Hello everyone,
My husband and I attended a home exhibition today featuring a local timber house builder (Schleswig-Holstein) and there we learned about the Vestaxx window heating system.
Is there anyone here who has experience with the Vestaxx window heating?
At first, it sounds unusual to have the heating integrated into the windows. For the triple-glazed windows, a nanotechnology-based, invisible layer is applied to the inner surface of the innermost pane, which warms the glass up to 40 degrees Celsius (104°F) via infrared and heats the room. The warmth actually felt very comfortable, and the windows were completely cold on the outside (today’s temperature was below 10 degrees Celsius (50°F)). Allegedly, the Vestaxx window heating transfers 92% of its heat to the room, and the Technical University of Berlin has tested this Vestaxx window heating system and rated it positively. It appears to have been on the market only recently.
Overall, I find this quite interesting. It is significantly cheaper than other heating systems, allows individual control of each room, and unlike underfloor heating, it is very responsive.
Of course, this only makes sense in a low-energy house (the timber builder mainly constructs 40+ standard homes), as the system runs on electricity. In that case, the Vestaxx window heating is said to consume very little power.
This is my impression from the expo; of course, they want to sell the system.
What are your experiences with Vestaxx? Have you heard of this system before? Could it be an alternative to conventional heating? Does it have a future?
My husband and I attended a home exhibition today featuring a local timber house builder (Schleswig-Holstein) and there we learned about the Vestaxx window heating system.
Is there anyone here who has experience with the Vestaxx window heating?
At first, it sounds unusual to have the heating integrated into the windows. For the triple-glazed windows, a nanotechnology-based, invisible layer is applied to the inner surface of the innermost pane, which warms the glass up to 40 degrees Celsius (104°F) via infrared and heats the room. The warmth actually felt very comfortable, and the windows were completely cold on the outside (today’s temperature was below 10 degrees Celsius (50°F)). Allegedly, the Vestaxx window heating transfers 92% of its heat to the room, and the Technical University of Berlin has tested this Vestaxx window heating system and rated it positively. It appears to have been on the market only recently.
Overall, I find this quite interesting. It is significantly cheaper than other heating systems, allows individual control of each room, and unlike underfloor heating, it is very responsive.
Of course, this only makes sense in a low-energy house (the timber builder mainly constructs 40+ standard homes), as the system runs on electricity. In that case, the Vestaxx window heating is said to consume very little power.
This is my impression from the expo; of course, they want to sell the system.
What are your experiences with Vestaxx? Have you heard of this system before? Could it be an alternative to conventional heating? Does it have a future?
R
RotorMotor4 Oct 2022 11:35Vestaxx GmbH schrieb:
So - now share your full cost calculations. I already did:
RotorMotor schrieb:
You could start here and say an extra €1000 (about $1100) per year at 35 cents/kWh.
With a €25,000 ($27,500) additional cost, the payback period for an air-to-water heat pump is 25 years.
At 60 cents/kWh (about 60 cents per kWh) it’s roughly 14 years.
If you use photovoltaic electricity at 8.2 cents/kWh (about 8.2 cents per kWh), the payback is 100 years.
However, one can definitely say that in winter, when heating is needed, hardly any electricity is generated from the solar panels.
So, direct heating benefits very little from photovoltaics. As you can see, it strongly depends on the electricity price.
But you can’t predict that without a crystal ball.
Since I expect electricity prices to continue rising, I would rather install more efficient heating systems or, even better, build the house completely passive.
And it seems we agree on that:
Vestaxx GmbH schrieb:
How will electricity prices develop? Will they return to pre-Ukraine levels? I don’t think so. Vestaxx GmbH schrieb:
The price of photovoltaics was stable for quite a while but is currently rising. The cost per kWh from a photovoltaic system was quite predictable. It ranged from 9 to 11 cents/kWh (about 9 to 11 cents per kWh), depending on system size. And this price doesn’t change once the system is installed. You can even separate yourself from the Renewable Energy Act feed-in tariff and go into direct marketing. For example, the market price per kWh in July 2022 was about 31 cents/kWh (about 31 cents per kWh). The point is that you always turn on the electric heating exactly when there is no sun. So doesn’t that argument lose its relevance?
One thing that should not require any numerical examples for anyone with common sense is that energy is conserved—no more and no less. It cannot be "created," only "converted" and "used." It is provided free of charge only in the form of solar input. Even a heat pump cannot generate energy; Kelvin is not a cryptocurrency. A windowpane is always at an interface and cannot do anything other than radiate the heat supplied to it in both directions. The efficiencies of different energy conversion processes may vary—but anyone who believes that one method or another can work like magic has certainly smoked too many chemtrails.
https://www.instagram.com/11antgmxde/
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https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
V
Vestaxx GmbH4 Oct 2022 12:27So – I know my colleagues very well ;o) and there definitely isn’t a Christian among them.
