Building Envelope Materials Research Articles

Optimizing the evaluation of building envelope design for thermal performance using a BIM-based overall thermal transfer value calculation

The thermal performance of building envelopes has a profound effect on maintaining indoor environmental conditions and is critical in obtaining an energy-efficient design. Choosing appropriate building envelope materials is one of the most effective ways to manage heat flows, prevent excessive building energy consumption, and maintain a comfortable temperature for occupants. The OTTV standards are popularly used worldwide for assessing the rate of heat transfer through building envelopes. However, manual calculation methods for OTTV are involved functions with various variables and coefficients that need to be considered. Furthermore, computing multiple functions using manual calculation method can be time-consuming and human error can be occurred throughout the completion of the calculation process. Accessing materials' thermal properties from BIM potentially reduce the time required to derive coefficients for the OTTV measurement. Therefore, this research presents a BIM-based approach to provide an automatic assessment of the OTTVs of building envelopes. This study proposes integrating BIM and a developed visual scripting to automatically extract thermal and physical properties from the BIM database for supporting thermal transfer value calculation. The applicability of the proposed system is validated in a BIM model of an office building. The proposed system provides a valuable decision support system for designers to select an appropriate envelope material to achieve an optimum OTTV for optimizing energy-efficient building design. This study proposes integrating BIM and a developed visual scripting to automatically extract thermal and physical properties from the BIM database, and provide a real-time thermal transfer value calculation.

Locally resonant meta-composite for sound-proof of building envelops: Analytical model and experiment

In this study, a new type of locally resonant unit is designed, analyzed and tested. Its effectiveness to be used as a sound-proof building envelop material is evaluated. Each unit consists of a hard circular plate adhered on the soft membrane that fixed in a rigid frame. This new type of locally resonant unit can easily be installed into building envelope materials, such as extruded hollow concrete, hollow wooden board and other types of light weight partition panels, to enhance their sound proof property. An analytical model is developed to describe the ability of this composite material in low-frequency sound blocking. The model provides a direct explanation for the nature of the system and an accurate method to calculate the effective mass per unit area. It is shown that the effective mass per unit area can turn to negative at certain frequency ranges, which could lead to a complete sound attenuation. In order to measure the sound transmission gap position and verify the theoretical model, experimental works are carried out. The experimental results show good agreement with the theoretical predictions.

Multi-criteria analysis of the construction technologies in the aspect of sustainable development

The complexity of sustainability complicates the design work and requires the implementation of Integrated Life Cycle Design. Due to the need of balance between environmental, social and economic aspects and the multitude of analysis indicators, the assessment of existing buildings is a multi-criteria problem too. The aim of the study is to compare three construction technologies – two traditional solutions and an innovative technology – in the aspect of sustainable development. The assessment was limited to the building envelope materials and included in entirety of 13 environmental, social and economic indicators, characteristic for the first stage of building life cycle. The absence of explicit dominance of one technology over another in terms of these factors was a starting point for the multi-criteria analysis. Based on the comparison of given technologies by WSM and TOPSIS methods, the multi-criteria analysis was carried out and the most advantageous technology was indicated. The results allow for an indirect selection of building materials to fulfil the sustainability requirements for the building.

Experimental analysis of using beeswax as phase change materials for limiting temperature rise in building integrated photovoltaics

Indonesia has the potential of saving from 10% to 30% of energy in the commercial sector which consists of trade, hotels, restaurants, finances, government agencies, schools, hospitals, and communications. By simultaneously serving as building envelope material and power generator, BIPV systems can represent savings in the cost of materials and electricity. It reduce the use of fossil fuels and emission of ozone depleting gases, and also add architectural interest to buildings. However, the temperature rise poses a challenge for BIPV, given that it manifests itself in electrical efficiency and overheating. The experiments present in this study aim at understanding the behavior of the PV-PCM systems in realistic outdoor uncontrolled conditions to determine how effective they are. In addition, the PV-PCM systems were tried in the low latitude and hot climate of Banda Aceh, Indonesia. Experiments were conducted outdoors at the Engineering Faculty in Syiah Kuala University, located in Banda Aceh, Indonesia (05:57 N, 95.37 E). In this study, both paraffin wax and beeswax were used as a phase change material. The final results showed that the electrical efficiency of PV panels without PCM is ranged between 6.1% and 6.5%. While for PV panels with PCM the efficiency is ranged at 7.0–7.8%. This proved that the process of water cooling is capable of increasing the efficiency of PV panels.

