External Wall Thermal Insulation Research Articles

USE OF MONOLITHIC FOAM CONCRETE IN ENCLOSING STRUCTURES OF BUILDINGS AND STRUCTURES WITH VARIABLE THERMAL CONDITIONS

This article considers the features of the use of monolithic foam concrete as a heat-insulating layer in the building enveloping structures of buildings operated under intermitt ent heating conditions. To assess the eff ectiveness of the use of monolithic foam concrete in building enveloping structures, a thermal engineering calculation of the outer wall, insulated with the use of monolithic foam concrete, was carried out. Based on the calculations carried out by the authors, graphs of the dependence of the heating time of multilayered enclosing structures on the thickness of the heat-insulating layer and the reduced resistance to heat transfer of the structure were obtained. The optimum range of thicknesses and densities of monolithic foam concrete for thermal insulation of external walls of buildings, operated in conditions of intermitt ent heating, is off ered. This calculation also showed that the use of foam concrete as a heater from the inside of the outer wall can reduce the load on the foundation of the building.

Experimental and analytical determination of water vapour transmission properties of recyclable insulation material

The article presents the results of preliminary research related to the development of a new solution for thermal insulation of external walls from the inside. The innovative material solution is based on a recyclable material (re-expanded polystyrene) combined with cement, creating a light concrete with high thermal and moisture parameters. Preliminary research included the determination of the basic features of the European Assessment Document (EAD). The paper presents the determination of diffusion parameters based on the model of water vapor transport in a porous material. The main assumption of the authors was to develop a material whose diffusion resistance coefficient was close to 6–7 [–]. The solution would ensure free flow of water vapor in brick walls insulated from the inside and it does not lead to thermal or moisture disturbances. The main aim of the article is to demonstrate the great potential of using recycling materials in construction.

Investigation of the Factors Affecting Technical and Economic Indicators of Thermal Insulation of External Walls of Buildings

The technology of insulation of enclosing constructions of buildings and constructions is characterized. The method of technological design on the basis of integrated production of technological processes, estimation and influence of organizational and technological reliability of building production depending on methods, technologies and constructive decisions is given.The data collection for the energy certificate of the building is shown. Energy certificate of the building is a document containing the geometrical, energy and heat engineering characteristics of the building being designed or operated, as well as the characteristics of the heat insulation. This document also establishes the compliance of the building with the requirements of regulatory documents. The energy passport of the building is not intended to be used to make payments for utility or other services provided to homeowners, tenants and apartment owners.Energy assessment of the building - energy efficiency of buildings should be determined on the basis of estimated or actual annual energy consumption necessary to meet various needs associated with its typical use in the building. These needs should include the energy consumption for heating and cooling to maintain the desired temperature, as well as hot water supply.

Joints in masonry walls

AbstractA correct design project should not only control the load‐bearing capacity and stability of the individual elements but also ensure proper cooperation between these elements. Connection of masonry walls is crucial for durability of the building, safety of its users, and thermal insulation of external walls. The design and construction process is successful only if loads can be transferred properly between the particular structural elements. The issue of joints between the walls and consequent transferring of vertical and horizontal loads between them is still not sufficiently recognized. Very few tests have been performed on this issue, while operating standards require that the designer ensures proper cooperation between intersecting walls. In this paper, information is collected on the code requirements, design procedures, producer's recommendations as well as the laboratory tests results, and conclusions in the topic of joints in masonry walls. Additionally, results of preliminary tests performed by the authors on the joints of autoclaved aerated concrete (AAC) masonry walls are presented.

Whole Life-Cycle Ecological Footprint of Rural Existing Houses in Northern China

To solve the increasing contradiction between the living environment and residential energy consumption in rural areas, it is urgent to alter the traditional living mode and create a new living pattern with a pleasant environment. Based on the theory of ecological footprint, in this article we compare the whole life-cycle ecological footprint between the northern rural house with various energy-saving measures and the urban multi-layer residence with only external wall thermal-insulation as the energy-saving measure. The results show that the sustainability of the multi-layer residence is obviously superior to the rural house. Therefore, rural house designers should learn the multi-layer residential design strategies, construction methods, and operation modes to reduce the unnecessary waste of the energy and resources. Through centralized planning, construction, and heating systems, the multi-level residence is conducive to sustainable human development. The study provides relevant theoretical support for low-carbon house construction in village areas.

