Hello,
this summer we are building a town villa with 135 m² (1453 sq ft) spread over two floors. On the roof (23° pitch), we are installing a solar system for domestic hot water heating, and I would like to know if it makes sense to have a ventilation system with heat recovery built and installed from the start.
I hear different opinions.
Some say that the exhaust air from the kitchen, including odors, will reach the bedroom, while others argue that such a system, costing between 12,000 and 15,000 euros, doesn’t make sense because it recovers very little energy and it’s better just to open a window for ventilation. What do you think?
I am grateful for any suggestions and tips.
this summer we are building a town villa with 135 m² (1453 sq ft) spread over two floors. On the roof (23° pitch), we are installing a solar system for domestic hot water heating, and I would like to know if it makes sense to have a ventilation system with heat recovery built and installed from the start.
I hear different opinions.
Some say that the exhaust air from the kitchen, including odors, will reach the bedroom, while others argue that such a system, costing between 12,000 and 15,000 euros, doesn’t make sense because it recovers very little energy and it’s better just to open a window for ventilation. What do you think?
I am grateful for any suggestions and tips.
Such a system costs around €10,000 (approximately $11,000) including all additional measures. However, it offers more benefits than just removing unpleasant odors. The biggest issue is that new houses are almost completely airtight. This increases the risk of mold unless you ventilate properly. Especially in rooms with higher humidity, you almost need to have an exhaust ventilation system. Whether this is a small unit or a large system does not matter. What definitely should be installed if you don’t have a ventilation system are trickle vents in the window frame. However, from a heating cost perspective, these are not the best solution. Financially, a ventilation system probably won’t pay for itself, but it will certainly provide great living comfort and completely eliminate worries about mold. In addition, you always have fresh air inside the house, and some systems can also regulate humidity to balance the dry air in winter.
Furthermore, for example in summer, you can bring more cool air into the house at night to compensate for the daily heat build-up.
A colleague of mine has such a system and said it is the best feature in the whole house.
If you are aiming for a KfW 55 loan, you must install a ventilation system. You then receive a one-time rebate of €2,500 (about $2,750) from KfW in addition to favorable interest rates.
Furthermore, for example in summer, you can bring more cool air into the house at night to compensate for the daily heat build-up.
A colleague of mine has such a system and said it is the best feature in the whole house.
If you are aiming for a KfW 55 loan, you must install a ventilation system. You then receive a one-time rebate of €2,500 (about $2,750) from KfW in addition to favorable interest rates.
B
Bauexperte27 Mar 2012 13:19Hello,
A ventilation system costs, as a decentralized system depending on house size, between €3,000 and €5,000 (approx. $3,300–5,500); a centralized system between €9,000 and €12,000 (approx. $10,000–13,200) depending on house size. The latter is often marketed as "with heat recovery," but in my opinion, that’s a bit of a gimmick.
However, this should not be the main point when deciding for ventilation! The primary goal is a good indoor climate and the removal of moist indoor air to the outside; with such a system—whether decentralized or centralized—you reduce the risk of mold growth. The claim that such systems carry kitchen odors into the bedroom would be new to me, unless the planners were completely negligent.
Regarding the other statement from so-called friends/acquaintances: ask yourself if you can manage at least three quick ventilation sessions per day for the first year after moving in. Could one person take over this task if you’re away for a weekend, not to mention a longer holiday absence?
The trickle vents ("falzlüfter") mentioned by "Der Da" are a makeshift solution, and if it weren’t so sad, I could even laugh about it. In the past—15 years ago or more—window installation included ventilation slots because common sense understood that moisture from people and their daily activities needed to escape. Then Brussels decided people waste too much energy unnecessarily and introduced the requirement for fully sealed windows using sealing strips. Now, moisture was neatly trapped and condensed on cold surfaces inside the house, leading to mold—then and now. To prevent this mold, the homeowner must either invest between €3,000 and €10,000 (approx. $3,300–11,000) or consistently open windows for shock ventilation.
Don’t get me wrong: it is absolutely right to reduce the increasing energy waste. But whether this goal should be reached by adding more energy-consuming devices and investing in extra technology is, in my view, questionable...
