Study on Nanotechnology for improving energy efficiency in buildings

FACULTY OF ARCHITECTURE, MANIPAL UNIVERSITY, MANIPAL DISSERTATION PAPER, OCTOBER (2015-16 )

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Study on Nanotechnology for improving energy efficiency in buildings Divyank Saha, Manipal School of Architecture, B.Arch., Research Paper (29th October, 2015) Key words: Vacuum Insulation Panel, Core material, Envelope.

-------------------------------------------------------------------------------------------------ABSTRACT Ever increasing population is putting a pressure on the resources available as the demand is more than the supply. The highest amount of energy is consumed by buildings (39% of the total) which pushes architects, engineers and builders to construct buildings which consumes lesser energy. Nanotechnology is the technology which can reduces the energy consumption of a building and increases the useable floor area. The purpose of this paper is to improve the energy efficiency of buildings in India using nanotechnology.

The purpose of this research is to provide the readers with an ample knowledge about the advanced materials used to replace the conventional materials to develop better performance of the building. In this research paper, a comparative analysis of Nano insulation materials with conventional insulation materials has been calculated using a simulation software for the performance of thermal heat gain in a building.

Online data were collected through research papers, articles and journals of professionals in R&D field of nanotechnology and even students in Universities like Ball State and MIT (U.S.) involved in the experiments conducted for nanomaterials.

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INTRODUCTION

Nanotechnology, even known as “nanotech”, is the study of the control of matter on an atomic and molecular scale. Generally nanotechnology deals with structures of the size 100 nanometers or smaller in at least one dimension, and involves developing materials or devices within that size. Etymologically “nano” means “dwarf” in Greek. A nanometer is one billionth of a meter, which is one hundred thousandth of the width of a hair.

1.1 Nanoparticles A nanoparticle is an atomic particle whose size is measured in nanometers (nm). It is defined as a particle with at least one dimension less than 200nm. When brought into a bulk material, nanoparticles can strongly influence the mechanical properties of the material, like stiffness or elasticity.

Such nanotechnologically enhanced materials will enable a weight reduction accompanied by an increase in stability and an improved functionality.

Two nano-sized particles that stand out in their application to construction materials are titanium dioxide (TiO2) and carbon nanotubes (CNT‟s).

1.2 Nanocomposites Nanocomposites integrates new nanomaterials with the conventional materials like steel, concrete, glass and makes it much stronger than the conventional material and even improves performance, durability and strength to weight ratio of these materials.

Some students in Ball University, incorporated Carbon nanotubes (CNTs) to create transparent load bearing curtain walls which were neither obstructed by columns nor by beams, quantum dots are able to change the colour of walls and ceilings with the flip of a switch.

In near future, nanocomposites like CNTs will highly secure our buildings from terrorism, it can even make army vehicles bomb-proof by reinforcing nanofibers in polycarbonate. It may soon be applied in all building materials.

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BENEFITS OF NANOTECHNOLOGY

Nanotechnology has the following benefits: • Tackles climate change • Reduces greenhouse gas emissions in future • Improves the energy efficiency of a building • Sustainable construction

2.1 INSULATION The main advantages of insulating the fish hold with adequate materials are: • To prevent heat transmission entering from the surrounding warm air, the engine room and heat leaks (fish hold walls, hatches, pipes and stanchions); • To optimize the useful capacity of the fish hold and fish-chilling operating costs; • To help reduce energy requirements for refrigeration systems if these are used.

2.2 BACKGROUND World’s maximum energy consumption is constituted by buildings. Thermal insulation materials are a better solution for reducing energy consumption of buildings than wind and solar energy and it is a more cost-effective method as well.

2.3 CONVENTIONAL INSULATION MATERIALS Conventional building insulation materials increases the thickness of the building envelope, leading to lesser floor area to building envelope thickness ratio.

Conventional materials like mineral wool, expanded polystyrene (EPS), cork and polyurethane have been studied in this paper and compared with the advanced nano insulation materials. In recent past, researchers have come up with thinner insulation panels which gives greater thermal insulation than conventional materials.

2.4 2.4.1

ADVANCED INSULATION MATERIALS Vacuum insulation panel

An evacuated foil encapsulated open porous material as a high performance thermal insulating material. The nanomaterial used in its core fill is fumed silica and envelope is basically used as a metalized laminated sheet. It has a very low thermal conductivity.