Optimization of thermal insulation of external walls of wooden frame constructions

The article deals with the optimisations of external structures and points to energy-savings and requirements of low energy construction. It defines and evaluates the problems of required thermal-technical characteristics achievement set by standard for external structures of low energy and energy passive houses. At the same time, it describes in detail different variants of their optimisation.

Study on Thermal Insulation Structure of Assembled Residential Graphene EPS Module Based on Energy efficiency 65% in Severe Cold Area

Based on the climatic and actual conditions in the severe cold region represented by Changchun, Jilin Province, this paper analyzes the problems in the exterior insulation materials currently used in the market. By studying the basic characteristics of grapheme EPS module, we put forward the construction method applied to the external wall thermal insulation of the assembled residential building in severe cold area where the energy efficiency rate is 65%.

Analysis of Fire Risk Associated with Photovoltaic Power Generation System

Because of increasing energy consumption and severe air pollution in China, solar photovoltaic power generation plants are being deployed rapidly. Owing to various factors such as technology, construction, and imperfection of construction standards, solar photovoltaic systems have certain fire risks. This paper focuses on the fire risks of building‐integrated solar photovoltaic buildings, as well as temperature and heat flow density near a photovoltaic system in a fire. Based on FDS simulation results, the influence of different building fires on photovoltaic systems is analysed. It is found that the influence of fire on photovoltaic systems installed on a building with a flat roof is stronger than that on a system installed on a building with a sloping roof; the influence of fire on a photovoltaic system installed on a building with external wall thermal insulation is stronger than that on a system installed on a building without such insulation; and in the presence of a skylight, a photovoltaic system installed on a building with a sloping roof is more dangerous.

Experimental investigations of wooden beam ends in masonry with internal insulation

Today’s stringent requirements on building energy performance and gradually increasing price of energy enforce complex refurbishment measures. Improvement of thermal insulation of building enclosure is the first logical step for climatic conditions of semi-continental climate. Refurbishment of many buildings with cultural value is possible only by accepting additional thermal insulation of external walls from interior side. Floors in such buildings are often supported by wooden beams placed in pockets embedded in brick walls. This paper deals with temperature and relative humidity in the air cavity behind wooden beam ends. To study this phenomena real scale experiments in University Center for Energy Efficient Buildings (UCEEB) of the Czech Technical University in Prague have been monitored for two years. Measured results indicated the fundamental difference between different types of joist pocket treatment. The relative humidity in open pockets approached to 100 % in cold season and corresponding mold growth index reached a maximum higher than one (germination of mold spores). Sealed pockets reached practically zero mold growth index throughout the experiment, although relative humidity in the pocket tended to exceed 80 % during cold seasons.

Improved prediction of deep retrofit strategies for low income housing in Ireland using a more accurate thermal bridging heat loss coefficient

In order to improve the energy efficiency of buildings, thermal insulation plays a pivotal role, however increasing external wall thermal insulation without also addressing construction details can lead to increased thermal bridging and mould growth. Detailed knowledge of a buildings thermal envelope is paramount to correctly analysing existing problems that promote cold bridging and low surface temperatures. No detailed database exists for housing in Ireland which describes the geometrical configuration of the existing stock. This paper presents findings from an investigation into the prediction of heating energy consumption performance for external envelope retrofit measures when adopting default standardised coefficients for thermal bridging as opposed to simulated values based on accurate geometrical information. Using a remote extraction methodology to obtain geometrical information on house typologies, this paper presents a study that produced a detailed building component database premised on stock aggregation theory using Cork City’s local authority housing as a case study. Three construction types; block on flat, cavity and composite cavity are identified with representative construction details for housing typologies modelled in Psi-Therm 2d enterprise. Linear thermal transmittance and minimum surface temperatures are evaluated and an energy efficient external retrofit for each construction detail is proposed. Thermal characteristics for each house archetype are developed using information extracted from 1551 asset rating surveys. Three case study terraced house typologies are then modelled using Ireland’s national asset rating software to demonstrate the importance of obtaining more accurate information regarding the building stock. The results highlighted up to 21.5% variation in energy performance when replacing a default thermal bridging coefficient for calculated values.

