CO₂ saved by renting LEGO.

To put it plainly: a set we own is made once and built by many people. A set that is bought is made once and built by one person. The rest is arithmetic.

Is LEGO sustainable?

LEGO bricks are made of ABS, a plastic made from crude oil, and most of their CO₂ is emitted before a set ever reaches a shop. In return, the bricks last for decades. So a set only becomes sustainable when it is built often, rather than gathering dust on a shelf after one evening.

What a new LEGO set costs the environment

We count from the refinery to your front door: the granulate for the bricks, the injection moulding, the box, instructions and bags, the lorry from the factory in Hungary or Denmark and the postman's last trip. That comes to around 4.3 kg of CO₂ per kilogram of bricks. For the Eiffel Tower with its 10'001 pieces, that is 55.7 kg. For Hogwarts, 14.9 kg.

We could have made it easier for ourselves. Divide the LEGO Group's total emissions by the plastic it uses and you land at about 18 kg per kilogram. But that figure also contains shops, offices and advertising, which have nothing to do with the set in your living room. We use the lower figure. It makes our balance worse, not better.

The CO₂ cost of renting out a LEGO set

Two postal journeys instead of one: once to you, once back. Add the reusable box, the label, and checking and cleaning the set when it returns. The return trip is the only real drawback of renting, and it barely registers. For the Eiffel Tower it is 3.73 kg, against a set that cost 55.7 kg.

LEGO sets bought second-hand do not count

We bought a good share of our sets second-hand, the big ones especially. Buying a set that already exists does not cause a new one to be made: the bricks were moulded long ago, with or without us. A copy like that only carries the parcel that brought it to us. Our database records for every copy whether we bought it new or used, and that is exactly what we count. Where the record is missing, we count the set as bought new.

The factors in our CO₂ calculation

Everything a set causes on its way from the refinery to you and back again goes into the calculation:

Weight

How much ABS a set contains is worked out from its piece count: 1.3 g per piece, checked against the published weights of the Titanic and the Eiffel Tower.

Plastic

3.13 kg of CO₂ per kilogram of ABS granulate, the European average from Plastics Europe.

Injection moulding

1.48 kWh of electricity per kilogram of bricks, using the electricity mix of the countries where LEGO manufactures. We do not count green electricity certificates.

Packaging

The box, instructions and inner trays come to 35% of the weight of the bricks, plus the numbered bags.

Transport from the factory

Around 1'000 km by lorry from Denmark, Hungary or the Czech Republic to Switzerland.

Delivery

The sorting centre and around 200 km in the Swiss Post parcel network, whose fleet is 57% electric.

Both directions

Every rental carries both parcels in full, including the return, which buying a set never involves.

Reusable box

Our sets travel in a sturdy plastic box that comes back to us and goes out again many times. We conservatively count 200 rentals per box. A cardboard box and tape would be waste after a single trip; the box spreads its manufacture across all its trips and comes to around 10 g of CO₂ per rental. Each shipment also gets a label.

Checking, cleaning, storage

Every returned set is washed and checked for completeness. That counts too.

Purchases replaced

Not every rental replaces a purchase. Someone who builds the Eiffel Tower for a month might never have paid CHF 699.– for it, and then nothing was avoided. That cannot be measured; it is a judgement. We use 60%. The balance would only tip below about 26%.

Sets on the shelf

Sets nobody has rented yet still count with their full debt.

Disposal

We have worked it out, but not counted it. LEGO rarely ends up in the bin: it is sold on and handed down, and our sets will go the same way eventually.