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How will graphene change construction?

By RISC | 1 week ago

We saw in the last post how graphene has extraordinary strength, thinness, and conductivity for heat and electricity. ​But how will graphene be used, especially in building? ​Concrete is the main material in construction, used in every building, house, bridge, tunnel, and road. It’s the planet’s top man-made resource. Concrete has 3 components: coarse aggregate, fine aggregate, and water. Cement is also a big factor in global pollution, accounting for 8% of global CO2 emissions. If cement manufacturing were a country, it would be the world’s 3rd largest carbon emitter, trailing only China and the United States. ​Concrete’s properties usually depend on the type and quantity of cement, coarse masses, fine masses of sand, and gravel. But adding graphene could boost efficiency and reduce the use of cement. ​So how does graphene enhance concrete? ​First, it speeds up hydration (nucleation effect), helping the reaction between cement and water. Calcium silicate hydrate (Ca-S-H) is a new compound that improves the strength of concrete against compressive forces. When dispersed in cement paste, its small size with high specific area can help stimulate the hydration reaction, resulting in an increased amount of Ca-S-H. ​Second, it can reduce porosity in composite concrete structures (nano-filling effect). As graphene is so small, it can help to fill gaps inside the cement paste. This allows for a reduction in the number and size of pores in the structure. Conventional cement pastes have a highly porous structure and crack after 28 days of curing, whereas cement pastes containing 0.05% graphene have less porosity and don’t crack. The cement paste's compactness and consistency will aid in compressive strength. ​Third, chemical bonding between graphene, cement particles, and compounds produced by hydration reactions increase strength and adhesion (bonding effect). The 2 bonds are an ionic bond between the hydrated compound (Ca-S-H) and the oxygen functional group on graphene oxide, and a hydrogen bond between water molecules in cement, Ca-S-H, and hydroxyl groups on graphene oxide. These chemical bonds will strengthen the concrete. ​Finally, graphene prevents the formation and spread of small cracks (toughening effect). When concrete is subjected to compressive stress, the force is transmitted to graphene, which is a very strong material capable of absorbing the force and distributing it to different parts of the concrete. This helps prevent cracking and crack propagation. Adding 0.02-1% graphene to concrete can significantly improve its mechanical properties such as bending, compression strength, and stretching. Furthermore, graphene reduces water absorption by up to 80% and increases durability for longer use. ​Graphene can improve the quality of building materials. But it remains more expensive than other chemicals. So graphene is still rarely used in composite concrete. But we’ll certainly see more of it in the future. ​Story by: Supunnapang Raksawong, Materials Researcher, RISC​References:   ​Youli Lin and Hongjian Du. Graphene reinforced cement composites: A review, Construction and Building Materials. 265 (2020) 120312.

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Why insulation matters

By RISC | 2 weeks ago

Thailand is hot and humid almost all year. Buildings have to keep out the heat or depend heavily on air-conditioning. ​The sun’s heat generally enters structures through heat transfer, in which hot air moves to cooler air. Heat gets into buildings in 3 ways: ​• Conduction: through a static medium like a wall, roof, or floor • Convection: like the wind delivering or removing heat ​• Radiation: without a medium, such from the sun to the earth, traveling through space, the atmosphere, and our home to usWe can reduce heat infiltration by installing insulation. If we choose a heat-resistant material, the temperature inside the building will be comfortable. We can cut the cooling load for air conditioners by up to 40%, also reducing greenhouse gas emissions. Insulation can also counter condensation, which produces humidity and mold.When examining the variables of keeping our home cool or comfortable indoors, the critical factor is decreasing heat transfer from outside. Good design takes account of the direction of the sun and the surroundings to keep homes cool. The building façade also plays a big role. Façade materials should limit heat transfer from the exterior to the interior. If we understand the heat transfer process, we can choose the best materials. Building façades can have 3 layers...Exterior surface​The first stage in reducing heat transfer into a building is the surface of the building façade:​• Because stagnant air on the material surface has a high heat resistance, the surface material must reflect radiation well. ​• It’s important to stop heat from flowing in the wrong direction, such as to the side of the wall or up or down from the roof. ​• A low-wind surface area will keep the air stationary at the material's surface, raising heat resistance.Material qualities ​Heat transmission can be divided into 2 elements:• Materials that reduce and slow heat transfer are based on 2 principles: 1) Materials with larger mass are better at absorbing and retaining heat, slowing heat transfer from heat transmission from one side to the other. 2) Materials with a narrow air gap and high porosity will reduce convective heat transfer, which we call "heat retardant" – aerated concrete materials and various types of insulating materials have this property.• Material layering of building façades is the process of layering materials with an "air gap" until we reach the system’s total thermal resistance. Efficiency depends on the size of the gap and the type of air in the gap, whether flowing or stagnant, and heat radiation reflection.Inner surfaceThe final phase in heat transmission from the outside is the inner surface of the building façade:• A surface with high radiation reflectance can enhance heat resistance in the stagnant air on the surface.• It’s important to prevent heat from flowing in the wrong direction, such as to the side of a wall or up or down the roof.Plenty of products can give you a cooler home. Rather than relying on AC you can select effective and healthy insulation. Find out more at by: Dr. Sarigga Pongsuwan, Vice President of RISC