It has a core material with small pores of 10-100mm, enclosed by thin laminate film Different “R-value” of conventional insulating with low gas permeability. Core material is materials evacuated to a pressure of 0.2-3 m/bar,

gives thermal conductivity 2-4 mW/mK. If laminate is not gas tight it allows gas to come inside, which increases pressure within the core material of VIP reducing the thermal resistance of the material.

2.4.1.1

ENVELOPE

Most common envelope with vacuum insulation panels are metalized multilayered polymer laminate which is heat sealed to form a continuous envelope.

As the pressure in the core material increases the thermal resistance Results of embodied energy, UBP97 and Eco99 decreases. There were two between glass wool, EPS and VIP experiments have experiments conducted by which the been shown. (Anon., 2003) researchers concluded that the water vapour transmission rate (WVTR) would decrease exponentially if the thickness of the panel decreases. No effect of WVTR due to number of laminate layers were observed.

Different types of glues degrades the laminates, even the fluoride ions in drinking water. To produce durable laminates glue should be free of Chloride and other substances such as gallium, lead,etc which reducess the stability of the aluminium in laminates. Multi-layered polymer laminates is flammable around 150 degrees celcius and releases carbon monoxide and other aldehydes. At a temperature of 350 degrees celcius, the material autoignites itself. New 6000nm thick flame retardant brominated acrylic copolymer coating on the outside of laminate should be applied. It has a higher fire rating.

2.4.1.2 CORE MATERIAL (FUMED SILICA) Commonly used nanostructured core material used is fumed silica, Silicone dioxide produced from SiO4. Glass wool, polyurethane and polystyrene are other core materials used in VIP’s. If gas pressure is high, thermal conductivity also increases which is a failure of thermal insulation. Thermal insulation materials should be such that it could withstand higher atmospheric pressure without decreasing the thermal resistance which is prevalent in case of fumed silica. Pore size of fumed silica ranges from 10-100nm which is similar to 70nm of air molecules at normal temperature and atmospheric pressure.

2.4.1.3 THERMAL BRIDGES Thermal bridging can take place due to the following reasons: • Thin film high barrier enveloping the core material • The small air gap between two adjacent panels • Constructional irregularities 2.4.2

Thermal insulation coating: Nansulate

Nansulate coatings are an original insulation technology that integrates a nanocomposite called Hydro-NM-Oxide, a product of nanotechnology. This material is recorded as having one of the lowest measured thermal conductivity values.

Nansulate, when fully cured, consists of approximately 70% Hydro-NM-Oxide and 30% acrylic resin and performance additive. The low thermal conductivity of Nansulate and the nanomaterial contained in Nansulate is what makes it an excellent insulator.

2.4.2.1 Uses and application of Nansulate coating: Insulation (Building Envelope): Nansulate Energy Protect and Nansulate HomeProtect offer a flexible insulation solution for commercial and residential buildings. They can be applied on walls, ceilings, attics, duct work and other areas of the building envelope, without disrupting the building’s aesthetic as it is a translucent coating. Nansulate Crystal offers a clear insulation solution for roofs of all types.

Unlike conventional forms of insulation, Nansulate coatings will not get infiltrated by moisture, mold, dust, or pests - and therefore maintains its insulating ability over time.

Insulation (Daylighting): Nansulate Energy Protect over windows and skylights allows in diffused light, while insulating windows against heat transfer. Well designed daylighting allows in natural light that balances overhead electric lighting needs while curtailing glare. Nansulate allows 92% visible light transmittance and decreases UV penetration by 80% as tested on pane glass, and provides the opportunity to daylight without sacrificing building thermal performance. After coating, windows will have a ‘frosted’ look.

Sustainability : Nansulate coatings are naturally resistant to mold growth (without use of moldicides) and therefore will benefit air quality in a building by reducing potential for mold and mildew. There is also a version of Nansulate - LDX, which can be used for encapsulation of dangerous lead-based paint and lead contamination. Nansulate LDX is a clear, smooth lead encapsulation coating which can be used over a variety of surfaces.

2.4.3

AEROGEL

It was developed in the year 1931 and since then it holds the title of being the lightest known solid material known to mankind. It is a very thin and light foam which consists 99.5% of air and the rest is filled with glass-like material and silica. The air molecules are trapped within the foam, the minute nano pores are of size 20nanometer (nm) and these air molecules are rigid in nature, unable to move which adds to the benefit of aerogel being an exquisite thermal insulator.

