ecosistency

Coldframes are like mini-greenhouses and can be used to extend the growing season in colder climates.   This post describes a “green technology” experiment i did in Spring 2010 to measure how much the temperatures increased in a simple coldframe.

Here is the coldframe i built, a simple wooden box with a semi-clear plastic cover tilted to the South:

Then i built an electronic circuit that measures the temperatures inside and outside (aka ambient, in the shade) and wirelessly sends the measurements once per minute to my main computer for logging and analysis:

Here are results from a full-sun Spring day in the Chicago area:

The blue line is the outside (ambient) temperature and follows a natural  curve from 9AM to 7PM.  The red line is the inside temperature and shows the “greenhouse effect”.  i manually intervened around Noon because the inside temperature got too hot (for healthy plants).

This illustration helps to explain other “anomalies”  in the above graph: