Hello,
I am planning to build in the near future and cannot decide between gas and geothermal energy. The single-family house with KfW 70 standard (basement, ground floor, first floor, and attic conversion) has 163 sqm (1754 sq ft) of living space and will be occupied by 2 people. Underfloor heating is also planned. What is the most cost-effective way to heat domestic hot water and the heating system? What is the best investment and why?
Good luck
I am planning to build in the near future and cannot decide between gas and geothermal energy. The single-family house with KfW 70 standard (basement, ground floor, first floor, and attic conversion) has 163 sqm (1754 sq ft) of living space and will be occupied by 2 people. Underfloor heating is also planned. What is the most cost-effective way to heat domestic hot water and the heating system? What is the best investment and why?
Good luck
misterknister schrieb:
...Currently planning: air-source heat pump combined with a ventilation system. Later on, photovoltaics.If all the key parameters are suitable for this, it can definitely make sense. If not, it could potentially become a money pit. There are plenty of examples of this 😉 Best regards
M
misterknister28 Sep 2011 14:49€uro schrieb:
If all the key conditions are suitable, this could definitely make sense. If not, it might turn into a money pit. There are plenty of examples of this 😉
Regards,Hi,
Could you please explain this in detail? Which key conditions are you referring to, and where exactly would the money pit be?
Hello,
A money pit would be a realized annual performance factor (seasonal coefficient of performance) below 3. Quite a few homeowners unfortunately have to live with this despite high investments (2.3...2.7).
Here is an example: annual thermal demand of 10,000 kWh. With an annual performance factor of 2.3, this results in costs of €696/year (at €0.16 per kWh). In contrast, with a factor of 3.5, the costs are €457/year. Now consider price increases (inflation) projected over 25 years.
A gas condensing boiler at €0.07 per kWh would create approximately €824/year in fuel costs but would be significantly cheaper in terms of initial investment.
Any economic assessment requires a consumption forecast based on actual conditions. Energy saving regulations/planning permission documents are generally not suitable for this and are not intended as such by law.
The key parameters are diverse and start with the climate location (design heating temperature), the building's energy efficiency status (insulation values), and end with the sizing of heating surfaces (hydraulics) as well as the heating capacity and COP curves of the intended manufacturer/device. If these factors do not match well (poor planning), achieving a good annual performance factor is unlikely, and consumption costs will become uncomfortably high. A “nicely calculated” energy saving regulation/planning permission certificate won’t help in such cases.
Best regards.
misterknister schrieb:
...Can YOU explain this to me in detail? What are the key parameters, and where would the money pit be?
A money pit would be a realized annual performance factor (seasonal coefficient of performance) below 3. Quite a few homeowners unfortunately have to live with this despite high investments (2.3...2.7).
Here is an example: annual thermal demand of 10,000 kWh. With an annual performance factor of 2.3, this results in costs of €696/year (at €0.16 per kWh). In contrast, with a factor of 3.5, the costs are €457/year. Now consider price increases (inflation) projected over 25 years.
A gas condensing boiler at €0.07 per kWh would create approximately €824/year in fuel costs but would be significantly cheaper in terms of initial investment.
Any economic assessment requires a consumption forecast based on actual conditions. Energy saving regulations/planning permission documents are generally not suitable for this and are not intended as such by law.
The key parameters are diverse and start with the climate location (design heating temperature), the building's energy efficiency status (insulation values), and end with the sizing of heating surfaces (hydraulics) as well as the heating capacity and COP curves of the intended manufacturer/device. If these factors do not match well (poor planning), achieving a good annual performance factor is unlikely, and consumption costs will become uncomfortably high. A “nicely calculated” energy saving regulation/planning permission certificate won’t help in such cases.
Best regards.
B
Brombadegs29 Sep 2011 10:01Hi,
I am currently planning a new house. At the moment, we have a liquid propane tank and piping on the property, so I was thinking of continuing to use that. In addition, I want to install solar panels and a hydronic fireplace. I’m not sure if that makes sense. Also, I’m considering underfloor heating throughout the house—is that a good idea?
Are there hydronic fireplaces that can also be heated with coal if necessary?
The budget for heating, buffer tank, and solar is around 10,000 euros for a 130 m² (1,400 sq ft) house. I’ve seen fireplaces starting at about 1,200 euros (10 kW).
I don’t want to ask companies yet since they tend to install whatever the customer wants.
Could someone please help?
