Bauexperte
2013-07-29 14:23:40
- #1
Hello,
Is your planning engineer from your supplier’s company or externally consulted?
**Central exhaust air systems with decentralized outdoor air supply are technically simpler because they only require one exhaust air duct network but no supply air duct network. The outdoor air flows in through several wall outlets. However, these systems have a decisive disadvantage: In winter, the outdoor air enters the room cold and unheated, and its room-by-room dosing strongly depends on wind pressure.
Decentralized or central exhaust air systems blow the used air along with its heat out of the house. The heating system must warm up the cold outdoor air drawn into each room from outside temperature to room temperature. This costs energy. Compared to window ventilation, a pure exhaust air system therefore does not save energy, but only provides the comfort of automatic moisture removal, fresh air supply, and better controllability. In contrast, if you build a central supply and exhaust air system with ducts for both supply and exhaust air, these ducts can be combined and the cold fresh air can be preheated with the heat from the exhaust air in a supply-exhaust air heat exchanger – this also works with decentralized ventilation systems.
Modern supply and exhaust air systems with heat recovery (HR) recover up to 94 percent of the heat from the exhaust air. With them, the cold outdoor air can already be preheated in winter without additional heating energy, for example, to 17 degrees Celsius.
*** For health and economic reasons, controlled ventilation cannot be dispensed with in new buildings.
This consists of combining cost-effective thermal insulation measures with heat recovery from residential ventilation. On the market for residential ventilation devices, there is a wide variety of units that differ in their design and performance data. Interested buyers and planners depend on receiving manufacturer-neutral technical information on comparable individual units. This can become quite tedious. They have to compile this information laboriously. Moreover, a pure description of a device cannot always be satisfactory. A neutral test report that allows a direct comparison with other devices is helpful for selecting a suitable device.
A prerequisite for selecting the appropriate device is the creation of a meaningful ventilation concept.
In the 21st century, we can only really protect ourselves from cold, but not sensibly from heat. You can only approximate solving this problem by installing thicker masonry, consistently avoiding windows on the south side, or at least continuously shading them during the sun-rich season. Everything else is wishful thinking or requires the use of air conditioning units; by the way, you can forget a system that also designs underfloor heating to “cool” because you will hardly notice the 2° difference ... except in construction costs.
See above.
Moreover – from my humble point of view, there are only two options when choosing a ventilation system, which certainly should not be considered from the point of view of payback, because they do not and in my opinion must not. Mold in new buildings is something that cannot be combated with conventional window ventilation – especially not with window frame ventilation. The current – and certainly the future energy saving regulations – prescribe increasingly airtight houses; the sense and purpose can be debated, but it is futile, as this trend can no longer be reversed. Builders are forced to build increasingly airtight if they want to take advantage of KfW loans. With this airtightness of the building envelope, they buy into negative side effects, which in turn must be fought with even more technology. There are decentralized and centralized ventilation systems for this; every smart builder should resort to one of the two options – always with heat recovery – depending on budget.
From my experience; nowadays both partners in a building community (whether married couple or living community) work and are not in a position to ensure the ventilation requirements of the house within the first two years. Although the bricks are mostly glued today, the screed still brings a lot of water into the house, which also has to go out => and the inclined and "internet-educated" builder would also like to move into the house immediately after signing. The later residents also produce 4 liters of water per person per day, which is released into the single-family house atmosphere. This is even more true for terraced houses, since the – disrespectfully called – plastic foil prevents the removal of water.
A decentralized ventilation system with heat recovery costs around 5,000 euros for an average single-family house including ventilation concept. This usefully invested money saves the trouble with mold and also ensures that there is no musty smell in the house. The same applies to central systems, but the costs are around 13,000–15,000 euros and not all builders can afford that.
Sources:** Federation of Energy Consumers
*** TZWL e.V. – European Test Center for Residential Ventilation Devices e.V.
Rhenish regards
Our house will be equipped with geothermal heat and underfloor heating. It is being built with Ytong without additional insulation. In addition, our construction company wants to install a exhaust air system from Lunos. Moist air will be extracted from the wet rooms (bathrooms, kitchen, utility room). According to the description, the resulting negative pressure causes fresh air to be drawn in through ventilation slots in the living rooms. This would ensure sufficient air exchange and the removal of any moisture that may occur.
