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.

Let's be honest – do you walk around your flat in a T-shirt in winter too? Most living rooms and bedrooms are too warm in winter – we walk around in T-shirts instead of putting on thick slippers and jumpers. The potential energy savings here are considerable.

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.

Do you sometimes throw food away? Or do your parents throw away food that you didn't eat in time? Food is wasted from the field to the factory and transport routes to the point where we, restaurants and supermarkets throw it away. Ultimately, this means that more land is needed for cultivation, which leads to deforestation and endangers biodiversity with pesticides and fertilisers. We can shop more selectively, avoid throwing away products just because of their best-before date, save food in the household (e.g. freezing bananas or making long-life spreads and soups from leftover vegetables), saving specifically rescued food (e.g. goods that are too small or shriveled) and, in many places, donating leftover food, e.g. to food banks.

Fortunately, tap water has long been a trend. Schools have drinking fountains and pupils bring their own water bottles, and managers also bring their water bottles to workshops. Many children are not even accustomed to unhealthy sugary drinks. Tap water is more strictly controlled than bottled drinks and saves a lot of energy and packaging. Even in motorhomes or boats, or in places where the water smells of chlorine, we can save a lot of money, energy and packaging by using good filters that are changed regularly.

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.

Tap water is preferable, possibly with homemade juices. Otherwise, use returnable glass bottles with drinks from the region. Plastic bottles are problematic, drinks cans are very bad, and Tetra Paks are not easy to recycle.

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.

All major discount drugstores now stock natural cosmetics in all areas – from deodorant and lipstick to sunscreen (although sustainable sunscreens are a real challenge, as tests repeatedly show). On the one hand, natural cosmetics are generally healthier, and on the other hand, no non-degradable substances end up in the environment and no animals were tortured to test the effects. For example, toothpaste often contains microplastics. These end up in the environment, where killer germs can settle in the microplastics.

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.

Firecrackers and fireworks are a problem in every respect: for the animal world, the environment and the people who produce them. The ultrafine particles pollution is horrendous. And all this only because people (mostly men) hope for attention and admiration about this.