@ wadi192
Current update:
What might change with the 2012 energy-saving regulation compared to the 2009 version?
Listening to presentations by representatives of the Federal Ministry of Construction, one cannot help but think of the 2004 energy-saving regulation, which was an amendment of the first 2002 regulation. Back then, the main focus was to incorporate the latest versions of standards since the 2002 regulation only referenced specific norm editions. The latest issue of VfW-aktuell from the Federal Association for Residential Ventilation assumes that “… the 2012 energy-saving regulation will probably remain a minor revision …” Concerning upcoming changes, some are quite likely while many details are still unknown publicly.
Here are a few examples:
New standard versions: The 2012 regulation will certainly refer to the newest version of DIN V 18599 (Energy Performance of Buildings) from December 2011. As professional users of energy-saving regulations, now is the time to familiarize yourself with the new content and methods of this updated standards series.
Nearly zero-energy new buildings: The EU directive mandates that from 2021 onwards, new buildings must have a very low energy demand, with public buildings already subject from 2019. How this standard will be introduced step-by-step by the energy-saving regulation remains uncertain because the new 2012 regulation can only require economically viable measures as prescribed by the current Energy Saving Act. This act is also being revised and will likely include the definition of a “climate-neutral building” equivalent to the “nearly zero-energy building” defined by the EU directive.
Simplifying residential building calculations: The “energy-saving regulation easy” approach is expected to be incorporated into the 2012 regulation. It was developed by the Fraunhofer Institute for Building Physics (IBP) in Stuttgart as part of a study. This method applies to new residential buildings, classified into five categories based on design and size: detached single-family homes, semi-detached houses, mid-terrace houses, and large and small multi-family houses (with usable floor area under 330 m² (3,552 sq ft) and up to 350 m² (3,767 sq ft), respectively). For each category, ten common system variants are defined to meet the requirements of the energy-saving regulation and the Renewable Energies Heat Act.
Alternative energy technologies: The EU directive requires consideration of alternative, highly efficient energy systems during new construction and major renovations, assessing their technical, ecological, and economical suitability. It is not yet publicly known how the 2012 regulation will incorporate this.
Display of energy certificates: Not only public service buildings but also those with regular public access (such as hotels, cinemas, department stores, theatres) must display energy performance certificates if their total usable floor area exceeds 500 m² (5,382 sq ft). From June 9, 2015, this threshold will be lowered to 250 m² (2,691 sq ft). This rule will likely be part of the 2012 regulation. It remains to be seen if the amendment will include the EU directive’s mitigation that this only applies to buildings already issued an energy certificate—primarily new builds from the past ten years, as certificates issued under the 2007 or 2009 regulations or demand certificates from 2002 or 2004 remain valid.
Energy performance values in commercial listings: Today, it is rare to see passive houses or particularly energy-efficient buildings advertised or sought after in commercial media like the Frankfurt Allgemeine Zeitung’s real estate pages on Fridays. The forthcoming EU regulation will likely be integrated into the 2012 regulation. The question is which indicators will be used. The EU directive requires that “commercial advertisements for sale or rent must state the energy efficiency indicator shown in the building’s energy certificate.”
Control system for energy certificates and inspection reports: The EU directive stipulates random spot checks of a statistically significant percentage of all energy certificates and inspection reports issued annually. How the 2012 regulation will adopt this is not yet known. Enforcement is managed by the federal states, and additional controls would require more resources and staff.
Independent specialists: The EU directive requires that only qualified, independent experts issue energy certificates and inspect HVAC systems. Member states must maintain public registers showing who is authorized and their qualifications. Currently, there is no legal obligation to register energy certificate issuers or HVAC inspectors in an official list. Architect and engineer chambers maintain lists of authorized experts, and the German Energy Agency (dena) has operated an online database of issuers for years.
When will the new nationwide mandatory Energy Efficiency Expert list by dena come into effect?
Whether and when the new dena Energy Efficiency Expert list becomes mandatory nationwide is unknown. The professional community remains skeptical. Currently, registration with the dena database is voluntary and initially costs €150 (approx. $165). The Federal Office for Economic Affairs and Export Control (BAFA) maintains its own list of recognized on-site consultants. The KfW recommends experts from dena’s new list for certain funding programs.
