Passive house as a logical consequence? Are there counterarguments?

...wrong Mycraft,

this is from the conditions of program 153 (0.75% interest)


During the initial fixed interest period, you can repay the loan amount in full or in partial amounts starting from 1,000 euros without additional costs.

The conditions at 153 and 124 are significantly different on this point!!!

If you now also consult Aunt Gurgle with "Passive House + certified Passive House components," you will surely be able to explain to me why a 2% surcharge is more realistic than 40% ...

If you then explain to me how anyone can still afford to build in Freiburg, for example? Passive House does not necessarily mean to me just being able to slap the Passive House Institute's paper on it. The actual requirements are an air exchange rate < 0.6 and annual heating energy < 15 kWh/m². Certified components are not necessarily required for this; more important are carefully working craftsmen.

The question about the surcharge, of course, also depends on the comparison level. If you compare with the cheap provider who barely complies with the Energy Saving Ordinance on paper, then 40% may still be realistic. If you compare with what the majority here seem to build, then in my opinion that is clearly exaggerated.

Almost everyone has controlled residential ventilation anyway, expensive underfloor heating can be saved in the PH, triple glazing is also standard. (I won't even talk about the fireplace that some install to save heating costs.) So where should the big additional costs come from?

Just as a thought: Yes, many build with triple glazing, controlled residential ventilation, and heat pumps, but despite the already high financial effort, they only reach Kfw 70 level. For the passive house, you really have to push yourself, financially too. If it were that easy and cheap, wouldn’t everyone else (including us) have upgraded to the passive house as well?

Good evening,

after a long day, I am still a little bit at the desk; preparation for tomorrow’s trade fair.

If you then explain to me how anyone else in Freiburg, for example, can still afford to build?

You have written this twice now… and since I can’t know – I live and work in NRW – I took a look at the website of the city of Freiburg.

Freiburg Efficiency House Standard 55 (new residential buildings)

This standard is set in urban development contracts for residential building plots in new development plans (public inspection resolution after September 30, 2011) and in purchase contracts for municipal residential building plots concluded after September 30, 2011.

The previously applicable Freiburg Efficiency House Standards 40 and 60 are merged into the new Freiburg Efficiency House Standard 55. The Fr-EH 55 corresponds to a KfW Efficiency House 55 (Energy Saving Ordinance 2014) with a demonstrated airtightness n50 ≤ 0.60/h and a controlled ventilation system with heat recovery (efficiency > 75%). The primary energy demand of 55% and the specific transmission heat loss of 70% of the respective requirement values according to the Energy Saving Ordinance 2014 must not be exceeded.

I do not find any indication that only passive houses would be approved; on the contrary, it reads as if all efficiency levels from KfW 55 are approved, provided and insofar as the plot comes from the municipality. These days, this is an affordable investment with additional costs in the order of TEUR 8.5.

For me, passive house does not necessarily mean you have to stick the paper from the Passive House Institute to it. The actual requirements are air change rate < 0.6 and annual heating energy < 15 kWh/sqm. For that, components do not necessarily have to be certified; more important are carefully working craftsmen.

The term "passive house" is not protected, nor are the components that may be used therein explicitly prescribed anywhere. **Certification as a "quality-tested passive house" (with the PHI label) is an offer from PHI. No one "has to" certify their passive house. But since these are really new requirements for many planners, developers, and contractors, the certificate is a good way to ensure that these requirements are met. Trust between provider and buyer is thereby strengthened. In addition, good quality assurance during the planning process often saves a lot of money. PHI stands behind this certification with its reputation – the PHI label is therefore also a protected trademark. Only certification bodies recognized by PHI are allowed to use this label.

Where are the major additional costs supposed to come from?

***A residential building is a passive house if it meets the following three requirements:

1. A comfortable indoor climate is achievable without a separate heating system and without air conditioning: the annual heating demand according to the Passive House Planning Package (PHPP) may be a maximum of 15 kWh/(m²a).

2. The comfort criteria must be met in every room in winter as well as in summer. This usually results in the following requirements:

[*]U-values of opaque exterior components must be below 0.15 W/(m²K).
[*]U-values of windows and other translucent components must be below 0.8 W/(m²K).
[*]Translucent surfaces oriented west or east (±50°) as well as translucent surfaces with inclinations less than 75° against the horizontal must not exceed 15% of the usable floor areas behind them or must have temporary solar shading with a reduction factor of at least 75%. For south-oriented windows, the limit is up to 25% of the usable floor areas behind them.
[*]The supply air temperatures at the air outlet in the room must not fall below 17°C. A uniform airflow through all rooms and in all rooms must be ensured (ventilation efficiency). The ventilation must primarily be designed for air hygiene (DIN 1946). The noise pollution from the ventilation system must be very low (< 25 dBa).
[*]The houses must have at least one openable outside air opening in every living space; through-flow of the apartment with outside air must be possible (free summer cooling).

3. The specific primary energy demand for all household applications (heating, hot water preparation, and household electricity) together must not exceed 120 kWh/(m²a). The calculation is carried out according to PHPP.

The values for the reference building according to the Energy Saving Ordinance are:

Roof: UREF 0.20 W/(m2K)
Wall: UREF 0.28 W/(m2K)
Thermal bridges: UREF 0.05 W/(m2K)
Base plate: UREF 0.35 W/(m2K)
Windows: UREF 1.3 W/(m2K)
Heating: gas condensing boiler + solar water heating
Primary energy demand: QREF 83.41 kWh/(m2a)

***The following principles apply to the construction of passive houses:

Thermal insulation
All opaque components of the building envelope are so well insulated that they have a heat transfer coefficient (U-value) of max. 0.15 W/(m²K), i.e. at one degree temperature difference and one square meter of exterior surface, a maximum of 0.15 watts is lost.

Passive house windows
The windows (glazing including window frames) should not exceed a U-value of 0.80 W/(m²K), with g-values around 50% (g-value = total solar energy transmittance, proportion of solar energy available to the room).

Ventilation heat recovery
The comfort ventilation with highly effective heat recovery primarily ensures good indoor air quality – secondarily, it serves energy saving. In the passive house, at least 75% of the heat from the exhaust air is recovered via a heat exchanger to the fresh air.

Air tightness of the building
Leakage through uncontrolled joints must be less than 0.6 building volumes per hour in the test with under-/overpressure of 50 pascals.

Freedom from thermal bridges
All edges, corners, connections, and penetrations must be planned and executed particularly carefully to avoid thermal bridges. Thermal bridges that cannot be avoided must be minimized as far as possible.

**Source: IG Passive House
***Source: Passive House Institute

Deviations from the reference building requirements for masonry, base plate, roof, insulation, windows, and ventilation as well as heating load model according to PHPP in relation to the reference building according to Energy Saving Ordinance 2014 quickly lead to additional costs in the area of 40%. This will certainly decrease in the coming years; at the moment, however, potential building clients should better not lose sight of this additional investment.

I always have to smile: in the heating load calculation of a PH, among other things, the body heat of the future residents is included in the calculation. In Lehrte, there is a passive house as a model house where the serving saleswomen put a small heater on at certain times of the year.

Rhenish regards

Sorry, your post is a bit unreadable. Just briefly about Freiburg:

verified airtightness n50 ≤ 0.60/h

This certainly won't approve normal KfW55 houses, because there only n50 ≤ 1.5/h is required. So at least very careful work is necessary. And that brings us to what I wrote, right? You also come up with an amount that is roughly around 2%.

PHI doesn't matter to me, as I said, PHPP is decisive, for example to get the KfW funding.