Thermal Behaviour Of Buildings Research Articles

Infrared thermography for the investigation of dynamic thermal behaviour of opaque building elements: Comparison between empty and filled with hemp fibres prototype walls

The analysis of the thermal dynamic behaviour of buildings is an important tool for reducing inefficiencies and then wasted energy. In this field, European Standards specify the procedures to obtain information about the thermal behaviour of building in terms of decrement factor and time lag. However, these procedures are based on a theoretical approach that does not take into account the real factors involved in the heat exchange phenomena such as the correct knowledge of thermo-physical parameters and the presence of non-homogeneous materials or defects in the investigated walls.In this work, we propose an innovative experimental procedure based on the application of stimulated thermography with the aim of investigate the thermal dynamic behaviour of walls. In particular, two prototype walls were compared: an empty wall and one made with an insulating filler of vegetable nature (hemp fibre).The results were then compared with those obtained with a numerical simulation and with the Standard procedure EN ISO 13786:2007, highlighting the differences between the three approaches.

Quantitative internal infrared thermography for determining in-situ thermal behaviour of façades

The thermal behaviour of a building is often underestimated or neglected during its construction and operation stages. In recent years, the heat flux meter (HFM) method has been commonly used to determine the U-value, a key parameter for assessing the thermal quality of the building envelope in steady-state conditions. However, this non-invasive test takes at least 72h to execute, the accuracy is 14–28%, and it is not reliable for non-homogeneous building elements. An alternative technique is based on infrared thermography (IRT). Although it is generally used for qualitative analysis, quantitative internal IRT methods may also be adopted for in-situ measurement of the U-value. This research presents a method for determining in-situ U-values using quantitative internal IRT with a deviation of 1–2% for single-leaf walls and 3–4% for multi-leaf walls. It takes 2–3h and can be used to provide information about the building envelope for the future refurbishment of existing buildings or to check the thermal behaviour of new building façades according to their design parameters.

Experimental investigation and EnergyPlus-based model prediction of thermal behavior of building containing phase change material

In this paper, the effect of phase change materials Natural TCM Energy Saver® (TCM) integrated in building for space heating and thermal comfort was investigated. The mean radiant temperature and asymmetric radiation of the house with and without TCM were compared to investigate the effect of TCM on the thermal comfort. The results showed that TCM can minimize the temperature fluctuation and improve the thermal stability of the test house. A conduction finite difference (ConFD) algorithm in EnergyPlus was used to model building integrated with TCM. The predicted results was compared with experimental data. Results showed that the model was able to follow the trend of the inner surface temperature.

An evaluation of the suitability of lumped-capacitance models in calculating energy needs and thermal behaviour of buildings

Simple, reliable building models have been receiving quite a bit of attention recently particularly with regard to diverse applications, such as building design for inexpert energy modellers, simulation of neighbourhood or city districts and model predictive control. The International Standard ISO 13790 and the German Guideline VDI 6007 use two different lumped-capacitance models (5R1C and 7R2C, respectively) based on deterministic, analytical procedures to identify their parameters. The current work investigates the suitability of these models in calculating peak loads and seasonal energy needs and their accuracy in estimating buildings’ dynamic behaviour. A room and an apartment were thus simulated using simplified models and with the benchmarked software TRNSYS. Four reference envelopes with different thermal insulation and heat capacities were examined in four climatic conditions. Each of the models was able to estimate quite precisely energy needs in both the heating and cooling modes, although the 7R2C model was slightly more accurate. The 5R1C model was, however, unable to follow the thermal response of the buildings during the cooling season, which in turn implied a systematic underestimation of the cooling peak load. The 7R2C model identified a significant reduction in the root mean squared error (RMSE) both in the indoor air temperature and in the heating/cooling loads with respect to the reference profiles. That model would seem then more suitable for the dynamic simulation of single thermal zones with hourly time steps in both heating and cooling modes.