Optimal combination of thermal resistance of insulation materials and primary fuel sources for six climate zones of Japan

Since the East Japan great earthquake disaster in March 2011, liquefied natural gas (LNG) to replace nuclear energy has become the most-used fuel source for energy generation in Japan. Japan is implementing energy conservation policy. Building energy consumption accounts for a large proportion of the total energy consumption. To better combine the thermal insulation of external walls and fuel source utilization will play an important role in building energy conservation. This paper aims at finding the optimal combination from four different insulation materials and four different fuel sources for residences using electricity for heating and cooling in the six climate zones of Japan. The optimal thermal resistance (OTR) of insulation materials, energy cost saving per unit area of external walls and payback periods if the OTR is adopted for six climate zones are estimated via a cost analysis and degree-day (DD) method. According to the results, the optimal combination for all climate zones has been obtained by using rock wool as the insulation material and LNG as the fuel source. The energy cost saving and payback periods are 20.4 $/m2-yr and 0.4 yrs respectively, while the OTR is 2.5m2K/W for Sapporo (in climate zone I), 14.1 $/m2-yr and 0.5 yrs respectively, while the OTR is 2.1m2K/W for Akita (in climate zone II),11.2 $/m2-yr and 0.6 yrs respectively, while the OTR is 1.8m2K/W for Fukushima (in climate zone III), 5.2 $/m2-yr and 0.8 yrs respectively, while the OTR is 1.3m2K/W for Osaka (in climate zone IV), 2.5 $/m2-yr and 1.2 yrs respectively, while the OTR is 0.9m2K/W for Kagoshima (in climate zone V), and there is no need to adopt thermal insulation for Naha (in climate zone VI).

Rheological and thermal properties of aerated sprayed mortar

This paper studies the rheological properties in aerated cement pastes in order to develop an aerated sprayed mortar with low thermal conductivity. For this purpose, different mixtures of cement with additions of metakaolin (MK) and sepiolite (SP) were tested. In addition, influence of yield stress on build-up thickness, as well as expansion speed and pore network were studied using cement pastes aerated with aluminum powder. At the same time, the volume increase during expansion, water retention and yield stress of the fresh foamed cement pastes were studied to characterize the fresh mortar. Results obtained show that the incorporation of siliceous fly ashes (SFA) in ordinary Portland cement together with additions of MK or/and SP provided the largest expansion speed increase and the lowest density of the aerated mortar. Pastes with greater yield stress show higher thermal conductivity but are better to be pneumatically gunited due to its bigger build up thickness. The most suitable paste from all them was selected, sprayed and aerated over ceramic bricks, checking the results on site. Results obtained by means of these tests confirm that is possible to spray an aerated mortar over vertical surfaces. In addition, this mortar has acceptable thermal insulation properties to be used in chambers of building façades and for external wall thermal insulation systems (EWIS).

Energy Consumption Analysis of Building with Typical External Thermal Insulation System

External wall thermal insulation system protects the major structure of building effectively. In this study, a student dormitory building with typical external wall thermal insulation system in Beijing was chosen as the research object and the energy consumption analysis was conducted to identify the optimal external thermal insulation system during the whole life cycle. The results show: for brick-concrete buildings, the consumption of clay brick, reinforced concrete and cement mortar account for more than 95% of the total materials consumption, where reinforced concrete contributes most to energy consumption. The external insulation system with similar heat transfer coefficient but consist of different insulation materials mainly affects energy consumption in materials production phase (the difference of building production energy consumption is about 7.2%), while has no significant effect in building operation phase and whole life cycle. With the increase of heat transfer coefficient, the energy consumption decreases in materials production phase, accounting for 16.3%-21.9% of the life cycle energy consumption, increases in building operation phase, accounting for 78.1%-83.7%, and can be neglected in the disposal phase. And there exists an optimization value in building whole life cycle, at which the minimum value of the energy consumption reaches, when the heat transfer coefficient is 0.3W / (m2 • K), equivalent to 127mm EPS insulation thickness or 151mm rock wool insulation thickness.

