Smart Nanocomposites Revolution for Energy-Savings Windows

Postdoctoral researcher Dr Anurag Roy is based you University of Exeter’s Environment and Sustainability Institute. His research is focused in the understanding and development of sustainable buildings, including passive cooling strategies, novel functional metal oxides and their employment of photovoltaic cells.

Achieving NetZero carbon emission by controlling energy exchange through buildings

Energy consumed by buildings for heating, cooling, and lighting needs accounts for CO2 emissions and government’s ambitious target of reaching zero emission cannot be achieved without controlling energy exchange through buildings. Currently, space heating and cooling consume 20% of the building’s total energy; if this trend continues, it will be 50% by 2050.

One of the most effective methods of reducing extreme cooling loads in hot environments is to prevent or reduce solar heat gain via glass windows by employing passive mechanisms that reduce the amount of direct radiant heat that passes through the window without impeding natural illumination, such as the use of solar shading. Basic glass windows are sensitive to incoming solar radiation, which may pass through a transparent sheet of glass with a transmittance of around 90% with no difficulty. With the development of materials, new technologies, and new techniques for decreasing energy use, the scientific research on more energy-efficient windows has progressed significantly. 

The mounting demand for better energy efficiency and visual comfort of buildings has led to the development innovative, high-performance intelligent glazing systems using nanocomposite material.

The trade-off between the transparency of windows and their thermal values.

Anurag Roy, a postdoctoral researcher from the Renewable Energy department, has the vision to undertake ambitious, innovative research and program to develop a feasible solution through a minimum trade-off between transparency and thermal characteristics using nanocomposites significantly reduce energy demand in the built environment at an acceptable cost.

Anurag is working under the team led by Prof. Tapas Mallick and Prof. Asif Tahir, one of the leading in the and only at the University those who are dedicated to working on sustainable build environment’ research and development.1

According to Prof. Tahir, “Building Energy efficiency should be on the priority list to reduce energy consumption to save money and our planet. Smart glazed fenestration is a way forward to achieve energy-efficient buildings.” Their targeted nanocomposite can be achieved by effective integration of phase change materials to enhance thermal capacitance, transparent insulating materials to increase thermal resistance, transparent infrared absorbers to absorb IR radiation and thermochromic materials to control light transmission and infrared-reflective coating to reduce heat loss and gain through the transparent envelope of the built environment.

Heat shielding and intelligent cooling

Anurag and team have developed the paraffin incorporated SnO2-Al2O3 composite coating on the glass using screen-printing technology, which signifies an intelligent cooling behaviour for a comfortable indoor environment irrespective of their emplacement and exhibits less transmission of infra-red light while keeping high visible light transmittance behaviour resulting superior heat-shielding performance. The composite coated glass’s average indoor temperature profile remains at ∼30 °C when the outside temperature reaches a maximum of 45 °C during outdoor testing.

While the same composite film is set inside, the indoor average temperature maintains ∼30 °C, whereas the outside temperature reaches a maximum of 80 °C.2 Besides, a multifold smart composite consisting of an optimized In2O3/ZnO-polymethyl methacrylate-paraffin composite was also developed, exhibiting a reduced heat exchange through the combined self-cleaning and energy-saving envelope. Emplacement with this nanocomposite glass maintained a steady average indoor temperature of ∼30 °C when the outside temperature reached ∼55 °C while maintaining good visibility.3 

They have also developed a switchable thermochromic perovskite material for window applications. This is because switchable materials with thermal actuation ability have a notable positive impact, as there is no external power supply requirement. The promise morphology-oriented semi-switchable thermochromic property evaluation for a mixed halide perovskite having a low transition temperature is an efficient candidate for window high-temperature thermal comfort and can be adopted for building-integrated photovoltaics in future.4 

This is a unique development where the composite can be achieved cost-effectively by employing readily available materials using building energy flow-modelling techniques. Further, the composite glazing showcases a comfortable daylight environment maintenance targeted to reduce annual energy consumption by 30-40% for buildings which are quite innovative compared to the traditional glass-based glazing.

The primary commercial beneficiaries of the project’s outcomes will be construction-related industries, including building designers, glazing/materials manufacturers and installation companies. Besides, people living in energy-efficient buildings will benefit from reduced energy costs, improved conditions and comfort. The improved internal environmental conditions will also enhance the occupants’ health and wellbeing.  

 

References  

1. https://gow.epsrc.ukri.org/NGBOViewGrant.aspx?GrantRef=EP/T025875/1 

1. https://doi.org/10.1016/j.conbuildmat.2022.127319  

1. https://doi.org/10.1021/acssuschemeng.2c00260 

1. https://doi.org/10.1021/acs.jpcc.1c05487