Insulation Of Building Envelope Research Articles

Heat insulation and thermal insulation method of passive low energy consumption residential building exterior envelope structure based on BIM

With the improvement of economic level, a continuous rise in building energy consumption brings about serious environmental problems. Therefore, this study proposes a passive energy-consuming residential building envelope thermal insulation and heat preservation method based on building information modeling technology for building energy consumption increasing and envelope structure's performance improving. Firstly, it is a study on the passive low-energy residential building envelope's thermal insulation materials and architecture, and secondly, it is a study on the improvement of the thermal insulation and heat preservation performance of the passive low-energy residential building envelope on the foundation of building information modeling. These experimental results show that in the residential building, the indoor temperature averages around 27.8 °C, of which the highest indoor ambient temperature is found at 21 o'clock, with a temperature value of 28.4 °C, which reduces 2.1 °C when comparing with the indoor temperature under the traditional residential building. Under the exterior wall construction utilizing this technology, the temperature change of the indoor environment is smoother, which satisfies people's requirements for the indoor living environment. At the same time, the area parameters of the ventilation area of the building and the area of the envelope obtained after the analysis of BIM technology have a significant effect on the cooling of the interior. This method reduces the use of resources and lays a good foundation for the further development of building informatization, which is significant in realizing the informatization developing in construction.

Rice Husk-Based Insulators: Manufacturing Process and Thermal Potential Assessment.

The development of bio-insultation materials has attracted increasing attention in building energy-saving fields. In tropical and hot-humid climates, building envelope insulation is important for an energy efficient and comfortable indoor environment. In this study, several experiments were carried out on a bio-insulation material, which was prepared by using rice husk as a raw material. Square rice husk-based insultation panels were developed, considering the ASTM C-177 dimensions, to perform thermal conductivity coefficient tests. The thermal conductivity coefficient obtained was 0.073 W/(m K), which is in the range of conventional thermal insulators. In a second phase of this study, two experimental enclosures (chambers) were constructed, one with rice husk-based insulation panels and the second one without this insulation. The measures of the temperatures and thermal flows through the chambers were obtained with an electronic module based on the ARDUINO platform. This module consisted of three DS18B20 temperature sensors and four Peltier plates. Daily temperature and heat flux data were collected for the two chambers during the dry season in Panama, specifically between April and May. In the experimental chamber that did not have rice husk panel insulation on the roof, a flow of up to 28.18 W/m2 was observed, while in the chamber that did have rice husk panels, the presence of a flow toward the interior was rarely observed. The rice husk-based insulation panels showed comparable performance with conventional insulators, as a sustainable solution that takes advantage of a local resource to improve thermal comfort and the reduction of the environmental impact.

Climate resilience and energy performance of future buildings in Nigeria based on RCP 4.5 and 8.5 scenarios

The predicted rise in global temperature by the Intergovernmental Panel on Climate Change IPCC appeals for a review of the methods and materials used for building construction for reduced emissions and comfort in buildings. Buildings account for the most carbon emissions in the globe. This study presents the impact of temperature change across the 36 state capitals in Nigeria, and the Federal Capital Territory, FCT, based on Representative Concentration Pathways, RCPs 4.5 for 2020 and 8.5 for 2090. A simple studio apartment with optimised alternatives for retrofits and new builds was simulated using EnergyPlus for both climate scenarios to determine the strategies for improving the energy performance of future buildings. The result of the study shows a significant increase in mean monthly outdoor temperature of about 5⁰c across the states, with potential heat stress affecting buildings in future climates. Moreover, about one-third of the locations experience a shift in climatic zones to hotter ones. The impact of this climate drift will be more severe in the Northcentral and Southwest regions of the country. The design strategies recommended to mitigate the effects of a changing climate focused on building envelope insulation, thermal mass, and solar shading. The performance of the optimised models under future scenarios accounts for up to 25% and 73% savings in cooling energy for retrofits and new builds, respectively. To protect existing buildings from the impact of future climates, developers must make massive investments in solar shading of buildings. In contrast, a combination of envelope insulation and solar shading strategies proves effective for new builds.

