If buildings the world over are to stay looking good for longer without the need for costly renovation or aggressive cleaning regimes, then the development of products which naturally protect and replenish a façade is essential.
Ben Warren, Managing Director at global building materials manufacturer, Baumit, considers the technology in the manufacture of the latest self-cleaning, topcoat systems, which have a positive impact on the environment in terms of upholding a building’s aesthetic properties and improving its energy efficiency.
Self-cleaning renders and paints have been available for some time now – and what a superb innovation they are. Products which require water or natural elements such as daylight, rain or air moisture to keep a building’s façade clean offer a huge benefit to the property owner in terms of cost-effectiveness. Self-cleansing systems eliminate the need for periodical maintenance as surfaces stay looking clean and healthy far longer than traditional coatings. The environment gains from the technology, too. Buildings adorned with self-cleaning materials do not require chemically-infused agents to maintain a dirt-free surface. A fact worth remembering as the government struggles to make good its pledge to reduce UK emissions by a minimum 80% from 1990 levels by 2050.
The two main self-cleaning topcoat systems currently available require different climatic conditions to trigger the cleansing process. One uses direct rain or water contact, allowing dirt contained within a droplet to simply roll of the surface. This system is fine in principle, but slightly flawed in practice. The electrostatic properties of the molecules contained within the topcoat means if a hand or other object such as a ball comes into contact with the surface, a dirty print will be left behind. Nanopor is different…
Nanopor systems require nothing more than sunlight, humidity and wind to provide a uniform, dirt-free surface. A special photocatalyst additive, which has been developed by Baumit, uses the power of light to activate the self-cleaning effect in its Nanopor range of renders and paints. The ‘Nanopor-effect’ is produced when sunlight activates the photocatalysis additive in the render or paint, affecting the upper-hydrophilic nano layer within the product whilst it dries. During the process, dirt is decomposed and lifted from the surface by air movement. Any remaining particles are removed by rain and evaporation of absorbed dampness. For a simpler explanation of the ‘Nanopor-effect’; when a drop of water falls on a normal hydrophobic render surface, it will appear as a ‘ball’ of water. A drop of water when dropped onto Baumit NanoporTop loses its surface tension. During evaporation the moisture releases dirt particle, resulting in a dry, clean and beautiful façade.
Because Nanopor doesn’t depend on direct contact with water to trigger the self-cleaning process, areas of a building not exposed to rain - such those as beneath the eaves – are also thoroughly cleansed. This enables a consistent, clean performance across the entire building and eliminates issues such as streaking or dark patches forming where water was unable to connect with the façade.
The photokat process is particularly effective against fungi or mould in a façade. It’s also superb for removing smoke or dust particles. Again, it’s worth making the point that the innovative Nanotechnology in renders and paints reduces the need for a building’s renovation, making it a cost-effective and environmentally-friendly alternative to other exterior coatings. As with most self-cleaning exterior finishes, Baumit NanoporTop, a ready-to-use dirt and pollution-repellent render, can be hand or machine-applied. It features unique nano-crystalline and non-organic additives which result in significant surface reduction of pollution compared to other coatings, leaving a building protected and looking clean and bright. The microscopically smooth surface of Baumit Nanopor render and paint offers a façade unique protective barrier against pollution, as dirt particles have nothing to cling onto.
It is estimated poorly-insulated homes account for 25% of emissions released in the UK, hence the need for a focus on improving the thermal performance of our new and existing properties. Airtight buildings are important, but they must also be able to breathe. Think about what goes on the inside of a house – washing, cooking, bathing…even breathing. All that moisture has to go somewhere - ideally out of the building. However, with some topcoats and renders, it’s like placing a plastic bag over a home’s exterior. Sure, the building’s better-insulated, but it’s also trapping escaping moisture which can result in damp and mould growth, and health issues for occupants.
Baumit’s topcoat and colour product range contains a "nanoporous" structure, which allows buildings to breathe - keeping them warm in winter and comfortably cool in summer whilst eliminating the potential for moisture retention and damp.
The development of self-cleaning top coats and renders has given a whole new lease of life to building facades. By focusing as much care and attention to the array of available technically-advanced, high-performance materials we apply to the outside of a building, will help ensure a more comfortable and healthy environment for those on the inside.
Find out more about Baumit Render Systems: Download our product catalogue