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Central ventilation system: Key to efficiency and optimal indoor climate
Central ventilation system: Key to efficiency and optimal indoor climate
An efficient and well-planned central ventilation system is the heart of a modern building that prioritizes comfort and energy efficiency. At a time when energy costs are rising and awareness of healthy living is increasing, the central ventilation system is gaining more and more importance. It not only ensures fresh air and a pleasant indoor climate, but also helps to reduce energy costs and protect the environment. Here you will find everything you need to know about planning and designing a central ventilation system so you can make an informed decision that meets your needs.
Fresh air in your home: Understanding the different ventilation methods
Imagine your home is like a large lung that needs to breathe regularly to stay healthy. Without good air, unpleasant odors, moisture, pollutants, and viruses can accumulate – which is like your apartment breathing “bad air.” To prevent this, regular ventilation is essential. This not only ensures a pleasant indoor climate, but also keeps your living spaces healthy.
A simple method for this is natural ventilation. This means that you simply open your windows to let fresh air in. This type of ventilation uses natural forces such as wind and temperature differences to renew the air in your home. Sometimes it is also enough for air to flow through small gaps in doors or windows – this is called infiltration ventilation.
However, in modern energy-efficient homes and during the renovation of older buildings, care is taken to ensure that as little heat as possible escapes. These buildings are almost airtight, which is great for energy efficiency, but can present a challenge for ventilation. If you are not at home during the day, it can be difficult to ventilate regularly. In such cases, simply opening the windows is often not enough to maintain air quality. A well-designed ventilation concept is therefore necessary for such modern or renovated buildings. This concept determines which technical ventilation systems are needed to ensure that your home is always supplied with optimal air quality, even when you are not there.
Introduction to ventilation concepts: Why they are important and who needs them
A ventilation concept is like a fitness plan for your house, ensuring that it is always sufficiently ventilated. This is particularly important when you are building a new house or renovating your old house to make it more comfortable and energy-efficient. If you insulate your house better to keep it warm and save energy, the air may no longer be able to flow as freely as it used to. You may need to change your ventilation habits to ensure that the air in your house stays fresh through controlled residential ventilation. This is especially the case when you insulate large parts of your house.
There is a rule, DIN 1946-6, which states how you should ventilate your house to prevent mold and moisture, even when you are not at home. A ventilation concept helps you show that your house always gets enough fresh air to avoid such problems. If that is not the case, it suggests what you can do. There are several ways you can ventilate your house without always having to remember to open the windows:
- Ventilation slots in the window frame,
- Ventilation openings in the exterior wall,
- Ventilation systems with fans, which can operate centrally or decentrally.
If you have rooms without windows, such as a bathroom or a toilet, there are special regulations (DIN 18017-3) that ensure these rooms are also well ventilated. Depending on how you use your house and how many people live in it, you can choose different ventilation levels to ensure that your house always remains fresh and healthy:
- Ventilation for moisture protection: This is the basic ventilation system that ensures your house stays dry even when it is vacant by actively removing humidity.
- Reduced ventilation: This ensures that pollutants and CO₂ are removed from the air, even when you are not at home.
- Demand-controlled ventilation: In addition to regular ventilation through windows, you can use special fans to improve air quality.
- Intensive ventilation: When there are many people in the house or you are cooking and doing laundry, this ventilation level helps keep the air particularly clean.
If you want to improve your house's energy efficiency, there is a Online tool by the Federal Association for Residential Ventilation (VfW), which helps you check if you need additional ventilation measures. This tool can also help you better plan your renovation plans.
Different ventilation systems for every home
Not every house “breathes” the same way. There are different types of ventilation systems, and depending on your house and your needs, a specific type might fit better than another. And the best part? Even if the residential building is a bit older, you can “retrofit” it with a modern ventilation system to let fresh air in. Here is a simple overview of the different systems:
Simple exhaust systems
They are like the small fans in your bathroom or kitchen. They pull out humid or “stale” air, ensuring that fresh air can flow in from the outside. Imagine opening a window, but without the draft. These systems are simple yet effective and are particularly suited for smaller rooms.
Residential ventilation: Central supply and exhaust air systems
These systems are like the central nervous system of your house for air exchange. They control air circulation throughout the entire house by extracting stale air and letting in fresh, preheated air. It is like opening the windows, but without losing the heat. These systems are particularly good for larger houses or if you want to improve the air quality throughout the entire house.
Decentralized residential ventilation: supply and exhaust air systems
It is a flexible solution that does not require major renovations. They operate locally in individual rooms and are therefore ideal if you only want to improve certain areas of your home. Imagine every room having its own small ventilation system that brings in air directly from outside.
reversible ventilation fan
And then there is also the reversible ventilation fan, a clever solution that alternately lets air in and out to retain heat. It is as if your house is learning to “breathe,” alternately inhaling and exhaling to keep the air fresh. Whether you are building a new house or want to improve your current home, there is a ventilation solution that fits. And remember: a good ventilation system not only makes your home more comfortable, but can also help save energy and ensure good air quality.