Production of insulation material using styrene acrylic resin from animal and agricultural waste part 1. Thermal insulation and water absorption

Decreased energy resources and subsequent increasing environmental pollution have increased the tendency towards the production of renewable and sustainable insulation materials. This study aimed to produce an innovative and sustainable insulation material using water-based resin from wastes such wood shavings, wheat straws, goose down, to bring the large amount of Kars regional waste into the economy. Response Surface Method Box-Behnken Design was used for process optimization. The result of the optimization optimum mixing ratio was determined as 125 gr binder, 80 gr wood shaving, and 30 gr wheat straw for 0,06 W/mK the thermal conductivity coefficient. It was observed that goose down added to the optimum mixture reduced the thermal conductivity coefficient. %5 Polydimethylsiloxane as hydrophobic agent was used to reduce water absorbency, which is one of the biggest disadvantages of materials produced from animal and agricultural wastes. As a result of this study, water absorbency was reduced from 175% to 20% and the thermal conductivity coefficient of the produced samples were determined between 0.055 W/mK − 0.0681 W/mK. The resulting samples were found to have thermal conductivity and waterproofing properties that make them suitable for building envelope insulation. Produced samples have the potential to be used as light and sustainable insulation materials produced from natural materials in future in building industry.

Feasibility study of developing hollow-core vacuum insulated panels

Super-insulation materials have become more commonplace as highly insulated building envelopes are required to reduce the energy demand of buildings aligned with the net zero targets. While several super insulation materials are available, their environmental impacts and practical on-site limitations hindered their large-scale adoption. The following paper investigates the feasibility of developing hollow-core vacuum insulated panels supported by an internal structural array with different configurations. The designed panel was simulated and measured to evaluate its performance as a thermal insulator for building applications. Panel samples were manufactured from polished stainless-steel plates separated by a PTFE structural array. The change in temperature and heat flux through the sample was measured in a vacuum chamber at a pressure of 0.01 Pa. Thermal conductance was obtained from gradual measurements of heat flux and temperature across the sample after a rapid increase in temperature. Numerical methods that combine molecular and macroscopic solvers were used to model unsteady behaviour recorded in empirical tests. Direct Simulation Monte Carlo (DSMC) was used to calculate the thermal conductivity of the rarefied gas, which was then used to solve the enthalpy equation for the multi-region model. Thermal resistance from empirical tests and numerical methods are in agreement within error bands, the greatest accuracy observed in high conductance models. Thermal resistance as low as 0.17 [Formula: see text] and as high as 4.75[Formula: see text] was measured. Low conductance sample configurations were sensitive to thermal contact conductance from the structural array contact interfaces, accounting for at least 40% of transferred energy. Gas conduction at a pressure of 0.01 Pa transfers up to 4% of energy in low emissivity sample configurations. Radiative energy transfer in high conductance configurations was responsible for up to 95% of transferred energy. The paper provides a comprehensive feasibility study, providing a solid foundation for further design optimization of the technology.

Comparative study of Chinese, European and ISO external thermal insulation composite system (ETICS) standards and technical recommendations

External thermal insulation composite systems (ETICS) are widely used all over the world for building envelope insulation. This paper lists the representative standards for ETICS in Chinese, European and ISO technical assessment documents, and it describes the results of a comparative study on standardization, technology and engineering. First, the standards are related to the project organization mode. The Chinese and ISO standards tend to be normative and different from the standards of the European certification system. Second, the problems of leakage and degradation occur frequently in ETICS in China. It is worthwhile to learn from successful experiences in waterproofing, drainage and other measures. Third, China has made some useful technical breakthroughs in wind load resistance design and quality acceptance by means of considerable amounts research, and has an advantage in engineering practice. Lastly, the types of external insulation systems are diversified in development, in order to meet multiple requirements; it is worthwhile to learn from the European certification system. This research and the conclusions can be used as a reference for the technology, engineering and standardization of ETICS, and for understanding the essential national standards to facilitate trade between countries.

Requirements for renovating residential buildings in the Netherlands towards lower temperature supply from district heating.

