Autonomous home: what are we talking about? What are the principles?

With the development of renewable energies, we hear more and more about autonomous houses. But what is this concept? It is also called “self-sufficient house”. Is it possible to have a house independent of all networks: gas, electricity and water? The energy self-sufficient house is definitely a very promising concept! Here are the principles.

What does “autonomous house” mean?

Autonomous comes from two Greek words which basically mean “to have one’s own law, to be independent”. Thus, energy self-sufficiency is synonymous with complete independence from any external supplier. On a small scale, all wireless or portable devices are already somewhat self-contained. Conversely, on a large scale, there are states called autonomous or self-sufficient in energy because they are completely independent in terms of energy production and/or distribution. Somewhere in between is the self-contained home.

The autonomous or self-sufficient energy house – what does it look like?

A building which does not obtain energy from the outside but which on the contrary can meet its needs independently is then considered to be self-sufficient in energy. This means that it must be able to supply itself with electricity, heating and hot water all year round, without connection to the network or external fuel supply. Implementing this concept in this way is not easy. There are various approaches that go in this direction but which are not completely autonomous houses. The best known are probably the passive house and the zero energy house.

Why the passive house is not energy self-sufficient

With the passive house, the main focus is on warmth. To put it very roughly, insulation is the decisive criterion here to achieve the goal of almost no additional heating at all. It works by installing special thermal insulation in the walls, windows and roof. Special ventilation systems prevent further heat loss and also regulate the supply of fresh air. Often passive houses also have a particularly high level of airtightness, which, however, does not lead to mold due to the general dryness of the house. By renovating, you can turn your home into a passive house. But independence concerns only the heating system. In this case, you must use external suppliers for electricity and hot water. Unless of course you light yourself with candles and wash yourself with cold water.

Why isn’t the zero-energy house self-sufficient either?

The purpose of these houses is, so to speak, for the energy inputs and outputs to be identical and to cancel each other out. To do this, it is necessary to inject exactly as much energy into the network as will be taken from it. To achieve this, buildings of this type have certain electricity generation systems, for example solar collectors. During the sunny summer months, these generally cover the needs of the house well and even produce a surplus which is fed into the general electricity network. Later in the winter, the internal system is no longer sufficient to meet the demand, because there is simply too little sunlight. It becomes necessary to obtain electricity from another supplier. However, if this quantity does not exceed the quantity previously injected, it is a neutral energy balance. The zero energy house can be a success. But if external resources are used, it cannot be called a self-contained house. It is the step after the passive house but not yet the completely energy self-sufficient house.

What is needed for an energy self-sufficient house?

The electricity must be produced entirely internally and does not require any external input. Water for heating and water for daily consumption must also be able to be heated independently. And that throughout the year. This is only possible with an intelligent combination of solar thermal and photovoltaic technology.

In order for these two systems to do their job optimally, certain structural requirements are also required. The property should therefore not be shaded. It must be possible to orient the building towards the south. And a roof pitch of 45° would be ideal! Only when all these conditions have been met can the roof be completely equipped with solar thermal collectors and photovoltaic modules and begin to function.

How does energy self-sufficiency work?

Setting up an energy self-sufficient house is not always easy. This requires very good planning, especially in areas that are not usually thought of. In the autonomous house, the energy is generally produced by solar or photovoltaic systems. Some also use wind power, which, however, is quite difficult to achieve on a normal property. Either way, the resulting energy is too low, especially in winter, while in summer, depending on the technology, a surplus can be produced. Appropriate storage is therefore the solution: during the day, an efficient solar storage system can accumulate the energy produced during the day, which is then consumed in the evening. Special batteries are already used in order to be able to store electricity over the long term and with as little loss as possible. However, it often happens that the energy is insufficient to meet the needs of a normal household. Consumption must therefore also be fine-tuned for the concept of energy self-sufficiency to succeed. Extremely economical devices and intelligent energy management, which the consumer effectively controls, also ensure minimum energy consumption.

The energy self-sufficient house – is it really feasible?

The concept sounds really appealing. On the one hand, the independence from energy suppliers is a great advantage, as are the annual cost savings. In addition, energy self-sufficiency is also part of the way of life, which is becoming more and more important today, and which also attaches great importance to environmental protection. Unfortunately, the autonomous house is still experiencing start-up problems. On the one hand, the purchase of the necessary systems and technology remains very expensive and therefore not necessarily affordable for every owner. In addition, the structural situation does not always allow this, for example because the property is in the wrong location or the southern orientation of the house is not approved by the building authority. And finally, the months with little sun are still a big problem! But the fact is that even a house that is not fully energy self-sufficient still saves a lot of energy, protects the environment and is definitely a step in the right direction.

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