Do you leave the lights on when you are no longer in the room? Modern lamps consume little electricity, but it is still worth not leaving them on unnecessarily, for example when we are not in the room for a long time.

Intelligent ventilation means not too late and not too long. It is too late when we become tired from stale air, get headaches and the humidity becomes too high. It is too long when the air has already been exchanged and is cool, but we continue to ventilate and then the materials (walls, furniture) also cool down. Ultimately, heat means that things or air vibrate. When the air has been replaced but the objects and walls are still vibrating, the fresh air quickly warms up. If the walls also become cold, mould can form on them and we need expensive heating energy to get everything vibrating again. CO2 measuring devices help to ventilate at the right time and not for too long. However, these should not be useless gadgets, but perhaps used to practise one after the other in the rooms and also lent out. A nice game is to compete to see how good people's sense of timing is when it comes to ventilating at the right time and not for too long.

Consistently separating waste, including green waste, glass and paper, is not as self-evident as can be assumed. Many make little effort here and don't really know what belongs in which bin. But also special waste, such as batteries, incandescent lamps, electrical appliances, etc. must be disposed of properly.

A lot of things are actually thrown away, even though others could still use them. It is more convenient for us not to repair them than to have a stall at the flea market or to have to send them off for little money. But the good feeling of doing the right thing is motivating.

Many devices from vacuum cleaners to cordless screwdrivers to TVs are amazingly inexpensive today. Relying on valuable devices that last a long time, or even buying used devices, helps to save raw materials and energy. Look for refurbished products.

Precisely because equipment is so inexpensive, we tend to buy all kinds of equipment ourselves rather than borrowing it, whether from neighbours or tool rental companies. All the major DIY stores now offer a rental service. Children and young people can also borrow and lend items – whether toys, clothes or anything else they need for their next party.

Unfortunately, many devices can no longer be repaired. However, there are still repair shops that fix mobile phones, washing machines, lawnmowers, etc. – and even if it costs about the same as buying a new device, it still feels good to have done something to make the world a better place.

Having something new makes you happy. We are offered more and more technical products, from flashing children's shoes to cheap e-scooters to the grill with a built-in fan. To consider here whether it can also be done without it and how long the devices will last and what the disposal of such electronic waste means emancipates us from the consumer traps.