Save CO2? As a tenant:in? - How do I know where I'm generating how much of it? Certainly complex - but there are ingenious tools that help you to get an overview. Mr Steinfeldt from co2online was kind enough to answer a few questions for us:

Mr Steinfeldt, how can I reduce my energy consumption most effectively as a tenant?

Tenants should be aware that a large part of their energy is used for heating and hot water (85 percent), while electricity accounts for only 15 percent. On the other hand, tenants are strongly dependent on their residential building - they cannot change anything about the energy condition, such as the insulation or the heating system, themselves.

But through conscious heating behaviour, they too can contribute to lower heating energy consumption and lower heating costs. After all, if you lower your average heating temperature by one degree, you already save 6 percent of your heating energy. The best way to regulate the temperature - separately for each room - is with programmable radiator thermostats and set them to the exact degree. If you leave the room or the flat, you should then turn down the heating. By the way, this also applies to airing: instead of leaving the window tilted for hours, you should regularly air the room for a few minutes with the heating turned down. This ensures fresh air and less heating loss. A lot can also be saved on hot water, for example by using a low-flow shower head or washing hands with cold water.

To save electricity, all light bulbs should be replaced with efficient LED lamps. The standby mode of televisions, computers and other electronic devices should also be avoided. Anyone buying new electrical appliances should pay attention to the efficiency label and only buy products in the best efficiency class. Especially for appliances that run all the time or frequently, such as refrigerators or washing machines, the higher purchase price of efficient appliances is worthwhile.

At www.heizspiegel.de and www.stromspiegel.de tenants can have their personal savings potential for heating and electricity calculated free of charge. They can also get more information and tips on how to save energy.

A house, a flat and so many individual aspects... How do I effectively keep track of building and renovation measures that bring the most benefits and the subsidies for them?

If you want to make your house or flat fit for the future, you should not go it alone. House and flat owners can obtain extensive information about renovation measures and renewable heating systems at www.co2online.de. The concrete planning should then be carried out with a specialist. Owners should then approach the concrete planning with a certified energy consultant. After an on-site inspection, the advisor will prepare an analysis of the energy status and an individual renovation roadmap agreed with the owner, which will show step by step how the energy consumption of the building can be reduced. The energy consultation is subsidised by up to 80 percent.

Sensible measures on the building to reduce energy consumption include insulating the entire building envelope, replacing the windows and installing a ventilation system with heat recovery. Only then should the heating system be replaced. Renewable heating systems are heat pumps and wood pellet heating systems, but also the connection to a local or district heating network that is fed with renewable energies. It should also always be checked whether solar energy can be generated on the roof, either electricity via a photovoltaic system or heat via a solar thermal system. These measures can be subsidised or financed through promotional loans. Consumers can find more information on subsidies at www.co2online.de/foerdermittel.

If you are not yet planning a major renovation of your building, you can still optimise your heating system. Replacing old heating pumps with high-efficiency pumps and adjusting the heating system correctly by means of hydraulic balancing costs only a few hundred euros and pays for itself after only a few years.

Regardless of whether it is a small optimisation or a complete renovation: owners should measure the energy consumption before and after the implementation of the measure and compare it on www.energiesparkonto.de in order to identify and eliminate possible errors.

What do you think are the biggest hurdles to overcome in the sustainable building and living sector?

There are still many new fossil fuel based heating systems being installed every year, in 2021 there were over 650,000 new gas heating systems. It is important to educate people about alternative heating systems and to show practical ways in which owners can convert their building to be climate neutral.

Difficulties are currently being compounded by supply bottlenecks, increased costs and the shortage of skilled workers, which are making the implementation of refurbishments more difficult. In our view, politicians need stricter requirements for building efficiency, more effective subsidy programmes and a quick and fair distribution of the CO2 price. The trades, energy consulting and industry are also called upon to leverage the potential of digitalisation and to invest in the education and training of skilled workers.

There is a lot to do, but that also means that there is still a lot to be done. Let's get to work!