[{"command":"openDialog","selector":"#drupal-modal","settings":null,"data":"\u003Cdiv id=\u0022republish_modal_form\u0022\u003E\u003Cform class=\u0022modal-form-example-modal-form ecl-form\u0022 data-drupal-selector=\u0022modal-form-example-modal-form\u0022 action=\u0022\/en\/article\/modal\/7382\u0022 method=\u0022post\u0022 id=\u0022modal-form-example-modal-form\u0022 accept-charset=\u0022UTF-8\u0022\u003E\u003Cp\u003EHorizon articles can be republished for free under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence.\u003C\/p\u003E\n      \u003Cp\u003EYou must give appropriate credit. We ask you to do this by:\u003Cbr \/\u003E\n      1) Using the original journalist\u0027s byline\u003Cbr \/\u003E\n      2) Linking back to our original story\u003Cbr \/\u003E\n      3) Using the following text in the footer: This article was originally published in \u003Ca href=\u0027#\u0027\u003EHorizon, the EU Research and Innovation magazine\u003C\/a\u003E\u003C\/p\u003E\n      \u003Cp\u003ESee our full republication guidelines \u003Ca href=\u0027\/horizon-magazine\/republish-our-stories\u0027\u003Ehere\u003C\/a\u003E\u003C\/p\u003E\n      \u003Cp\u003EHTML for this article, including the attribution and page view counter, is below:\u003C\/p\u003E\u003Cdiv class=\u0022js-form-item form-item js-form-type-textarea form-item-body-content js-form-item-body-content ecl-form-group ecl-form-group--text-area form-no-label ecl-u-mv-m\u0022\u003E\n        \n\u003Cdiv\u003E\n  \u003Ctextarea data-drupal-selector=\u0022edit-body-content\u0022 aria-describedby=\u0022edit-body-content--description\u0022 id=\u0022edit-body-content\u0022 name=\u0022body_content\u0022 rows=\u00225\u0022 cols=\u002260\u0022 class=\u0022form-textarea ecl-text-area\u0022\u003E\u003Ch2\u003ESmart windows could reduce the need for energy-hungry air conditioners\u003C\/h2\u003E\u003Cp\u003ERoughly \u003Ca href=\u0022https:\/\/publications.jrc.ec.europa.eu\/repository\/bitstream\/JRC117739\/cost_optimal_energy_renovations_online.pdf\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003E75% of EU buildings are energy inefficient\u003C\/a\u003E and countries now are looking to retrofit old buildings to prevent a costly leakage of heat. But despite the brainpower invested to make buildings more energy efficient, the design of windows has until recently not used a lot of modern technology, says Ioannis Papakonstantinou, a professor of nanoengineering at University College London, UK.\u003C\/p\u003E\u003Cp\u003EHis research project \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/679891\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EIntelglazing\u003C\/a\u003E is using new ideas in nanotechnology and photonics (the physics of light) to create nanometre-thin window coatings that better insulate buildings.\u003C\/p\u003E\u003Cp\u003EThis had been tried before in industry, but all the previous efforts fell short - they either blocked out too little sunlight or were too expensive to make.\u003C\/p\u003E\u003Cp\u003E\u2018If you start blending these (window) coatings with nanotechnology, then you can push the performance boundaries to much higher levels,\u2019 he said.\u003C\/p\u003E\u003Cp\u003EThe Intelglazing glass technology has two parts. The first is a microscopically thin layer of nanostructured glass shaped like tiny hair combs which are less than a micrometre (or one thousandth of a millimetre) in height. These \u2018nanocomb\u2019 structures overlap with each other and scatter sunlight, reducing the glare that enters through the window.\u003C\/p\u003E\u003Cp\u003EThe second part is where the windows become energy efficient. Here the researchers are experimenting with a material called vanadium oxide, which can attach to the nanocombs. This chemical compound is thermochromic - meaning it can change its colour depending on the temperature. For example, hot days will cause the vanadium oxide to change its structure, causing it to darken and reject most of the warming near-infrared sunlight, whereas on cold days it will lighten and let most of it in.