How much energy does an email take? What about a text message? How much power is needed to keep a mobile device roaming and ready for instant Wi-Fi duty?

With 1.5 billion people using the internet daily, it's clear that everyday actions such as surfing the web, sending emails and downloading and sharing documents have a planetary impact.

A report prepared for the European commission in 2008 by BIO Intelligence Service, an environmental assessment agency, found that the use of such technologies contributes 2% to European greenhouse gases. And that figure is set to double by 2020 if lifestyles don't change.

Curious about this environmental impact, the French environment and energy agency Ademe made its own assessment of technology use, including email, web searches and document transmission using USB flash drives.

Consider email. In 2009, an estimated 247bn emails were sent around the world daily, a number that's expected to rise to somewhere near 500bn within three years.

In France, for example, someone working in a company that employs 100 people receives an average of 58 emails a day and sends an average of 33. Taking an average email size of 1MB, the base figure (possibly excessive) used in its calculations, Ademe estimated that professional emails generate an astonishing 13.6 tonnes of CO 2 equivalent greenhouse gas emissions a year, or 136kg per employee. That's equivalent to about 13 return journeys from Paris to New York.

Why is there such a high carbon impact? It's all because of the energy required by computers to send and receive email – including the centres that store and process the data – as well as the energy required to make the electronic components.

But Ademe offered some hope. The environmental impact can be substantially reduced if an email is sent to fewer recipients, the agency found. By adding 10 addressees, greenhouse gas emissions increased fourfold. However, removing one addressee for each email resulted in a 6g CO 2 equivalent gain, or 44kg per year, per employee.

"A 10% reduction in emails that copy a manager or a colleague in a company of 100 employees saves approximately one tonne of CO 2 equivalent over the year," Ademe said. That increases exponentially with the size of the emails.

Storing emails and attachments on a server may be convenient, but it takes an environmental toll. The longer the email is retained, the greater its impact on the climate, Ademe found.

Printing, too, creates problems. A 10% reduction in printing saves five tonnes of CO 2 equivalent over a year. Non-colour printing and double-sided printing also help to reduce the impact.

When it comes to the web, how we love to browse. According to Médiamétrie Institute, a media monitoring organisation, the average French web user conducts 2.66 internet searches a day, or 949 a year. But browsing is polluting since the servers that undertake these searches use electricity, generate heat, and must be kept cool. Ademe says that using a search engine to obtain information generates about 10kg of CO 2 equivalent per web user, per year.

So how can the impact of browsing be reduced? Some suggestions include using precise keywords, directly pasting a URL into a web browser, and saving frequently used sites as favourites or bookmarks. Such steps can save each of us about 5kg of CO 2 equivalent annually.

Finally, little research has been done into USB flashcards – those tiny sticks that make carrying masses of information so very convenient. A flashcard's manufacture is the most polluting aspect of its lifecycle, using energy, water and rare metals.

Transmitting the documents housed on such cards also comes at a cost. In the case of a file handed out to 1,000 people at a conference, for example, the emissions are equivalent to an 80km car journey.

This article originally appeared in Le Monde