Polymers as Building Envelope Materials

Polymers as Building Envelope Materials

Studies into structural and thermal properties of building envelope materials

The structural and thermal properties of masonry units influence the behaviour of masonry. In load bearing masonry, wall elements play a major role in supporting the structure through load transfer mechanism from roof to foundation. Also, wall elements regulate the thermal interaction between the indoor and outdoor environment. A variety of masonry units are available as an alternative to burnt clay brick masonry. Fly ash-Lime-Gypsum (FaL-G) brick is one such alternative, which is a low carbon and energy efficient brick made of industrial waste fly-ash. The current paper investigates the characteristic properties of FaL-G bricks and compares them with the locally available conventional table moulded brick (TMB). The characteristic results reveal that the FaL-G brick performs better as a masonry unit and also for building envelopes in tropical conditions. Based on investigations regarding structural and thermal performance, suitable guidelines can be issued to integrate this material in the building envelope.

Study on the Thermal Environment and Indoor Comfort of Half Glass Curtain Buildings – a Case of Kouhu Visitor Center in Yunlin County, Taiwan

Located in the subtropics, the high temperature in summer affects indoor living environments in Taiwan. The use of perspective glass material for modern public buildings increases the transparency of landscape views; however, the solar radiation heat also increases the heat in indoor environment. In particular, visitor centers which offer service functions for large quantities of visitors should satisfy the demands for indoor environment comfort and energy saving. “Numerical simulation” and “field data” are therefore utilized in this study for mutual comparison and the analyses of duration of sunshine, temperature distribution, heat balance, and space comfort. The research result reveals that different building envelope materials, with distinct thermal resistance and thermal conductivity coefficients, as well as sunshine direction and duration, affect the heat transmitting indoors, change the indoor temperature and further influence the comfort of the indoor environment. In the future indoor venue comfort will affect visitors’ recreational behaviours.

Analysis of Building Envelope Materials Retrofitting of Timber Dwellings Based on Energy Efficiency

To find out the optimum building envelope retrofitting methods for timber dwellings in Western Hunan, China, energy efficiency retrofitting strategies of building envelope materials are optimized by an orthogonal test and energy simulation tool, DeST-h. On the premise of protecting their architectural styles, a comprehensive materials retrofitting strategy, a polyurethane foam insulation layer for the double-fir external wall envelope, reed foil for the clay insulation layer roof, using ordinary insulating glass units window material, is provided for the existing timer-structured dwellings in rural area of Western Hunan. After retrofitting, this passive strategy can achieve an energy-saving rate of 64.97%, short 4 years dynamic payback period of investment, and increase by 847h acceptable temperature hours in one year.

Thermal and mechanical performance of oil palm fiber reinforced mortar utilizing palm oil fly ash as a complementary binder

This paper provides an in-depth analysis of the recycling potential of oil palm industrial waste which is abundantly available in Malaysia that is posing serious environmental concerns. Much research has been undertaken regarding the processing of palm oil production waste, however there is lack of attention regarding the thermal performance of oil palm waste and its attended mechanical properties as fiber reinforced mortar, stifling its wide applicability within the construction industry. This paper focuses on the utilization of oil palm residue to develop thermally insulated building envelope material. The palm oil fly ash is used as a replacement for cement, and the oil palm fibers are incorporated as an additive to reduce thermal conductivity of wall systems. Various proportions of fiber reinforced mortar were prepared to study the effects of fibers on thermal and mechanical performance. Thermal performance was studied using steady state approach by using Hot Guarded Plate apparatus. The experimental findings have revealed that the porous nature of fiber makes it a suitable choice for enhancing thermal performance of mortar, with some acceptable reduction of mechanical strength and marginal fluctuations in flexural strength.

