Hello
First, let me briefly introduce myself. My name is Julian, and I’m from the beautiful Saarland region. Since my partner and I are gradually thinking about buying a home and gathering some ideas, I have a few questions.
We are planning to build a single-family house with a living area of 160 m² (1,722 sq ft). Now the question is how to save money despite rising energy and heating costs.
Now to my main idea:
I would build a house with a large solar thermal system and a photovoltaic system. Inside the house, there would be a large water storage tank with a capacity of about 20–30 cubic meters (7,057–10,594 cubic feet). I would use the solar thermal system to heat the water in the storage tank to provide domestic hot water. Additionally, I could use the stored heat to warm the house in winter through underfloor heating. For very cold winters, I would also install a large wood-burning stove. This stove might have an integrated heat exchanger to heat water as well. Do you think such a setup could work without any additional heating system? What would the approximate cost be? I have also been considering installing an automatic ventilation system to prevent mold and other issues in a highly insulated house.
What do you think? Feasible or a rather unrealistic idea?
First, let me briefly introduce myself. My name is Julian, and I’m from the beautiful Saarland region. Since my partner and I are gradually thinking about buying a home and gathering some ideas, I have a few questions.
We are planning to build a single-family house with a living area of 160 m² (1,722 sq ft). Now the question is how to save money despite rising energy and heating costs.
Now to my main idea:
I would build a house with a large solar thermal system and a photovoltaic system. Inside the house, there would be a large water storage tank with a capacity of about 20–30 cubic meters (7,057–10,594 cubic feet). I would use the solar thermal system to heat the water in the storage tank to provide domestic hot water. Additionally, I could use the stored heat to warm the house in winter through underfloor heating. For very cold winters, I would also install a large wood-burning stove. This stove might have an integrated heat exchanger to heat water as well. Do you think such a setup could work without any additional heating system? What would the approximate cost be? I have also been considering installing an automatic ventilation system to prevent mold and other issues in a highly insulated house.
What do you think? Feasible or a rather unrealistic idea?
T
Thomas46317 May 2012 21:41So, an architect (unless specialized in this area) is probably not the best choice. I would rather recommend consulting an engineer expert in building physics calculations or contacting one or two suppliers of these systems to ask what you can typically expect from such an installation.
Regarding energy demand:
A heat pump does consume electricity, but in addition to the electricity used, it delivers roughly three times that amount of heating power extracted from geothermal energy.
To put it simply: about 1 part electricity + about 3 parts geothermal energy = 4 parts usable heat energy (this can vary somewhat depending on the model and manufacturer).
You can definitely cover this electricity consumption through photovoltaic panels. The key factor here is your annual energy balance — in summer, you earn money for the electricity you feed into the grid, which you can then use in winter when your demand is higher. The rest of the system, besides the heat pump itself, mainly consists of small pumps that circulate fluids (for example, a pump for the ground heat exchanger and a pump for controlled ventilation) plus their control electronics.
However, to calculate the heating demand of the house and, therefore, the size of the entire system, you need some basic data or assumptions (number of occupants, floor area, heating demand, and associated approximate location of the future building), among other factors.
Thus, such calculations are relatively pointless unless you have a specific project being evaluated.
You can, however, get a rough estimate of the requirements for the building (insulation, airtightness, heating system) and thereby approximate the general costs of a passive house compared to a conventional house.
I hope this helps you somewhat in that respect.
As my predecessor already mentioned: besides vertical and horizontal ground collectors, there are also various hybrid forms (e.g., geothermal baskets) and variations. Such systems can also be integrated into foundation concepts (for example, bored pile walls or even tunnel walls). I don’t want to go into too much detail here, as my explanation is already quite long ;-)
Regarding your question about potential problems:
Usually, these systems don’t cause issues. However, they are not completely risk-free (especially vertical ground collectors). Possible problems could arise with pressurized groundwater (groundwater under pressure that, when drilled, tends to escape through the borehole), but this is generally very rare. Additionally, for such systems (at least here in Austria), water law permits are required because the microbiological system in the soil/groundwater can be affected by temperature changes. This permit should not be a problem but should be applied for early to avoid unpleasant surprises if things do not proceed smoothly immediately. The biggest risks should be ruled out by a geotechnical survey (which you will need for the foundation design of the house anyway, perhaps in greater detail).
One small tip: definitely get legal protection insurance before building and, if possible, also hire an independent expert or building inspector during construction because minor issues that are not detected early can become serious problems. This starts with the proper installation of windows and doors and extends to waterproofing of the basement/foundation. This way, you minimize the chances of problems during construction.
Best regards,
Thomas463
Regarding energy demand:
A heat pump does consume electricity, but in addition to the electricity used, it delivers roughly three times that amount of heating power extracted from geothermal energy.
To put it simply: about 1 part electricity + about 3 parts geothermal energy = 4 parts usable heat energy (this can vary somewhat depending on the model and manufacturer).
You can definitely cover this electricity consumption through photovoltaic panels. The key factor here is your annual energy balance — in summer, you earn money for the electricity you feed into the grid, which you can then use in winter when your demand is higher. The rest of the system, besides the heat pump itself, mainly consists of small pumps that circulate fluids (for example, a pump for the ground heat exchanger and a pump for controlled ventilation) plus their control electronics.
However, to calculate the heating demand of the house and, therefore, the size of the entire system, you need some basic data or assumptions (number of occupants, floor area, heating demand, and associated approximate location of the future building), among other factors.