\u003C\/p\u003E\u003Cp\u003EManufacturers can apply this layer directly to new windows as a layer of glazing, or DIY retrofitters can apply it to old windows as an adhesive layer of polymer film. An added benefit of this, says Prof. Papakonstantinou, is that manufacturers can customise windows or films with these layers to switch on at a different temperature point.\u003C\/p\u003E\u003Cp\u003E\u2018You can change the chemical composition of vanadium dioxide in a way that it can switch at a higher or lower temperature,\u2019 he said. \u2018So you have some quite good control.\u2019 For example, windows in southern Spain could be customised to block out sunlight at a lower temperature to prevent buildings warming up during the day. Likewise, a building in northern Sweden will want to get as much warmth from the sun as possible, so their windows could only start blocking out sunlight at a higher temperature.\u003C\/p\u003E\u003Cp\u003E\u003Cblockquote class=\u0022tw-text-center tw-text-blue tw-font-bold tw-text-2xl lg:tw-w-1\/2 tw-border-2 tw-border-blue tw-p-12 tw-my-8 lg:tw-m-12 lg:tw--ml-16 tw-float-left\u0022\u003E\n  \u003Cspan class=\u0022tw-text-5xl tw-rotate-180\u0022\u003E\u201c\u003C\/span\u003E\n  \u003Cp class=\u0022tw-font-serif tw-italic\u0022\u003E\u2018Renovation of buildings is carried out all the time \u2026 It\u0026#039;s important that when we do this, that we do it in the most energy efficient way so we don\u0026#039;t replace an old window with a poorly performing new window.\u2019\u003C\/p\u003E\n  \u003Cfooter\u003E\n    \u003Ccite class=\u0022tw-not-italic tw-font-normal tw-text-sm tw-text-black\u0022\u003EProfessor Per Heiselberg, Aalborg University, Denmark\u003C\/cite\u003E\n  \u003C\/footer\u003E\n\u003C\/blockquote\u003E\n\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EHydrophobic\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EWindows with this nanocomb-vanadium oxide layer are also hydrophobic (water repellent) - rain quickly runs off the glass and picks up any dirt along the way, making the windows self-cleaning. This makes the windows more efficient when they are used in skyscrapers, for example.\u003C\/p\u003E\u003Cp\u003EThe project\u2019s aim is for their windows to \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/679891\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Ereduce people\u2019s energy use\u003C\/a\u003E by 25% by blocking or allowing sunlight when needed, and be more than 50% more efficient compared to existing window tech on the market, since no extra energy is needed to activate the vanadium oxide.\u003C\/p\u003E\u003Cp\u003EIn fact, window retrofitting technology has changed drastically since the project started in 2016, says Prof. Papakonstantinou. He says when he first discussed the project in the mid-2010s, nanotechnology in windows was unheard of but now \u2018the field has started booming.\u2019\u003C\/p\u003E\u003Cp\u003EProfessor Per Heiselberg of Aalborg University in Denmark says that discussions on retrofitting buildings has been around for decades, though the environmental element has only recently been a priority.\u003C\/p\u003E\u003Cp\u003E\u2018It has been the topic for 40 years, but of course the argumentation has changed,\u2019 he said. Back in the 1970s he says that people were saving energy so as not to be dependent on countries in the Middle East who had an oligopoly on oil supply. \u2018Now the focus is to reduce your carbon emissions and avoid greenhouse gases.\u2019\u003C\/p\u003E\u003Cp\u003EProf Heiselberg\u2019s \u003Ca href=\u0022http:\/\/www.reco2st.eu\/\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EReCO2ST\u003C\/a\u003E project is looking at ways to retrofit every surface that envelops a building to be more cost efficient and environmentally friendly.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EVentilation systems\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EA central feature of the project is using smart window technology to provide ventilation for retrofitted buildings, where installing modern ventilation systems like air conditioners is difficult or expensive. \u2018(A window is usually the) weak part of the envelope because it\u0027s typically leaky and not so well insulated,\u2019 he said. \u2018On the other hand, it\u0027s also where we get some heat from the sun into our buildings.