Thermal transients simulations of a building by a dynamic model based on thermal-electrical analogy: Evaluation and implementation issue

The thermal behaviour of buildings in transient conditions is established by the temperature evolution of the external environment. Determining the thermal evolution of buildings is of crucial importance for building energy design, as well as for energetic performance evaluation. Building energy performance evaluation and calculation of energy use for space heating and cooling can be carried out by several methods of various degrees of complexity and accuracy. These methods are implemented in such simulation codes as NBLSD, Il DOE-II, ENERGY PLUS and others. In order to comply with the Energy Performance of Buildings Directive (EPBD), the studies and research in this field start from the Directive 91/2002/CE and subsequently lead to the EN ISO 13790:2007. The latter proposes a thermal model for a building composed of five resistances and one capacity, called R5C1, and also offers its dynamic solution with a simple hourly computational model. The present paper suggests the solution and dynamic simulation of the R5C1 model and an evaluation of its use in building energy design. Finally, a case study regarding a typical average day in June in Catania (Sicily, Italy) is presented. The implemented model and the relative simulation results have confirmed the advantages of such a solution and have been validated for some modules of the CONPHOEBUS scrl Research Building in Catania. The proposed model has the advantage of a small number of parameters (5 thermal resistances and 1 thermal capacity) and has a simple formulation and then requires low computational resources. Furthermore, this model allows the correct estimation of the user profile with few and not sufficiently precise input data. Due to the above listed properties the proposed model was adopted by the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) for an extensive energy consumption simulation campaign involving 5000 buildings in Italy (a campaign of measurements on 20,000 buildings planned for 2017) for the calculation of statistical consumption data for public buildings.The results ENEA has obtained from our model are in excellent agreement with the statistical data determined by the Italian National Institute of Statistics (ISTAT).

Effect of thermal insulation using leather and carpentry wastes on thermal comfort and energy consumption in a residential building

In this work, we investigate the effect of the thermal insulation by leather wastes (wet-blue chrome shavings and buffing dust) and carpentry wastes (wood shavings and sawdust) on the energy consumption of a model building using the average climatic data of the city of Casablanca (Morocco). For this study, we used the dynamic thermal simulation tool “TRNSYS 16” which predicts the thermal behavior of building and systems associated with it. Using this software, we evaluated the effect of the above material wastes on thermal comfort and building energy consumption. The type and the thickness of the materials were considered as variants to choose the better solution. The average temperatures of building supposed thermally insulated compared to those obtained without insulation clearly show the thermal insulation ability of tested materials during the cold and warm periods of the year. Increasing the thickness of the insulator makes locals increasingly comfortable. Because of their performance, leather and carpentry wastes can compete with conventional insulating materials such as polystyrene and cork.

Analysis of the influence of wood cladding on the thermal behavior of building façades; characterization through simulation by using different tools and comparative testing validation

New policies on energy efficiency in buildings aim to improve our environment. EU requirements on reduced energy demand to achieve Nearly Zero Energy Buildings are of equal importance to pollution and raw-material consumption. Addressing these parameters, building life-cycle analyses are needed, not only to reduce energy consumption, but also to encourage the use of renewable materials. Other priorities are building maintenance and construction material management at the end of the useful life of the building. The use of wooden façades is not very common in Spain. In this study, its energy efficiency is assessed against Spanish Government Regulations, through the Building Technical Code. Hence, this analysis of wooden façades examines their influence on the thermal behavior of the whole building, considering both material properties and structural design, focused on the exterior cladding or protective layer. These structures imply an optimized assembly design together with the application of a protective treatment, depending on its natural durability. “Radiata pine” was selected as one of the most common pine species in the Basque Country, suitable for cladding and grown in sustainable forestry programs. Several commercial simulation tools were used, such as: Therm, Wufi, and DesignBuilder aiming to a full thermal characterization of these particular enclosures, whereas the results obtained were finally validated through an experimental facility.