Ventilation system with heat recovery: The clever way to heat and save energy
Imagine your heating system could recover the heat from the air you are blowing out of your house anyway and reuse it. That is precisely what a ventilation system with heat recovery does. It captures the heat from the stale air before it escapes outside and uses this heat to warm up fresh air coming in from the outside. That is not only clever, but also saves a lot of energy. Thanks to this technology, less energy is needed to keep your home warm. In addition, the pre-warmed fresh air ensures a pleasant indoor climate and helps prevent moisture damage and mold growth, which is often the case with mechanical ventilation systems.
Another plus: These systems are extremely efficient. Many models achieve an efficiency rate of over 80 percent. This means they recover more than 80 percent of the energy from the exhausted air, primarily through techniques such as heat recovery and efficient air exchange. Some systems are even so efficient that they save 15 to 20 times more energy than they consume themselves. That is like getting 15 to 20 EUR back for every euro you put into the system. In short, a ventilation system with heat recovery not only makes your home more comfortable and healthier, but also more economical.
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Which technologies are used for heat recovery in ventilation systems and how do they differ from one another?
Answer:
Air-to-air heat exchanger: These devices work using a trick where heat is transferred from the old, outgoing air (exhaust air) to the fresh, incoming air (supply air). Imagine two trains passing each other: one releases heat while the other absorbs it, similar to an efficient central ventilation unit. This happens either directly next to each other (cross-flow principle) or in opposite directions (counter-flow principle). In smaller, decentralized systems that are installed directly in the wall, this exchange takes place within a compact unit.
Heat pump This uses a heat exchanger to extract heat from the outside air. This heat can then be used to warm up drinking water or to support your heating system. It is like using the residual heat of an oven to keep your dinner warm.
Earth-to-air heat exchanger: With this method, air ducts are laid in the ground to pre-cool or pre-heat the air, depending on the season. This sounds great at first because it uses the natural temperature of the earth. However, this technique is expensive and can pose hygiene risks, as moisture and thus bacteria and mold can form in the ducts.
Earth-brine heat exchanger This variant is a further development of the earth-air heat exchanger. Here, the geothermal heat is first transferred to a fluid (brine), which then heats the air. This prevents the air from coming into direct contact with the earth, which is more hygienic.
Each of these methods has its pros and cons, but all aim to use the energy you use to heat your home more efficiently.
How do you plan an effective ventilation system?
Answer:
If you are planning to install a ventilation system in your new build or during a renovation, there are a few important points you should consider to ensure the system operates efficiently and economically. Here is an easy-to-understand guide to help you optimize the planning of your ventilation system:
- airtight building envelopeImagine your house like a thermos. To keep the warmth (or the coolness in summer) inside the house, it needs to be well sealed. An airtightness test helps ensure that air only enters and exits where it is supposed to, rather than escaping through cracks and gaps.
- Clever arrangement of the exhaust zones: Similar to a well-organized workplace, the rooms from which air is extracted – such as the kitchen, bathroom, and toilet – should be located as close to each other as possible. This saves materials and installation costs because fewer long pipes are required.
- SKeep an eye on power consumption: The fans in the ventilation system are the main consumers of electricity. In well-adjusted systems, especially those with heat recovery, however, more energy is saved than consumed. For a single-family home, you can expect an annual electricity consumption of about 200 to 400 kilowatt-hours.
- Check the energy label: Like other household appliances, ventilation units have an energy efficiency label that shows you how energy-efficient the appliance is. Look for appliances in classes A+ to D to ensure that your ventilation system is environmentally friendly and cost-efficient.
- Indoor Air Quality Seal: In the future, there will be a quality seal recognizing ventilation systems that not only exchange the air, but can also treat or air-condition it. This seal confirms that the system operates efficiently and provides good indoor air quality. Here you can learn more about the Indoor Air Quality seal of approval for central ventilation systems.
- Consider room-air-dependent fireplacesIf you use a wood-burning stove or gas stove that draws air from the room, you must take this into account when planning your ventilation system. An early discussion with your chimney sweep can help combine both systems safely and efficiently.
- Ensure ease of maintenance: A ventilation system must be serviced regularly to maintain its performance and cleanliness. Therefore, plan easily accessible maintenance openings from the beginning and protect the ducts from dust and dirt during the construction phase.
Optimal operating settings for the central ventilation system are crucial
Before your ventilation system starts up, it is important to set it correctly. This means that the airflows must be adjusted precisely to your needs – this is called “balancing”. It is a good idea to have an expert show you how everything works.
With simple exhaust systems that you switch on and off with a switch, the whole thing is pretty straightforward. With larger, central ventilation systems, you can adjust the basic ventilation directly on the ventilation unit, which ensures optimal air exchange. And the great thing is: you can even individually adjust the ventilation intensity in different rooms. To ensure that the air in your home is always fresh and pleasant, you can use technology to help: CO₂ sensors and moisture meters (hygrometers) monitor the air quality and automatically adjust the ventilation when necessary. It is like having an invisible helper that ensures the air is always just right.