Thus, such calculations are relatively pointless unless you have a specific project being evaluated.
You can, however, get a rough estimate of the requirements for the building (insulation, airtightness, heating system) and thereby approximate the general costs of a passive house compared to a conventional house.
I hope this helps you somewhat in that respect.
As my predecessor already mentioned: besides vertical and horizontal ground collectors, there are also various hybrid forms (e.g., geothermal baskets) and variations. Such systems can also be integrated into foundation concepts (for example, bored pile walls or even tunnel walls). I don’t want to go into too much detail here, as my explanation is already quite long ;-)
Regarding your question about potential problems:
Usually, these systems don’t cause issues. However, they are not completely risk-free (especially vertical ground collectors). Possible problems could arise with pressurized groundwater (groundwater under pressure that, when drilled, tends to escape through the borehole), but this is generally very rare. Additionally, for such systems (at least here in Austria), water law permits are required because the microbiological system in the soil/groundwater can be affected by temperature changes. This permit should not be a problem but should be applied for early to avoid unpleasant surprises if things do not proceed smoothly immediately. The biggest risks should be ruled out by a geotechnical survey (which you will need for the foundation design of the house anyway, perhaps in greater detail).
One small tip: definitely get legal protection insurance before building and, if possible, also hire an independent expert or building inspector during construction because minor issues that are not detected early can become serious problems. This starts with the proper installation of windows and doors and extends to waterproofing of the basement/foundation. This way, you minimize the chances of problems during construction.
Best regards,
Thomas463
Culli schrieb:
.....or who does something like that? For this, a building services engineer and energy consultant is probably suitable 😉 You can send me a private message.Best regards
Hello, thank you all for the informative answers.
@Thomas463
Of course, I can generate my own electricity again. It would even be sensible since, due to the recent changes in photovoltaic feed-in tariffs for self-consumed electricity, I now receive at least 30% more than if I feed the electricity directly into the grid. Unfortunately, there are still no really good and affordable batteries to store the unused electricity long-term.
I definitely have to commission a soil survey. For a standard basement, I believe I only need a report down to five meters (16 feet) soil depth. Anything deeper would then require an additional survey.
@€uro
I will definitely get in touch with you. Thanks.
@Thomas463
Of course, I can generate my own electricity again. It would even be sensible since, due to the recent changes in photovoltaic feed-in tariffs for self-consumed electricity, I now receive at least 30% more than if I feed the electricity directly into the grid. Unfortunately, there are still no really good and affordable batteries to store the unused electricity long-term.
I definitely have to commission a soil survey. For a standard basement, I believe I only need a report down to five meters (16 feet) soil depth. Anything deeper would then require an additional survey.
@€uro
I will definitely get in touch with you. Thanks.
T
Thomas46318 May 2012 21:06Culli schrieb:
Hello, thanks to all of you for the informative answers.
@Thomas463
Of course, I can produce my own electricity again. It would even make sense because, due to the changed feed-in tariffs for self-consumed photovoltaic electricity, I now receive about 30% more than if I feed the electricity directly into the grid. Unfortunately, there are still no really good and affordable batteries to store the unused electricity long-term.
I definitely have to arrange a soil survey. For a standard basement, I believe I only need a survey down to five meters (16 feet) soil depth. Anything deeper would then have to be commissioned additionally.
@€uro
I will definitely get in touch with you. ThanksYes, self-storage with batteries is practically out of the question, but simply feeding into the grid and drawing electricity from the grid when needed works fine. In a way, the grid acts as a battery ;-).
Well, you can’t generalize the five-meter (16 feet) rule. It depends on how deep you have to drill to reach solid and load-bearing ground. In hillside locations or on filled ground, it can vary significantly from those five meters (16 feet).
For a deep geothermal probe, you should drill deeper, but if the drilling rig is already on site, it shouldn’t add too much extra cost. However, you should know in advance which type of geothermal system you want to use. That will determine what exactly you need.
But I hope we have helped you find a good starting point for your initial planning in construction.
Best regards, Thomas
Hello, self-supplying is currently the only solution.
As I mentioned, I actually receive more compensation for self-consumption than if I feed the electricity directly into the grid. But that should be manageable. :-)
So, on the site where the house will be built, definitely no fill has been added.
I will probably opt for deep geothermal probes. For horizontal ground loops, a huge amount of soil would have to be moved again.
Best regards.
As I mentioned, I actually receive more compensation for self-consumption than if I feed the electricity directly into the grid. But that should be manageable. :-)
So, on the site where the house will be built, definitely no fill has been added.
I will probably opt for deep geothermal probes. For horizontal ground loops, a huge amount of soil would have to be moved again.
Best regards.
T
Thomas46320 May 2012 14:26The deep probe is generally very effective. The deeper you go into the ground, the warmer it gets there.
Adding a heat pump, controlled indoor ventilation with a heat exchanger for heat recovery, and you have a solid system.
Oh, and you can also run the fresh air intake pipe a few meters underground at about 2-3 meters (6.5-10 feet) depth to the house, so the air is slightly pre-warmed in winter and pre-cooled in summer.
Best regards
Adding a heat pump, controlled indoor ventilation with a heat exchanger for heat recovery, and you have a solid system.
Oh, and you can also run the fresh air intake pipe a few meters underground at about 2-3 meters (6.5-10 feet) depth to the house, so the air is slightly pre-warmed in winter and pre-cooled in summer.
Best regards
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