Do Patio Heaters Really Produce Less CO2 Than My Phone Charger?

There was news this week that the pub trade would lose £250 million of revenue if patio heaters were to be banned, a move being looked at by the European Commission. An impartial 'climate change expert' was wheeled out to say the impact of patio heaters on global warming was 'minimal'. Strangely he was talking about domestic models and usage patterns, which seems to be irrelevant to the point of the article, but let's go with it.

The expert being quoted was 'Dr Eric Johnson, National Expert Reviewer for the United Nations Framework Convention on Climate Change (UNFCCC) and managing director of Atlantic Consulting', which sounds very impressive. However, an internet search for Atlantic Consulting doesn't yield much - is this them? A static page with a phone number? Not doing a great job of selling the consultancy's services there!

Searching for Dr Eric Johnson doesn't yield much more. But wait a minute - here he is on a web site set up by...Calor. One of the biggest sellers of...patio heaters! So perhaps we shouldn't accept at face value this expert's view on the 'minimal' impact of patio heaters on the environment before we know how much he's being paid by a large company with a vested interest in pushing that view.

Interestingly Calor are now offering patio heater owners the ability to purchase carbon offsets to salve their environmental consciences. Elsewhere on the site they try to bust some myths by claiming, amongst other things, that patio heaters produce less CO2 than mobile phone chargers. This sounded like a ludicrous claim to me, so I decided to investigate.

My mobile phone charger quotes an input current of 65mA at 240V. Multiplying these together and dividing by 1000 this produces a power consumption of 15.6W (incidentally, the output figures - 350mA at 5V - show that just 1.75W are delivered into the phone, meaning that this charger is only 11% efficient. Perhaps a subject for another blog entry).

Now I am assuming that the charger is left plugged in 24/7 and that its low efficiency means that it uses the same power whether or not the phone is attached to it. 15.6W represents 0.0156 kWh of electrical power per hour, or 136.6 kWh per year (0.0156 x 24 x 365). Now to convert that figure to kg of carbon dioxide this site gives a conversion factor of 0.43. The final figure for the CO2 produced by my charger in a year, then is 58.76 kg.

This is a shocking figure, but remember it is only accurate if the charger is left plugged in all the time.

Now to look at patio heaters. This article says that a typical heater produces 34.9kg of CO2 in 13 hours, but it also says that the average one produces 50kg in a year. This means that the average patio heater is only used for 18.5 hours per year! And this is the average - remember that those used in pubs are running for thousands of hours per year. This means that most domestic ones sitting in people's garages gathering dust. No wonder Dr Johnson can say the impact of domestic patio heaters is minimal -it's because most of them are never used! (Incidentally, Calor say the average patio heater produces 35kg per year, which implies just 13 hours use per year!)

OK, so I can use a patio heater for 21.5 hours per year (i.e. hardly at all) and produce less CO2 than leaving my charger plugged in all the time. But I always unplug my charger when the battery is full and I'm sure if I had a patio heater I would use it a lot more than one hour a week during the summer.

Perhaps a more instructive comparison is the rate of production of CO2. At 34.9kg in 13 hours, the typical patio heater produces CO2 at a rate of 2.68kg per hour. My charger, on the other hand, produces 58.76kg in the 8760 hours that make up a year, a rate of 0.0067kg per hour.

In other words the patio heater churns out CO2 at 400 times the rate of my mobile charger. Which one looks like the least friendly to the environment now?

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