Assessment of Direct and Indirect Impacts of Vegetation on Building Comfort: A Comparative Study of Lawns, Green Walls and Green Roofs

Following development and validation of the Solene-microclimat tool, the model was used to compare the impacts of various “greening strategies” on buildings’ summer energy consumption and indoor comfort. The studied strategies were greening walls, roofs, and ground (lawns). Solene-microclimat enables to simulate simultaneously a building's thermal behavior and the microclimate at the district scale, with the retroaction of buildings on climate. Distinguishing between direct (due to the modification of building’ characteristics) and indirect impacts (due to the modification of boundary conditions) of these surfaces is also possible. Thus, the strategies were successively implemented on the studied building, the surroundings, and both of them. The simulations were carried out using Solene-microclimat considering insulated vs. non-insulated buildings. Findings confirm that the direct and indirect effects of theses surfaces are almost negligible on insulted buildings. For non-insulated ones, green walls have a direct effect on indoor comfort throughout the entire building, whereas the effect of green roofs is primarily confined to the upper floor. Moreover, the indirect effect of a green wall is greater, mainly due to the drop in infrared emissions resulting from a lower surface temperature. It has also been proven that the indirect effects of green walls and surrounding lawns can help reduce the loads acting on a non-insulated building. Direct and indirect effect can’t be directly added. This is particularly interesting for heritage buildings or highly glazed ones the refurbishment of which is often difficult.

A Study on the Impact of Changes in the Materials Reflection Coefficient for Achieving Sustainable Urban Design

A lot of geographers, scientists believe that the current climate has changed. Especially, since the rapid increment of world's population. Indeed, rapid urbanization led to an increased demand of basic facilities, such as public transport services, hospitals, housing &, etc. Accordingly; the urban areas of cities have been expanded compared to rural areas, and many modifications and changes have been happened on their surface's materials. These modifications made our cities hotter than the Countryside, UHI effect phenomenon now well-known. One of the main reasons behind these changes is construction materials in both buildings and urban spaces, which play a major role in affecting the urban temperatures, precisely near-surface air temperatures positively or negatively, which depend mainly on the behaviour of the surface with solar radiation and how the energy is reflected, emitted, and absorbed. Thus, the current study aimed to investigate the direct and indirect impacts of materials reflection coefficient on the environmental performance and external urban surface temperature; by using the SOLENE-microclimate model tool (developed by the laboratory CRENAU - ENSA Nantes); which is a direct effect on external air temperature in terms of sustainability in the urban context. This study applied on one of the most important residential complexes in Mosul city - Iraq as a case study. The results were proved that when used a material with high reflectivity; Comparing low albedo Scenario(1) with high albedo Scenario(3); it can improve the thermal behaviour of building and urban surfaces, where the surfaces temperature of rooftop, walls, urban spaces, road have been changed by, respectively, 25°C, 18°C, 20°C, and 18°C. As well as changed the urban air temperature by 11°C. However, the results showed that in some cases the surface temperatures increased slightly even when reflectivity increased in the scene, (comparison scenario 3 and scenario 5) where the change of albedo value of external walls surfaces have affected increasing the average urban spaces & pavement temperature about 2°C. The tool that is used in this study (SOLENE-microclimate) has effectively helped in achieving all the analysis required successfully, which it represent the most specialized tool in this field.

Analysis of uncertainty indices used for building envelope calibration

Nowadays there is a growing concern about climate change and the global warming effect produced by the concentration of greenhouse gases (GHG). At the Paris climate conference (COP21), 195 countries adopted a global climate agreement, limiting global warming to well below 2°C. Buildings are large producers of GHG and therefore international standards such as ISO 50001 focus on improving their energy performance, including energy efficiency, use and consumption. To achieve this goal it is important to have a detailed knowledge of the thermal behaviour of buildings. The International Performance Measurement and Verification Protocol (IPMVP), proposes a calibrated simulation model (Option D) to gather this knowledge and to determine the savings associated with Energy Conservation Measures (ECMs).This paper improves the calibration methodology proposed by Ramos et al. (2016) [1], solving the limitations regarding the number of thermal zones and the use of free-floating time periods. Through a real case-study that guides the process, the paper explains how to achieve a calibrated Building Energy Simulation (BES) model using an optimisation process based on a meta-heuristic strategy (genetic algorithm - NSGA-II). Different uncertainty indices such as: CV(RMSE) and Goodness of Fit (GOF) are used as objective function to obtain the calibrated model. These indices, frequently used to measure the accuracy of models, are combined to provide a double possibility to find the best solution, as they are an objective function and a model accuracy measure.