Maybe that’s not your real first name either, in which case I can’t help further.
I know – it’s probably unusual to share your profession and place of residence/work here, but that might help driver55 with his assessment.
I’ll start: I’m now 61 years old, living near Bielefeld, working in Berlin. I studied electrical engineering with a focus on energy technology, worked for 25 years in middle and upper management at three companies (two window system manufacturers, one thin-film solar producer). I voluntarily gave up these well-paid jobs and have been passionate about the window heating system since 2014.
Maybe that’s not your real first name either, in which case I can’t help further.
I know – it’s probably unusual to share your profession and place of residence/work here, but that might help driver55 with his assessment.
I’ll start: I’m now 61 years old, living near Bielefeld, working in Berlin. I studied electrical engineering with a focus on energy technology, worked for 25 years in middle and upper management at three companies (two window system manufacturers, one thin-film solar producer). I voluntarily gave up these well-paid jobs and have been passionate about the window heating system since 2014.
V
Vestaxx GmbH4 Oct 2022 13:06Rotormotor: I actually had one a long time ago.
-> I cannot follow your calculations, and unfortunately, they do not represent a full cost calculation according to VDI 2067.
Basically, this should include: investment, operating costs over the lifetime, maintenance costs, inflation, and interest.
But at least you calculate that the heat pump has a payback period of 25 years – it simply doesn’t last that long, so after 60 years it still isn’t economical and needs to be subsidized with taxpayers’ money.
Rotormotor:
Since I expect electricity prices to rise further, I would rather install more efficient heating systems or, even better, build the house completely passive.
-> With rising electricity prices, you should generate your own electricity, and building a passive house is great. With today’s insulation standards, we are already close to that. The less energy the house needs, the less a heat pump makes sense in these houses. This is what I have been trying to explain all along.
Rotormotor:
The issue here is that you always turn on the window heating when there is no sun shining anyway. So this argument falls apart, right?!
That is just absurd. So you always turn your heating on in winter when the sun doesn’t shine. OMG!
A heat pump system runs throughout the winter months because underfloor heating is far too slow to be controlled properly. A concrete slab has about 1000 kg/m² (205 lbs/ft²) of mass – a heated glass pane about 10 kg/m² (2 lbs/ft²). And again: this system makes sense because we don’t only supply the heating panes in winter (of course not fully – I have never claimed that), but the photovoltaic system generates energy year-round – significantly reducing the household electricity drawn from the grid.
11fant: A window pane always sits at an interface and can only radiate supplied heat in both directions.
-> For decades, radiators have been installed under windows – but why? To reduce the discomfort caused by cold air falling near the glass by the rising warm air from the radiator. So it is actually entirely consistent to move the heat source completely into the glass and thus maximize comfort. And of course, a heat source radiates in both directions. Only in our case (I cannot speak for other manufacturers) about 5% of the heat goes outward and a proven 95% goes inward. At 50/50, this would not make sense. And for those who say again … the window is the weakest component regarding heat transfer … you should carefully separate U-value and efficiency. I can gladly write something about this again.
Basically, I would now ask those who consider the heat pump system in new buildings (!) to be the absolute best and are firmly convinced that other systems at similar costs are pointless not to continue reading my threads – I will never convince you nor attempt to persuade you. No offense intended, it just consumes too much of my valuable time.
However, if you regard the heat pump as a very sensible system in new buildings (!) but would like to also explore new and previously unknown innovations beyond the usual, I am happy to continue discussing here and answer any specific questions (see the many questions from Rotormotor).
Einstein said: "The purest form of insanity is to keep doing the same thing and expect different results."
-> I cannot follow your calculations, and unfortunately, they do not represent a full cost calculation according to VDI 2067.
Basically, this should include: investment, operating costs over the lifetime, maintenance costs, inflation, and interest.
But at least you calculate that the heat pump has a payback period of 25 years – it simply doesn’t last that long, so after 60 years it still isn’t economical and needs to be subsidized with taxpayers’ money.
Rotormotor:
Since I expect electricity prices to rise further, I would rather install more efficient heating systems or, even better, build the house completely passive.
-> With rising electricity prices, you should generate your own electricity, and building a passive house is great. With today’s insulation standards, we are already close to that. The less energy the house needs, the less a heat pump makes sense in these houses. This is what I have been trying to explain all along.