In the Netherlands, district heating with a lower temperature supply (<70°C) will play a crucial part in accomplishing the energy transition goals of delivering natural gas-free sustainable heating to dwellings. The existing dwellings often require energy renovations to make them suitable for lower temperature heating. However, choosing renovation strategies that promote the transition to lower temperature district heating while improving energy efficiency and thermal comfort is challenging. This study aims to identify minimum renovation requirements for comfortably heating homes using lower temperature heat from district heating. Identifying minimum renovation strategies to prepare existing dwellings for lower temperature district heating would be vital in addressing the European Renovation Wave’s target of improving worst-performing buildings. For the same, the study uses a typical intermediate terraced house built before 1945 as a case study to investigate renovation strategies based on four levels of renovation intervention (no renovation, basic, moderate and deep). The impact of renovations on space heating demand and thermal comfort was tested with medium (70/50°C) and low supply (55/35°C) temperatures against key performance indicators (KPIs) using dynamic simulation. The study found that for the case study dwelling, moderate renovation strategy of upgrading the building envelope insulation by 0.40 W/m2K for opaque parts and 1.5 W/m2K for glazing, improving the airtightness by 0.3h-1 and replacing existing radiators with LT radiators can be considered as a no-regret solution for comfortably heating homes with both medium and lower temperature supply from district heating.

The overlooked criteria in green building certification system: Embodied energy and thermal insulation on non-residential building with a case study in Malaysia

A green building certification system (GBCS) is essential for sustainable city development. However, the building's embodied energy (EE) and thermal insulation have often been overlooked in GBCSs. The correlation of thermal insulation envelopes to EE and operational energy (OE) has also yet to be extensively investigated. This study adopts life cycle energy assessment methodology to evaluate the EE and OE of non-green and green-rated non-residential buildings with hotspot analysis and analyse the trade-offs between EE production and OE saving for five types of insulation envelopes. Taking Malaysia as a reference, results show EE holds 16–19% of total energy in non-green and green-rated non-residential buildings; hence EE should not be neglected in GBCS. The material consumption phase incurs half a quarter of the total EE, indicating that major recycled and low-embodied building materials (e.g., recycled steel and green cement) should be rewarded with higher points in GBCS. Insulated building envelopes save 84–87% of cooling demand than non-insulated walls, with cellulose fibre insulators consuming the least EE. It is hoped that this study can provide evidence-based outcomes to policymakers when formulating the proportion of EE and OE, and integrating insulation envelopes in GBCS to enhance energy savings further.

Mould-Growth Study in Building Materials Exposed to Warm and Humid Climate Using Heat and Mass Transfer (HAMT) EnergyPlus Simulation Method

Commercial energy consumption currently accounts for 8.6% of the total national energy consumption in India and it is predicted to surge in upcoming years. To tackle this issue, building envelope insulation is being promoted through codes and standards to reduce the cooling and heating demand and hence reduce the overall energy demand. However, with prolonged exposure to humid ambient conditions in warm-humid locations, building materials undergo decay in their hygrothermal properties, which induces mould growth and increases the energy that is needed to tackle the latent cooling load. Mould growth, in turn, harms the occupant and building health. Therefore, this study attempts to evaluate the mould-growth index (MGI) in the coastal city of Mangalore, Karnataka, India using the heat and mass transfer (HAMT) model. The MGI for one autoclaved aerated concrete (AAC) wall assembly in a representative commercial building has been studied by integrating EnergyPlus through the Python plugin. The simulated results suggest that the annual mean MGI for the AAC assembly is 3.5 and that mould growth will cover about 30–70% of the surface area. Furthermore, it was concluded that surface temperature, surface humidity, and solar radiation are key parameters for mould growth on the surface of a material.

