. If a different control strategy with a highly intermittent thermostat schedule is implemented, the energy use of the lightweight construction can conversely have a lower heating energy expenditure, with a reduction of up to -4.5%. Modelling assumptions on the HVAC system capacity, the timing of the start-up moment of intermittent heating and the type of thermostat control – either based on air temperature or operative temperature – can have a significant influence on the simulation outcomes. Depending on the modelling assumptions and temperature control strategies implemented, the detailed dynamic simulations display that heavy mass buildings will not necessarily yield a lower heating demand as would be predicted by simplified monthly quasi-steady state calculations. In general, it is advocated that a better understanding of control strategies and resulting comfort sensations is required in building design and performance simulation.

SOFTWARE AND ALGORITHMIC SUPPORT FOR ENERGY AUDIT OF BUILDINGS AND FOR THEIR ENERGY CERTIFICATION

The insufficient supply of Ukraine with its own energy resources determines the topicality of the reduction of energy consumption, in particular in the housing and communal sector. The important means, which are supposed to promote energy efficiency increasing, are energy passport and energy certificate. Their development requires an energy audit. The basis for carrying out the energy audit and drawing up an energy passport and an energy certificate is the current regulatory framework, which has undergone significant changes in recent years in order to adapt it to international regulatory framework. The changes form new requirements which the software of energy management should correspond to. The most significant changes are the transition to the estimation of energy efficiency of the building from the specific heat consumption for heating to the annual energy demand for heating, cooling and heat water supply and the need to calculate the energy demand according to the energy balances of all building zones. The changes are the basis for the formation of basic software objects such as building, building zone and energy balance. Next each basic object can be supplemented by other necessary components. This is illustrated in the article on an example of describing the several objects by UML-tools. It allows us to describe the relationships among objects in concepts of UML-scheme according to the properties of an object type. According to the capabilities of modern software the structure scheme of each application should contain subsystems as application software as information provision. The structure of such a structural-functional scheme includes both general-purpose subsystems of the lower level, as well as applications that provide the specialization of the software. According to the described structure the program “Energy efficient building”, which is part of the specialized package, is modernized in Lviv Polytechnic. The program allows performing the main tasks such as performance of energy audit of building, substantiation of system of energy-saving measures and drawing up of energy passport and energy certificate of building.

The Transient Conjugate Heat Transfer Analysis in Multi-zone of an Apartment House by using Crank-Nicolson Finite Difference Method (FDM)

Purpose: This study was conducted for the purpose of accurate energy analysis of apartment house which is composed of multi-zones such as a bedrooms, a livingroom, and a kitchen. Those of multi-zonal spaces have different indoor thermal environment requirements depending on space usage. For the analysis of this study was selected the 74 ㎡ type unit, which has the largest amount of supply in residential needs. The orientation of the apartment house unit was divided into the southeast and southwest directions, and the annual heating energy demand was calculated and compared. Method: A multi-zone heat transfer is done in dynamic and a very complex, such as conduction, convection, radiation and the solar radiation in a various building elements. In this paper, the Crank-Nicolson FDM scheme and the ISO 13790 algorithm were employed to analyze a complex and transient heat transfer in the multi-zone of apartment house. Result: The results of the analysis are as follows; the total amount of annual energy requirement for the apartment house unit which oriented in the southwest is 756 ㎾h. and equivalent to 10.2 ㎾h /㎡. When the required amount of primary energy was converted equivalent to electricity by unit floor area, it was 28.1 ㎾h /㎡. On the other hand, the total amount of annual energy requirement for a unit oriented in the southeast direction is 1,037 ㎾h and 14.0 ㎾h /㎡. The result of conversion (electricity) to primary energy is 38.5 ㎾h /㎡. This result indicates that the energy demand is about 27% higher than the southwest.

Estimation of Indoor Temperature for a Passive Solar Building with a Combined Passive Solar System

AbstractPassive solar design strategies for buildings are necessary for annual heating energy demand reduction. This paper presents a mathematical model for interior room temperature calculation of...