Building Heat Loss Research Articles

The analysis of heat engineering parameters of building’s thermal protection

Energy efficiency is a one of most important goals in a building sector, namely reduction of heat losses for heating of housing stock. The article presents the results of analysis of heat engineering parameters calculation of building’s enclosing sheath by applicable building codes. Purpose. To define an optimal parameters of heat resistance of constructions on an example different design schemes of building walling. Methodology. The calculation method of building heat losses with considering its architectural and design features was implemented. Conclusion. The difference in calculations of thermal insulation systems in a different codes was researched. Originality. The numerical data concerning results of the insulation parameters selection in systems with a ventilated facade and industrial finishes was received. Practical value. The practical recommendations concerning insulation of existing building in the Ukraine's conditions was represented.

Evaluating Thermal performance of Earth-sheltered Buildings in Heating Season(Case Study: Hot-Arid Climate of Yazd)

This study is done with the aim of evaluating heat loss of earth-sheltered buildings in heating season in comparison with conventional buildings above the ground. Literature review of earth-sheltered architecture shows that although this idea has a long rich history in Iranian architecture and urban design, limited researches related to evaluating thermal performance of this kind of structures has been done. Additionally, previous researches have usually considered thermal behavior of earth-sheltered buildings in cooling season and neglected the effect of earth’s thermal stability on mitigating heat loss in heating season. In this research, different modes of contact with earth are modeled for an earth-sheltered building in the city of Yazd and the heat loss in heating season is calculated and compared with buildings above the ground. In addition, to calculate soil temperature, the formula developed by Labs, is employed. The findings show that heat losses of earth sheltered models decrease with increasing contact with earth’s surface, insomuch that heat loss in a model with three surfaces in contact with earth (North, East & West), was estimated about 44% of the model above the ground. Altogether, it can be concluded that earth-sheltered architecture can make considerable energy savings during heating season in hot arid climates.

QUB: A fast dynamic method for in-situ measurement of the whole building heat loss

QUB is an innovative method enabling the experimental measurement of the total heat loss coefficient (HLC) of a building envelope in one night only. It is based on a simple theory, yet can be demonstrated to be accurate even in a short time and in real buildings, as long as certain experimental conditions are fulfilled.This study combines analytical and numerical approaches to exactly solve the temperature response of an equivalent building submitted to a QUB test. This allows understanding that even with a short time experiment (less than a night), a reasonable accuracy on the estimated HLC can be obtained. The experiment has to be designed following a simple heating power criterion.Calculation is then tested experimentally in various cases whether in climate chamber or in real field, and whether on light weight/not insulated building or a heavy weight/highly insulated building. Results show that the QUB method performed by fulfilling this criterion is a promising method to estimate the HLC of a real building in the field with a reasonable accuracy in one night.

The selecting of building insulation material by the analytic hierarchy process

Today one of the Federal programs implemented in Russia at the state level, is a program of energy conservation and energy efficiency to reduce the specific consumption of fuel and energy resources. In developed countries, private landlords are using almost 30% of all generated power, i.e. almost as much as industry and more than all transport combined. About 80% of the energy consumed goes to space heating, but much of it is often wasted due to a mismatch of home insulation with the adopted standards. Thus, a rational choice of insulating material is one of the most important tasks to reduce heat losses in residential buildings. There is a wide variety of building insulation materials available for purchase. For heat insulation of external walls of residential buildings are most often used single-piece insulation materials – batts, blankets, panels. Their essential advantage in comparison with loose-fill materials, such as crushed expanded polystyrene, expanded vermiculite, claydite, are the simplicity and speed of installation, acceleration of construction works and improvement of their quality. Autoclaved aerated concrete blocks are used traditional for thermal walls insulation, they does not rot, does not burn, does not emit toxic substances during operation, has an average water vapor permeability and, therefore, well regulates the humidity in the room. However, the masonry of aerated concrete blocks has a significant disadvantage – a large average density. Alternatively, the modern industry offers a wide range of synthetic insulating materials, the most popular are fiberglass, mineral (rock or slag) wool, plastic or natural fibers, polystyrene, polyisocyanurate, polyurethane foam boards. As well become increasingly popular natural materials such as cellulose, peat blocks, cork, fiberboard, insulation from flax or hemp fibers. All of these materials have their advantages and disadvantages, so the task of choosing the optimal variant is complex and requires special methods to eliminate the subjectivity of evaluation. The article describes the approach to selecting the best option of building insulation material from the available options by the set of its quantitative and qualitative characteristics. It is proposed to carry out the evaluation of options and selection of the best option based on the analytic hierarchy process. The article presents the results of the selection of the most appropriate thermal insulation material for residential buildings.

