Sunday, June 5, 2011

More Temperature Stats

Lettuce, green onions, basil, green beans, cilantro, tomatoes, and radishes are growing nicely in pots my Juwel 1000 cold frame. It is just sitting on the pavement in front of my house. Here are the latest statistics from my thermochons.

Temperature in degrees Fahrenheit 

At this point I've had to move the lettuce out to the greenhouse because it was getting to tall. I would still be ok, if the top of the pots was the same level as the bottom of the cold frame. I installed an automated opener  since I shared the last set of numbers.

What next. I would like to build a small box that this can sit on top of so that the top of the containers will be at the bottom of the cold frame or just below it. This would also allow me to hold in more thermal mass to help stabilize the temperatures. Once that gets setup I'll consider adding a grow light and an warming light as a heat source to get things started earlier next spring. Until then I'll be enjoying my fresh tender lettuce and green onions.

Sunday, April 24, 2011

Juwel 1000 Cold Frame: Temperature Testing Research Part 2

After looking at the previous results (see part 1) of my temperature experiment with my Juwel 1000 I decided to add a row of bottles of water around the perimeter of the inside of the cold frame to see what effect that would have.

Click to enlarge
Here are the statistics from the data for the graph above.
Maximum temperatures: 85.1F (inside), 63.5F (outside), and 23.4F (difference)
Minimum temperatures: 37.4F (inside), 27.5F( outside), and 3.6F (difference)

The thermal capacity of the water bottles was enough to keep the temperature inside of the cold frame above freezing when the weather is clear during the day and the temperature drops below freezing at night.

Greenhouse Temperature Comparison Results

After experimenting with my cold frame recently (see Juwel 1000 Cold Frame: Temperature Testing Research Part 1) I decided to do a little research about the temperatures in a greenhouse. Here are the results. All three days were clear skies and calm. The maximum inside temperature was 98.6F and the maximum difference in temperature between the inside and outside was 37.8F while the minimum temperature difference was 6.3F
Click to open interactive graph
The greenhouse is a south facing lean to style with a concrete floor. Currently there is a lot of miscellaneous stuff in the greenhouse, but nothing with very much thermal mass.

The design and size of the greenhouse seem to be able to absorb a lot of thermal energy but there is not enough mass to retain it over the night.