Regards,
Bromi
I am currently planning a new house. At the moment, we have a liquid propane tank and piping on the property, so I was thinking of continuing to use that. In addition, I want to install solar panels and a hydronic fireplace. I’m not sure if that makes sense. Also, I’m considering underfloor heating throughout the house—is that a good idea?
Are there hydronic fireplaces that can also be heated with coal if necessary?
The budget for heating, buffer tank, and solar is around 10,000 euros for a 130 m² (1,400 sq ft) house. I’ve seen fireplaces starting at about 1,200 euros (10 kW).
I don’t want to ask companies yet since they tend to install whatever the customer wants.
Could someone please help?
Regards,
Bromi
Hello,
The more heat generators you combine, the lower the overall efficiency and, consequently, the economic viability, since each system has its own requirements to achieve maximum efficiency. These rarely fit well together. It is better to focus on one solution and design it as efficiently as possible (planning). However, technically, “mixing” whatever generates heat is not a problem.
Best regards
Brombadegs schrieb:There probably won’t be natural gas available there.
.. Therefore, I thought to reuse/continue using this.
Brombadegs schrieb:That always depends on the specific conditions. In most cases, a standard solar thermal system does not pay off for a single-family house.
.. In addition, I wanted to use solar and a water-heated fireplace. Unfortunately, I have no idea if that makes sense.
The more heat generators you combine, the lower the overall efficiency and, consequently, the economic viability, since each system has its own requirements to achieve maximum efficiency. These rarely fit well together. It is better to focus on one solution and design it as efficiently as possible (planning). However, technically, “mixing” whatever generates heat is not a problem.
Brombadegs schrieb:Sometimes yes, sometimes not. That also depends on the specific conditions.
.. Oh, and I wanted underfloor heating everywhere—does that make sense?
Brombadegs schrieb:That probably won’t be enough, unless it’s low-quality work with comparatively high running costs later.
.. Costs for heating, buffer tank, solar should be around 10k for a 130 sqm (1400 sqft) house.
Best regards
Hello
So, we moved into our new house in January (130 sqm (1400 sqft)) with underfloor heating.
We thought a long time about what to choose.
Oil heating: You can buy oil in bulk when it’s cheap, but you need a separate storage room, which means losing an entire room.
Gas heating: You have to pay whatever the price for natural gas (for example, today €1 per m³ (about $1.10 per yd³), tomorrow €2 per m³). Liquefied petroleum gas (LPG) also requires storage space.
In the end, we went for an air-to-air heat pump. There are special electricity tariffs for it (at least from our regional energy provider). We just received our first electricity bill in October, and we even got money back. Plus, I don’t have to install solar panels on the roof because the heat pump covers the 20% renewable energy requirement.
Additionally, we have a 7 kW wood stove in the living and dining area, which is enough to heat the ground floor and part of the upper floor.
Of course, I could add solar panels for water heating and space heating, but according to our heating installer, that only pays off after several years, if at all (higher upfront costs, maintenance, and repairs). He would have installed everything we wanted, so he would have earned more, but he calculated everything for us and advised against it.
The same goes for water-driven wood stoves. They’re a great option, but you still have to buy the wood.
But everyone needs to decide that for themselves.
Best regards, Shorty
So, we moved into our new house in January (130 sqm (1400 sqft)) with underfloor heating.
We thought a long time about what to choose.
Oil heating: You can buy oil in bulk when it’s cheap, but you need a separate storage room, which means losing an entire room.
Gas heating: You have to pay whatever the price for natural gas (for example, today €1 per m³ (about $1.10 per yd³), tomorrow €2 per m³). Liquefied petroleum gas (LPG) also requires storage space.
In the end, we went for an air-to-air heat pump. There are special electricity tariffs for it (at least from our regional energy provider). We just received our first electricity bill in October, and we even got money back. Plus, I don’t have to install solar panels on the roof because the heat pump covers the 20% renewable energy requirement.
Additionally, we have a 7 kW wood stove in the living and dining area, which is enough to heat the ground floor and part of the upper floor.
Of course, I could add solar panels for water heating and space heating, but according to our heating installer, that only pays off after several years, if at all (higher upfront costs, maintenance, and repairs). He would have installed everything we wanted, so he would have earned more, but he calculated everything for us and advised against it.
The same goes for water-driven wood stoves. They’re a great option, but you still have to buy the wood.
But everyone needs to decide that for themselves.
Best regards, Shorty
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