Study on Thermal Behavior of an Experimental Low-energy Building in the Hot Summer and Cold Winter Zone of China

This paper is based on a study of the expansion part of the architecture department building in Huazhong University of Science and Technology (hereinafter referred to as the experimental building). Thermal environment parameters, building energy consumption and other aspects of the experimental building are monitored. The results show that indoor air temperature can be improved to about 14°C in winter and 28°C in summer by the thermal regulation system, which was limited by the underground soil temperature in Wuhan. Because of the function of the under floor air distribution system, an uneven air temperature distribution is formed in the experimental building. The building energy consumption is 10.7kWh/(m2*a), much lower than the ordinary office buildings in Wuhan. In general, the experimental building can achieve a certain indoor thermal environment with low energy consumption, meeting the requirements of buildings with no-strict thermal comfort demands in the rural areas of hot summer and cold winter zone of China. A heat pump or auxiliary heating/cooling source should be added in the system to achieve a more comfortable indoor environment.

Comfort air temperature influence on heating and cooling loads of a residential building

The paper presents the thermal behavior and energy loads of a two-level residential building designed for a family of four, two adults and two students, for different inside comfort levels reflected by the interior air temperature. Results are intended to emphasize the different thermal behavior of building elements and their contribution to the building's external load. The most important contributors to the building thermal loss are determined. Daily heating and cooling loads are computed for 12 months simulation in Bucharest (44.25°N latitude) in clear sky conditions. The most important aspects regarding sizing of thermal energy systems are emphasized, such as the reference months for maximum cooling and heating loads and these loads’ values. Annual maximum loads are encountered in February and August, respectively, so these months should be taken as reference for sizing thermal building systems, in Bucharest, under clear sky conditions.

Investigating the Influence of Light Shelf Geometry Parameters on Daylight Performance and Visual Comfort, a Case Study of Educational Space in Tehran, Iran

Daylight can be considered as one of the most important principles of sustainable architecture. It is unfortunate that this is neglected by designers in Tehran, a city that benefits from a significant amount of daylight and many clear sunny days during the year. Using a daylight controller system increases space natural light quality and decreases building lighting consumption by 60%. It also affects building thermal behavior, because most of them operate as shading. The light shelf is one of the passive systems for controlling daylight, mostly used with shading and installed in the upper half of the windows above eye level. The influence of light shelf parameters, such as its dimensions, shelf rotation angle and orientation on daylight efficiency and visual comfort in educational spaces is investigated in this article. Daylight simulation software and annual analysis based on climate information during space occupation hours were used. The results show that light shelf dimensions, as well as different orientations, especially in southern part, are influential in the distribution of natural light and visual comfort. At the southern orientation, increased light shelf dimensions result in an increase of the area of the work plane with suitable daylight levels by 2%–40% and a significant decrease in disturbing and intolerable glare hours.

Diagnosing thermal behaviour of the administration block of the University of Colombo for retrofitting passive design strategies

Existing non-domestic buildings in developing countries account for a substantial percentage of energy usage for indoor climate control and therefore contribute to carbon dioxide emissions. High levels of air temperatures associated with radiation in warm-humid climates contribute to heat gain and thus indoor overheating conditions and indoor thermal discomfort. These trends have contributed to introducing active systems in building operation resulting in increase of energy consumption. The method used in the study involved on site investigations of thermal behavior of commercial office buildings in urban warm humid climates in Sri Lanka. Literature showing that thermal behavior of building microclimates, form and envelope are important design variables which can act as modifiers of outdoor climate into favorable indoor climates in buildings. The study evaluates the potential of these variables in maintaining indoor thermal comfort. Based on the thermal analysis of the building and immediate surroundings a retrofitting proposal was developed to improve building thermal performance.

