High additional costs in old buildings - despite renovation

Good day,

I registered in this forum hoping to receive good advice here. :)

Two years ago, we renovated our 40-year-old bungalow. The bungalow has a floor area of 170 m², fully basemented. We only use the ground floor as living space. Above the ground floor is also a concrete ceiling. The exterior wall consists of clinker brick, a small, uninsulated, and empty cavity, and 40 cm of calcium silicate stone. So the exterior walls are not insulated.

During the renovation two years ago, the following was renewed:
-New plastic windows (many sliding doors and panoramic windows) were upgraded to the latest standard with triple glazing)
-Floor ceiling to the attic was insulated with 5 cm styropor panels (which had always been there) and additionally with 30 cm of mineral wool. A new roof (gable roof) was also installed for €40,000. Since we do not use the attic, only the floor ceiling was insulated with mineral wool. The roof was professionally covered (a foil between the tiles and the roof structure is present).
- Completely new heating pipes, wall radiators, and underfloor heating. The heating pipes were laid under the basement ceiling and insulated. The 18-year-old oil heating from Buderus (according to the installer and chimney sweep top values regarding emissions) was retained.

Exactly one year ago, we filled the 1st oil tank (5000 liters) and now I have measured the oil level. The consumption in one year (3-person household) is 3700 liters. We have large rooms to heat. Living room, dining room, and kitchen are completely open (70 m²) and the heating in these rooms will now run continuously again when we are in the house. Also, three people shower every day, and in winter underfloor heating runs in both bathrooms and the kitchen.

The house is pleasantly cool in summer, probably due to the massive construction (reinforced concrete and calcium silicate stones). In winter, however, it is also quite cool. We are now no longer sure whether we made the right decision to renovate the house. Insulating the exterior walls is an alternative but certainly extremely expensive.

I am an absolute layman in this regard and hope for tips and advice from you! Many thanks!

Hello,

Two years ago we renovated our 40-year-old bungalow.

Who advised on this?

...The 18-year-old oil heating system from Buderus (according to the installer and chimney sweep top values regarding emissions) was retained.

That is not an energetic evaluation in the overall context!

... The consumption in one year (3-person household) amounts to 3700 liters.

That is more than excessive!

... Insulating the exterior walls is an alternative, but certainly extremely costly.

That is probably not so easy with a clinker brick cladding.

...I am hoping for tips and advice from you! Many thanks!

First, the consumption must be assigned to the corresponding causes before taking further measures. This includes initially determining the actual demand (capacity, energy) for heating and hot water. It may be possible to reduce a lot already through system optimization, especially if radiators are used as heating surfaces.

Best regards

So I cannot avoid an energy-technical consultation. I cannot provide data on the actual demand for power and energy. I can only measure the oil consumption. Due to the size of the house and the long hot water pipes that really lead everywhere (20 m to each side of the house), I can only explain it by the fact that an oil heating system is simply no longer up to date. Furthermore, the oil tank worries me greatly, as I fear that it will eventually become leaky and then it will certainly be very expensive. However, the question arises whether maintenance is worthwhile. Because I have decided that in the event of a major damage, a modern heating system will be purchased immediately, even if it is expensive. The only alternatives left to me are basically only a new heating system and the insulation of the exterior facade. Because otherwise everything has really been renewed and insulated. We also do not have municipal water but an own water supply. Therefore, I cannot provide a value for water consumption if it is necessary. Best regards

Yes, get yourself a new heating system! It would have made sense to have an insulation layer between the inner and outer masonry, which also has an air insulation function.

So I can't avoid an energy technology consultation.

not just consultation => calculation! Energy consultant is not a protected professional title, it can also be a building material dealer. Whether they are technically competent in system engineering is doubtful.

...Because I have decided that in case of major damage, a modern heating system will be purchased immediately, even if it is expensive.

Just changing the heat generator often only helps to a limited extent.

Best regards.

Hello,

So I can’t avoid an energy technical consultation.

THAT is the wrong attitude! It should be important to you to clarify this topic with an energy consultant. What happens if you neglect it, you are currently experiencing through your own behavior => your problem of high energy costs is not solved despite considerable capital investment.

Furthermore, the oil tank worries me greatly because I fear that it will eventually leak and then it will definitely get really expensive. However, the question arises whether maintenance is worthwhile. Because I have decided that in the event of a major damage, a modern heating system will be purchased immediately, even if it is expensive.

Sealing the oil tank in the worst case is not a big problem for a specialist; maintenance of technical systems is worthwhile btw. always!

The only alternatives left to me are basically only a new heating system and insulation of the exterior facade. Because otherwise everything is really new and also insulated.

There is the possibility to insulate the facing facade afterwards by pressing insulation material into the cavity. However, it seems more reasonable to me to first invest money in an energy consultant; maybe the oil heating system is indeed the cause or something completely different that you haven’t considered yet .... Btw., the costs of the consultant are deductible within your tax return ;)

Kind regards