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How to keep your ventilation system in top shape: Practical tips for maintenance and cleaning
To ensure your ventilation system operates efficiently and the air in your home stays clean, regular maintenance and cleaning are essential. Here is a simple guide on how to keep your ventilation system in top shape:
- Annual maintenance: It is recommended to have your ventilation system serviced and cleaned by a professional at least once a year. This helps to extend the lifespan of the system and maintain its efficiency.
- Filter change: The filters play a crucial role by filtering pollen, dust, and other suspended matter from the air. F7 class fine dust filters, for example, capture over 90 percent of these particles. For hygienic reasons, the supply air filters should be changed every 3 to 6 months depending on air quality, but at the latest after one year. Exhaust air filters should also be checked regularly and replaced if necessary, depending on the dust and pollen load.
- Automatic filter monitoring: Many modern ventilation systems feature automatic filter monitoring that indicates when a filter change is necessary. This is more effective than systems that merely provide time-based reminders, as they take the actual condition of the filters into account.
- Cleaning of the air ducts: This is particularly important for central ventilation systems to ensure efficient air exchange. To facilitate a thorough cleaning of the air ducts, inspection openings and the shortest possible ducts are advantageous. It is recommended to hire a specialist company for cleaning after about 10 years. On this occasion, the original settings of the system should also be checked, as they might have changed due to the cleaning.
Cost overview: From planning to operation of a ventilation system
The costs for a ventilation system and a ventilation concept vary depending on various factors such as the system type, structural conditions, and individual comfort requirements. A ventilation concept for a single-family or two-family house usually costs between 300 and 400 EUR, with precise information being provided by energy consultants or HVAC planners who also create the concept.
Acquisition costs for ventilation systems depend heavily on the type of system. Decentralized ventilation systems start at around 2,500 euros, while central ventilation systems can cost between 8,000 and 16,000 EUR, depending on the equipment and whether they are equipped with heat recovery.
In addition to the purchase costs, there are ongoing costs for operating electricity, maintenance, filter replacement, and cleaning. The annual electricity requirement of a ventilation system can be, for example, 300 kWh, which costs about 120 EUR per year at an electricity price of 40 cents/kWh. The costs for a complete filter set range between 40 and 90 EUR per year, and duct cleaning, which is only necessary every 10 years, can cost between 400 and 800 EUR.
To calculate the operating costs of a ventilation system, the specific fan power (SFP) can be used, with central ventilation units often enabling more efficient air distribution. The annual electricity demand is determined by multiplying the specific fan power by the air volume flow and the annual operating time, and dividing it by 1000. This value is then multiplied by the electricity price per kilowatt-hour to calculate the annual electricity costs.
FAQ: Frequently asked questions about central ventilation systems
Can I open the windows even if I have a central ventilation system?
Answer:
Yes, you can open your windows even when a ventilation system is in operation. Outside of the heating season, this is not a problem at all. However, you should be more careful during the heating period. Although the heating can compensate for some of the heat loss caused by opening the windows, it has its limits. Therefore, it is advisable to only open the windows selectively in winter to avoid unnecessary energy loss.
Can ventilation systems transmit noise in the house?
Answer:
Whether ventilation systems transmit noise within the building depends entirely on the design of the system. It is important not to cut corners here in the wrong place. Through the targeted use of crosstalk silencers and compliance with certain basic rules when designing the duct network, crosstalk noise can be reduced to a normal level.
Can I use a wood-burning stove if I have a ventilation system?
Answer:
No, you do not have to do without a wood-burning stove if you install a central ventilation system. However, it is crucial that you obtain the approval of the responsible chimney sweep. We recommend involving the chimney sweep early in the planning process. For the safe operation of a wood-burning stove together with a ventilation system, it is advisable to choose a room-air-independent heating appliance. In addition, provision should be made for the possibility of installing a safety device such as a differential pressure switch.
Does a ventilation system lead to dry air in the house?
Answer:
No, a correctly sized ventilation system does not lead to excessively dry air. It is crucial that the ventilation system is designed so that it does not supply more fresh air than is hygienically necessary. In comparison, ventilation through windows or gaps can often lead to a higher air exchange, which can make the air drier than with a well-adjusted ventilation system.
Why does indoor humidity drop during the heating months?
Answer:
Indoor humidity is often low during the heating months because the fresh air coming from outside contains less moisture due to low outdoor temperatures. When this colder air is warmed inside the building, its relative humidity drops further. To counteract this, adjusting the ventilation settings during the heating months can be helpful. Alternatively, there is the option to use a humidifier to increase the moisture in the rooms.
How often should a central ventilation system be cleaned?
Answer:
Manufacturers of central ventilation systems generally recommend changing the filters at least every six months. However, this is only a general guideline. Depending on the air quality at your location, it may be sufficient to change the filter only once a year.
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