Be sure to do the math. A lot of programs use negligible power. If you spend an hour more writing your program, with your computer on during that time, you may

Be sure to do the math. A lot of programs use negligible power. If you spend an hour more writing your program, with your computer on during that time, you may find it can take you literally years to recover that. In fact it's not hard for it to take centuries or worse. Programming spans a lot of orders of magnitude. If you're writing code for a multi-hundred system cluster, then by all means consider energy consumption. But it's also easy to spend hours, days, weeks to save a net total of several milligrams of CO2, because your program won't even spend as long in its total life time executing as you spent writing it, in which case the costs of execution are actually less that the development.