Rotormotor:
The issue here is that you always turn on the window heating when there is no sun shining anyway. So this argument falls apart, right?!
That is just absurd. So you always turn your heating on in winter when the sun doesn’t shine. OMG!
A heat pump system runs throughout the winter months because underfloor heating is far too slow to be controlled properly. A concrete slab has about 1000 kg/m² (205 lbs/ft²) of mass – a heated glass pane about 10 kg/m² (2 lbs/ft²). And again: this system makes sense because we don’t only supply the heating panes in winter (of course not fully – I have never claimed that), but the photovoltaic system generates energy year-round – significantly reducing the household electricity drawn from the grid.
11fant: A window pane always sits at an interface and can only radiate supplied heat in both directions.
-> For decades, radiators have been installed under windows – but why? To reduce the discomfort caused by cold air falling near the glass by the rising warm air from the radiator. So it is actually entirely consistent to move the heat source completely into the glass and thus maximize comfort. And of course, a heat source radiates in both directions. Only in our case (I cannot speak for other manufacturers) about 5% of the heat goes outward and a proven 95% goes inward. At 50/50, this would not make sense. And for those who say again … the window is the weakest component regarding heat transfer … you should carefully separate U-value and efficiency. I can gladly write something about this again.
Basically, I would now ask those who consider the heat pump system in new buildings (!) to be the absolute best and are firmly convinced that other systems at similar costs are pointless not to continue reading my threads – I will never convince you nor attempt to persuade you. No offense intended, it just consumes too much of my valuable time.
However, if you regard the heat pump as a very sensible system in new buildings (!) but would like to also explore new and previously unknown innovations beyond the usual, I am happy to continue discussing here and answer any specific questions (see the many questions from Rotormotor).
Einstein said: "The purest form of insanity is to keep doing the same thing and expect different results."
R
RotorMotor4 Oct 2022 13:25Vestaxx GmbH schrieb:
Rotormotor: I’ve had that for a long time.
-> I can’t follow your calculation, and unfortunately, it’s not a full cost accounting according to VDI 2067.
Basically, it should include: investment, operating costs over the lifetime, maintenance costs, inflation, and interest. If you’re going to be so pedantic, you should realize that this cannot be universally applied.
Discussions like this are about estimates.
Vestaxx GmbH schrieb:
But at least you calculate that the heat pump has a payback period of 25 years – it won’t last that long, so -> after 60 years it still isn’t economical and must continue to be subsidized by taxpayers. How do you know it won’t last 25 years?
And even if you need a new compressor after 20 years, you can keep the rest of the system (heating loops, valves, hot water storage, …). The cost for that would probably be between 2,000 and 5,000 euros (about $2,000–$5,000). So, a payback of 2 to 5 years. 😉
How long is your warranty at Vestaxx? More than 25 years? What does the warranty cover?
Vestaxx GmbH schrieb:
So you only turn on your heating in winter when the sun isn’t shining. OMG! How much of the energy needed for the window heating can actually be generated by the photovoltaic system?
Maybe 20%?
But a completely different comparison: electric underfloor heating instead of window heating.
The underfloor heating has a comparable efficiency, is just as comfortable, and is cheaper to install.
V
Vestaxx GmbH4 Oct 2022 15:21If you are that particular, you should understand that it is not generally possible.
-> Then just use the values you have available – I'll let you keep the annual performance factor of 10.
But simply throwing some numbers out there that nobody (at least I) can verify is not helpful.
Maybe you have a heat pump and can share your consumption data here (but please all of it).
How do you know it won’t last 25 years?
And even if you need a new compressor after 20 years, you can keep the rest of the system (heating circuits, valves, water storage, etc.). You can expect costs between 2,000 and 5,000 euros (about $2,000 to $5,000). So that would be 2–5 years’ worth of expenses.
-> These are experience-based values, and the VDI 2067 guideline assumes them as such. Maybe they have no clue ;o). And I never said that every heat pump breaks down after 15 years. If yours lasts 20 years, you believe that you only need a new compressor and will spend just 2,000 to 5,000 euros (about $2,000 to $5,000) in 2042. I wouldn’t want your optimism ;o). Just this weekend at a housing fair, heat pump owners shared their problems with me. Not because the heat pump or any component failed after 20 years, but because the warranty period (3 years) had expired and they were generously compensated €150 (about $150) as goodwill for the pump itself. The user had to pay €800 (about $800) for removal and installation out of pocket. Another owner had constant error messages and eventually found the cause himself. The manufacturer had to admit it quietly later on. I’d be happy to invite both gentlemen here to the forum so they can tell their stories themselves—after all, this is an experience-sharing group.
