Anyone for tea? Just give me a bike and half an hour...

Cycling shorts, suitable attire for a trip to a shopping centre? And a well-known one at that.

In fact, Lycra and fingerless mitts were just the outfit, though you could also have made a case for wearing flippers, a mask and a snorkel.

It's Global Climate Week and between Saturday 19 and Saturday 26 September 2009 each of the 5 floors of Hamburg's Europa Passage has a climate-related theme.

There's the future level, the research level, the information level and the technology level, each with exhibitions and hands on (or, in one case, feet on) activities aimed at alerting visitors to their impact on the environment. There was everything from fabulous photos and the results of research on a reef in Belize to suggestions for homeowners on how they could save money.

I was headed for the fourth floor - the campaigns level - and the stand of the Hamburg Verbraucherzentrale (Consumers' Centre). As a cycle campaigner (a member of the London Cycling Campaign almost continuously since 1984 and a very active member of its voluntary offshoots Lambeth Cyclists and Southwark Cyclists) the mention of cycling in the overview of the week's events had caught my eye...

Energy bike

Your chance to participate: How hard do you need to pedal to make a cup of water hot enough to brew coffee? A climate and energy consultant advises.

("Energie Fahrrad

Mitmachaktion: Wie stark muss man für eine heisse Tasse Kaffee in die Pedale Treten - Klima und Energieberater informieren")

This experience taught me (the hard way!) what Jens Schwarz, co-ordinator of RCE Hamburg und Region, has been saying since I started this work experience placement - that lessons that teach people to adapt their behavour to be more sustainable need not take place in the classroom.

I consider my carbon footprint to be very small but I don't merit a halo made out of wood from a sustainable forest, or didn't, because I had a very bad habit.

Despite the pleas and finger-pointing, in the face of reminders and ridicule, I always filled the kettle even when I was only making a cup of tea for myself. Until 1pm on Tuesday 22 September 2009, that was.

On that day I got onto a stationary bike and in full view of visitors coming up or going down the escalator in the upmarket shopping centre, pedalled for 32 minutes.

This was the time it took me to raise the temperature of one mug of water in a kettle from the 21 degrees it was when I started to the 70 degrees Ms Andrea Grimm from the Consumers' Centre said would make a decent cup of instant coffee.

When I got off the wretched machine, though, coffee was the last thing I wanted. I had my eye on the ice cream of the man sitting watching my efforts.

So, Dave, you can now trust me to use your kettle. Though, if you don't mind I'll plug it into the mains rather than use your exercise bike to heat the water.