Hello everyone,
so far, I have been an advocate for a ventilation system with heat recovery (decentralized in the new build – a central system is too expensive for us in terms of purchase and maintenance).
Our general contractor (GC) is planning a simple exhaust ventilation system from Lunos. I had asked him to obtain quotes from two companies (Lunos and Seventilation) for a ventilation system with heat recovery. The price difference would be between 3,000 and 4,000 euros.
On Saturday, we had another discussion with the planning engineer from our GC.
He raised the question of how much savings a heat recovery system would actually provide and when it would likely pay off.
The geothermal heating system (after a startup phase of about 1 year with higher costs) is expected to have an annual electricity consumption of around 600 euros (I am cautiously estimating 700 euros).
The ventilation system is supposed to recover and return 80-90% of the waste heat (the airflow direction changes every 75 seconds). I don’t believe, for example, that this could save as much as 50% of the electricity costs for the geothermal system.
If around 100 euros are saved per year, the ventilation system with heat recovery would take about 30 years to pay off at current electricity prices (assuming everything lasts and no additional costs arise).
This does not yet include the electricity consumption of the ventilation system itself or possible regular additional maintenance.
On the other hand, I am not under the illusion that electricity prices will remain the same.
What are your thoughts on this?
f-pNo
so far, I have been an advocate for a ventilation system with heat recovery (decentralized in the new build – a central system is too expensive for us in terms of purchase and maintenance).
Our general contractor (GC) is planning a simple exhaust ventilation system from Lunos. I had asked him to obtain quotes from two companies (Lunos and Seventilation) for a ventilation system with heat recovery. The price difference would be between 3,000 and 4,000 euros.
On Saturday, we had another discussion with the planning engineer from our GC.
He raised the question of how much savings a heat recovery system would actually provide and when it would likely pay off.
The geothermal heating system (after a startup phase of about 1 year with higher costs) is expected to have an annual electricity consumption of around 600 euros (I am cautiously estimating 700 euros).
The ventilation system is supposed to recover and return 80-90% of the waste heat (the airflow direction changes every 75 seconds). I don’t believe, for example, that this could save as much as 50% of the electricity costs for the geothermal system.
If around 100 euros are saved per year, the ventilation system with heat recovery would take about 30 years to pay off at current electricity prices (assuming everything lasts and no additional costs arise).
This does not yet include the electricity consumption of the ventilation system itself or possible regular additional maintenance.
On the other hand, I am not under the illusion that electricity prices will remain the same.
What are your thoughts on this?
f-pNo
S
syrincsandy22 Jul 2013 05:43Hello
A ventilation system without heat recovery will still bring cold air into the house from somewhere.
Or is the air supposed to be preheated in some way?
The ventilation system saves energy that would otherwise be lost when airing out the house.
To me, it seems contradictory to insulate a house very well, make it airtight, and then just extract air while creating supply air at the windows. This kind of energy waste is obviously not included in the heating demand calculation.
Regards, Andy
A ventilation system without heat recovery will still bring cold air into the house from somewhere.
Or is the air supposed to be preheated in some way?
The ventilation system saves energy that would otherwise be lost when airing out the house.
To me, it seems contradictory to insulate a house very well, make it airtight, and then just extract air while creating supply air at the windows. This kind of energy waste is obviously not included in the heating demand calculation.
Regards, Andy
my opinion:
The ventilation system will never pay for itself by energy recovery alone.
The purpose of such a system lies in other aspects, with heat recovery being just a nice bonus.
The system ensures good indoor air quality, meaning fresh air from outside. You can, of course, achieve this by regularly opening windows for ventilation, but I prefer it this way… it’s simply more convenient. Additionally, it relieves my concerns about mold. Our system also has humidity recovery, which is a significant advantage in winter. Without the system, our indoor humidity was below 20 %, but with it, it is somewhere between 35 and 40 %. Furthermore, the system provides good air quality throughout the house, especially in the room where the diaper pail is located, where the difference is very noticeable.