Pautas de diseño para disminuir las temperaturas urbanas en regiones con alta productividad solar. Parámetros morfológicos y materiales

This study examined the numerical modeling performance of morphological and materials alternatives for reducing urban temperatures. The aim was to identify design and urban regeneration guidelines that enable the densification of residential areas in the city of Mendoza, Argentina. To this end, using ENVI-met 3.1 software 32, scenarios were simulated that combined: different levels of solar reflectance (albedo) of building envelope materials, different urban profile morphologies, the presence or absence of forestation in urban canyons, and E-W/N-S variation in orientation. From the simulation results it can be inferred that there is more efficient thermal performance in the vegetated scenarios that morphologically have a continuous urban profile above the municipal building line. Regarding envelope materiality, there are high albedo levels (0.7) on roofs and pavements, and low albedo levels (0.3) on facades.

Exploring impact of opaque building envelope components on thermal and energy performance of houses in lower western Himalayans for optimal selection

The building envelope plays crucial role of both protecting its occupants from external environment and controlling indoor environment to maintain indoor thermal comfort condition and energy-efficiency. The main aim of present day building design should be eliminating the need for mechanical heating and cooling equipment wherever possible. A novel approach is applied in this study to find empirical data through field experimentation conducted in the study area to derive the proposal suitable for the buildings of that location. Field studies of naturally ventilated residential buildings were conducted at Mandi town, located in western Himalayan Indian state of Himachal Pradesh with composite climate, during winter and summer months of 2013 and 2014 to assess the impact of opaque building envelope materials on indoor thermal condition. Further, energy performance of residential buildings is analyzed using e-QUEST building-energy simulation tool to find the potential annual energy consumption and energy savings during the functioning of buildings. The study found that the use of thermal mass in wall and roof construction can maintain indoor thermal comfort during winter and summer months in composite climate. The study also found that the application of wall and roof insulation can maintain indoor thermal comfort condition in modern houses during winters and summers and can also improve energy-efficiency of partially and fully air-conditioned buildings significantly – the heating, cooling and mechanical ventilation load can be reduced up to 60%, 40% and 40% respectively; the peak energy demand during summer and winter can also be reduced. Further research area is also identified.

Multiobjective optimization design of green building envelope material using a non-dominated sorting genetic algorithm

To realize the goal of environmental sustainability, improving energy efficiency in buildings is a major priority worldwide. However, the practical design of green building envelopes for energy conservation is a highly complex optimization problem, and architects must make multiobjective decisions. In practice, methods such as multicriteria analyses that entail capitalizing on possibly many (but in nearly any case limited) alternatives are commonly employed. This study investigated the feasibility of applying a multiobjective optimal model on building envelope design (MOPBEM), which involved integrating a building envelope energy performance model with a multiobjective optimizer. The MOPBEM was established to provide a reference for green designs. A nondominated sorting genetic algorithm-II (NSGA-II) was used to achieve a tradeoff design set between three conflicting objectives, namely minimizing the envelope construction cost (ENVCOST), minimizing the envelope energy performance (ENVLOAD), and maximizing the window opening rate (WOPR). A real office building case was designed using the MOPBEM to identify the potential strengths and weaknesses of the proposed MOPBEM. The results showed that a high ENVCOST was expended in simultaneously satisfying the low ENVLOAD and high WOPR. Various designs exhibited obvious cost reductions compared with the original architects' manual design, demonstrating the practicability of the MOPBEM.

