Improve existing roof insulation for the Energy Saving Ordinance 2014

Hello

What and how do we need to improve the roof insulation to comply with the energy saving regulations?
The attic is insulated with 16 mm (we don’t yet know with what), the roof only has a vapor barrier.
A photovoltaic system is also planned for the roof.

"I" can't tell you. But how much has to be calculated for you by someone with expertise. You obviously don't just want to insulate a little, but have a target value ([Energieeinsparverordnung]) in mind.

It is not quite clear to me what one is actually "seeing" there: I can't make much sense of 16 mm insulation*, the pictures look like a rafter roof, but also like an insulation above the rafters. What approximate year of construction and which federal state is this?

And: what is it about? - if the attic is only used as a storage room, I would consider the ceiling between floors as the more suitable "insulation layer" than the roof itself.

The standard Energy Saving Ordinance 2014 confuses me: with an extensive renovation that triggers the application of current standards, it should actually be Energy Saving Ordinance 2016 (?) - although that probably depends on the time of house purchase ...

*) in terms of size, I am thinking of some kind of sandwich panels from hall construction

Thank you for your interest and the answers

There should be 16 cm of insulation under the panels / roof floor. As far as I can see, nothing has changed in this regard in the Energy Saving Ordinance 2016 compared to 2014

Located in NRW

Unfortunately, during the first inspection, we were not able to look underneath or behind it

I just don't know if we are above the thermal transmittance coefficient of the top floor ceiling of 0.24 watts/(m²K).
The house was built in 1969 and renovated in 2005, including this insulation. The architect / real estate agent said the roof would need to be reroofed and insulated more.
Yes, I am also rather of the opinion that it would be enough to possibly increase these 16 cm to 20 cm or 24 cm. If it can stay as it is, all the better. It's a lot of money after all.

Just wanted to get some advice here.

The lead glass windows will also be replaced with double-glazing and the folding staircase insulated.

Hello Luzyferia,

When it comes to insulation, you have to calculate quite precisely whether it is worthwhile.
I once contacted 3 companies out of boredom after a marten completely damaged my insulation. Cost estimates ranged from 8,000 to 12,000 euros.
Currently, I heat 210 sqm of living space with a gas boiler and a house from 1990 and have costs of about 85 euros or also 1580 cm3 per year, but this also includes the hot water preparation via a gas water heater.
After the "repair," I had additional costs of about 80€ per month for cost recovery and would at best save 10€ per month on heating costs. So I let it be.

With the existing 16 cm of glass wool with an assumed lambda value / WLS of 035 (standard for glass wool), you ONLY achieve a U-value of 0.21 through the insulation, thus meeting the requirements of the Energy Saving Ordinance 2014/16. All other layers (chipboard, ceiling construction) further reduce the U-value, but not significantly.

In the pictures, at least something also seems to have been installed on the rafters, which improves the whole thing further.

Increasing the insulation on the floor here does not make financial sense, as the area is currently walkable and covered with chipboard. If some storage areas are not needed, another 10 cm of non-walkable compressed felt/glass wool mats could be laid here. Costs are about 5€/m². Walkable with chipboard top surface would rather come to 20€/m² if done DIY – these costs cannot be justified by the existing insulation and therefore only minimal additional energy savings.

If, contrary to expectations, there is no insulation under the chipboard or if it is damp/damaged/holed, a rebuilding should be carried out. Logically with a thickness of 20-25 cm. Whether walkable or not depends on the requirements for storage space.

We had a similar case with us with 150m² attic area (bungalow) but completely without insulation. We insulated 50m² walkable with 220 mm stone wool boards + chipboard and 100 m² with 240 mm glass wool mats non-walkable.