Valuation Supports Green University: Case Action at Mediterranea Campus in Reggio Calabria

Civil society, economies, governments are asking to Universities to find a solution for Global Warming problems. Since they are mainly due to human settlement and continuous development and construction, research strategy has singled out Architecture Passivation or Building Greening as a first solution; thereby establishing as its main goal the start-up of real world prototype works, experimental chantiers or building sites, as well as their implementations and monitoring. Geomatic Valuation University Laboratory (GeVaUL) is carrying out a direct experience in real-world implementation of sustainability, designing a strategy for the Mediterranea University campus greening and “passivation” (= energy efficiency). It is done through careful climatic calculation of academic building thermal behavior, and the consequent economic and physical cost-effectiveness valuation of interventions for passivation, i.e. for radical enhancement of energy efficiency. Knowledge of cost-effectiveness valuation has been applied to architectures i.e. buildings or facilities of University Campus in Reggio Calabria. GeVaUL designed greening and building insulation obtained by using ecological cork and bio-ecological lime plaster with impressive well-being regulatory power. Technical Bodies of Central State (Ministry of Industry) and Regional Governments found this approach innovative and appropriate. They are investing in passivation of some University buildings using bio-ecological cork and natural lime plaster, and providing investment capital. Furthermore real world bio - ecological sustainable retrofitting sites have been set up for selected University buildings. Evidence gained thanks to the above experimentation has been applied to simulate passivation of the entire Latin Quarter area (surrounding the University), producing relevant impact with potential influence on local and regional economy.

Retrofit interventions in non-conditioned rooms: calibration of an assessment method on a farm winery

In the Mediterranean area, most wine farms make use of unconditioned above-ground buildings for wine conservation and ageing. Those buildings are usually constructed without a specific temperature control design, therefore indoor temperature distributions and trends can be suboptimal for wine storage. At the same time, various elements (commonly available in farms such as straw bales and climbing plants) could be used to create cheap constructive solutions capable of improving building's thermal behaviour. This study aims to test the effectiveness of different retrofit interventions for thermal behaviour improvement in unconditioned above-ground farm buildings, referring to wine-ageing requirements. The alternative design solutions are evaluated through energy simulations, calibrated and validated on an Italian case study. The results show the importance of roof insulation, and the improved performance of the combination of more retrofit strategies. The proposed approach can be extended to other passive strategies and proves useful to provide information to optimize, or even avoid, conditioning systems.

Urban and outdoor building thermal behavior with green façades

Na busca de solucoes mais sustentaveis para o desenvolvimento urbano das cidades, a utilizacao de fachadas verdes em grandes centros urbanos e uma importante ferramenta de combate aos efeitos das alteracoes de condicoes climaticas. No entanto, e necessario quantificar os beneficios e o impacto na reducao termica urbana gerados na presenca de fachadas verdes, por ser variavel a magnitude do desempenho termico que podera ser atingido. O estudo de caso tem como foco demostrar qual a reducao termica do meio urbano imediato na presenca de uma fachada verde. Seu objectivo e quantificar, analisar e comparar o comportamento termico de uma fachada recoberta por vegetacao e uma fachada “convencional”, em funcao de variaveis climaticas de temperatura, umidade e velocidade do ar, coletadas in situ , inseridas no mesmo microclima no centro da cidade de Madrid, Espanha, relacionando o comportamento termico destas fachadas em diferentes estacoes do ano e periodos do dia. A investigacao experimental abrange duas campanhas de medicoes realizadas em diferentes estacoes do ano: no verao, em que sao observadas temperaturas medias mais elevadas, e no periodo do outono, no qual as temperaturas medias sao inferiores. O monitoramento das medicoes in situ dos parâmetros climaticos foram efetuados durante seis dias e em tres periodos do dia.Os valores e resultados encontrados estao em consonância com estudos similares desenvolvidos em diferentes paises. A analise comparativa dos resultados experimentais obtidos entre a fachada recoberta por vegetacao e a fachada “convencional” demostram que, a fachada verde tem significativo potencial de reducao da temperatura no microclima urbano circundante, sendo uma ferramenta eficaz no desenvolvimento urbano de cidades mais sustentaveis. A B S T R A C T The use of green facades in large urban areas has been used in search for more sustainable solutions for the urban development of cities and as an important tool to strike the effects of climate change. However, it is necessary to quantify the benefits and the impact on the urban thermal reduction achieved due to green facades, because the magnitude of thermal behavior that might be achieved is variable. The main goal of this paper is to quantify, analyze and compare the thermal behavior between a green facade and a bare facade. Both facades are located in the same microclimate in the city center of Madrid, Spain. The presented case study demonstrates the impact of green facades in the thermal reduction in urban areas. Data of climate variables such temperature, humidity, and air velocity were collected in situ, in different seasons and different daytime periods. The experimental research stage took place in two different seasons of the year: in summer, when the average temperatures are higher; and in autumn, when the average temperatures are lower. The climate variables were monitored during 6 days and at 3 different time periods. The measured values are in accordance with similar studies conducted in different countries. The comparative analysis of experimental results obtained between the green facade and the bare one shows that the green facade has a significant potential of thermal reduction in the surrounding urban microclimate, being an efficient tool for the sustainable urban development of cities . Keywords: green facades, urban thermal behavior, urban sustainability, microclimate.

