ᐅ Semi-detached bungalow 8 m² KfW70 without ventilation / basement, Y-Tong

We want to buy and build a newly constructed, fully planned half of a bungalow without a basement and with a hipped roof.

Please excuse any incorrectly spelled or misnamed technical terms – we are laypersons.

After reading a lot, we are now in the “phase of uncertainty,” which is probably familiar to many here ;-)

Here are some details about the project:

Hipped Roof Bungalow Half

- Building foundation made of glass foam gravel with reinforcement, compacted, concrete, base slab covered to be moisture-tight (this is probably the slab-on-grade)?

- 6cm (2.4 inches) insulation layer, 6cm (2.4 inches) floating screed

- Exterior shell 36.5cm (14.4 inches) aerated concrete in system blocks or Y-Tong plan blocks W-PPW 2-040, MSH steel profile 120/80/5 as support in the bathroom (ceiling) window area – for what purpose?

- Double layer reinforcement with mesh and scratch coat on the exterior

- Windows with Uw = 1.0, triple glazing

- All rooms have windows (open plan kitchen/living area, utility room, bedroom, bathroom)

- Room height about 2.5m (8.2 ft), house height up to the ridge 6.11m (20 ft)

- District heating (underfloor heating in all rooms)

- Attic accessible via hatch, insulation between rafters in the roof

- Usable floor area 114m² (1,227 sq ft) (footprint 88m² (947 sq ft))

That’s the rough information so far. More details gladly available.

Through this forum, I learned about passive and active ventilation (and also KfW 70 due to funding incentives ;-)).

Our question regarding active/passive ventilation: Is it necessary under these circumstances? We both work full-time and often don’t have the chance to ventilate additionally around midday. We would prefer to invest the money saved from not installing or discussing a ventilation system into our list of special features.

A thermal protection certificate with data for our house type and even the house number, according to the Energy Saving Ordinance 2009 (KfW 70 standard), and an energy performance certificate are included in the building description. The values are difficult for me to understand. The energy certificate specifies "natural ventilation," valid until 2021.

Could someone please help or share their opinion?

Thank you in advance

Heiko and Martina

In my opinion, building a house today without a controlled residential ventilation system is highly negligent and a false economy. However, you can find plenty of discussions about this here in the forum. There is even more information on bosy-online.

Hello ypg,

Thank you for your opinion. While browsing, I noticed this is a much-discussed topic 😎. I think most people would buy a controlled residential ventilation system as a precaution, but like most, they would rather spend the money on more “visible” upgrades :o

Since the bungalow has a living area of 88m² (947 sq ft) and consists of only 2 rooms plus a utility room and bathroom, maybe installing two units of the Viessmann Vivovent 200-d could be a cost-reducing alternative? The open-plan kitchen/living area is about 45m² (484 sq ft).

Possibly combined with window frame ventilators? What are your thoughts on this?

Thanks in advance

Heiko

Attached is the proposed layout

So-called window rebate ventilators are the most ridiculous invention ever... You build a window as airtight as possible, with whatever U-value, spend a lot of money to make sure it's sealed properly, and then cut holes into the rubber seal or the frame???

Something about this logic just doesn’t add up, does it?

What you need:

Utility room: exhaust
Bathroom: exhaust
Kitchen: exhaust

Living room: supply
Bedroom: supply

So, at least 5 units.

You need to calculate what’s cheaper... Since you only have 88 m² (950 sq ft), you don’t need a huge system. A compact central unit with 180 cubic meters per hour (6,360 cubic feet per hour) would be sufficient.

Mycraft schrieb:
...since you only have 88 sqm (947 sq ft), you don’t need a large system; a compact central unit with 180 cubic meters (6,360 cubic feet) would be sufficient.

Thanks for the tip.

We have a walkable attic with a pull-down ladder included in our order. If we place the system on the attic floor and drill a hole in each ceiling, we could easily clean the system since the ducts would be lying on the floor.

Or is this maybe not allowed (the attic has insulation between the rafters) 😕? Also, does such a ventilation system require a water supply or drainage connection 😕?

Thanks in advance 🙂
Heiko