Assessment of Factors Affecting the Energy Efficiency of High-Rise Buildings in Modern Cities

The problem of energy consumption of modern high-rise buildings is becoming increasingly important. The growing number of high-rise buildings and the development of urban infrastructure have resulted in the increased energy consumption. Modern high-rise building construction affects the density of urban space and significantly changes local climatic conditions. The development of local climatic factors in thigh-rise building construction and their impact on the energy efficiency of buildings is a relevant and insufficiently studied problem. The article analyzes the influence of modern urban development on the climatic and aerodynamic conditions of the terrain. The assessment of climatic factors influencing heat losses of a high-rise building is carried out. High-rise buildings in the city of Moscow are considered; calculations are made and qualitative and quantitative parameters of the variation in the main climatic factors are given with reference to the architecture of the building. Using the example of the Evolution Tower, calculations have been made and dependency graphs of the temperature and wind speed on the height of the building are presented. The results of the research can be used to assess the influence of climatic factors on the energy costs of high-rise buildings, and can be taken into account in the design of modern energy-efficient buildings.

Study of infiltration through sliding windows with respect to closing mechanisms and their locations in a building during winter season

ABSTRACTInfiltration through windows accounts for a significant heat loss in buildings during winter, leading to the need to minimize uncontrolled air flow. Improvement of window air tightness is important for reducing heat loss by infiltration through windows. In this study, infiltration is measured for general sliding (GS), parallel sliding tilt (PST) and lift sliding (LS) windows according to ASTM E283, a standard for window infiltration measurement. Measured window infiltration data, pressure coefficients calculated with STAR-CCM+ and outdoor weather data of Seoul are used in CONTAM, a network based ventilation simulation program to estimate infiltration during winter season for three sliding window types and their locations in a building. The results show that infiltration is highest for east located general sliding type window, and lowest for west located parallel sliding tilt window. Monthly analysis shows that for an east located window, infiltration is highest during January and lowest during December.

Humidity Distributions in Multilayered Walls of High-rise Buildings

The limitation of free territories in large cities is the main reason for the active development of high-rise construction. Given the large-scale projects of high-rise buildings in recent years in Russia and abroad and their huge energy consumption, one of the fundamental principles in the design and reconstruction is the use of energy-efficient technologies. The main heat loss in buildings occurs through enclosing structures. However, not always the heat-resistant wall will be energy-efficient and dry at the same time (perhaps waterlogging). Temperature and humidity distributions in multilayer walls were studied in the paper, and the interrelation of other thermophysical characteristics was analyzed.

Optimization of thermal stability of structural elements of high-rise buildings to increase their energy efficiency

The problem of improving energy efficiency of modern urban buildings is becoming increasingly important. Urbanization, which con-tributes to the growth of megacities, causes an increase in the number of modern high-rise buildings and the development of urban infrastructure, resulting in increased energy consumption. When dealing with the energy efficiency of high-rise buildings, it is necessary to take into account such factors as the location, building orientation with respect to the cardinal di-rections, functional purposes, a three-dimensional and design solutions. Conservation of energy inside high-rise buildings, which contributes to minimum energy consumption in order to create and maintain a comforta-ble temperature, is one of the urgent tasks. This problem can be solved by thermal insulation of cladding and the use of effective heat-insulating ma-terials to reduce the negative impact of climatic factors on high-rise build-ings. Using the example of the Evolution Tower, we analyzed Moscow City high-rise buildings, made calculations and graphs of variation in the temperature and wind speed throughout the height of the building. An in-crease in wind speed and a decrease in temperature throughout the height of the building create extreme conditions that affect the heat loss of high-rise buildings, which must be taken into account in the heat protection of external enclosing structures.