Green Control of Microclimate in Buildings

Abstract In the Mediterranean area the solar heat gain in buildings needs to be controlled during the warm seasons in order to keep the internal temperature at comfortable levels and to mitigate the phenomenon of urban warming, known as Urban Heat Island. This phenomenon contributes to increase the outdoor pollutants concentration and the energy demand for air conditioning. Indoor microclimate conditions depend on several parameters related mainly to the building destination, envelope materials and orientation, its technological equipment, and to the specific region climate. The use of green shading can induce energy savings also in winter, by reducing heat losses from the external surface during mainly the night. An experimental study was carried out at the University of Bari (Italy, 41° 05 ‘N, 16° 53 ‘E) from June 2014 to April 2015 with the aim of investigating the effective influences of this green passive system on a building vertical wall. Three vertical walls were built and equipped with a sealed structure on the backside; the walls were made with perforated bricks. The walls were covered with different evergreen climbing plants: Pandorea jasminoides variegated for the first wall and Rhyncospermum jasminoides for the second one. A third wall was kept uncovered and used as control. A data logger and sensors were used to measure and collect the temperature of the wall, on the surface exposed to the solar radiation and on the inner surface protected by the sealed structure, the external air temperature, the wind speed and direction, the solar radiation falling on the wall. The experimental tests showed that during the daytime of warmest periods the use of the green walls allowed a reduction of the external surface temperature registered on the walls shielded by the green systems: the temperatures observed were lower than the respective temperatures of the control wall of about 3-4.5 °C. During the nighttime of coldest periods the use of the green wall allowed to keep the external surface temperature of the walls shielded by the green systems at values higher than the control wall ones: the temperatures observed were higher than the respective temperatures of the control wall of about 2-3 °C.

Analysis of Thermal Behavior of Materials in the Building Envelope Using Building Information Modeling (BIM)—A Case Study Approach

Building envelope is a fence that controls heat exchange between interior and exterior and plays an essential role in providing thermal comfort conditions of residents. In recent years, due to the necessity of conserving energy and also preventing increased environmental pollution, the importance of sustainable construction has been doubled. Checking the problems of thermal behavior of the building envelope materials, and what influences in the heating and cooling loads exerted and energy consumption of buildings, are the questions that this research seeks to answer. In this regard, building information modelling analysis (BIM) has worthy contribution in the completion process of sustainable design; thus using software Design Builder, it is paid attention to simulation of the thermal behavior of two types of defined materials for the building envelope that was designed as a Research Institute of Renewable Energy of Yazd University. For Type 1 materials, two layers of brick have been selected, and for Type 2 a thermal insulation layer also added it. Results of the analysis showed that the use of materials Type 2 in the cooling load %4.8 and in the thermal load %62.5 reduction can be achieved which means reducing the load on active system and thus reducing the initial cost of building. Also reduction in annual energy consumption by almost %2.4 for cooling and %62.9 for heating buildings have been achieved, which makes saving non-renewable energy consumption, and consequently reducing environmental pollution as well as reducing current costs will be established.

Manufacture and multi-physical characterization of aluminum/high-density polyethylene functionally graded materials for green energy building envelope applications

An aluminum/high-density polyethylene (HDPE) functionally graded material (FGM) has been fabricated as an essential component of a multifunctional building envelope for high performance of energy efficiency and sustainability. The mass production of the FGM was realized by using coarse aluminum (Al) particles and fine HDPE powder through a vibration-sedimentation process. The gradation of the FGM across its thickness direction was analyzed by developing a modified Rice method, from which five different uniform Al-HDPE samples were made to characterize the material properties of the five sub-layers of the FGM. The mechanical and thermal physical properties of the FGM such as Young's modulus, Poisson ratio, thermal expansion coefficients and thermal conductivities were obtained by various experimental characterizations. A prototype FGM panel with water tubes embedded was fabricated by the vibration and sedimentation combined approach and the thermal efficiency of the FGM panel was evaluated. Under an irradiation level of 620w/m2 and a water flowing rate of 60ml/min, a 22.3°C water temperature increase and an average 18.7°C surface temperature decrease of the FGM panel were achieved, which demonstrates that significant PV conversation efficiency improvement can be realized for both electricity generation and heat collection by the presented FGM panel. The presented fabrication procedures and the associated experimental characterization methods and results can serve as a baseline for quality control of the manufacture of the green energy building envelope materials.

