ᐅ Renovation of Older Homes and Choosing a Heating System

Hello everyone,

A question that regularly concerns me is the choice of the _future_ heating system in renovations; I would therefore like to pass this on to owners of renovated existing properties.

How have you solved this issue for your home and why? Gas condensing boiler + solar, air-to-water heat pump + photovoltaic, biomass heating, combined heat and power (CHP), or a hybrid system? Did you consult an energy advisor? And related to this, have you replaced existing radiators with newly installed underfloor heating, and are you still satisfied with your choice today?

I would be happy to hear from those of you who have renovated, as this topic will certainly remain of great interest in the coming years.

Thanks and best regards, Bauexperte

Air-to-water heat pumps combined with underfloor heating are often chosen when they can be implemented in line with all requirements for floor construction and building insulation. This naturally assumes a full energy-efficient renovation with an energy certificate, heating load calculation, ventilation concept, blower door test, etc., to meet a KfW-EE standard, which also enables access to KfW funding programs.

Otherwise, there is still the more cost-effective gas condensing boiler for those with a smaller budget, using standard convectors or underfloor heating. I personally prefer to avoid photovoltaic or solar thermal systems whenever possible because they complicate and increase the cost of the system technology and, in our latitudes, serve primarily as an expensive superficial addition without real benefit according to the Energy Saving Ordinance and the Renewable Energy Heat Act. Photovoltaics will become interesting in the future when affordable and efficient storage modules are available and a heat pump with its own power supply is feasible.

In my opinion, the whole topic of building services technology should become simpler rather than increasingly complicated and expensive. Since 2000, building costs have risen by about 35% due to the requirements of the Energy Saving Ordinance and the expanding complexity of building services technology.

We carried out the following work during our major renovation:
Removed the old oil heating system with 25 kW output and radiators.
Installed a new condensing oil boiler with modulation from 6 to 15 kW and underfloor heating.
No ventilation system was installed, but we added a new roof with insulation, new windows, new screed plus insulation, and no insulation on the exterior walls.

We chose to continue using oil because there is no natural gas connection available in our town. Otherwise, we would have had to opt for liquefied petroleum gas (LPG) or wood pellets. LPG was ruled out because we did not want a tank in the garden, and the pellet system would have cost over €10,000 more upfront.
Advice was provided by an architect and heating engineer.

wpic schrieb:

Otherwise, of course, there is still the cost-effective gas condensing boiler option for smaller budgets, with standard convectors or even underfloor heating.

Yes, the total cost of ownership (TOC) over 20 years for a gas condensing boiler is still very reasonable at the moment. How this will develop with changing regulations and gas prices remains to be seen. Convectors don’t have to be bad either; some people simply don’t like underfloor heating... We are very happy and satisfied with our radiators.

wpic schrieb:

I prefer to avoid using photovoltaics or solar thermal systems if possible, as they complicate and increase the cost of the system technology. In our latitudes, and considering energy efficiency regulations and the Renewable Energies Heat Act, they mostly represent an expensive symbolic addition without real benefits. Photovoltaics will become interesting in the future when affordable and efficient storage modules are available and a heat pump with its own power supply becomes possible.

I fully agree. Solar thermal is a toy in this country that never pays off, only gives a good conscience. I say this because I know—I have such a system; I know what it cost and what it delivers.

Photovoltaics are also a toy—but they become more interesting with batteries.
No one knows how electricity prices (for end consumers) will develop. I prefer photovoltaics over solar thermal and enjoy having that “toy.”
Photovoltaics with a high proportion of self-consumption definitely make sense and reduce CO2 emissions.
However, you have to be aware: the overall calculation currently breaks even at best, or photovoltaics are even more expensive.

wpic schrieb:

In my opinion, the whole topic of building services should become simpler instead of increasingly complicated and expensive. Since 2000, building costs have increased by about 35% due to the requirements of energy efficiency regulations and ever more complex building services systems.

Finally, an architect who calls a spade a spade. Thumbs up.
When I enter my technical room, I increasingly feel like I’m in the engine room of a nuclear-powered aircraft carrier, not in a house.

Best regards,
Thorsten

During the renovation of our 1936 house, we removed all radiators and the old gravity-fed heating pipe system. We completely rewired it, but with radiators again. The 25 kW natural gas boiler from 1996 was kept for now on the recommendation of our heating, ventilation, and plumbing (HVP) specialist because it requires little maintenance and is rarely faulty. We have not regretted this decision so far. However, the boiler could be replaced within a day if necessary.

Hello

The rocket science aspect is actually desired by many homeowners, by the way. The industry offers a solution for a problem that is rarely or never present.

Olli