The graph shows the temperature in the chicken coop, the temperature of the air in the vent pipe coming from the biomeiler, and the temperature of the outdoor air. The electrical energy usage would be shown for any days when the electric heater was used, but it was not needed this month.
During the month of June, the temperature of the air entering the coop through the vent rose significantly. At the beginning of the month, it was the same temperature it had been all through the winter. By the end of the month, enough heat had been added to the mantle of the pile to raise the vent temperature by almost 30 Fahrenheit degrees.
June was a month filled with confounding variations. The outdoor air temperatures rose unsteadily during the month. The heat generated by the birds changed considerably over time as we twice harvested some birds and slowly replaced them with birds from the outdoor pen. Also, we changed the airflow conditions in the coop in the middle of the month. Thus, any rigorous analysis of the coop temperature variations this month would be an impossibility.
In the second week of the month, the coop temperature began rising above 80F. I fully opened the window and propped the door open by an inch with the goal of cooling the coop by means of greater airflow. Those changes made no discernible improvement. So, on the 13th, we moved all but the largest 18 broilers to the outdoor pens. The coop cooled slightly after so much body heat was removed, but the outdoor air temperature was so uncomfortably high that the improvement was slight.
On the 21st, we harvested the 12 largest broilers, which, again reduced the body heat contribution to the coop temperature. The outdoor air temperatures also decreased at that point, which makes it difficult to say which change had the greater effect on the coop temperature. Broilers were moved from the outdoor pen back to the coop, one per day, in preparation for the second harvest.
On the 27th, we harvested the second dozen broilers, again choosing the largest of the flock. After that day, the coop occasionally was cooler than the outdoor air temperature, even though we had begun the daily replacement of broilers in preparation for the third harvest. I think it is safe to attribute those cooler days to the air coming through the vent. The biomeiler likely had enough cooling power to outweigh not only the heat generated by the small number of birds inside, but also remove some heat brought in through the window and doorway.
The biomeiler continues to successfully reduce the temperature of the incoming air to such an extent that it feels noticeably cool to the hand. However, the triumph is suffering attrition from the summer heat. The cooling power of the incoming air is no longer sufficient to keep the coop temperature continuously below the outdoor air temperature.
Confounding, it is. You exercise terrific patience with this process, and I can just imagine your mind considering what steps you will next try to add consistency to the results.