Construction project - ventilation system, heating - your experiences?

Hello everyone,

after I informed myself about prefabricated houses in this forum over two years ago and through several posts was also made aware of the possibility of a solid house, we have now decided to build such a solid house. We bought the corresponding plot of land in RLP this month. We successfully completed the first architect meeting (the architect was recommended to us by several friends). The meeting was very pleasant and we were able to present our ideas. The next step is that he will create a first draft to see if it suits our taste and which changes we would like.

Since I have frequently been active as a reader in forums and on many construction sites over the past two years, I have of course received many opinions and have asked him for his opinion on certain things. I would like to pose these questions to you as well in order to gain some impressions specifically for my case. By the way, the building project will be a 1.5-story single-family house with a gable roof and 145-150 sqm of living space without a basement.

1. We would like to have a central ventilation system. He advises against it due to the high costs (probably 18k - 20k) and recommends the classic use of windows. Is the amount 18k - 20k realistic? I once read something in the range of 12k.

2. The choice of heating... we would like 3-4 sqm of solar thermal for domestic hot water heating. For that, I personally would probably have chosen a gas condensing boiler for the underfloor heating. He recommends an air heat pump. I have read something about power guzzlers and would also not find even a slight humming in the outdoor area particularly appealing. I would probably not be that satisfied with the gas condensing boiler either. The ground is very rocky (Slate Mountains). Everything that is drilled into the earth he finds risky (costs could rise quickly). Trench collectors he also does not like – there could be problems with the roots of the plants. Somehow everything has disadvantages, I feel. What types of heating do you have? What did they cost and how satisfied are you? How are the running costs?

3. We love the clinker look. We would like to fully clad the facade with real clinker. For this he advised to preferably involve companies from NRW or Northern Germany. It is common there, they know their way around. I actually see it exactly the same. What does clinker cost per sqm now? Has anyone recently had this done? How long did it take? Brick slips are not an option for us by the way.

4. If possible, we would like to aim for KFW 55. With the ventilation system and solar thermal, we are (I think) well positioned in this regard. Then of course there is the question of the building material. He recommends monolithic Poroton. But one could also work with probably cheaper pumice if it is actually going to be a clinker masonry. Would pumice + clinker be enough for KfW 55? WDVS is not planned. How big is the price difference between Poroton and pumice?

If there are any questions, I will of course be happy to answer them.

Thanks in advance and don’t be too hard on me

I can say something about 1 and 2.

1. Ventilation central approx. 12k, it shouldn't cost more than that. Very cool!
2. Do gas. Cheap and good. Air-water heat pump also good, but much more expensive and no advantages. On the contrary, noise is always an issue there

Controlled residential ventilation is awesome. Solar thermal energy is not cost-effective. Prefer photovoltaics.

An architect does not just draw pretty little houses, he also plans buildings technically. Therefore, I advise to reconsider the choice of the architect if he has a different preference for the heating concept than the client – in that case, it is to be feared that he has less experience with the desired technology.

[Klinker] and [Riemchen] are exactly the same stuff – once cut and once in one piece. If you do not want [WDVS], the facing shell does not need to "stand on its own feet," so it can be easily glued. A whole brick-thick layer of [Klinker] will here only add more wall thickness with the same overall U-value. If you read carefully here, you will also notice that with [Riemchen] there are less often processing differences between the client and the executors. Rationally, you are better off with [Riemchen].

Price differences between porous bricks and pumice are not consistent and do not need to concern you: they would only be relevant if you want to buy the bricks yourself and provide them to the shell constructor. The trading margin on the brick will, however, be taken by the contractor himself. My experience (since birth in northern [RLP], so a pronounced pumice area) is that pumice construction contractors usually also process porous bricks so often that they partially decide on a daily price basis which brick is currently used. This applies both to pure shell constructors and complete general contractors or even those active as building developers. And since you mentioned both prefab houses and solid houses: solid prefab houses exist both from some porous brick makers and from some bloated clays. In Rheinhessen and the Palatinate I do not know, but in Westerwald and Eifel / Pellenz, especially a general contractor will quite often build your house with [KLB] or [Bisotherm], with porous bricks coming in third here. If the architect has a preference for one type of brick, he usually also has such for the entire range of lintels / roller shutter boxes / ceilings (and possibly also stairs); and like-minded contractors "on hand."

An architect doesn’t just draw pretty little houses, he also plans buildings technically.

Unfortunately, this is a common misunderstanding. An architect is only involved with building services engineering in the sense that he "coordinates" the necessary planning. That ultimately means: He obtains the plans of each technical trade, incorporates them into his execution planning, and, if necessary, points out any apparent problems.
Certainly, most experienced architects will have picked up enough over time to provide rudimentary advice, but by definition, this is not their job. This is also reflected in the fees, where the costs of building services engineering are not fully included as chargeable costs.

For building services engineering, there is the MEP planner, who is also remunerated according to HOAI; however, no one in the single-family house sector can or wants to afford one, so it ultimately falls to the clients and craftsmen.

Heating:
We have a modulating air-water heat pump from Novelan, indoor installation. LICV 8.2R1/3. Of course, I can hear it in the utility room, very quietly in the kitchen when listening carefully through the door. Not at all in the living room directly adjacent to the utility room (timber frame construction). Naturally, also directly at the air outlets outside. Our neighbors have noticed nothing yet and we don’t sit outside in winter either. Investment costs were high, but I couldn’t get gas approved with my "government." We have had a separate electricity meter for only 6 weeks and since then have consumed 200 kWh of electricity for heating and domestic hot water and produced about 1000 kWh of heat. I’m quite satisfied with that. KfW 40, 146 sqm without basement, NAT - 12, living room 22°C+ !, my wife gets cold quickly...
I would avoid solar thermal if possible, prefer photovoltaic instead.
Your architect’s statement about the trench collector only applies to tree plantings. Low-rooting vegetation is apparently not a problem.
Educate yourself about ring trench collectors in the HTdialog forum. There you will get valid information. Ask your architect how often he has commissioned a ring trench collector. Then you can assess the reliability of his statement.