Fabrication and characterization of form-stable FA ternary eutectic mixture/GO nanocomposite for thermal energy storage

The thermal conductivity of commonly used phase change materials (PCM) for thermal energy storage (TES), such as, fatty acids, paraffin etc., is relatively poor, which is one of the main drawbacks for limiting their utility. In the recent past, few attempts have been made to enhance the thermal conductivity of PCM by mixing different additives in the appropriate amount. Graphene nanoparticles, having higher thermal conductivity may be a potential candidate for the same, when mixed appropriately with different PCM. In present study, acetic acid , tristearin and stearic acid (CA-PA-SA) ternary eutectic mixture was impregnated into nano-graphene oxide (nano-GO) to prepare a form-stable composite PCM (CAPA-SA/nano-SiO2). The phase change temperature range of the composite PCM is 17.2 ◦C–26 ◦C, which is suitable for indoor thermal environment. The high latent heat value and thermal conductivity of the composite PCM are 169.43 kJ kg-1 and 0.68239 W (m K)-1, which is helpful to stabilize the indoor temperature for a long time and improve human comfort. Furthermore, after 500 heating/cooling cycles, the composite PCM showed good thermal and chemical stability. All the results indicated that the composite PCM is suitable for storing excess solar radiation and reducing the amount and rate of heat loss of buildings in the winter, which will help reduce building energy consumption.

Measuring and accounting for solar gains in steady state whole building heat loss measurements

To ensure good thermal performance is delivered consistently and at scale, there is a need to measure and understand the as-built heat loss of dwellings. Co-heating is a steady state, linear regression method, used to measure whole building heat transfer coefficients. This paper assesses the uncertainties in such outdoor, in situ, measurements due to the presence and treatment of solar gains. Uncertainties relating to solar gains are explored through both a number of field test results and simulated co-heating tests. Results demonstrate the potential for fractions of solar gains received on one day to be re-emitted on subsequent days. This dynamic behaviour can lead the steady state analysis to underestimate heat loss. Furthermore, inappropriate measurements of on-site solar radiation are shown to lead to bias in heat loss measurements. In particular, horizontal on-site solar radiation measurements are shown to significantly overestimate heat loss in buildings experiencing high proportions of direct gains through vertical openings. Both forms of uncertainty are dependent upon both the environmental test conditions and the characteristics of a test dwelling. Highly glazed, low heat loss and heavyweight buildings prove to be the most susceptible to such uncertainties, which ultimately limit both when tests can be successfully performed and which buildings can be tested.

Comparison of the Intensity of Ventilation at Windows Exchange in the Room - Case Study

Abstract Doing the replacement of old wooden windows in a new plastic windows, in the old buildings, we get the great reducing of the building heat loss. Simpler maintenance and attendance of window is the next advantage. New windows are characterized by better tightness. The aim of the article is determination due to the performed experimental measurements, how much more are reduce the uncontrolled ventilation that is caused of the infiltration windows. In the article there is presented the experimental measurement of indoor air quality in the room in two phases. In the first phase there is the room installed by 55 year old wood window. In the second phase there is the same room installed by new plastic window. Due to the experimental measurement of indoor air quality it is calculated intensity of ventilation - infiltration. These results of ventilation intensity are reciprocally compared.

Fabrication and characterization of form-stable capric-palmitic-stearic acid ternary eutectic mixture/nano-SiO2 composite phase change material

Phase change materials (PCMs) have great potential for the regulation of indoor temperature and building energy saving. In this study, capric acid-palmitic acid-stearic acid (CA-PA-SA) ternary eutectic mixture was impregnated into nano-silicon dioxide (nano-SiO2) to prepare a form-stable composite PCM (CA-PA-SA/nano-SiO2). The phase change temperature range of the composite PCM is 17.16°C–26°C, which is suitable for indoor thermal environment. The high latent heat value and the low thermal conductivity of the composite PCM are 99.43kJkg−1 and 0.08239W (mK)−1, which is helpful to stabilize the indoor temperature for a long time and improve human comfort. Furthermore, after 500 heating/cooling cycles, the composite PCM showed good thermal and chemical stability. The maximum CA-PA-SA mass fraction of the composite PCM was determined as high as 75wt.%, with no melted CA-PA-SA seeping from the composite PCM. All the results indicated that the composite PCM is suitable for storing excess solar radiation and reducing the amount and rate of heat loss of buildings in the winter, which will help reduce building energy consumption.