Heat recovery is a nice add-on. When the outdoor temperature is -5°C (23°F), our supply air temperature was 17°C (63°F), which I think is quite good.
The power consumption of the system can be neglected; it costs less than $50 per year. What is more expensive are the replacement filters.
The ventilation system will never pay for itself by energy recovery alone.
The purpose of such a system lies in other aspects, with heat recovery being just a nice bonus.
The system ensures good indoor air quality, meaning fresh air from outside. You can, of course, achieve this by regularly opening windows for ventilation, but I prefer it this way… it’s simply more convenient. Additionally, it relieves my concerns about mold. Our system also has humidity recovery, which is a significant advantage in winter. Without the system, our indoor humidity was below 20 %, but with it, it is somewhere between 35 and 40 %. Furthermore, the system provides good air quality throughout the house, especially in the room where the diaper pail is located, where the difference is very noticeable.
Heat recovery is a nice add-on. When the outdoor temperature is -5°C (23°F), our supply air temperature was 17°C (63°F), which I think is quite good.
The power consumption of the system can be neglected; it costs less than $50 per year. What is more expensive are the replacement filters.
Der Da schrieb:
my opinion:
The ventilation system will never recoup its purchase cost if you only focus on heat recovery. This needs to be considered in more detail. Heat recovery can significantly affect the sizing of a heat generator, depending on its step increase (manufacturer). It might be possible to operate at a lower output during part of the weekend, resulting in considerable savings on investment capital costs! Der Da schrieb:
...When the outside temperature is -5°C (23°F), our supply air temperature was 17°C (63°F). I don't find that too bad. Users of decentralized supply air systems can probably only dream of that. Best regards.
Hello everyone,
Thank you very much for your feedback. After two weeks of research, I have a better understanding now, but a final decision is still pending.
The initial situation:
Our house will have geothermal heating with underfloor heating. It will be built with Ytong blocks without additional insulation. Additionally, our construction company wants to install a exhaust air system from Lunos. Moist air is extracted from wet rooms (bathrooms, kitchen, utility room). According to the description, the resulting negative pressure draws fresh air through ventilation slots in the living areas. This would ensure sufficient air exchange and removal of any humidity that forms.
According to the plans, the geothermal heat pump in this setup should have an electricity consumption of about 600 euros per year, excluding the first year.
Personally — based purely on intuition — I would prefer to convert this into a decentralized ventilation system with heat recovery. However, our planning engineer raised the question of when and whether the additional costs (3,000 – 4,000 euros) would pay off.
As the main decision-maker, I am currently looking for solid arguments supporting a decision in favor of a ventilation system.
In February 2013, there was apparently a subsidy program in Rhineland-Palatinate for ventilation systems with heat recovery. We are currently awaiting a response from the Rhineland-Palatinate Energy Agency on whether this program has been extended.
Okay — after receiving your responses, I have contacted a ventilation consultancy. So far, communication has been via email. Possibly on August 5th, I will visit a model home with a corresponding system (to inspect and listen on site).
Arguments in favor of heat recovery ventilation and assessment:
According to the ventilation consultancy, the system is used less in summer, with occupants often opening windows instead. The reason: the ventilation system would draw in warm outside air just like open windows would. Either way, the house warms up over time.
The exhaust air system would draw in cold, not preheated, air in winter. However, this has already been factored into the estimated electricity costs of 600 euros per year.
The argument that “exhaust air systems are outdated technology” does not hold for me if the new technology does not pay off economically. (I would not buy a refrigerator rated A+++ if it consumed more electricity than my old one.)
Therefore, in my opinion, the only remaining argument in favor of the system with heat recovery is the very likely continuing increase in electricity prices. But — provocatively asked — wouldn’t it make more sense to address this issue with a photovoltaic system instead?
Can you provide me with other arguments FOR a decentralized ventilation system with heat recovery?
