Building a greenhouse can be a challenging task, especially when it comes to maintaining a consistent temperature throughout the year. In a recent interview, the speaker discusses their experience with building a greenhouse and the challenges they faced with the current design. The current greenhouse design is good for winter as it can hold snow without collapsing, but it struggles to maintain a consistent temperature during the summer and winter months.
To address these challenges, the speaker plans to build a new greenhouse that is partly underground and uses polycarbonate glazing to help maintain a more moderate temperature. They also plan to increase the surface area of the parts of the greenhouse that can hold heat while decreasing the surface area of the glazing. The new greenhouse will be designed to provide a more stable environment for growing plants, especially during the winter months.
Key Takeaways
- Building a greenhouse can be a challenging task, especially when it comes to maintaining a consistent temperature throughout the year.
- The speaker plans to build a new greenhouse that is partly underground and uses polycarbonate glazing to help maintain a more moderate temperature.
- The new greenhouse will be designed to provide a more stable environment for growing plants, especially during the winter months.
Understanding the Current Greenhouse
The speaker is building a greenhouse and is having trouble growing certain plants due to the extreme temperatures. The current greenhouse is designed for winter and can hold snow without collapsing, but it gets too hot in the summer and too cold in the winter. The speaker has tried using a double bubble to moderate the temperature, but it still requires a lot of energy to heat.
To address this issue, the speaker is building a new greenhouse that is partly underground. The walls will be made of insulated concrete and the roof will be transparent polycarbonate. This will help moderate the temperature by reflecting the infrared heat back into the greenhouse.
The speaker is also adjusting the ratio of glazing to elements that hold heat, such as soil, rocks, benches, and water barrels. By increasing the surface area of the parts that hold heat and decreasing the surface area of the glazing, the greenhouse will be able to hold heat better.
The new greenhouse will not require as much energy to heat and will provide a more moderate winter environment. The placement of the greenhouse is based on the way the land goes and the location of windows on the building.
Challenges with the Current Greenhouse
The current greenhouse design has some limitations that make it challenging for the owner to grow certain plants. The greenhouse is designed as a high tunnel with a double layer of plastic, which is great for season extension in the beginning of the year. However, the high tunnel is not suitable for growing plants in the middle of summer because it gets too hot. Additionally, in the winter, the greenhouse is not a good overwintering environment, as the temperature drops to 15 below zero, which makes it difficult to heat.
The owner has tried to use a double bubble on the greenhouse to moderate the temperature, but it did not work well. The current design is apparently good for winter, as it can hold the snow, but heating it would require a lot of energy. The owner uses a 100,000 BTU gas heater to keep the greenhouse from freezing, but it uses a lot of propane, which is not sustainable.
To address these challenges, the owner is building a new greenhouse that will be partly underground. The new greenhouse will moderate the temperature, making it easier to grow plants that require a more moderate winter environment. The walls of the new greenhouse will be made of insulated concrete, which will be opaque and provide better thermal properties than the current plastic walls. The roof will be made of double-wall polycarbonate, which will reflect the heat back in, making it feel warmer inside.
The owner has also realized that the ratio of glazing to the amount of soil, rocks, benches, concrete, and water barrels that hold heat is important. The new greenhouse will have a lower ratio of glazing to the parts that hold heat, which will help to keep the heat inside. The new greenhouse will also be placed on a specific site, taking into account the way the land goes and the position of the building’s windows.
Desired Features in the New Greenhouse
The greenhouse being built aims to address the challenges faced by the previous greenhouse. The new greenhouse will have the following desired features:
- Moderate winter environment: The temperature in the new greenhouse will be moderated to stay in the 20s during the winter. The goal is to avoid extreme cold temperatures, such as 10 below, and to keep it from freezing. This will require less energy to heat and maintain the temperature.
- Cooler summer environment: The new greenhouse will be designed to prevent excess heat buildup during the summer season. The goal is to make it hot but not as hot as the previous greenhouse, where the heat from the outside amplified due to plastic.
- Partially underground: The new greenhouse will be partly underground to help regulate the temperature and reduce heat loss. The previous greenhouse was entirely above ground, which caused a lot of heat loss.
- Ratio of glazing and heat-holding elements: The new greenhouse will have a lower ratio of glazing and a higher ratio of elements that can hold heat, such as water barrels, soil, rocks, benches, and concrete. This will help prevent heat loss and maintain a consistent temperature.
- Polycarbonate roof: The new greenhouse will have a polycarbonate roof, which has better thermal properties than polyethylene. The polycarbonate roof will reflect the heat back in, keeping the greenhouse warmer during cold nights.