Best regards
eifohn schrieb:"Der Da" has already given you some valuable suggestions.
Some say that you end up with kitchen exhaust air including odors in the bedroom, while others argue that for the €12,000–15,000 (approx. $13,000–16,000) cost it makes little sense since you hardly save any energy and it’s better to just open the window for ventilation... what do you think?
A ventilation system costs, as a decentralized system depending on house size, between €3,000 and €5,000 (approx. $3,300–5,500); a centralized system between €9,000 and €12,000 (approx. $10,000–13,200) depending on house size. The latter is often marketed as "with heat recovery," but in my opinion, that’s a bit of a gimmick.
However, this should not be the main point when deciding for ventilation! The primary goal is a good indoor climate and the removal of moist indoor air to the outside; with such a system—whether decentralized or centralized—you reduce the risk of mold growth. The claim that such systems carry kitchen odors into the bedroom would be new to me, unless the planners were completely negligent.
Regarding the other statement from so-called friends/acquaintances: ask yourself if you can manage at least three quick ventilation sessions per day for the first year after moving in. Could one person take over this task if you’re away for a weekend, not to mention a longer holiday absence?
The trickle vents ("falzlüfter") mentioned by "Der Da" are a makeshift solution, and if it weren’t so sad, I could even laugh about it. In the past—15 years ago or more—window installation included ventilation slots because common sense understood that moisture from people and their daily activities needed to escape. Then Brussels decided people waste too much energy unnecessarily and introduced the requirement for fully sealed windows using sealing strips. Now, moisture was neatly trapped and condensed on cold surfaces inside the house, leading to mold—then and now. To prevent this mold, the homeowner must either invest between €3,000 and €10,000 (approx. $3,300–11,000) or consistently open windows for shock ventilation.
Don’t get me wrong: it is absolutely right to reduce the increasing energy waste. But whether this goal should be reached by adding more energy-consuming devices and investing in extra technology is, in my view, questionable...
@ wadi192
wadi1982 schrieb:Then you know more than anyone else. It’s true that the new energy-saving regulation is supposed to be finalized by December 31, 2012. But it’s also true that the decision-makers can’t agree.
As far as I know, controlled residential ventilation with heat recovery will be mandatory in 2012.
Current update:
What might change with the 2012 energy-saving regulation compared to the 2009 version?
Listening to presentations by representatives of the Federal Ministry of Construction, one cannot help but think of the 2004 energy-saving regulation, which was an amendment of the first 2002 regulation. Back then, the main focus was to incorporate the latest versions of standards since the 2002 regulation only referenced specific norm editions. The latest issue of VfW-aktuell from the Federal Association for Residential Ventilation assumes that “… the 2012 energy-saving regulation will probably remain a minor revision …” Concerning upcoming changes, some are quite likely while many details are still unknown publicly.
Here are a few examples:
New standard versions: The 2012 regulation will certainly refer to the newest version of DIN V 18599 (Energy Performance of Buildings) from December 2011. As professional users of energy-saving regulations, now is the time to familiarize yourself with the new content and methods of this updated standards series.
Nearly zero-energy new buildings: The EU directive mandates that from 2021 onwards, new buildings must have a very low energy demand, with public buildings already subject from 2019. How this standard will be introduced step-by-step by the energy-saving regulation remains uncertain because the new 2012 regulation can only require economically viable measures as prescribed by the current Energy Saving Act. This act is also being revised and will likely include the definition of a “climate-neutral building” equivalent to the “nearly zero-energy building” defined by the EU directive.
Simplifying residential building calculations: The “energy-saving regulation easy” approach is expected to be incorporated into the 2012 regulation. It was developed by the Fraunhofer Institute for Building Physics (IBP) in Stuttgart as part of a study. This method applies to new residential buildings, classified into five categories based on design and size: detached single-family homes, semi-detached houses, mid-terrace houses, and large and small multi-family houses (with usable floor area under 330 m² (3,552 sq ft) and up to 350 m² (3,767 sq ft), respectively). For each category, ten common system variants are defined to meet the requirements of the energy-saving regulation and the Renewable Energies Heat Act.