By the way, why doesn’t this system accept the “Enter” key? I have to compose everything in Word first just to get some paragraphs in.
Thank you very much for your feedback. After two weeks of research, I have a better understanding now, but a final decision is still pending.
The initial situation:
Our house will have geothermal heating with underfloor heating. It will be built with Ytong blocks without additional insulation. Additionally, our construction company wants to install a exhaust air system from Lunos. Moist air is extracted from wet rooms (bathrooms, kitchen, utility room). According to the description, the resulting negative pressure draws fresh air through ventilation slots in the living areas. This would ensure sufficient air exchange and removal of any humidity that forms.
According to the plans, the geothermal heat pump in this setup should have an electricity consumption of about 600 euros per year, excluding the first year.
Personally — based purely on intuition — I would prefer to convert this into a decentralized ventilation system with heat recovery. However, our planning engineer raised the question of when and whether the additional costs (3,000 – 4,000 euros) would pay off.
As the main decision-maker, I am currently looking for solid arguments supporting a decision in favor of a ventilation system.
In February 2013, there was apparently a subsidy program in Rhineland-Palatinate for ventilation systems with heat recovery. We are currently awaiting a response from the Rhineland-Palatinate Energy Agency on whether this program has been extended.
Okay — after receiving your responses, I have contacted a ventilation consultancy. So far, communication has been via email. Possibly on August 5th, I will visit a model home with a corresponding system (to inspect and listen on site).
Arguments in favor of heat recovery ventilation and assessment:
- Energy savings for heating – according to the ventilation consultancy, this ranges from 10% to 25% (equivalent to approximately 60 – 150 euros), not including electricity consumption for the system itself
- Continuous supply of fresh air and removal of humidity – also achieved with the exhaust air system
- Reduction of allergy risk due to pollen filters – an important argument, but:
According to the ventilation consultancy, the system is used less in summer, with occupants often opening windows instead. The reason: the ventilation system would draw in warm outside air just like open windows would. Either way, the house warms up over time.
syrincsandy schrieb:
An exhaust ventilation system without heat recovery still pulls cold air into the house somewhere, does it not?
Or is this air somehow preheated?
The ventilation system saves the energy that would otherwise be lost through ventilation.
To me, it seems contradictory to build a house that is highly insulated and airtight and then simply extract air and create air supply through the windows. This form of energy waste is naturally not included in the heating demand calculation.
Regards, Andy
The exhaust air system would draw in cold, not preheated, air in winter. However, this has already been factored into the estimated electricity costs of 600 euros per year.
The argument that “exhaust air systems are outdated technology” does not hold for me if the new technology does not pay off economically. (I would not buy a refrigerator rated A+++ if it consumed more electricity than my old one.)
Therefore, in my opinion, the only remaining argument in favor of the system with heat recovery is the very likely continuing increase in electricity prices. But — provocatively asked — wouldn’t it make more sense to address this issue with a photovoltaic system instead?
Can you provide me with other arguments FOR a decentralized ventilation system with heat recovery?
By the way, why doesn’t this system accept the “Enter” key? I have to compose everything in Word first just to get some paragraphs in.
B
Bauexperte29 Jul 2013 10:59Hello,
Maybe this helps you too
PS: The only error this system sometimes creates is duplicate posts; who knows why that happens.
Regards, Bauexperte
f-pNo schrieb:I have found that the issue is not with the system’s software but with the browser used. Some time ago, I switched entirely to Firefox and quickly realized that this browser is quite unsuitable for navigating the HBF clearly. So I reverted exclusively to Safari for this forum; however, for my own security, I use Startpage as a search engine beforehand.
Why doesn’t this system accept the "Enter" key? I have to prepare everything in Word just to get a few paragraphs in.
Maybe this helps you too
PS: The only error this system sometimes creates is duplicate posts; who knows why that happens.
Regards, Bauexperte
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