Fifty shades of grey: Automated stochastic model identification of building heat dynamics

To reach the carbon emission reduction targets set by the European Union, the building sector has embraced multiple strategies such as building retrofit, demand side management, model predictive control and building load forecasting. All of which require knowledge of the building dynamics in order to effectively perform. However, the scaling-up of building modelling approaches is still, as of today, a recurrent challenge in the field. The heterogeneous building stock makes it tedious to tailor interpretable approaches in a scalable way. This work puts forward an automated and scalable method for stochastic model identification of building heat dynamics, implemented on a set of 247 Dutch residential buildings. From established models and selection approach, automation extensions were proposed along with a novel residual auto-correlation indicator, i.e., normalized Cumulated Periodogram Boundary Excess Sum (nCPBES), to classify obtained model fits. Out of the available building stock, 93 building heat dynamics models were identified as good fits, 95 were classified as close and 59 were designed as poor. The identified model parameters were leveraged to estimate thermal characteristics of the buildings to support building energy benchmarking, in particular, building envelope insulation performance. To encourage the dissimination of the work and assure reproducibility, the entire code base can be found on Github along with an example data set of 3 anonymized buildings. The presented method takes an important step towards the automation of building modeling approaches in the sector. It allows the development of applications at large-scale, enhancing building performance benchmarks, boosting city-scale building stock scenario modeling and assisting end-use load identifications as well as building energy flexibility potential estimation.

A predictive multiphase model of silica aerogels for building envelope insulations

This work develops a systematic uncertainty quantification framework to assess the reliability of prediction delivered by physics-based material models in the presence of incomplete measurement data and modeling error. The framework consists of global sensitivity analysis, Bayesian inference, and forward propagation of uncertainty through the computational model. The implementation of this framework on a new multiphase model of novel porous silica aerogel materials is demonstrated to predict the thermomechanical performances of a building envelope insulation component. The uncertainty analyses rely on sampling methods, including Markov-chain Monte Carlo and a mixed finite element solution of the multiphase model. Notable features of this work are investigating a new noise model within the Bayesian inversion to prevent biased estimations and characterizing various sources of uncertainty, such as measurements variabilities, model inadequacy in capturing microstructural randomness, and modeling errors incurred by the theoretical model and numerical solutions.

Natural Fibre Insulation Materials: Use of Textile and Agri-food Waste in a Circular Economy Perspective

Fibrous materials are among those most used for the thermal and acoustic insulation of building envelopes and are also suitable for a wide range of applications. In building construction, the demand for products with low environmental impact — in line with the Green Deal challenge of the European Community — is growing, but the building market is still mostly oriented towards traditional products, missing the many opportunities for using waste materials from existing industrial production. The paper presents the experimental results of new thermal and acoustic insulation products for building construction and interior design, based on previous experiences of the research group. They are produced entirely using waste sheep’s wool as a “matrix” and other waste fibres as “fillers”. The materials proposed originate from textile and agri-industrial chains in the Piedmont region and have no uses other than waste-to-heat biomass. The panels have characteristics of rigidity, workability, and thermal conductivity that make them suitable for building envelope insulation.

DEA Modelling Effectiveness of Building Envelopes

Today, insulated building envelopes must not only meet thermal-technical, mechanical, and economic requirements but must also be environmentally friendly. These requirements are often contradictory, and it is not clear what the effective option is for a particular case. The aim of the paper is to compare twenty different variants of building envelopes, not only in terms of thermal-technical properties but also in terms of environmental parameters and time and financial demands. The result of the paper is the determination of effective variants by a suitable mathematical method with consideration of all the above-mentioned influences.

Investigation of the envelope’s thermal transmittance influence on the energy efficiency of residential buildings under various Mediterranean region climates

Improving the energy efficiency of residential buildings is of outmost importance for reducing their environmental footprint. Recent studies demonstrate that a highly insulated building envelope may burden the building’s performance during the cooling period, especially in regions with hot summers. In this study, the energy performance of a residential building in different Mediterranean regions (Jordan, Greece, Iraq, Egypt, Syria, Morocco, Cyprus, Saudi Arabia, Libya, and Spain) is investigated. Two thermal transmittance values are applied to the building shell, a scenario with a very low one and a scenario with a higher one, to examine under which conditions the cooling performance is improved. A dynamic insulation configuration is also implemented, and its operation is studied for the cooling period of each city. It is concluded that in Southern European and Northern African regions building envelopes with lower thermal resistances perform better, while in even Southern regions an increased thermal resistance may prevent the heat from entering the building more effectively. With the switching insulation system, a great reduction in the cooling demands was reported, which reached up to 50% in Spain, and it was shown that in the southern regions the configuration’s operation should be customized to the ambient conditions to optimize its performance.