Dynamic Heat Production Modeling for Life Cycle Assessment of Insulation in Danish Residential Buildings

Residential building insulation is regarded as an easy solution for environmentally friendly building design. This assumption is based on the perception that the amount of thermal energy used to create insulation in most cases is much smaller than the amount of thermal energythat is needed for space heating without insulation over the lifespan of a building. When the energy sources for insulation production are similar to the energy mix that supplies heat, this logic is valid to very high level of insulation. However, in Denmark, as well as many other countries this assumption is becoming increasingly incorrect. Given the generally long service life of buildings, the significance of future energy mixes, which are expected/intended to have a smaller environmental impact, can be great. In this paper, a reference house is used to assess the life cycle environmental impacts of mineral wool insulation in a Danish single-family detached home. This single-family house, is based on averages of current Danish construction practices with building heat losses estimated using Be10. To simulate a changing district heating grid mix, heat supply fuel sources are modeled according to Danish energy mix reports of fuel mix since 1972. Both the dynamic impact potentials saved by using insulation and the impacts induced from insulation's production are utilized to create an overall dynamic energy inventory for the lifecycle assessment. Our study shows that the use of such a dynamic energy inventory is necessary for increasing the validity of optimization assessment, and our study further shows that it is likely that current Danish regulation will not promote optimum levels of insulation in the near future.

Bayesian estimation of a building's base temperature for the calculation of heating degree-days

Measuring the energy efficiency of a building requires adjusting for factors that affect the energy demand, such as the weather. When dealing with heating energy demand, this implies calculating heating degree-days for that building from climate data and the building's base temperature. This work describes a method for estimating a building's base temperature from periodic energy consumption records such as utility bills and weather data. This method derives not only the base temperature, but also the building's heat loss coefficient, base load, and daily heating variability. Unlike other techniques, this method uses Bayesian inference and provides exact confidence intervals. The theory is laid out before testing the method first on synthetic, “ideal” data, then on a set of real energy consumption data. The heating degree-days calculated from this estimated base temperature are almost perfectly proportional to the heating demand, unlike those obtained by the use of an officially recommended base temperature. The method is implemented in a freely available package in the R programming environment.

The Influence of Thermal Bridges for Buildings Energy Consumption of “A“ Energy Efficiency Class

From 2016 energy effieiency class buildings should be designed and built in Lithuania, as their energy consuptions are considerably less comparing with the ones that were built before. In order to meet high requirements of energy efficiency class buildings, not only thermal insulating thickness layer of building's envelopes should be enlarged, not only effective windows and building's energy using engineering systems should be used but also new energy efficient structural and insulating solutions should be made. One possibility to reduce building's energy consumption is to join building's envelopes and units that value of thermal coefficient of linear thermal bridges was smaller in joint places. Moreover, in order to evaluate overall heat losses in these joints more exacly it is required to calculate values of heat transmission coefficients of linear thermal bridges in energy class buildings.The project of semi-detached building was chosen in order to analyse influence of linear thermal bridges for building's energy consumption as there are all kinds of linear bridges wich values must be calculated. Buildings energy efficiency designing program, wich based on EN ISO 13790, was used to calculate building's heat losses. Heat transmission coefficients of linear thermal bridges were calculated using program THERM. Two variations were analysed: building's energy consumptions are close to the lowest point of A class requirements when building's envelopes and joints of units in joint places are the same as they are in currently built houses; and effective energy solutions of building's joints.The results analysis showed that requirements of class can be reached using ordinary solutions for building's envelopes and joint units but if linear thermal bridges are designed like that, it makes 16 % heat losses through envelopes, and it is similar to heat losses through building's walls (17 %), furthermore, it is about 1.5 times bigger than heat losses through roof (10 %) or floors (10 %). Specific heat losses of thermal bridges make 7.80 kWh/m2 per year. The biggest overall heat losses are through walls and windows joint thermal bridges (specific heat losses make 13.55 W/K). Another significant part of heat losses comes from walls and floor joints (specific heat losses make 11.88 W/K).After solutions of buildings with energy effective building's envelopes and joints were analysed it can be stated that overall heat losses decreased about 10 kWh/m2 per year, it is 20 %. Heat losses through thermal bridges make only 3 % of overall heat losses through envelopes, it is 122 kWh/m2 per year.According to results of the analyse general specifications were made for designing building envelopes energy efficient class:The building of class can be designed using ordinary solutions of linear thermal bridges, bigger heat losses through thermal bridges can be covered by increasing thickness of thermal insulating layers and using windows of better thermal bahavior but as a result the costs of building house increase too.When effective solutions of linear bridges are used, the same energy efficiency of the building can be reached using less thermal insulating layers, windows and doors of less thermal behavior if the building of better energy characteristics is designed.The usage of effective structural solutions, also of linear thermal bridges, increases energy efficiency of the building, improves conditions of interior microclimate and makes assumption to decrease additional cost of building house comparing to the ordinary ones. DOI: http://dx.doi.org/10.5755/j01.sace.15.2.15351