According to the plan, the geothermal heating system in this constellation, apart from the first year, is expected to have an electricity consumption of about 600 euros.
Personally – just based on feeling, I would like to convert this into a decentralized ventilation system with heat recovery. However, our planning engineer raised the question of when and whether the higher costs (3,000 – 4,000 euros) would pay off.
Is your planning engineer from your supplier’s company or externally consulted?
**Central exhaust air systems with decentralized outdoor air supply are technically simpler because they only require one exhaust air duct network but no supply air duct network. The outdoor air flows in through several wall outlets. However, these systems have a decisive disadvantage: In winter, the outdoor air enters the room cold and unheated, and its room-by-room dosing strongly depends on wind pressure.
Decentralized or central exhaust air systems blow the used air along with its heat out of the house. The heating system must warm up the cold outdoor air drawn into each room from outside temperature to room temperature. This costs energy. Compared to window ventilation, a pure exhaust air system therefore does not save energy, but only provides the comfort of automatic moisture removal, fresh air supply, and better controllability. In contrast, if you build a central supply and exhaust air system with ducts for both supply and exhaust air, these ducts can be combined and the cold fresh air can be preheated with the heat from the exhaust air in a supply-exhaust air heat exchanger – this also works with decentralized ventilation systems.
Modern supply and exhaust air systems with heat recovery (HR) recover up to 94 percent of the heat from the exhaust air. With them, the cold outdoor air can already be preheated in winter without additional heating energy, for example, to 17 degrees Celsius.
*** For health and economic reasons, controlled ventilation cannot be dispensed with in new buildings.
This consists of combining cost-effective thermal insulation measures with heat recovery from residential ventilation. On the market for residential ventilation devices, there is a wide variety of units that differ in their design and performance data. Interested buyers and planners depend on receiving manufacturer-neutral technical information on comparable individual units. This can become quite tedious. They have to compile this information laboriously. Moreover, a pure description of a device cannot always be satisfactory. A neutral test report that allows a direct comparison with other devices is helpful for selecting a suitable device.
A prerequisite for selecting the appropriate device is the creation of a meaningful ventilation concept.
No matter how you look at it – the house heats up over time.
In the 21st century, we can only really protect ourselves from cold, but not sensibly from heat. You can only approximate solving this problem by installing thicker masonry, consistently avoiding windows on the south side, or at least continuously shading them during the sun-rich season. Everything else is wishful thinking or requires the use of air conditioning units; by the way, you can forget a system that also designs underfloor heating to “cool” because you will hardly notice the 2° difference ... except in construction costs.
Can you give me other arguments PRO decentralized ventilation system with heat recovery?
See above.
Moreover – from my humble point of view, there are only two options when choosing a ventilation system, which certainly should not be considered from the point of view of payback, because they do not and in my opinion must not. Mold in new buildings is something that cannot be combated with conventional window ventilation – especially not with window frame ventilation. The current – and certainly the future energy saving regulations – prescribe increasingly airtight houses; the sense and purpose can be debated, but it is futile, as this trend can no longer be reversed. Builders are forced to build increasingly airtight if they want to take advantage of KfW loans. With this airtightness of the building envelope, they buy into negative side effects, which in turn must be fought with even more technology. There are decentralized and centralized ventilation systems for this; every smart builder should resort to one of the two options – always with heat recovery – depending on budget.
From my experience; nowadays both partners in a building community (whether married couple or living community) work and are not in a position to ensure the ventilation requirements of the house within the first two years. Although the bricks are mostly glued today, the screed still brings a lot of water into the house, which also has to go out => and the inclined and "internet-educated" builder would also like to move into the house immediately after signing. The later residents also produce 4 liters of water per person per day, which is released into the single-family house atmosphere. This is even more true for terraced houses, since the – disrespectfully called – plastic foil prevents the removal of water.
A decentralized ventilation system with heat recovery costs around 5,000 euros for an average single-family house including ventilation concept. This usefully invested money saves the trouble with mold and also ensures that there is no musty smell in the house. The same applies to central systems, but the costs are around 13,000–15,000 euros and not all builders can afford that.
Sources:** Federation of Energy Consumers
*** TZWL e.V. – European Test Center for Residential Ventilation Devices e.V.
Rhenish regards