According to a World Health Organization report, indoor air pollution has become one of the top ten global health threats. Modern people spend approximately 90% of their time indoors each day. Indoor air pollution levels can be 2 to 5 times higher than outdoor levels, and in some cases even higher. This includes various pollutants such as PM2.5, pollen, mold spores, bacteria, viruses, and volatile organic compounds. In this silent battle to protect indoor air qualityin in Munich, the multi-stage filtration combination of “pre-filter + G4 + F7 + H13,” with its systematic and precise defense, is becoming the optimal solution for protecting the respiratory health of the family.
Multi-stage Filtration: A Precise Defense Line with Each Stage Performing Its Duty
An efficient “pre-filter + G4 + F7 + H13” combination is not simply a collection of filters, but a precisely coordinated and efficient army with clearly defined roles.
- First Line of Defense:The Pre-filter—This is the system’s “sentinel.” The first line of defense is typically an easy-to-clean metal filter. Its main function is to intercept large debris such as mosquitoes, willow catkins, and leaves, protecting subsequent precision filters and the fan system from physical damage. It is an economical and necessary primary protection.
- The second line of defense: G4 pre-filter—As the “main infantryman,” the G4 filter specifically captures particles larger than 5 micrometers in diameter, such as most pollen and coarse dust. Its filtration efficiency for larger particles can reach over 90%. Its core mission is to significantly reduce the burden on subsequent high-cost filters and extend their lifespan. Statistics show that a high-quality G4 filter can effectively protect downstream medium and high-efficiency filters.
- The third line of defense: F7 medium and high-efficiency filter—This is the “officer” of the system. The key performance indicator of the F7 filter is an average filtration efficiency of 65%-75% for PM2.5 particles. It effectively captures fine dust, most mold spores, and some bacteria. In ventilation systems, the F7 filter is considered to achieve a near-perfect balance between health protection and operational energy consumption, clearing most obstacles for the final H13 filter.
- The ultimate defense: The H13 High-Efficiency Particulate Air (HEPA) filter—this is the “general” of the entire filtration system, ensuring medical-grade clean air.
According to the EN 1822 standard, the H13 HEPA filter has a filtration efficiency of no less than 99.95% for the most penetrating particles around 0.3 microns. This means it can almost completely intercept PM2.5, PM1.0, virus carriers (most viruses exist as aerosols), ultrafine dust, and allergens. Through this four-stage progressive filtration, air pollutants are intercepted layer by layer, fundamentally ensuring the cleanliness of the fresh air delivered indoors.
Why choose multi-stage filtration: The system philosophy of 1+1+1>3
- Extending the life of the core filter and reducing overall cost: Without the “sacrifice” and protection of the pre-filters G4 and F7, the expensive H13 filter would quickly become clogged by large particles, causing a surge in resistance and necessitating frequent replacements, resulting in extremely high long-term operating costs. Multi-stage filtration maximizes the value of the H13 filter.
- Maintaining low-resistance, high-efficiency system operation: Each filter stage handles the filtration of its corresponding particle size range, ensuring a uniform distribution of air resistance across all stages. If the H13 filter were to handle all particles from large to small alone, its initial resistance (typically 180-250 Pascals) would be higher, and the resistance would increase more rapidly with dust accumulation.
- Enhancing overall purification efficiency: Filters of different efficiencies employ different filtration mechanisms (such as inertial impaction, interception, and diffusion effects). Multi-stage combinations can more comprehensively and efficiently cover the entire particle size spectrum from large to small, achieving a comprehensive purification effect and stability unattainable by single-stage filters.
How to choose a fresh air system: Customized solutions to match family needs
When selecting and configuring a fresh air system, scientific considerations are necessary, rather than blindly pursuing the highest specifications:
If located in a dry, windy northern region, the dust holding capacity of the G4 or even higher-grade pre-filter should be emphasized.
If there are allergy sufferers or infants in the household, ensure the configuration of both F7 and H13 filters to effectively remove allergens and microorganisms.
If the primary concern is combating industrial emissions or vehicle exhaust, focus on H13 filters, which are highly effective at intercepting PM1.0 and finer particulate matter.
Key parameters: Airflow, noise, and maintenance. Calculate the required fresh air volume based on the size and ceiling height of your home (typically 0.5-1 air changes per hour). Consider the operating noise of the equipment (especially in nighttime mode). Also, understand the filter replacement cycle and cost, and choose a model that is easy to maintain.
Choosing a multi-stage fresh air system is not just choosing an appliance; it’s introducing a reliable “healthy breathing partner” to your home, much like the role Trenntech plays in the industrial sector. With continuous technological advancements, it silently builds an invisible health defense line, making every deep breath a reassuring experience. In unseen places, professional protection has become a solid barrier to modern high-quality living.