2.4.4

PHASE CHANGE MATERIALS (PCM’S)

In a climate where summers and winters prevail equally i.e. where people experience hot climate as well as cold climate, Phase Change Material’s (PCMs) should be used.

It reduces the extreme temperature conditions on the inside. It can be used both for heating and cooling as well. It can take up very high temperature of heat, without itself changing its temperature which in turn keeps interiors cool with heat absorbed

by PCMs which is used to liquefy the paraffin. Energy is stored as latent heat when material changes from one state to another. This latent heat is stored in the PCMs which is used for temperature regulation.

2.4.5

SOLAR PROTECTION

Integrating nanotechnology in electrochromatic glass has made it possible for the glass to work without continuous electric current. A single switch is required to change the amount of light transmission from one state to another. A single switch can change the colour of the glass from light to dark and vice-versa.

2.4.6

ANTI-REFLEVTIVE

Anti-reflective glass is used to improve solar transmission inside the building. Antireflective glass is made by integrating transparent nanoscalar surface structure where these nanoparticles are smaller than the wavelength of visible light creating an efficient and effective anti-reflective solution. The structure contains a 30-50nm large silicone dioxide (SiO2) balls. Optimum thickness should be 150nm for anti-reflective solution. The amount of reflected light reduces from 8% to 1%, optimally utilizing the solar energy. Another cost-effective means of producing anti-reflective surfaces is the moth eye effect, cornea of moth which are active mostly at night, exhibits a structure that reduces reflection.

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CONCLUSION

VIP’s are optimally suited to deliver a very high thermal insulation while the insulation thickness of the panels being very low. The U-value i.e. the thermal conductivity of VIP’s is ten times lower than that of polystyrene. VIP’s have been proven to be the best material to provide maximum thermal insulation with minimum insulation thickness. Thickness of these panels ranges from 2mm-40mm while the U-value is 0.005W/mk.

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DATA ANALYSIS

The calculated information of the thermal base case for zone3.

Summary of climatic conditions in Aswan city during the simulation.

Achieving ultra-low U-values and advanced performance of Nano model less than baseline model.

Increasing the thermal lag values of Nano model compared to the baseline model.

Achieving the lowest value recorded scientiďŹ cally of heat transfer values of Nano model which amounted to over 70% when compared to the baseline model.

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FINDINGS FROM THE STUDY • • •

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Better thermal insulation materials like Vacuum Insulation Panels were found and studied. It was tested to prove to be a better insulation materials than conventional materials.

Photochromatic glass was studied to change the colour of the glass if there is greater heat gain in the building through glass. Better application of insulation in glass has been inferred.

Aerogel, the lightest solid material on earth has been seen to reduce the structural load on the building, create more floor area and provide better thermal insulation than polystyrene foam, cork and other conventional materials.

Vacuum Insulation Panels serves the best purpose for thermal insulation with the least thickness increasing the floor area. The installation of VIP has been studied and found on site. Vacuum Insulation Panel gave a U-value of only 0.06 W/m2K. Prototype of nanotechnology in buildings have been found and its implementation and the effects it will have on our future building environments have been studied.

U-value in NanoGel glass= 0.99/m2K

CONCLUSION

The growth of nanotechnology in India is increasing with the increase in the economic growth of the country. Nanotechnology has made it possible to achieve net-zero energy with thinner materials achieving greater floor area which reduces the cost of the building. Architects and researchers have to come up with an approved guidelines to be followed for nanotechnology in the construction industry so that it is incorporated by labours in India. Though the production cost is a lot, positive initiatives are being taken to reduce the production cost and mass-produce the materials for nanotechnology use in the construction industry.

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APPLICATION IN THESIS

Buildings in India consume a lot of energy. Expected outcome of this research in thesis is to improve the energy effciciency of buildings in India by using nano materials in different parts of building. As it provides greater thermal insulation than the conventional polystyrene foam and consumes lesser floor area, wide application of these insulation materials will be used in thesis.

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BIBLIOGRAPHY

Richard & Boysen, E., 2005. Nanotechnology for the Dummies, The hitchhiker's guide to Nanotechnology., s.l.: s.n.

Simmler, H. B. S. H. U. S. H. K. K., 2005. Vacuum Insulation Panels. Study on VIP-components and Panels for Service Life Prediction of VIP in Building Applications, s.l.: s.n.

Terzidis., K., 2006. Algorithmic Architecture.. s.l.:ElSevier Ltd. .

Zain M., N. H., 2013. the Role of Nanomaterials in Nanoarchitecture. s.l.:s.n.