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Comparative Study of Air Exchange Rates in A High-Rise Residence by Using Both Tracer Gas Dilution and Fan Pressurization Methods

By RISC | 3 weeks ago

  High-rise condominium living is becoming increasingly popular in the city while urban heat island effect has caused residents to close windows and use air conditioning unit all night. There is a buildup of indoor carbon dioxide (CO2) concentration within bedroom(s) of residential unit that will affect the quality of sleep and productivity on the following day. Thus, providing sufficient bedroom air exchange is highly important in order to maintain low CO2 concentration level within the residence. This study investigates room air change rate by conducting fan pressurization and tracer gas dilution experiments in a 30 m2 one-bedroom type unit of a condominium in Bangkok, Thailand. The two method yields similar air exchange results, achieving 1.215 ACH via fan pressurization and 1.387 ACH via tracer gas dilution when bedroom and living room spaces are connected to each other. The air exchange rate and CO2 concentration level are acceptable since the measured air change rate is higher than that required by design standards and CO2 concentration level is found to be lower than 1,000 ppm. After closing the bedroom door, however, CO2 concentration rises rapidly above 1,000 ppm while ACH drops to a level lower than suggested by design standards. Based on this experiment, it can be concluded that bedroom of conventional high-rise residential unit requires higher air exchange rate to ensure appropriate CO2 concentration level at night while occupants are sleeping.   Read full research article at: References: Ai, Z. T., Mak, C. M., Cui, D. J., & Xue, P. (2016). Ventilation of air-conditioned residential buildings: A case study in Hong Kong. Energy and Buildings, 127, 116–127.   Cheng, P. L., & Li, X. (2018). Air infiltration rates in the bedrooms of 202 residences and estimated parametric infiltration rate distribution in Guangzhou, China. Energy & Buildings, 164, 219-225.   Jareemit, D., Julpanwattana, P., & Choruengwiwat, J. (2015). Impact of outdoor air exchange rates on sleep quality and the next-day performance with the application of energy recovery ventilator. Journal of Architectural/ Planning Research and Studies (JARS), 14(1), 22-32.   Schofield, W. (1985). Predicting basal metabolic rate, new standards and review of previous work. Human nutrition. Clinical nutrition, 39(1), 5–41 . Sreshthaputra, A. (2016). Ventilation effectiveness of door-sided operable shutter (air post) in high-rise residential building. Academic Journal of Architecture, 65, 111-124.   Sherman, M. (1987). Estimation of infiltration from leakage and climate indicators. Energy and Buildings, 10(1), 81–86.   Strøm-Tejsen, P., Zukowska, D., Wargocki, P., & Wyon, D. P. (2014). The effects of bedroom air quality on sleep. Proceedings of the 13th International conference on indoor air quality and climate - indoor air 2014 [HA0506] International Society for Indoor Air Quality and Climate (ISIAQ). Hong Kong.   Bibliography:   American Society of Heating, Refrigerating and Air-Conditioning Engineers [ASHRAE]. (2010). ANSI/ASHRAE Standard 62.1-2010, Ventilation for acceptable indoor air quality. Atlanta, GA: Author.   American Society of Heating, Refrigerating and Air-Conditioning Engineers [ASHRAE]. (2016). ANSI/ASHRAE Standard 62.2-2016, Ventilation for acceptable indoor air quality. Atlanta, GA: Author.   American Society for Testing and Materials [ASTM]. (2003). Standard test method for determining air leakage rate by fan pressurization. ASTM E779-03. USA.: Author.   Chartered Institution of Building Services Engineers. (2006). Environmental design: CIBSE guide A. London: Author.   Deutsches Institut für Normung e. V. (2012). Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics (DIN EN 15251:2012-12). German: Author.   Ministerial Regulations No.39. (1994). Issued under the building control Act (1979). Thailand: Author.   Persily, A., & Jonge, L. de. (2017). Carbon dioxide generation rates for building occupants. Indoor Air, 27, 868-879.

