Rooftop cooler

What it does

Sheep wool takes water out of the air at night and then vaporises it when the temperature rises during the day to cool the local climate. It also has a reservoir to store rain and use it later in the dry times.

Your inspiration

While doing a project on school and learning about the heat stress in the cities and the importance of cooling them down. I got fascinated by it and it was running through my mind for the next weeks. The idea of using sheep wool to hold water and let it vaporise water for cooling came when I was laying in the sun. I just read an article about the disposal of sheep wool. It is an environmentally friendly material and cheap because currently there is not enough demand for it. Plants are widely used to cool down the city, but they do not live under solar cells. This is the solution for cooling down the city and creating a wool market.

How it works

The principle is based on the evaporation of water. It stores rainwater in a reservoir and the wool collects condensed water at night. Warming up the system will evaporate the water into the air. The cooling works by taking energy out of the environment to evaporate the stored water in the wool. When the wool is dry and there is water in the reservoir, the capillary effect transports the water into the wool where it again has the chance to evaporate into the air. This takes energy for the transformation from liquid to vapour in the same way we cool down by sweating. The system will be used on roofs that lay full of solar cells or places where farming plants are not an option. When you place the system under solar cells, it must be ensured that there is enough airflow A positive side effect that also influences the return on investment is, that cooling the air and solar cells will increase the efficiency of the solar cells.

Design process

It started with the idea of reinventing the purpose of sheep wool and cooling down cities. This helped me set boundaries for this concept and realise the project in a relatively short period. Next, I thought about the impact. Cooling down a city needs a lot of vaporised water. Therefore, a lot of systems must be rolled out. Mass production will lead to lower production prices. To maximise environmental impact green materials will be used for production. After the first sketches, I got some real sheep wool to experiment with. While experimenting and cleaning wool, I learned a lot just by having it in my hands. This gave me enough motivation to make a first system prototype. While making the prototype found out that the wool must lay in straight lengths horizontal and vertical layered. Compressing it will increase the material contact which will stimulate the capillary effect. Finally, I made a CAD model combining all the results and learnings of the prototype.

How it is different

The system is different in the way that it uses wool and water from nature to cool down the city. Although it can be placed under solar cells it does not require electricity. It is based only on physics laws. This will make it easy to build and recycle later. While using physics the system will play a constant impact role in the ecosystem.

Future plans

More research to improve the capillary effect. Design some proper mounting system, maybe in combination with solar cell mounts. Some more wool research to get an optimal cost-benefit ratio (think about cleaning and other preparation costs). If it is good enough to be produced, a company needs to be found (solar cell producer, roofing company or municipality) that will produce and implement the concept in a bigger real-world test and set up a production line.

Awards

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