Really,  ammonia, hydrogen sulfide, sulfur dioxide emission origin are the pig metabolism. I don't see any relation, exept that the conditions into the pig house are more comfortable for the animals and the have less estress. Another possible explanation is the pig food, but only if it is different into the testing.

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Was only the source of energy different or were the heating systems themselves also different? In that case you might be comparing apples to pears.

Dr. Kan, we compared two heating system in a side by side pig houses, one is ceiling mounted electric heater and another is geothermal heating maintaining same temperature and humidity. However, we found reduced ammonia, hydrogen sulfide and sulfur dioxide gas emission in geothermal heating system compared to control. So, I need to know the scientific explanation.

Dr. Alejandro, geothermal fan coil unit can supply hot air by moving system, while ceiling mounted electric heater is fixed. Is there any effect of these two different system on noxious gas emission in the house?

Your answers clearly indicate that the two heating systems are operating in different ways. So although your setpoints are identical the result in terms of climate in the room  might very well be different. The fans of the geothermal system might cause a better mixing of air in the room resulting in a lower reading of the gases at the checkpoints.

By the way how and at how many points did you measure the gas concentrations?

I have measured the emission by using Gastec, Japan; and measured at 6 points entrance, middle and back of lower and upper level (lower position one feet above the floor and upper one feet below the roof).

Dr. Kan, is there any reference that the fans of the geothermal system can mix the air? and so so. Thanks for your cooperation.

Did you measure the gases once or several times or continuously?

I am not an expert on air mixing, but I have learned in practice that obtaining a similar climate at most places in animal house is far from easy, but very important in carrying out comparative trials. Fan do generally give rise to (horizontal) air movement and mixing of air, while natural flow of air generally only goes up or down depending on temperature gradients

One other point: Some 25 years ago my colleagues tried to measure the total nitrogen balance during a broiler growth out of 6 weeks by measuring nitrogen intake excretion by manure and by air. There was an ca 10 % gap indicating,  that probably some nitrogen escaped with the air and not measured by the available instruments most likely in the form of N2. If you should have a similar situation your conclusions on N containing gases might also be compromised.

Yes, I measured the gases two times a day (morning at 8 am and night at 8 pm) continuously three weeks