ᐅ Semi-detached house – Which type is best? Does anyone have experience with this?

nordanney schrieb:
First of all, it’s (more or less) easily possible, and secondly, buying a used property consumes much less energy than building a new one.

If you are environmentally conscious and want to think about the environment, you definitely should not build new. You cannot save as much energy as you waste during construction and all the environmental damage it causes.

But it’s still nice to live in a new house...

If you all say that, there must be some truth to it. Good thing I didn’t just jump in but asked first! Is there a way to quantify the differences? And how old or up to what standard should an existing building be to still make sense?

New construction is certainly nice but not a deciding factor! I want to consider the environment, but also not exclusively—rather within a reasonable framework... and if it ends up being a renovation, that’s fine too...

DirkB schrieb:
As far as I know, it is not possible to achieve a reasonable energy consumption in existing buildings without significant effort ...

There are two vague definitions here.

1. Existing buildings:
Buildings for which the building permit / planning permission was applied for and granted after November 1, 1977, that is after the first thermal insulation regulation came into effect, have a certain construction standard that basically includes thermal protection. Therefore, any subsequent investments to improve insulation of walls, roofs, basements, floors, etc., are less “worthwhile” compared to older buildings with lower energy standards. In addition, thicker structural elements are already present, making reinforcement more difficult, sometimes impossible, or very expensive.
So if you want to lower energy use considerably, you should either buy an older house or, in the case of newer ones, pay attention to upgrade potential. For example, with a 40cm (16 inches) wall containing 5cm (2 inches) of insulation, there is not much more you can do. But with a 24cm (9.5 inches) wall, adding 15cm (6 inches) of insulation is still possible.
It is true, it’s not always feasible; the building fabric must allow it. When it does, however, it is often cheaper than building new.

2. “Reasonable” energy consumption
Where does reasonable start and when is it “very reasonable,” or at what point does the effort outweigh the benefits? Most existing buildings can be brought to a “reasonable” heating demand level of about 100–120 kWh/m² annually with manageable effort and without special tricks.
Compared to the average demand of almost 200 kWh/m²a, that is only about half. Compared to new construction, it can still be double. So what is reasonable? Anything lower requires suitable building fabric, as mentioned above. There, no limits exist (passive house standards are achievable).

A major advantage with your goal when renovating existing buildings is that you are not bound by the Renewable Energies Heat Act or the primary energy factor requirements of new building energy regulations. This allows you to focus on what actually saves energy and omit measures that would make the process expensive (such as whole-house ventilation systems, etc.).

What makes renovation costly is altering existing structures, such as changing floor plans, extensions, dormers, etc. However, wall openings are among the least expensive interventions.

Caspar2020 schrieb:
No, it doesn’t work like that. Either you are ideologically committed to it and go all the way.

Especially if it’s meant to be sustainable and meets your own standards for building biology. But if you plan something like that, you can hardly make any compromises.

Or you look at how much house you can get for your budget; realize it’s not that much; cut out one or two extras (meaning expensive features; so the house ends up more square-shaped; ask yourself if this is really necessary, etc.).

Sometimes, for the sake of a green conscience, you might opt for more insulation, thicker walls, or a photovoltaic system; but that’s close to greenwashing. How the pipes, mortar, etc. were produced becomes more or less secondary.

And 600,000 with 200,000 for the plot is not really abundant but rather a good standard.

As you already mentioned yourself, I probably won’t be able to go all the way.

But it should at least move in the right direction...

dertill schrieb:
There are two vague definitions here.

1. Existing buildings:
Houses for which a building permit / planning permission was applied for and approved after November 1, 1977, that is after the first thermal insulation regulation came into effect, have a certain construction standard that fundamentally considers thermal protection. Therefore, all subsequent investments to improve insulation of the walls, roof, basement, floor, etc. are less "effective" than with older buildings having a lower energy standard. Additionally, thicker constructions are already in place, which makes reinforcement more difficult or even impossible, or very expensive.
So, if you want to reduce energy consumption drastically, you should buy an older house or, in the case of newer ones, pay attention to retrofit potential. For example, with a 40 cm (16 inch) wall that already contains 5 cm (2 inch) insulation, there’s not much more you can do. But with a 24 cm (9.5 inch) wall, you can still add 15 cm (6 inch) easily.
It is true that it’s not always possible; the existing structure must allow it, but if so, it is also cheaper than building new.

2. "Proper" energy consumption
Where does "proper" start, and when is it "very proper" or when is the effort too much for the benefit? Most existing buildings can be brought, with manageable effort and no magic tricks, down to a reasonable heating demand level of about 100–120 kWh/m² per year.
Compared to an average demand of almost 200 kWh/m² per year, that is only half. Compared to newly built houses, it can be twice as much. What is considered proper?
Anything below requires suitable structures as mentioned above. Then there is no limit (passive house possible).

The big advantage of renovating existing buildings, with your goal in mind, is that you are not bound by the Renewable Energy Heat Act or the new building requirements of the Energy Saving Ordinance regarding the primary energy factor. This way, you can carry out what really saves energy and omit what makes it expensive (such as residential ventilation systems, etc.).

What is expensive in renovation is remodeling existing structures: changing floor plans, extensions, dormers, etc. Wall openings are the least costly measure here.

So, based on this, the best approach would be to find a very old building with a sound structure, pay as little as possible for it, and then invest as much as possible in the sensible improvements?

Dirk78 schrieb:
So, would it be best to look for something very old where the structure is still sound, pay as little as possible for it, and then spend as much as possible on sensible renovations?

I generally agree with you, but at the moment the market is a bit out of balance. I don’t know exactly where the thread starter lives, but here, older properties sell for so much that it’s better to build new—assuming you can get your hands on a plot of land somehow...

Dirk78 schrieb:
So it would be best to look for something very old where the structure is sound, pay as little as possible for it, and then invest as much as possible in meaningful renovations?

“Very old” is also tricky. It always depends on the individual case. There’s not much you can do with 50 cm (20 inches) sandstone walls in an Art Nouveau villa that has heritage protection.
But if the wall consists of 24 cm (9.5 inches) solid brick, 15 cm (6 inches) air gap, and 11 cm (4.5 inches) plastered brick (like a property owned by an acquaintance on my street), you can bring the house up to new-build standards with relatively little material and financial effort.

From an energy renovation perspective, post-war buildings up to the mid-1960s are the easiest. Ideally from 1955 to 1966. These usually do not include the worst construction shortcuts just after the war, funding was available thanks to the economic upswing, open floor plans with plenty of natural light were common, and energy saving was not yet a consideration—so there are no poorly done 3 cm (1 inch) insulation layers behind brick façades.
But again: it’s always a case-by-case decision.