Simulating Building Thermal Behaviour: The Case Study of the School of the State Forestry Corp

The building thermal performance plays a fundamental role in reducing the national energy consumption, especially considering that the majority of the existing structures were built before energy efficiency was a concern at all. The paper presents the case study of the School of the State Forestry Corp in Sabaudia (Italy). The aim is to simulate the thermal behaviour both in stationary and dynamic conditions, and to identify the most appropriate action to improve the building energy efficiency, ensuring occupants’ thermal comfort during the year. The results clearly show that considerable thicknesses of insulating material do not represent an advisable retrofitting in summer.

Experimental and numerical studies of hybrid PCM embedded in plastering mortar for enhanced thermal behaviour of buildings

This paper proposes a methodology for improvement of energy efficiency in buildings through the innovative simultaneous incorporation of three distinct phase change materials (here termed as hybrid PCM) in plastering mortars for façade walls. The thermal performance of a hybrid PCM mortar was experimentally evaluated by comparing the behaviour of a prototype test cell (including hybrid PCM plastering mortar) subjected to realistic daily temperature profiles, with the behaviour of a similar prototype test cell, in which no PCM was added. A numerical simulation model was employed (using ANSYS-FLUENT) to validate the capacity of simulating temperature evolution within the prototype containing hybrid PCM, as well as to understand the contribution of hybrid PCM to energy efficiency. Incorporation of hybrid PCM into plastering mortars was found to have the potential to significantly reduce heating/cooling temperature demands for maintaining the interior temperature within comfort levels when compared to normal mortars (without PCM), or even mortars comprising a single type of PCM.

Experimental and numerical investigation of thermal bridging effects of jointed Vacuum Insulation Panels

Vacuum Insulation Panels (VIPs) are characterised by very low thermal conductivity, compared to traditional insulating materials. For this reason, they represent a promising solution to improve the thermal behaviour of buildings, especially in the case of energy retrofitting (where a higher performance and less thickness is desirable). VIPs are insulating components in which a core material is surrounded by an air tight envelope which allows a high degree of internal vacuum to be maintained. Such features, on the one hand, allow excellent thermal insulation properties to be achieved, but, on the other, require the manufacturing of prefabricated panels of fixed shape/size. This means that the use of these super insulating materials in the building envelope involves the problem of joining the panels to each other and of fixing them onto additional supporting elements.As a result, purposely studied supporting structures or systems are required. However, these structures and systems cause thermal bridging effects. The overall energy performance of the resulting insulation package can therefore be affected to a great extent by these additional elements, and can become significantly lower than that of the VIP panel alone.In order to verify the incidence of thermal bridges on the overall energy performance of an insulation system that makes use of VIP panels, an experimental campaign has been carried out using a heat flux metre apparatus and analysing different joint materials/typologies. First, a measurement method was proposed, tested and verified on the basis of data from the available literature. A series of measurements on different samples was then performed. The experimental results were then used to calibrate and verify a numerical model that allows the performance of various “VIP packages” to be predicted and the performance of the overall package to be optimised.