Surface modification of light hollow polymer microspheres and its application in external wall thermal insulation coatings

Purpose – The purpose of this paper is to modify light hollow polymer microsphere (LHPM) with titanium dioxide nanoparticles (nano-TiO2) to improve its compatibility with latex and apply the obtained nano-TiO2/LHPM composite particles in external wall thermal insulation coatings. Design/methodology/approach – The nano-TiO2/LHPM composite particles were prepared via vigorous stirring. The morphology and chemical composition of the produced nano-TiO2/LHPM composite particles were characterized using scanning electron microscopy, energy dispersion spectrum, thermo-gravimetric analyzer and Fourier transform infrared. The performance of this new composite coating was evaluated by checking its stability, density, radiation reflectivity, thermal conductivity and the resulting insulation temperature difference when forming coating film. Findings – It was found that a 9:1 mass ratio of nano-TiO2/LHPM with total 10 weight per cent composite particles in the thermal insulation paint showed low density, good stability, low thermal conductivity (0.1687 W/m·K) and high insulation temperature difference (5.8°C). Research limitations/implications – The LHPM can be modified by other nanoparticles to improve its insulation performance in thermal insulation coatings. Practical implications – This work provides a simple, robust, but effective approach to produce new thermal insulation coatings with nano-TiO2/LHPM composite particles. Originality/value – This method for surface modification of LHPMs is novel and the modified hollow polymer microspheres could be applied to external wall insulation coatings.

The Influence of Additional Insulation of Facades to their Aesthetic Devaluation by Vegetation of Algae, Fungi and Cyanobacteria

The purpose of the facade insulation is to reduce transmission heat loss from the heated interior to exterior. After some time, it can be said that the insulation of the building envelope served its purpose and significantly reduce heat use for heating of insulated buildings. Time, however, showed the risks of external thermal insulation composite system (ETICS). One side effect of reducing transmission heat loss of buildings by using of ETICS can be considerable aesthetic devaluation of facades. Sometimes façade with ETICS become a suitable substrate for the growth of microorganisms. These are algae, fungi and cyanobacteria, which creates unsightly green and black growths on facades. The article deals with the connection between thermal insulation of external walls and the presence of vegetation microorganisms.

冬夏交替环境下EPS外保温系统有限元分析

EPS板因其优良的保温性能，使得EPS墙体外保温系统成为当今建筑保温体系的主流。本文通过有限元分析软件，对EPS外保温系统在冬季低温和夏季高温环境下的影响进行了模拟。模拟结果表明，高温和低温的交替作用，是引起外保温墙体产生裂缝和脱落的主要原因之一；EPS板具有优良的保温性能；墙体四周以及窗户处变形最为突出，故此处应当引起重视。通过对外墙保温系统的数值模拟，得出了墙体应变的发展规律，为外墙外保温系统的局部节点设计以及相应工程灾害的处理，提供了科学分析和理论依据。 EPS external wall thermal insulation system has become the mainstream of today’s construction insulation system because of its good thermal insulation performance. EPS external thermal insulation system under the influence of winter low temperature and summer high temperature environment is simulated by finite element analysis software. The simulation results show that high temperature and low temperature alternating effect is one of the main reasons for cracks and falling off of external thermal insulation wall; EPS board has excellent insulation properties; the deformation of the walls around and windows around is the most prominent, and therefore should be taken seriously. Through the numerical simulation of the external wall thermal insula-tion system, the regular of wall strain development is obtained, which provided scientific analysis and theoretical basis for nodes design and processing of the corresponding engineering disasters of external wall thermal insulation system.

