R
ralph1234511 May 2010 18:08We are planning a new build as an energy-efficient house according to the Energy Saving Ordinance, KfW70 standard. The developer claims that with very good insulation, solar thermal systems, and a condensing boiler, etc., this can be achieved without mechanical ventilation. A new build is sealed quite tightly as verified by a blower door test. The developer says we do not need to worry about moisture problems.
We are also used to regular manual ventilation from living in our old house... However, there the cold, fogged-up window was a reliable indicator...
The additional costs for a ventilation system would be significant...
What do the experts here think? Is it better not to forgo such a system, or does it not matter? I do not want to suffocate at night or discover mold after two years...
We are also used to regular manual ventilation from living in our old house... However, there the cold, fogged-up window was a reliable indicator...
The additional costs for a ventilation system would be significant...
What do the experts here think? Is it better not to forgo such a system, or does it not matter? I do not want to suffocate at night or discover mold after two years...
Hello,
I don’t believe it will be the developer; it will be a general contractor (GC) instead!
In my opinion, there is often an exaggeration here. For calculations related to new construction projects according to the standardized DIN 1946, a ventilation measure (LtM - ventilation technical measure) is almost always required. The reason for this is the assumption of infiltration according to the DIN standard. This does not always have to be a mechanical ventilation system. Since in new buildings, heat losses due to ventilation represent a higher percentage of the total energy demand compared to existing buildings, and these losses are naturally something you want to reduce, the only remaining option from this perspective is controlled residential ventilation with heat recovery. However, the advertised heat recovery efficiencies are rarely achieved in practice!
The cost-effectiveness is debatable and I have often calculated it. Comfort, on the other hand, is difficult to quantify financially. It definitely provides an improvement in comfort!
It is not mandatory but can sometimes be necessary. This depends on the specific conditions of the building and the occupant’s behavior. Without knowledge of these factors, it is impossible to give a universal recommendation!
If the decision is made in favor of controlled residential ventilation, please ensure that the air volumes according to the air volume plan are taken into account in the heating load calculation!!!
You will then have to do without your indicator. If everything is done correctly, your windows may occasionally fog up from the outside under certain weather conditions!
Best regards.
I don’t believe it will be the developer; it will be a general contractor (GC) instead!
In my opinion, there is often an exaggeration here. For calculations related to new construction projects according to the standardized DIN 1946, a ventilation measure (LtM - ventilation technical measure) is almost always required. The reason for this is the assumption of infiltration according to the DIN standard. This does not always have to be a mechanical ventilation system. Since in new buildings, heat losses due to ventilation represent a higher percentage of the total energy demand compared to existing buildings, and these losses are naturally something you want to reduce, the only remaining option from this perspective is controlled residential ventilation with heat recovery. However, the advertised heat recovery efficiencies are rarely achieved in practice!
The cost-effectiveness is debatable and I have often calculated it. Comfort, on the other hand, is difficult to quantify financially. It definitely provides an improvement in comfort!
It is not mandatory but can sometimes be necessary. This depends on the specific conditions of the building and the occupant’s behavior. Without knowledge of these factors, it is impossible to give a universal recommendation!
If the decision is made in favor of controlled residential ventilation, please ensure that the air volumes according to the air volume plan are taken into account in the heating load calculation!!!
You will then have to do without your indicator. If everything is done correctly, your windows may occasionally fog up from the outside under certain weather conditions!
Best regards.
R
ralph1234511 May 2010 23:06Hmm, the usage pattern is clear so far... Occupied by a family with two children, we cook and do laundry. A dryer could still be purchased if necessary.
The additional cost for the controlled residential ventilation system was estimated by the developer at around 9000€ (for a 160 m² (1720 sq ft) house), quite a high price... It is not clear whether this includes heat recovery or not.
The additional cost for the controlled residential ventilation system was estimated by the developer at around 9000€ (for a 160 m² (1720 sq ft) house), quite a high price... It is not clear whether this includes heat recovery or not.
Hello,
This information is not sufficient! Additionally, the specific conditions of the building (building structure, location, climate) are important for making an assessment. My clients receive a form to complete before the heating load calculation and the sizing of the heating surfaces.
The price naturally depends on the supplier and the system configuration. If financed, this can quickly rise to 18,000 to 22,500€. It is worthwhile to carefully evaluate the necessity. If there is sufficient budget, comfort will likely be the priority!
Best regards,
NB:
Modern heating systems require precise calculations and proper sizing. Otherwise, the client should expect an inefficient system, especially when using heat pumps and condensing boilers as heat generators and general contractor projects.
