I agree it is a collective problem. But I feel guilty if I don't try to limit my emissions (reasonably, because I AM contributing to the problem) and so it's rational in a way to try to limit that feeling by acting to conserve energy. But there are situations where I feel the benefit to me of doing something (e.g. I would suffer health consequences and significant discomfort if I never turned the heating on in winter) outweighs the guilt. I guess everyone's calculation is different, depending on their circumstances and conditioning.