\u003C\/p\u003E\u003Cp\u003EThe main idea is to use smart windows to both provide better shade from the sun and supply fresh air into a building. This is especially useful for older buildings retrofitted with modern windows. Since these modern windows are more airtight they can cause moisture and emissions to build up in the building, which might require another costly retrofit of the building\u2019s ventilation system.\u003C\/p\u003E\u003Cp\u003E\u2018It can be difficult - especially in old buildings - to find space for pipes and ventilation systems to supply fresh air to the spaces \u2013 and all spaces usually have access to the outside through a window,\u2019 said Prof. Heiselberg.\u003C\/p\u003E\u003Cp\u003E\u2018It would be more cost effective if, instead of installing both a new window and a ventilation system, we use the window for supply of fresh air, and then we use the chimneys or the stacks you have in old buildings for the exhaust of the air.\u2019\u003C\/p\u003E\u003Cp\u003ETheir smart window idea is based on research done in a previous EU project called \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/262262\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003ECLIMAWIN\u003C\/a\u003E. In their triple-glazed window frame there is a small gap (around 5mm wide) at the bottom level on the outside. This gap allows air to pass in between the window\u2019s glazing layers and be warmed by sunlight. It then enters the room through a small valve at the top of the window facing inside the building. \u0026nbsp;\u003C\/p\u003E\u003Cp\u003EThe result is a preheated draft of fresh air through the window that can then leave the building through another ventilation exhaust.\u003C\/p\u003E\u003Cp\u003EAt the moment the team is experimenting with different materials that can store latent heat in the windows during the day and then release it at night, says Prof. Heiselberg. \u2018During a time where we have sunshine, we can collect and store it,\u2019 he said. \u2018And then we also have the possibility to preheat air in periods where the sun is not shining.\u2019\u003C\/p\u003E\u003Cp\u003EThis material could also be shaded from the sun during the summer so that instead of storing latent heat, it instead cools the air passing through it. Another idea being developed is fitting the windows with sensors to know the optimal time to store and release heat, and adding miniature fans to control the direction of the airflow.\u003C\/p\u003E\u003Cp\u003E\u2018Renovation of buildings is carried out all the time because components have a certain lifetime and need to be replaced,\u2019 said Prof. Heiselberg. \u2018It\u0027s important that when we do this, that we do it in the most energy efficient way so we don\u0027t replace an old window with a poorly performing new window.\u2019\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThe research in this article was funded by the EU. If you liked this article, please consider sharing it on social media.\u003C\/em\u003E\u003C\/p\u003E\u003C\/textarea\u003E\n\u003C\/div\u003E\n\n            \u003Cdiv id=\u0022edit-body-content--description\u0022 class=\u0022ecl-help-block description\u0022\u003E\n      Please copy the above code and embed it onto your website to republish.\n    \u003C\/div\u003E\n  \u003C\/div\u003E\n\u003Cinput autocomplete=\u0022off\u0022 data-drupal-selector=\u0022form-fffjvbga7zyt2y-akmxxluegviismpxceqfhj5gac5c\u0022 type=\u0022hidden\u0022 name=\u0022form_build_id\u0022 value=\u0022form-FFfjVbga7ZYt2Y-akmxxlUegViISmpXceQFHJ5gAc5c\u0022 \/\u003E\n\u003Cinput data-drupal-selector=\u0022edit-modal-form-example-modal-form\u0022 type=\u0022hidden\u0022 name=\u0022form_id\u0022 value=\u0022modal_form_example_modal_form\u0022 \/\u003E\n\u003C\/form\u003E\n\u003C\/div\u003E","dialogOptions":{"width":"800","modal":true,"title":"Republish this content"}}]