In-situ U-value monitoring of highly insulated building envelopes: Review and experimental investigation

In-situ U-value monitoring of building envelopes are investigated in this article by reviewing past studies and monitoring the performance of highly insulated building envelopes. Specific past research studies have concluded both over- and underperformance of the building fabric when measured in situ. This current research has found that when analysing all studies and results over the full range of envelope U-values together there is no evidence of over- or underperformance. However, when highly insulated envelopes (U-values <0.3 (W·m−2·K−1)) are investigated in isolation a clear trend in underperformance becomes evident with 93% of tests from past studies reporting underperformance. In-situ monitoring results from this study conclude that 9 out of the 10 tests on envelopes with very low U-values (<0.2 (W·m−2·K−1)) result in underperformance with an average deviation of more than 100%. The significance of this finding is two-fold. First, this means that some of the insulation is redundant and adds to the embodied energy of the building without offering a beneficial increase in thermal resistance. Second, under-sizing of heating systems in low energy buildings will result, which in turn will result in lower efficiencies and greater overall energy consumption.

Capturing variability in material intensity of single-family dwellings: A case study of Toronto, Canada

The need to reduce resource use in the built environment is widely recognized, but quantitative understanding of material use in buildings is limited, especially at neighbourhood and city scales. Existing bottom-up material inventories largely rely on typology-based methods, using representative buildings with little quantification of variability in material use. They also typically focus on advancing material replacement or recycling with less attention to reducing material use. This paper quantifies the material intensity of 40 single-family wood framed dwellings in Toronto, Canada. Design and construction drawings from the Toronto Committee of Adjustment and local building codes were used to estimate material quantities for each building. The variability in material use and intensity is explored per building, floor area and number of bedrooms and the largest drivers determined to identify opportunities for building design modifications to meaningfully reduce material intensity. Variability in the quantities of construction materials used within the single-family dwellings studied is large, with coefficients of variation ranging from 13% up to 160%. Concrete basements are the largest driver of material use by mass (mean 56% of total material mass) and building envelope insulation by volume (37%). This paper advances our understanding of the range of material intensities within a single building type in one city and the largest drivers of material use within single-family dwellings. This provides valuable information for including variability in typology approaches to bottom-up urban material intensity and insights for policy/design pathways for reducing material use in single-family dwellings.

The effect of flanking element length in thermal bridge calculation and possible simplifications to account for combined thermal bridges in well insulated building envelopes

A well-insulated, airtight, thermal bridge free building envelope is a key factor for nearly zero energy buildings (nZEB). However, increased insulation thickness and minimised air leakages increase the effect of thermal bridges on the overall energy efficiency of the nZEBs. Currently, the calculation of linear thermal transmittance follows ISO 10211, which requires the separate numerical assessment of combined thermal bridges, where two or more junctions are positioned in close proximity within delimiting cut-off planes. This poses a practical problem, as the number of different combinations (mainly related to window to wall connections in combination with corners, intermediate ceiling etc) is too large in practice to follow the standard procedure.In this study, a parametric numerical assessment of different thermal bridges in well-insulated constructions showed that with linear thermal transmittance up to 0.2 W/(mK) in lightweight construction and up to 0.1 W/(mK) in heavyweight construction the reduction of flanking element length from 1.440 m to 0.288 m (80% reduction) had no effect on numerically calculated linear thermal transmittance in steady-state conditions. For thermal bridges inside heavyweight construction with linear thermal transmittance below 1.1 W/(mK) the flanking element length could be reduced by 50% without any effect and by 70% with marginal effect (<2%) on linear thermal transmittance.The shorter flanking element length, roughly equal to its thickness, can then be used to minimise the amount of combined thermal bridges in complex building envelopes. Compared to ISO 10211 requirements, the amount of different combined thermal bridges in two exemplary building envelopes was reduced by 35% to 76%, depending on the building type, and allowed deviation of 0.5%, 1.0% or 2.0%, thus significantly reducing the working hours of practitioners.

