IP Polná s.r.o. has been researching the quality of air inside buildings since 2013, and the experience gained are being put into practice. The Rezidence Prachnerova project is using the knowledge obtained from the previous project of Vítkovka residence.
The company finished this residential building in Prague Žižkov (Koněvova 39 street) and handed it over to the users in 2016. The unique air recuperation works successfully in there. Despite the building being situated near the centre of Prague, which is polluted by car emissions, the residents have got a healthy environment inside their flats. This is thanks to the central recuperation ventilating with a premium intake air filtration. With the experience gained, the Rezidence Prachnerova shall also be equipped with a premium intake air filtration, fine-tuned in accordance with the air pollution of the borderline locality of Košíře and Smíchov.
The five step filtration takes into account the level of air pollution in the particular locality where the residential building is situated. Not only the gaseous pollution (nitrogen dioxide, sulphur dioxide, ozone, volatile organic substances, and gaseous polycyclic aromatic hydrocarbons) is removed from the intake air, but above all the extremely fine solid particles. An extraordinary attention is paid to the effective filtration of solid particles in dimensions between one tenth of a micrometer and one micrometer which are the most carcinogenic substances in the polluted city air. The filtered air inside the flats may, in terms of cleanness, be compared to the top of the Swiss Alps.
Ventilating unit machine room in the Vítkovka residence
Ventilating system
Detail of the heat exchange plates
What is the logic of the effective filtration ventilating?
Gaseous substances occur inside each flat as a consequence of human activity, or they are emitted by the construction materials and the flat equipment. If the substances are not removed by ventilating, they start accumulating in the rooms, and cause health problems. Namely they are the following substances:
- Carbon dioxide (CO2)
- Water vapour
- Radon
- Formaldehyde
Why have we selected the controlled recuperation ventilating?
Ventilating through windows is not effective and inefficient in terms of energy. From the health and energy point of view, the most advantageous solution is a controlled recuperation ventilating for the entire building which continuously ensures air circulation in the defined quantity per unit of time.
Why have we decided to filter the intake outside air?
Pollution is present in the outside air. Car traffic is the main source of it in Prague. Minor sources are also heating plants, waste incineration plants, and local furnaces. Since we wish to have not only fresh, but also clean air inside each of the flats, we equip the residential buildings’ ventilation systems with highly efficient filtration which removes all of the polluting substances from the intake air.
Heat exchanger fitted into the ventilation system
What pollutes the air in Prague?
- Airborne dust (solid particles)
- Polycyclic aromatic hydrocarbons (PAH)
- Carbon oxides (NOx)
- Sulphur dioxide (SO2)
- Volatile organic compounds (VOC)
- Surface ozone (O3)
How have all the pollutants been removed from the air in the first project, the Vítkovka residence?
A filtration unit with the five step filtration has been fitted into the ventilation system. The filter organisation in the intake air pathway is as follows:
| Filtration step | Filtration agent type | Filter type |
|---|---|---|
| 1. | Polymer fibre | Dust |
| 2. | Glass fibre | Dust |
| 3. | Activated carbon | Molecular |
| 4. | Alkaline impregnated activated carbon | Molecular |
| 5. | Glass sub micron filter paper | Dust |
In the first step, coarse contamination, such as for instance insects, pollen grains, dust particles larger than 10 µm (micrometers), is removed from the air.
In the second step, fine dust with dimensions of 2,5 µm – 10 µm (PM10) is removed. These extremely fine particles, spread in the air, reach the alveoli where they penetrate the blood stream. Individual particles of airborne dust are not visible for the naked eye. The scheme shows the comparison of their size to a human hair and grains of fine beach sand.
Dust particles smaller than 2,5 µm (PM2,5) are extremely dangerous for there are solid polycyclic aromatic hydrocarbons bonded to their surface. They are bonded there by 50%.
In the third step, the physical principle of adsorption removes the volatile organic compounds, the gaseous polycyclic aromatic hydrocarbons, and the ozone using the activated carbon.
The fourth step represents the filtration of gasses of sour nature (NO2 and SO2) on the alkaline impregnated activated carbon using the principle of chemisorption.
The fifth step is the premium filter. Namely it is a compact filtration segment made by fluting technology from the glass sub micron filter paper. In this step, the finest particles with dimensions of 0,01 µm – 2,5 µm (PM2,5) are removed with extreme efficiency. With those, also the bonded polycyclic aromatic hydrocarbons are removed.
Comparison of dust to a human hair and grains of sand
Third level of filtration
Last level of filtration