Gartenbau schrieb:
Hm, the usage pattern is clear so far... Occupied by a family with two children, we cook and do laundry. A tumble dryer could still be purchased if necessary.
This information is not sufficient! Additionally, the specific conditions of the building (building structure, location, climate) are important for making an assessment. My clients receive a form to complete before the heating load calculation and the sizing of the heating surfaces.
Gartenbau schrieb:
The additional costs for the controlled residential ventilation system have been estimated by the developer at about 9,000€ (160m² (1,722 sq ft) house), quite a high price... It's not clear whether this includes heat recovery or not.
The price naturally depends on the supplier and the system configuration. If financed, this can quickly rise to 18,000 to 22,500€. It is worthwhile to carefully evaluate the necessity. If there is sufficient budget, comfort will likely be the priority!
Best regards,
NB:
Modern heating systems require precise calculations and proper sizing. Otherwise, the client should expect an inefficient system, especially when using heat pumps and condensing boilers as heat generators and general contractor projects.
I would generally recommend choosing a ventilation system because there is otherwise a conflict in a low-energy house: the goal is to create a low-energy building to become independent of energy costs and reduce them as much as possible. On the other hand, natural ventilation through windows is planned, which, if done correctly, certainly works but definitely does not save energy. The costly energy used to heat the house is simply lost through air exchange with the outside! Do you really do that often in winter? Probably not, and then there is the problem with moisture and mold.
A controlled ventilation system with heat recovery is a truly worthwhile investment. The heat already paid for in the exhaust air (waste heat from cooking in the kitchen, showers, computers, TVs, washing machines) is extracted and supplied to the fresh incoming air. The warmth of the sun, which is freely available, is also utilized. This means that only a small amount of additional energy is needed to heat this air to warm the house. Other positive effects, such as less dust, the possibility of a pollen filter, and cooling in summer, have not been mentioned here. If underfloor heating is not desired, there are also very good systems for heating, ventilation, and cooling.
Best regards,
Mario
A controlled ventilation system with heat recovery is a truly worthwhile investment. The heat already paid for in the exhaust air (waste heat from cooking in the kitchen, showers, computers, TVs, washing machines) is extracted and supplied to the fresh incoming air. The warmth of the sun, which is freely available, is also utilized. This means that only a small amount of additional energy is needed to heat this air to warm the house. Other positive effects, such as less dust, the possibility of a pollen filter, and cooling in summer, have not been mentioned here. If underfloor heating is not desired, there are also very good systems for heating, ventilation, and cooling.
Best regards,
Mario
Hello,
How much is that exactly?
That is physically not possible. In practice, at best, 60 to 70% of the exhaust air energy can actually be recovered!
Every building component exposed to solar radiation, including opaque ones, naturally absorbs part of the solar energy! No ventilation is required for this.
Here, too, the question should be asked: how many kilowatt-hours?
As already mentioned, improved comfort is a key argument in favor of mechanical ventilation with heat recovery!
The question of the investment’s cost-effectiveness can only be answered through an exact calculation (energy balance). Everything else is pure assumption and speculation. For buildings close to the passive house standard, mechanical ventilation with heat recovery is indispensable. There is generally no fundamental "pro" or "con." Individual and project-specific conditions are always decisive.
Best regards.
PenK schrieb:
... The costly energy used to heat the house is simply lost through air exchange to the outside!
How much is that exactly?
PenK schrieb:
... The exhaust air transfers the already paid-for heat (waste heat from the kitchen during cooking, showering, PC, television, washing machine) to the incoming fresh air.
That is physically not possible. In practice, at best, 60 to 70% of the exhaust air energy can actually be recovered!
PenK schrieb:
...
Even the heat from the sun, which is available free of charge, is used.
Every building component exposed to solar radiation, including opaque ones, naturally absorbs part of the solar energy! No ventilation is required for this.
PenK schrieb:
...
As a result, only a small amount of energy is needed to heat this air to warm the house.
Here, too, the question should be asked: how many kilowatt-hours?
As already mentioned, improved comfort is a key argument in favor of mechanical ventilation with heat recovery!
The question of the investment’s cost-effectiveness can only be answered through an exact calculation (energy balance). Everything else is pure assumption and speculation. For buildings close to the passive house standard, mechanical ventilation with heat recovery is indispensable. There is generally no fundamental "pro" or "con." Individual and project-specific conditions are always decisive.
Best regards.
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