Feedback loops don't always do what you expect

I am chuffed. I have checked the carbon footprint of my house and it is very very low for the square feet - about equal to a highly efficient UK house that is half the size. All those CFL's and LED's have lowered the electricity bill over the last decade, and that in Mumbai is a feat.

We will not talk about the travel footprint, though cutting up the frequent flyer cards and moving to coolie class is on the cards.

Trying to keep going on the energy reduction front we replaced our old and worn a/c's with new direct drive jobs, and insulated the roof and double glazed the windows, all of which are supposed to increase efficiency - sure enough the bill dropped further but there was a horrific consequence. The temperature in the room was becoming unbearably hot though the new a/c was the same power as the old, which had worked fine in uninsulated conditions (no waste except capital because direct drive a/c's adjust to the workload within a very high band, and one wanted to keep the domestic peace - the wife believes in polar bear conditions in the bedroom).

The hotter it got the more we jacked up the fan settings and the dropped the set temperature. And it got even hotter. I borrowed a laser temperature meter from the a/c wallah and spent a night poking about to check temperature differentials. At the start all was well; at 6 a.m. the foot of the bed was at the set 19 degrees and the head was at 24. How could this be? Efficiency - the low set temperature and the huge blast of the air from the machine allowed the direct drive to hold the temperature at the measure point at 19 while allowing it to rise everywhere else. Spot cooling.

A change to the a/c fan and circulation settings has allowed us to drop the set temperature and maintain it in the necessary zone.

This is a small and foolish example of what we do not know. So, climate change will have feedback effects but we do not know which way they will go - the weather is a bit more complex than a single room a/c.