A novel process for synthesis of tobermorite fiber from high-alumina fly ash

A new two-step process was developed for the synthesis of tobermorite fiber from high alumina fly ash. The results reveal that high alumina extraction efficiency from the fly ash can be achieved in the first step and tobermorite fiber with excellent properties can be produced from the dealumination slag in the second step. FETEM images show that typical single crystal fibers with a length of 5–10 μm and a length-to-diameter ratio of 50–100 have been synthesized successfully. The strength tests after compression molding demonstrate that the compressive and flexural strengths of the products are greater than 0.34 MPa and 0.85 MPa, respectively, with a low bulk density of 218 kg/m3 and a thermal conductivity of 0.059 W/(m·k). It fully complies with China's national standards for calcium silicate insulation materials. Therefore, the fibers production is very promising to be used in the building external wall thermal insulation application.

Probabilistic assessment of failure risk of the building envelope thermally insulated from the inside

Thermal insulation of external walls is designed in particular to reduce energy performance of buildings. Insulation placed on the outer side of walls act as an effective protection against the external environment. On the contrary placing the thermal insulation layer on the inner side of the building envelope is quite hazardous as the internal insulation does not fulfil the protective function. It actually exposes the bearing layer of the building envelope to the immediate effect of the environment and therefore it enhances the negative impacts of the cyclic temperature changes on structural system of the building. This paper focuses on probability risk of development of failures on such construction depending on variable boundary conditions (rigidity of the structure, strength of the materials, and range of the temperature load). Besides this there is also comparison of probability and deterministic approach to the evaluation of static reliability of the building constructions. Using of probabilistic approach in this context is still very rare. The aim of this paper is to analyse the effects of internal insulation on load bearing system of buildings, and to verify the applicability of probabilistic methods in the analysis of structural reliability. Like the deterministic approach, it draws attention to the high risk of failure of the structures insulated from the inside. At the same time, however, it shows the high demands of the probabilistic method on the amount of input data. If the data are not available, it is possible to replace some of them results of deterministic method; this approach has negative consequences in mutual dependency of accuracy of achieved results.

Investment-savings method for energy-economic optimization of external wall thermal insulation thickness

This article analyses the optimum energy-economic thickness of thermal insulation layer for external wall. The analysis was performed by applying a new method ‘investment-savings’. An appropriate mathematical model was developed during the work. The mathematical model consists of energy and economic part. The economic part of the model contains algebraic equations for investment, exploitation and savings. The considered wall was made of brick and polystyrene was used as thermal insulation material. The heat transfer through the wall was steady-state. An analytical-numerical and graph-numerical methods were applied to solve the mathematical model. The minimum payback period of the investment was the optimization criterion. The numerical results obtained by the simulation are presented graphically. The optimum thickness of the thermal insulation layer is shown in the diagrams. In addition, by applying the developed mathematical model the optimum thickness of thermal insulation layer for energy-economic conditions in Serbia in 2014 was obtained. By applying the current prices in Serbia, the energy-economic efficient optimum thickness of the thermal insulation layer of the polystyrene is 6.89cm which is rounded to ≈7cm. Polystyrene can be bought in 1, 2, 3, …, 7, …, 10, …cm thickness only. The payback period is 1.22 years if the price of electric energy is 0.09€/kWh. A significant result of the study: increase in thickness by 4.86 times, while investment increases only by 1.69 times.

Study on Energy Saving of External Wall Thermal Insulation Based on City Green Building

In recent years, with the continuous development of society, people's awareness of energy conservation has also been enhanced. Among them, building energy consumption occupies a very large proportion in all their energy consumption. Therefore, people have taken various measures to reduce the energy consumption of building its own. External wall thermal insulation is a new building energy saving technology. Through verification, application of external wall insulation technology in building energy saving greatly reduces the energy consumption of buildings. This paper mainly introduced on the city building external wall thermal insulation technology and some related measures.