Dumb eco-questions you were afraid to ask

Thanks to the Friends of the Irish Environment website, I found this brilliant article on NewScientist.com. It's a long article so I haven't copied the whole text here, but it poses and answers a multitude of tricky eco-questions, many of which I'm grateful to have an answer to at last!

Dumb eco-questions you were afraid to ask
http://www.newscientist.com/article/mg20026821.300

Here are the questions:

If I switch the light on and off every time I enter and leave a room, does this use more energy than leaving it on all evening?

How clean does the pizza box have to be for it to be recyclable? Likewise cans and bottles

Are laminated juice cartons recyclable?

What's the most fuel-efficient way to drive?
Is it worth recycling when stuff gets shipped to China and back in the process? Given the carbon footprint of all that, maybe we should just let the stuff rot

Can I save the planet by staying slim?

What's worse, the CO2 put out by a gas-fuelled car or the environmental effects of hybrid-car batteries?

What is recycled organic waste used for?

If I offset my flights, can I fly as much as I want?

If I'm stuck in a stop-start traffic jam, do I use more petrol turning my car on and off repeatedly or leaving it running?

Can I put window envelopes in the paper recycling?

How long does it take for a micro-windmill to pay for itself?

Is it better to buy an eco-friendly car, with all the energy that is needed to produce it, or just run my old one into the ground?

What's the best way to charge my laptop - little and often or let the battery run down completely?

Will washing my clothes at 30 °C really get them clean?

Why can't the machines in my gym be used to generate electricity?

Does switching from bus to bike really have any effect? After all, cycling isn't completely carbon neutral because I've got to eat to fuel my legs

Is a full commercial plane more fuel-efficient over long distances than a car?

If I turn my appliances off but don't unplug them will they still use up some electricity?

Does it really take more energy to recycle an aluminium can than to make a new one?

What is the single most effective thing I can do for the environment?

How environmentally damaging is barbecuing?

When and how is the most energy-efficient way to defrost my fridge-freezer, and is a self-defrosting fridge more eco-friendly?
What does the circling-arrows logo on European packaging mean?

What's greener, paper/cardboard or plastic packaging?