The placement of the new greenhouse was chosen based on the land’s slope and the building’s location. The greenhouse was not oriented based on the sun’s position, as the goal is to get ambient light from the sky.
Previous Experience with Underground Greenhouse
The speaker has previously built an in-ground greenhouse around 20 years ago in 2004. It was built like a basement with a roof over it, and the walls were concrete and opaque. The walls were about 3 to 6 feet deep, with a little bit of a knee wall on the outside. When inside, it felt like being 5 to 8 feet underground. The greenhouse roof was transparent, made of double-wall polycarbonate. The polycarbonate has different thermal properties than polyethylene. It won’t let infrared radiation, making it more or less opaque to infrared. The sun comes in and heats the soil during the day, and at night, the soil wants to re-radiate. The polycarbonate will reflect that heat back in, making it feel warmer than a polyethylene high tunnel on a cold night.
The speaker is building a new greenhouse that is partly underground to moderate the temperature. The design of the current greenhouse is good for winter, but it’s challenging to heat it. The speaker is not looking to grow tropical plants in the winter, just a more moderate winter environment. The current greenhouse is too hot in the middle of summer. The speaker wants it to be hot but not as hot as the current greenhouse.
The speaker is increasing the surface area of the greenhouse that can hold heat and decreasing the surface area of the glazing. The speaker found before that it was okay to just have the roof, and it doesn’t matter which way it points. The site was chosen because of the way the land goes and the building’s location. There are a lot of windows on one side of the building that the speaker didn’t want to block.
Benefits of Polycarbonate over Polyethylene
Polycarbonate is a popular material for greenhouse construction due to its superior thermal properties when compared to polyethylene. The main difference between the two materials is that polycarbonate has an air space between its double walls, which makes it more opaque to infrared radiation. This means that the heat generated by the sun during the day is reflected back into the greenhouse at night, keeping the temperature more consistent.
On the other hand, polyethylene is transparent to infrared radiation, which means that the heat generated during the day is lost to the sky at night. This can make the temperature inside the greenhouse drop significantly, making it difficult to maintain a consistent environment for plants.
Polycarbonate is also more durable than polyethylene, as it is resistant to impact and weathering. This makes it a better choice for areas with harsh weather conditions, where polyethylene may become damaged over time.
Overall, the use of polycarbonate in greenhouse construction offers several benefits over polyethylene, including better thermal properties and increased durability. This makes it a popular choice for those looking to create a stable environment for their plants.
Importance of Glazing to Soil Ratio
The glazing to soil ratio is an important factor to consider when building a greenhouse. The ratio refers to the amount of glazing, such as windows or polycarbonate panels, compared to the amount of soil, rocks, benches, concrete, and water barrels that hold heat.
According to the speaker, if a greenhouse has a lot of glazing and only a small amount of soil, it will lose heat faster than it can hold on to it. This is because the soil absorbs and radiates heat at a certain rate, while the glazing radiates heat through at a different rate.
To address this issue, the speaker suggests increasing the surface area of the parts of the greenhouse that can hold heat and decreasing the surface area of the glazing. This can be achieved by partially burying the greenhouse underground, as the soil can act as a heat sink.
The speaker also notes that the type of glazing used can affect the thermal properties of the greenhouse. Polycarbonate and glass, for example, reflect infrared radiation back into the greenhouse, which can help to retain heat.
Overall, the glazing to soil ratio is an important consideration when building a greenhouse, as it can impact the ability to maintain a consistent temperature and grow desired crops.
Choosing the Site for the New Greenhouse
The speaker is building a new greenhouse and has chosen a specific site based on the way the land goes and the placement of the existing building. The site was not chosen based on the number of windows on a specific side of the building that the speaker did not want to block.
The speaker plans to partially bury the greenhouse in the ground, with walls made of insulated concrete. The roof will be made of double-wall polycarbonate, which has different thermal properties than polyethylene. The polycarbonate will reflect infrared heat back into the greenhouse, making it feel warmer than a polyethylene high tunnel on a cold night.
To moderate the temperature in the greenhouse, the speaker plans to increase the surface area of elements that can hold heat, such as water barrels and stones, and decrease the surface area of glazing. The ratio of glazing to heat-holding elements is important, as too much glazing will result in heat loss faster than it can be retained.
The speaker is not looking to grow tropical plants in the greenhouse during the winter, but rather to create a more moderate winter environment that does not get as cold as 10 below zero. The greenhouse will be heated to prevent freezing, but the speaker wants to avoid using excessive energy.
Overall, the speaker’s choice of site for the new greenhouse takes into account the need to moderate temperature and maximize the surface area of heat-holding elements, while minimizing the surface area of glazing.