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Impact of Outdoor Air Exchange Rates on Sleep Quality and the Next-Day Performance with Application of Energy Recovery Ventilator

By RISC | 3 weeks ago

  Sleep quality can affect human health and the next-day performance. High indoor CO2 concentration levels due to insufficient supplied air ventilation could cause poor sleep quality. Bedrooms in condominiums in Thailand commonly uses a wall-mounted split type system without supplied outdoor air ventilation. The rooms are typically constructed having airtight envelopes which have air infiltration rates ranging from 0.4-0.64 ACH. This study aims to evaluate the impact of increased ventilation rates on sleep quality and the next-day performance, and the surveys were collected from two occupants living in a one-bedroom condominium. The field measurement and survey were conducted for twenty days with supplied outdoor airflow rates at 0, 40, and 60 m3 hr-1 through an energy recovery ventilator (ERV). The room air exchange rates were calculated from a linear regression method obtained from a decay tracer gas technique using indoor carbon dioxide generated by occupants. To overcome the maximum limit of CO2 concentration level specified in the standard health guidelines, the ERV unit has to supply an outdoor air ventilation rate of 60 m3 hr-1. Overall, the increase in outdoor air ventilation rates can improve sleep quality by 2-13 percent and occupants have better work performance  the next day by 2-20 percent. The increase of outdoor air ventilation through the ERV unit does not affect indoor relative humidity.   Read full research article at:  

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The Eco-efficiency Model for Outdoor Environmental Design of the Mixed-use Real Estate Development in Bangkok, Thailand