The warranty period for Vestaxx heating glass is 5 years. Heat pumps get 2 years. The lifespan of insulated glass is 20 years. Now look at which windows in older buildings are still completely fine after 30 years. They don’t have pumps, compressors, valves, etc. Our glass units don’t either ;o).
How much of the energy required for the window heating can be generated by photovoltaic panels? Maybe 20%?
-> Of course, that depends on the size of the photovoltaic system. I already ran the numbers here once. For the saved amount of €25,000 (about $25,000), you can now get a 15 kWp system that produces at least 13,500 kWh per year. Since you rely on general estimates: roughly two-thirds of that is generated in the summer half-year and about one-third in the winter half-year. So in the winter half-year, about 4,500 kWh (15,000 kWh) comes from the roof. The heating demand in new buildings is about this scale. Still, it’s not a direct 100% input into the windows since no power is generated at night. But overall, the photovoltaic system produces in the winter half-year exactly what the house needs for heating (space heating) in this example.
But here’s a completely different comparison: Electric underfloor heating instead of window heating. Underfloor heating has the same efficiency, is just as comfortable, and is cheaper to install.
-> Hey—you’re completely on the electric direct heating side already—great ;o). I can’t say exactly what the efficiency of electric underfloor heating is because it depends on many factors. It is as comfortable as other underfloor heating systems, except that it stirs up fine dust and dust mites in the air. But who tells you that underfloor heating is cheaper than window heating? 150 m² (1,615 ft²) x €60 (about $60) per m² plus embedding into the screed plus connection costs. That’s much more expensive than our solution. Sorry.
-> Then just use the values you have available – I'll let you keep the annual performance factor of 10.
But simply throwing some numbers out there that nobody (at least I) can verify is not helpful.
Maybe you have a heat pump and can share your consumption data here (but please all of it).
How do you know it won’t last 25 years?
And even if you need a new compressor after 20 years, you can keep the rest of the system (heating circuits, valves, water storage, etc.). You can expect costs between 2,000 and 5,000 euros (about $2,000 to $5,000). So that would be 2–5 years’ worth of expenses.
-> These are experience-based values, and the VDI 2067 guideline assumes them as such. Maybe they have no clue ;o). And I never said that every heat pump breaks down after 15 years. If yours lasts 20 years, you believe that you only need a new compressor and will spend just 2,000 to 5,000 euros (about $2,000 to $5,000) in 2042. I wouldn’t want your optimism ;o). Just this weekend at a housing fair, heat pump owners shared their problems with me. Not because the heat pump or any component failed after 20 years, but because the warranty period (3 years) had expired and they were generously compensated €150 (about $150) as goodwill for the pump itself. The user had to pay €800 (about $800) for removal and installation out of pocket. Another owner had constant error messages and eventually found the cause himself. The manufacturer had to admit it quietly later on. I’d be happy to invite both gentlemen here to the forum so they can tell their stories themselves—after all, this is an experience-sharing group.
The warranty period for Vestaxx heating glass is 5 years. Heat pumps get 2 years. The lifespan of insulated glass is 20 years. Now look at which windows in older buildings are still completely fine after 30 years. They don’t have pumps, compressors, valves, etc. Our glass units don’t either ;o).
How much of the energy required for the window heating can be generated by photovoltaic panels? Maybe 20%?
-> Of course, that depends on the size of the photovoltaic system. I already ran the numbers here once. For the saved amount of €25,000 (about $25,000), you can now get a 15 kWp system that produces at least 13,500 kWh per year. Since you rely on general estimates: roughly two-thirds of that is generated in the summer half-year and about one-third in the winter half-year. So in the winter half-year, about 4,500 kWh (15,000 kWh) comes from the roof. The heating demand in new buildings is about this scale. Still, it’s not a direct 100% input into the windows since no power is generated at night. But overall, the photovoltaic system produces in the winter half-year exactly what the house needs for heating (space heating) in this example.
But here’s a completely different comparison: Electric underfloor heating instead of window heating. Underfloor heating has the same efficiency, is just as comfortable, and is cheaper to install.
-> Hey—you’re completely on the electric direct heating side already—great ;o). I can’t say exactly what the efficiency of electric underfloor heating is because it depends on many factors. It is as comfortable as other underfloor heating systems, except that it stirs up fine dust and dust mites in the air. But who tells you that underfloor heating is cheaper than window heating? 150 m² (1,615 ft²) x €60 (about $60) per m² plus embedding into the screed plus connection costs. That’s much more expensive than our solution. Sorry.
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