Effect of Used Binders in Lightweight Plaster Mixtures on their Thermal Insulation Properties

Good thermal insulation properties of the surface structures lead to reduction of heat losses in buildings. This reduces the energy required for heating which is positive fact from the view protection of the environment. The aim of the research intent, which is going at Faculty of Civil Engineering in Brno, is the development of high-quality, thermal insulating plasters using both conventional binders, and alternative binders, whose acquisition-production is in comparison with the technology production of cement less energy intensive. Due to the fact that increasing moisture leads to deterioration of the thermal insulating properties, further research works were devoted to the study of the influence of relative humidity and moisture content on the thermal insulation properties of lightweight plasters, including of the determination of capillary absorption coefficient. This paper describes evaluation of the development of insulating plasters based on lightweight aggregates, using different ratio of cement and lime hydrate and other chemical additives. There are presented results of the study of basic physical and thermal insulating properties, including the study of sorption properties developed lightweight plaster mixtures.

Effects of added glazing on Balcony indoor temperatures: Field measurements

In this study the temperatures on 22 balconies (17 glazed) and adjacent flats were monitored with an aim to determine the key factors affecting the ability of a glazed balcony to warm up and remain warm without a heater. Considered were glazed balconies in different locations, the amount of glazing and building heat loss, the tightness of balcony vertical structures, and balcony ability to capture solar radiation.Temperature monitoring showed that over a year the air temperature of both glazed and unglazed balconies remained almost without an exception above the outdoor air temperature. On average, the temperatures of unglazed balconies were 2.0°C and those of glazed balconies 5.0°C higher than the outdoor air temperature. The three key factors affecting the glazed balcony temperatures seemed to be the level of air leakage in the balcony vertical structures, the balcony’s ability to capture solar radiation, and the heat gain from an adjacent flat, in that order. The air tightness of the glazing was the most crucial factor, since it affected the results all the year round. Solar radiation was important from spring to autumn and heat gain in midwinter.

Glazed spaces: A simplified calculation method for the evaluation of energy savings and interior temperatures

Previous studies have shown that temperatures inside glazed balconies are almost without exception higher than those of outside air. This is due to the space's ability to capture and store the building's heat losses and solar radiation. The interior temperatures and energy saving effects of glazed balconies are, however, not particularly good in Finland, because the implemented solutions are not optimized for these issues. The purpose of this study is to introduce simplified evaluation methods for the energy saving and interior air temperature evaluation of glazed spaces and to verify the method reliably with the help of measured and simulated values of typical Finnish 1970s apartment blocks. The presented method can be used for optimizing and showing the energy saving impact as well as the mean, maximum and minimum temperatures of different type of glazed spaces in the preliminary design stage. The results show that the accuracy of the method is sufficient for designing if nine parameters are changed at most. The accuracy is affected by the number of changes made in relation to the typical 1970s apartment blocks in Finland, which was chosen as a starting point for the method's development.

The Building Fabric Thermal Performance of Passivhaus Dwellings—Does It Do What It Says on the Tin?

The Passivhaus (or Passive House) Standard is one of the world’s most widely known voluntary energy performance standards. For a dwelling to achieve the Standard and be granted Certification, the building fabric requires careful design and detailing, high levels of thermal insulation, building airtightness, close site supervision and careful workmanship. However, achieving Passivhaus Certification is not a guarantee that the thermal performance of the building fabric as designed will actually be achieved in situ. This paper presents the results obtained from measuring the in situ whole building heat loss coefficient (HLC) of a small number of Certified Passivhaus case study dwellings. They are located on different sites and constructed using different technologies in the UK. Despite the small and non-random nature of the dwelling sample, the results obtained from the in situ measurements revealed that the thermal performance of the building fabric, for all of the dwellings, performed very close to the design predictions. This suggests that in terms of the thermal performance of the building fabric, Passivhaus does exactly what it says on the tin.

Behaviour: Seeing heat saves energy

Household energy conservation can help to significantly lower energy consumption. Visual cues provided by thermal imaging of heat loss in buildings are now shown to increase energy conserving behaviours and implementations among homeowners more effectively than just performing carbon footprint audits.