Alternative energy technologies: The EU directive requires consideration of alternative, highly efficient energy systems during new construction and major renovations, assessing their technical, ecological, and economical suitability. It is not yet publicly known how the 2012 regulation will incorporate this.
Display of energy certificates: Not only public service buildings but also those with regular public access (such as hotels, cinemas, department stores, theatres) must display energy performance certificates if their total usable floor area exceeds 500 m² (5,382 sq ft). From June 9, 2015, this threshold will be lowered to 250 m² (2,691 sq ft). This rule will likely be part of the 2012 regulation. It remains to be seen if the amendment will include the EU directive’s mitigation that this only applies to buildings already issued an energy certificate—primarily new builds from the past ten years, as certificates issued under the 2007 or 2009 regulations or demand certificates from 2002 or 2004 remain valid.
Energy performance values in commercial listings: Today, it is rare to see passive houses or particularly energy-efficient buildings advertised or sought after in commercial media like the Frankfurt Allgemeine Zeitung’s real estate pages on Fridays. The forthcoming EU regulation will likely be integrated into the 2012 regulation. The question is which indicators will be used. The EU directive requires that “commercial advertisements for sale or rent must state the energy efficiency indicator shown in the building’s energy certificate.”
Control system for energy certificates and inspection reports: The EU directive stipulates random spot checks of a statistically significant percentage of all energy certificates and inspection reports issued annually. How the 2012 regulation will adopt this is not yet known. Enforcement is managed by the federal states, and additional controls would require more resources and staff.
Independent specialists: The EU directive requires that only qualified, independent experts issue energy certificates and inspect HVAC systems. Member states must maintain public registers showing who is authorized and their qualifications. Currently, there is no legal obligation to register energy certificate issuers or HVAC inspectors in an official list. Architect and engineer chambers maintain lists of authorized experts, and the German Energy Agency (dena) has operated an online database of issuers for years.
When will the new nationwide mandatory Energy Efficiency Expert list by dena come into effect?
Whether and when the new dena Energy Efficiency Expert list becomes mandatory nationwide is unknown. The professional community remains skeptical. Currently, registration with the dena database is voluntary and initially costs €150 (approx. $165). The Federal Office for Economic Affairs and Export Control (BAFA) maintains its own list of recognized on-site consultants. The KfW recommends experts from dena’s new list for certain funding programs.
Best regards
The obligation is often mentioned by sellers. However, as long as it is not officially decided, you can do whatever you want.
Regarding the costs: we are having a ComfortAir 350 from Zehnder installed ... if I buy it myself, it costs around 4000 € (approximately 4300 USD) without installation. Additional costs for hoses, etc., will certainly apply.
If you plan to install a wood stove, it must be room-air-independent. These are more expensive than standard models.
In the kitchen, only a recirculating hood is allowed.
The chimney sweep may require a pressure monitor if the room is too small for the wood stove.
The doors need a narrow gap at the bottom to allow air circulation.
The electricity consumption of such a system is almost negligible... I think your TV uses more power in standby mode.
Regarding the costs: we are having a ComfortAir 350 from Zehnder installed ... if I buy it myself, it costs around 4000 € (approximately 4300 USD) without installation. Additional costs for hoses, etc., will certainly apply.
If you plan to install a wood stove, it must be room-air-independent. These are more expensive than standard models.
In the kitchen, only a recirculating hood is allowed.
The chimney sweep may require a pressure monitor if the room is too small for the wood stove.
The doors need a narrow gap at the bottom to allow air circulation.
The electricity consumption of such a system is almost negligible... I think your TV uses more power in standby mode.
Der Da schrieb:
The obligation is often mentioned by sellers.... Yes, that is probably true. The value of a controlled residential ventilation system should primarily be assessed based on comfort. The energy savings from heat recovery alone are lower than commonly assumed and marketed. However, the "controlled" ventilation system does have an important role that is hardly achievable with a more or less "uncontrolled" window ventilation.
I see the solar thermal system as significantly more problematic.
Best regards
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