By RISC | 3 weeks ago

  Nowadays, the dramatic increase of urban land developments affects various environmental problems, especially in urban heat and the reduction of natural porosity surfaces, then increasing outdoor temperature and surface water runoff problems. These problems relate to urban residents' outdoor living, especially in the large mixed-use real estate developments in Bangkok; the capital city of Thailand. Therefore, the Magnolia Quality Development Corporation Limited (MQDC) has concerned about mitigating such problems by applying the eco-efficiency modeling to use as a sustainable design guideline for the new project development; named Whizdom 101. The term of eco-efficiency is defined as the ratio of improvement cost per unit of the environmental impacts. This study formulates the eco-efficiency model by using the change in construction cost of the outdoor environment and their impacts which refer to the physiological equivalent temperature (PET) as an indicator for the thermal comfort index of humans and stormwater runoff. The cost is calculated by a simple cost estimation technique. Meanwhile, the microclimate model ENVI-met BioMet (V4) was used for predicting the effect of different design options on outdoor thermal comfort using PET, and the Stormwater Runoff Test (SRT) is also calculated by the academic Green Stormwater Infrastructure (GSI) for Autodesk Infraworks 360 software. The results presented as the prediction function of the eco-efficiency of the outdoor environmental design. Research suggests that previous paving materials are broadly capable of lowering temperatures and improving human thermal comfort, and when integrated with trees have the potential to meet eco-efficiency objectives. Moreover, the models can be used as a useful guideline for the outdoor environmental design of the Whizdom 101 to toward the most eco-friendly for urban residents’ outdoor living of mixed-use real estate development in Bangkok, Thailand.   Read full research article at:   References: Boonmee, K. (2005). Eco-efficiency and competitiveness - State-of-the-Art and perspectives in Thailand. Bangkok, Thailand: German Technical Cooperation (GTZ) Chappell, E. (2015). Autodesk Drainage Design for InfraWorks 360 Essentials: John Wiley & Sons. Höppe, P. (1999). The physiological equivalent temperature – a universal index for the biometeorological assessment of the thermal environment. International Journal of Biometeorology, 43(2), 71-75. Huppes, G., & Ishikawa, M. (2005). A framework for quantified eco-efficiency analysis. Journal of Industrial Ecology, 9(4), 25-41. Jaber, F., Woodson, D., LaChance, C., & York, C. (2012). Stormwater Management: Rain Gardens: Texas A&M Agrilife Extensiono. Document Number) Klaylee, J. (2015). The Assessment of Physical Design for Outdoor Thermal Comfort: Case Study of Thammasat University (Rangsit Center) (in Thai). Thammasat University, Patumthani. Lehni, M., & Pepper, J. (2000). Eco-efficiency creating more value with less impact. Geneva, Switzerland: World Business Council for Sustainable Development (WBCSD) McCuen, R. H., & Bondelid, T. R. (1981). Relation between Curve Number and Runoff Coefficient. Journal of the Irrigation and Drainage Division, 107(4), 395-400. Rinchumpoo, D. (2012). The rating tool of subdivision neighbourhood sustainability design (SNSD) for Bangkok Metropolitan Region (BMR), Thailand: An eco-efficiency modelling approach. Queensland University of Technology, Brisbane, Queensland, Australia. Shonnard, D. R., Kicherer, A., & Saling, P. (2003). Industrial applications using BASF eco-efficiency analysis: Perspectives on green engineering principles. Environmental Science & Technology, 37(23), 5340-5348. Simion-Melinte, C. (2016). Factors Influencing The Choice Of Cost Estimates Types And The Accuracy Of Estimates For Construction Projects. Paper presented at the Proceedings of the International Management Conference. Sorvari, J., Antikainen, R., Kosola, M.-L., Hokkanen, P., & Haavisto, T. (2009). Eco-efficiency in contaminated land management in Finland – Barriers and development needs. Journal of Environmental Management, 90(5), 1715-1727. Sukul, C., Rinchumphu, D., & Suttiwongpan, C. (2017). The Study of Runoff Efficiency in the Garden Area of Middle Tier Housing Project in Bangkok and Vinicity Provinces (in Thai). Paper presented at the ICMSIT 2017: International Conference on Management Science, Innovation, and Technology 2017, Faculty of Management Science, Suan Sunandha Rajabhat University. Suropan, P., Rinchumphu, D., & Srivanit, M. (2017). The Study of Eco-efficiency from Outdoor Thermal Impacts for Hi-end Condominium Project in Central Business District of Bangkok (in Thai). Paper presented at the The National Conference on "Vernacular Creativity Wisdom", Faculty of Architecture, Chiang Mai University. Thitisawan, N. (2009). Guidelines for materials selection to enhance post-occupancy satisfaction and reduce environment impact in common area of middle tier single detached house projects (in Thai). Thammasat University, Bangkok, Thailand.

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Graphene: the World-Changing Material​

By RISC | 1 month ago

Imagine a material clearer than glass, thinner than a hair, and stronger than steel… Sound incredible? But graphene already exists. ​Graphene’s unique properties make it an important material for the future. Read on to discover more... ​Graphene was discovered in 2004 by two scientists, Andre Geim and Konstantin Novoselov. They won the Nobel Prize in Physics in 2010 for bringing graphene to the attention of the world. ​Graphene conceals many miracles due to its structure and properties. It is composed of carbon atoms connected by covalent bonds in a hexagonal structure, like a honeycomb in a 2-dimensional plane. Graphene is the world's thinnest material, measuring 0.34 nm thick and equal to the size of a carbon atom. It is also one million times thinner than hair. Because of its thinness, it allows up to 97% of light to pass through. It is a lightweight transparent material that can be stacked to the size of a football field with less than 1 gram of graphene. ​Another intriguing aspect is the way the carbon atoms are linked by covalent bonds. As a result, graphene is 100-300 times stronger than steel. A sheet can withstand the weight of an elephant standing on a pencil without tearing. Sheets can be stretched or bent without deformation. ​Graphene also has a sp² electron arrangement in its 2s orbital, which allows electrons to move freely (delocalized), resulting in better electricity and heat conductivity than copper. Graphene is not a conductor or a semiconductor material, but it has a zero-energy gap (Band Gap Semiconductor), which allows electrons to move at the speed of light. Furthermore, it is used in the production of electronic devices that operate quickly and efficiently, are non-toxic to humans, and are biodegradable. ​Graphene interests various industries around the world as a future material due to its strength, light weight, ability to conduct electricity, and small size. Stay tuned for the next article to learn how to use graphene in various applications. ​Story by: Supunnapang Raksawong, Materials Researcher, RISCReferences:

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