Life cycle thinking-based energy retrofits evaluation framework for Canadian residences: A Pareto optimization approach

Building energy retrofits have been identified as key to realizing climate mitigation goals in Canada. However, retrofit solutions that only produce greenhouse gas emission savings can place economic burdens on residential building owners and hinder the community penetration of building energy retrofitting projects. Therefore, investigating trade-offs between environmental and economic impacts of retrofitting is essential to identify optimal retrofit strategies that can produce emissions savings while delivering economic benefits for the stakeholders. This paper proposes a community-level building energy retrofit evaluation framework for residential buildings. The proposed framework evaluates building energy retrofits using a multi-objective optimization approach that accounts for associated life cycle economic and environmental impacts. Life cycle CO2 emissions were selected as the indicator for environmental performance. The net present value of the cash flows involved in a given retrofit project throughout the project life cycle was selected as the economic performance indicator. Building energy simulation results were combined with economic and environmental impact data to quantify these performance indicators. The performance results were used to identify Pareto-optimal retrofit solutions. The results indicate that retrofitting existing residential buildings can produce considerable emission reductions (up to 245.1 tonCO2eq/residence) and cost savings (up to 12,900 $/residence). Moreover, retrofit packages should prioritize upgrading building envelope insulation and space heating systems. This study introduces a decision support tool for community-level retrofit planners that can account for life cycle environmental and life cycle economic performance of retrofitting while fulfilling capital investment constraints.

Life-cycle cost optimization of a solar combisystem for residential buildings in Nepal

ABSTRACT Current solar thermal systems used in Nepal are mostly for domestic hot water heating. Meanwhile, there is a growing need for space heating. A solar heating system can be configured to provide heat for both space heating and domestic hot water, leading to a solar combisystem. Research on residential solar combisystems in the Nepalean context barely exists in literature. This paper intends to propose, model and optimize a solar combisystem for typical single-family houses in Nepal. The optimization problem is formulated to have life-cycle cost as the objective function and a total of 11 variables, which are related to the sizing of combisystem components and the insulation thickness of building envelope. The number of hours not satisfying the thermostat heating set point is treated as the constraint. TRNSYS is used for modeling the solar combisystem. Particle Swarm optimization and the Hooke-Jeeves algorithm implemented in GenOpt are sequentially applied to solve the optimization problem. The results show that the optimization is effective to reduce the life-cycle cost by 66% for the Terai region and 77% for the Hilli region. The findings have demonstrated the importance of building envelope insulation to spread the use of solar combisystems in Nepal.

An adsorption-based CO2 treatment unit for ultra-low fresh air HVAC system using solid amine

Fresh air load is an important factor in reducing overall building energy load as the building envelope insulation and various passive building technologies develop. A large amount of fresh air is needed to meet the high requirement of indoor hygiene and air quality. Although various energy-efficient technologies have been studied to reduce fresh air load, the energy savings are limited to only cold climate conditions. Traditionally, outdoor air is introduced to dilute indoor pollutants. In this paper, a novel independent CO2 treatment unit (CTU) with the solid amine adsorbent (HP2MGL-PEI (600)-50) was investigated, which uses pollutant purification method instead of the conventional ventilation-based method to remove CO2. Experimental investigation and robust theoretical energy simulations were carried out to validate the effectiveness and practicability of this unit and to evaluate the energy savings in real buildings. Experimental results show the CTU could effectively reduce the CO2 concentration under normal atmospheric conditions in real buildings. Specifically, the adsorbent has a better adsorption performance with lower air velocity, but air velocity had a slight influence on desorption performance. The temperature has significant effects on both adsorption and desorption properties. An increment in adsorbent volume could also improve the adsorption performance. Simulations show that the indoor CO2 concentration could be always controlled below 1000 ppm under proper control strategies. Thus, the amount of required fresh air could be dramatically decreased. The amount of energy savings of the reference building was approximately 13.18%. The static payback time of this new system was approximately 6.85 years.