ᐅ Exterior Wall for KfW 40 (+) Standard: With or Without External Thermal Insulation Composite System (ETICS)?

guckuck2 schrieb:

Our ancestors probably thought the same 50 years ago. Energy was basically free.
Who knows what changes the next 50 years will bring.

There is definitely a difference. Zero is a hard limit for heat loss in a building. In practice, you will always lose some heat because you need to exchange the air occasionally, and people have to come in and out through the front door. Even if you improve a 90% heat recovery ventilation system and halve the losses, some loss still remains. A house with energy consumption of <=25 kWh/sqm (<=8 kBtu/sqft) will still be fine in 50 years. Technically, much more is already possible today, but it is neither financially reasonable nor environmentally sensible. Also, the issue of reducing CO2 by more efficient heating will soon lose political significance—simply because in 20 or 30 years, electricity will no longer come from coal-fired power plants.

Actually, energy will no longer be a concern, as it will be very affordable to obtain, and houses already require very little. The focus will shift more towards comfort and cost savings. We will see completely new construction methods that will have almost nothing in common with today’s houses.

Exactly, since the positive energy regulation update in 2035, electricity must mandatorily come from private households. Vacuum insulation will be mandatory starting in 2040.
Those with a negative energy balance in their household will face heavy taxation. The KfW is providing funding equivalent to 1 Bitcoin for the energy-efficient renovation of these old buildings.

Well, to be honest, this timeframe is hard to predict. It’s all speculation. However, I believe it’s wise to learn from the past. What will actually happen remains unknown.

Learning from the past is never wrong. However, it is important to ensure that the right conclusions are drawn and certain limits are taken into account. The topic of insulation has been almost fully explored with KfW40 standards and completely with Passive House standards. Other issues will come into focus; for example, mandatory photovoltaic systems are already required in many new housing developments, and this has also been frequently discussed for renovation projects on existing buildings. Here in Baden-Württemberg, a similar approach is already somewhat in place: when replacing an old heating system, some form of renewable energy must be added (solar thermal or photovoltaic) or significantly better insulation must be installed. This will likely become mandatory in the coming years.

Heating with fossil fuels will also be pushed out of the market over the next few decades. The CO2 tax is only just beginning, and CO2 reduction targets will only be met if prices increase significantly. This process will probably take longer than the implementation of mandatory photovoltaic systems, as many large rental apartment buildings can only be economically heated with oil or gas in the foreseeable future. However, the trend is clear, and once the CO2 tax system is established, it will be much easier to adjust prices accordingly.

Exactly, they will manage that building a house becomes unaffordable for average earners.
These eco-conscious elites and red wine sippers.

Nothing will surpass the Passive House standard anytime soon. Any higher performance and the waste heat from occupants will become an issue.

I believe future technology will include better heat recovery systems with efficiencies up to 99%, windows that allow solar gains in winter while reducing them in summer without shading. Methods to keep houses cooler in summer without air conditioning and warm in winter, with heat pumps achieving annual performance factors in the double digits.

The walls of Passive Houses will become thinner.