Thermophysical properties of masonry units: Accurate characterization by means of photothermal techniques and relationship to porosity and mineral composition

The concerns on saving energy and CO2 emissions in residential sector made the measures adopted in the last years to be focused on using building envelope materials with low embodied energy and improved thermo-technical properties. Considering that the sustainable behavior of materials during the buildings entire life cycle is much influenced by its mineralogical content, thermo-technical characteristics and physico-mechanical properties, the paper analyze from this point of view three types of masonry units (tuff, limestone, autoclaved aerated concrete) in order to be used as units in masonry works or for wall cladding. The mineralogical content has been determined microscopically in thin sections and by X-ray diffraction while the samples’ porosity was measured into laboratory by volumetric methods and by using a new binary image analysis algorithm. Contact photopyroelectric calorimetry and non-contact infrared lock-in thermography have been used in order to measure with high accuracy the dynamic thermal parameters (thermal diffusivity, effusivity and conductivity) of these materials.The results highlights that mineralogical content, size and distribution of pores directly influence the thermal characteristic of materials and their behavior to moisture transport and decay process in aggressive environment.

Sensitivity Analysis on the Relationship Between Building Envelope Material and Human Body Exergy Balance

This study is reports the calculations of human body exergy balance and its applicability to measurement of human comfort indoors. Using equations for human body exergy balance, I calculated the integrated exergy consumption for enclosures made of wood, metal, and concrete of varying thicknesses. For maximum thermal comfort, the integrated exergy consumption should be minimized, and I found that for typical winter and intermediate season conditions in Shizuoka, Japan, a wooden enclosure offers more thermal comfort than concrete and metal structures for cases of no insulation and no heating source. This study reaches conclusions similar to those of another experiment performed on the survivability of mice in various enclosures in different thermal environments.

OTTV (SNI 03-6389-2011) and ETTV (BCA 2008) Calculation for Various Building’s Shapes, Orientations, Envelope Building Materials: Comparison and Analysis

The Indonesian National Standard SNI 03-6389-2000 adapted the 1983 Singapore’s Handbook on Energy Conservation and limited the Overall Thermal Transfer Value (OTTV) of the building envelope to 45 Watt/m 2 . In 2008, the Singapore’s Building and Construction Authority (BCA) shifted to Envelope Thermal Transfer Value (ETTV) value of 50 Watt/m 2 , while SNI 03-6389-2011 continues to use OTTV. This paper reviewed the new SNI 03-6389-2011 and compared it with BCA by calculating OTTV and ETTV of prismatic buildings with eight different shapes and building orientations, 11 Window to Wall Ratio, and 27 building envelope materials. This study also tested those variables to find the best building shape and orientation for an energy saver building. The result shows that ETTV (BCA) is stricter than OTTV (SNI 03-6389-2011) except the OTTV with black building envelope, while parallelogram shape building with North-South orientation is the best combination of energy saver building.

An investigation on energy-related occupancy behavior for low-income residential buildings

Previous studies show that individuals’ energy consumption tends to outweigh the technical efficiency gains. Occupancy behavior accounts for about 30% of the variance in overall heating consumption and 50% in cooling consumption. In addition, overall energy savings of 10%–20% due to simple behavioral adjustments are a reasonable expectation. Unfortunately, few studies have focused on the specific cases of behavior in low-income houses, where unique individual energy behavior, demographic, and socio-economic factors come into play. This article investigates energy-related occupancy behavior in low-income families through real-time power, indoor environment, and occupancy presence measurement. Four residential houses with different building envelope materials are used as test-beds. Occupancy behavior includes thermostat schedules, occupancy presence, and major appliance usages. A simulation study is further conducted to show the energy impact of occupancy behavior.

Long term self-cleaning and photocatalytic performance of anatase added mortars exposed to the urban environment

Building envelope materials containing titanium dioxide have been proposed to exploit their photoactivated depolluting and self-cleaning potential, but a full appraisal of their durability and long-term performance is still missing. This study reports a two-year campaign of natural exposure in Milano, Italy, of photoactive and non-photoactive fiber-reinforced mortars, analyzing the evolution of lightness, solar reflectance, porosity and photoactivity. After aging, photoactive samples showed limited color variation. The photocatalytic activity of TiO2 containing samples, characterized with dye degradation tests, was minimal after aging. Then, after alternated cycles of UV–Vis irradiation and rinsing, almost 70% of the initial photocatalytic efficiency was recovered.