The Mind of a Greenhouse, Nangqen Prototype #1

surrounding of Yushu county

2018 March, August, November | Founder of Tashi Getsen Charity School: Tsangsar Kunga ཚང་སར་ཀུན་དགའ། | principal of Tashi Getsen Charity School: Dawa Konpu ཟླ་བ་མཁན་པོ། | project founder of the greenhouse construction: Tsangsar Kunga ཚང་སར་ཀུན་དགའ།, Wiriya Rattanasuwan, site landlord: Tsangsar Metok ཚང་སར་མེ་ཏོག | local coordinators: Tsangsar Mohji ཚང་སར་མོ་སྐྱིད།

How it started

In August to November 2018, I voluntarily participated in a charity project alongside weather engineer Wiriar Rattanansuwan and the founder of Tashi Gatsen school, Tsangsar Kunga. The initial objective of the project was to construct a greenhouse in Nangqen, Quinhai, situated at an altitude of approximately around 3,700 meters, capable of withstanding harsh winter conditions. The greenhouse aimed to provide year-round vegetables for the orphan children under the care of Tashi Gatsen School, located at 32°31’45.2”N 96°03’05.2”E. Additionally due to the over priced vegetable imported from other provinces in China. We sought to establish a connection between the charity project, art, and science, by exploring an interdisciplinary production system. Hence, constructing a greenhouse with solar cells dyed with local plants held educational and community development value.

Site location

The prototype was constructed in Tsansar Kunga’s family house located in Yushu County, which is approximately a 3-hour drive from the airport. It is highly recommended to stay at this location for at least 3 days to acclimatize to the high altitude of 3,400 meters before traveling to Tashi Gatsen School, which is situated far away from medical services. Since 2018, the school has undergone a name change to Tashi Gatsen Professional School after officially receiving the school license from the Chinese government. To reach the school from Tsangsar Kunga’s house, it takes an additional 5-hour car ride.

school students in Tashi Gatsen School

Travels and telecom service

All international flights are required to transfer from Chendu Airport (CTU). It takes approximately 5 hours to travel from Chendu to Yushu. Due to the presence of the China firewall, it is recommended to use a VPN service. Personally, I use Taiwan roaming service, which costs around 200 NTD per day, and I have not encountered any issues. However, please note that the signal is only available in Yushu County and Chendu. In 2018, there was no signal coverage within the school campus area. According to Dawa Konpu (达哇堪布 ཟླ་བ་མཁན་པོ།), the principal of Tashi Gatsen, the telecom service reached the school area in 2019, and now the school has 4G signal coverage.

Design of the first prototype

In the initial phase of the design, we attempted to incorporate various solutions and combine them into a single design. These solutions included the use of an earth battery, pit-house, and earth-sheltered design to create a passive solar house. The dimensions of the first prototype were 4 by 6 by 2 meters, with a depth of 2 meters.

Regarding the pit-house, the history of it history of pit-house can be found here, considering the harsh weather conditions in Nangqen county, we decided to construct our greenhouse with a depth of two meters. The roof frame was made of welded white iron and covered with transparent PC (Polycarbonate) boards, which had a multilayered structure and were sealed with silicon. Concrete bricks were utilized to build the walls around the pit, serving as support for the welded iron roof. However, we did not place bricks on the floor, nor did we provide a well-designed shelf to efficiently utilize the interior space for storing raised beds. Consequently, the local people ended up growing their plants directly on the floor, which was not an ideal outcome. It is worth noting that the interior of the house tends to be approximately 4 to 6 degrees warmer than the outdoor temperature.

