PyraTENT – an all season tent that uses the sun for heating and cooling

PyraTENT is so far the smallest POD structure with a double-layer cavity wrapping around a space that is 4 meters in edge length and in height, enough to protect a single person, a couple, or even a small family from cold in winter and heat in summer.

It uses water soap bubbles to fill the cavity, forming a relatively thick and protective bubble foam layer that is proactive in capturing and storing solar thermal energy during the day for night use.

Anyone knows that it is impossible to camp outside in cold winter without a heating source. If you have ever spent a night camping outside in summer with a conventional tent, while it is fun to cook outside and sit around a camp fire chatting or roasting mesh mellow, but the hardest thing to endure is the cold temperature inside the tent from midnight to morning, with the morning being the worst. Things get even bad when you have to get up in the middle of night to washroom. Well, no such a bad memory if you use our PyraTENT!

PyraTENT, as its name implies, uses the sun as the “fire” source to create a double layer tent that is equipped to capture solar thermal heat during the day and store it in water for night use. It uses a transparent fabric to form the double layer cavity. Once the bubble foam is contained in the enclosed cavity, it lasts longer and it insulates the entire tent from heat loss at night and solve the problem of too much heat gain from the sun during the day.

No matter what kind of conventional tent you buy, whether single layer or double layer with/without air inflation, you will experience the same problem: the interior temperature is almost the same as the exterior temperature, swinging up and down with the sun. Why? Because the tent heats up when you have the sun and cools off after sunset, just like how the outside open air behaves. Without storing the thermal energy collected during the day, there is no way you can use it after sunset. The result? The interior temperature swings with the sunrise and sunset, just like what you see in the temperature curve on the left.

However, once you fill the double layer cavity with wet soap bubbles, the temperature swing is smoothed out because of the heat transfer from air to water, i.e. the soap liquid. As the wet bubbles fill the cavity, they do multiple things: (1) capturing the infra red solar energy for heat transfer and storage, (2) letting in the high frequency solar rays for lighting, and (3) trapping air in them to reduce heat loss caused by air convection, etc. This way, the interior air remains cool for our comfort while the solar thermal heat is transferred from bubbles to soap liquid.

A 2x2x1 meter heat storage space with its bottom covered with pond liner is shown in the center with half buried down in gravel/water and half in the air. This setup helps with solar/geo thermal coupling and air humidity control. The snow melting feature is built in as fresh bubbles generated from the soap liquid (normally stays around 15°C) in the central heat storage tank are always warmer than the exterior temperature in winter time. Because of gravity, the bubbles at the bottom are wet bubbles while bubbles on the top are relatively dry and light.

Due to their light weight, high transparency and superb capacity for heat transfer and storage, soap bubbles are the best medium for solar heating and cooling. PyraTENT is designed as a low cost, easily deployed climate controlled shelter. It is great for anyone to start and get on the learning curve with SolaRoof technology. If you do not want to start with a new structure, you can consider converting a Gazebo into PyraTENT.

Note for building PyraTENT DIY, we suggest that you use PE pipes re-enforced with metal rods inside as posts. The four central posts need to be buried and anchored to the solar-geo heat storage and exchange zone and platform, the rest can be built with bamboo sticks or carbon fiber pipes. For starting, you can use low-cost plastic films to form the double-layer cavity.

For off-grid purpose, a solar panel with a battery is needed to power the fans and water pumps. Note that fans and pumps only run when needed, normally just a few minutes for each two or three hour period. Click here for our YouTube playlist that is dedicated for PyraTENT.

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