In the earth battery section, we buried a PC pipe connecting the indoor and outdoor spaces of the house. This allowed us to expel the cold air and circulate it back into the house after heating it underground through an 11-meter-long tube. Inside the house, we sealed a toy fan obtained from a local vendor to the end of the tube. Our intention was to charge the fan with solar panels so that it could run overnight using the power collected during the day. However, the charger and battery were not properly set up, and the 11-meter-long tube proved to be too short to sufficiently heat the cold air. Personally, I believe this aspect can be significantly improved in the next phase. Earth battery and earth-sheltered greenhouse were the two main prototypes of our initial design. Unfortunately, there wasn’t enough time to complete the earth battery component during my visit due to it being our first attempt, coupled with the difficulty of finding suitable pipes for air circulation. However, the earth-sheltered design proved effective. Upon receiving feedback from the local community after my return to Taiwan, they mentioned that they perspired inside the greenhouse and observed water dripping, indicating that the indoor temperature was above 0º. However, some individuals reported feeling dizzy and experiencing nausea after prolonged stays inside. This may be attributed to the installation of only one fan for air circulation, resulting in inadequate oxygen and an excess of CO2.

The orientation and the size of the greenhouse was discussed and decided with the members of Tsansar family.

This two-meter deep basement was excavated by the hired goons.

the 50 meters long pipe was placed underneath the greenhouse in 2 meters deep.

A computer fan was attached at the end of pipe

the organic solar cell was placed inside the greenhouse.

3 pieces of organic solar cells were connected together in parallel.

The organic solar cell is used to power the fan, cells were sponsored by Meng Hsin Fei from NYCU Institute of Physics.

I thought it was easy to install an raspberry pi board with a v2 camera module as simple monitor but then it took me 3 or 4 days to find a local internet cafe to install Raspian. The cafe staff became quite concerned when they saw me working with wires and codes, and I was swiftly asked to leave. Eventually, I managed to complete the installation and successfully obtain sensor data and camera vision via SSH. Regrettably, I didn’t have enough time to properly install it inside the house before my flight to Taipei. I use this library for the weather station.

the temperature sensor.

the moisture sensor.

the box of IoT to collect data.

Roof: We thought about to cover the greenhouse with glass windows but eventually we choose transparent PC with honeycomb layers, it's very light so the construction was quick, much cheaper than the glass with aluminum frame. There were some difficulties to install the roof because it was only sliced into 9 pieces in the design, ideally it should be 12 to 20 slices to make the construction much easier.

honeycomb shape transparent PC board for greenhouse.

For the Roof design, initially, we considered covering the greenhouse with glass windows with aluminum frame, but ultimately we opted for transparent PC with honeycomb layers. This material is lightweight, making the construction process quicker and more cost-effective compared to using glass with aluminum frames. However, we encountered some difficulties during the roof installation due to it being divided into only 9 pieces in the design. Ideally, it should have been divided into 12 to 20 pieces to facilitate the construction process. We determined that the sun azimuth angle was approximately 79º, and accordingly, the slope of our roof was set at 23º. The greenhouse is positioned facing south, with an additional 11º counterclockwise rotation to maximize sunlight exposure.

sketch drawn by Wiriar Rattanansuwan.

the roof orientation calculation.

solar elevation angel from sun azimuth.

Progress photos and the final status of the first prototype

The white frame is soldered by the local iron factory.

The finishing look of the greenhouse before my flight.

The current status of the school

The project was concluded following the construction of the first prototype in Kunga’s house. The greenhouse demonstrated potential for vegetable cultivation during spring and summer but not in winter. However, it was short-lived and quickly deteriorated due to a lack of maintenance. This experience taught us that effective management is crucial in greenhouse design, even more so than the engineering aspect. A second greenhouse was unexpectedly built next to Tashi Gatsen School without informing us, indicating that it is a separate project from ours. I inquired about its condition with the principal upon learning of its existence. The principal Dawa Konpu (达哇堪布 ཟླ་བ་མཁན་པོ།) clarified that it was their own design and not related to our prototype which was built in Nangqen. It was made by him and the students. The construction began on April 19th, 2020, and was completed on May 11th, 2020. Although the school now has access to the internet and public electricity, they still rely on solar cells to power the modem, resulting in unstable signal quality. Currently, the school’s focus has shifted away from vegetable cultivation, and their immediate needs are a library and storage space for medicine, as per my conversation with Principal Dawa Konpu via WeChat.