PODCIŚNIENIOWY I NADCIŚNIENIOWY SYSTEM WENTYLACJI GRAWITACYJNEJWentylacja grawitacyjna, polega na wymianie powietrza, powstałej z powodu róż-nicy ciśnień, odbywająca się w sposób ciągły, poprzez przewody wentylacyjne. Jest to stary, sprawdzony i najczęściej stosowany sposób wentylowania pomieszczeń. Złe rozwiązania projektowe, powodują brak skutecznego jej działania. Najczęstszym popełnianym przez projektantów błędem jest zły dobór przekroju poprzecznego pola powierzchni wywiewnego kanału wentylacyjnego w stosunku do jego wysokości, a zatem do występującego w nim ciągu. Wielokrotnie pomijane są wymogi normowe dotyczące konieczności zapewnienia, odpowiedniej krotności wymiany powietrza lub strumienia przepływu powietrza mierzonego w m 3 /s. Na skutek tych zaniedbań dochodzi do zróżnicowanych efektów wentylacji pomieszczeń występujących na różnych kondygnacjach. Przedstawiony artykuł ma na celu omówienie i spopularyzowanie opracowanej przez autora metody, która umożli-wia uzyskanie na każdej kondygnacji tych samych wyników poprawnego działania wymiany powietrza. Rodzaj systemu; podciśnieniowy lub nadciśnieniowy zależy jedynie od kondygnacji, na której został zastosowany. Przedstawione rozwiązanie jest bardzo prostym pomysłem na modernizację istniejących i projektowanie nowych budynków. Nie wymaga dużych nakładów finansowych i działa samoczynnie, ponieważ jest to system wentylacji grawitacyjnej bez żadnych elementów wspomagania. Poprawnie działająca wentylacja grawitacyjna odpowiada za zdrowie i dobre samopoczucie ludzi przebywających w budynku, a także za uzyskanie dobrych parametrów mikroklimatycznych np. wilgotność, temperatura czy prawidłowa, ujemna jonizacja powietrza. Odpowiedni stan techniczny przegród budowlanych i innych elementów obiektu, bez występujących zawilgoceń, zagrzybień to także efekt dobrze działającej wentylacji grawitacyjnej.Słowa kluczowe: nadciśnienie, podciśnienie, nawiew, wywiew, krotność wymiany, strumień powietrza

Abstract. In the following article the author proposes the solution for a properly functioning natural ventilation system based on the use of supply and exhaust ducts, i.e. by designing a natural balanced ventilation system. The paper is devoted to test results of air flow through natural ventilation supply-exhaust ducts in the rooms located on the lower floor of the building. The simulations conducted in ANSYS Fluent software relate to such issues as: pressure system inside the room and in the exhaust duct, distribution of air temperatures in the room, vector direction of airflow through supplyexhaust ducts and in the analysed room. Three types of solutions were selected for the tests: air inflow into the room through the air intake located at the basement level, air inflow through the window ventilator (although no longer used, this solution can be found in many existing residential buildings) and the natural ventilation system supported with the so-called "solar chimney". All simulations were conducted with an outdoor temperature of +3 degrees C. The indoor temperature is + 20 degrees C, considered to be the minimum thermal comfort level. In the era of common building sealing, the presented ventilation system may be a good solution that guarantees proper functioning of natural ventilation. In all cases presented, it meets the normative regulations and requirements for the ventilation air stream and the air exchange rate in the room. The paper (first part) describes test results concerning the room located on the lower floor of the building, i.e. with a short supply duct and a 12-meter long exhaust duct. The choice of topicFrequently conducted construction works involving thermal modernization of a building limit the inflow of the appropriate air stream to the living quarters. This is the reason for the emerging problems associated with improperly functioning gravity ventilation that operates periodically and with variable efficiency. In the vast majority of cases, existing residential buildings in Poland are created on the basis of a natural ventilation system. In accordance with the requirements of PN-83/B-03430, new structures of up to 9 storeys can also be equipped with a natural ventilation system. In both cases, the proposed solution can have a broad scope of application in our country. It does not require large financial outlays or the use of complex, expensive ventilation devices. Following the example of many world famous construction projects that have been created on the basis of a selected natural ventilation system, it can bring satisfactory results, primarily related to human health and good technical

This paper discusses the results of research conducted with the Ansys Fluent programme on the air flow through natural ventilation supply and exhaust ducts of rooms located on the ground and upper floor of a building. A scenario with air inflow to a room through an air intake located on the basement floor level was selected for the tests. All simulations were performed for outdoor temperatures of +3,+12, and -15°C (simulations run for an outdoor air temperature of +12°C are discussed in detail). The temperature inside the room is +20°C, i.e. at the minimum temperature level for thermal comfort. The simulations address such issues as the pressure system inside the room and in the exhaust duct, the distribution of air temperature in the room and the vector direction of airflow through the supply and exhaust ducts.

Various cases from history indicate that the chimney is an important architectural detail in a building. Its shape, size and place where it rises above the roof affect the outline of a building and can even testify to the wealth of the family that inhabits it, as was the case in Portugal, among others. However, a chimney sometimes transforms from an architectural detail into a dominant element, which is not beneficial to the building’s overall massing. At present, ventilation is not only based on the design of ventilation ducts, but also on a comprehensive approach to design that affects the shaping of a building’s massing.

The paper is devoted to test results of air flow through natural ventilation supply-exhaust ducts in the rooms located on the upper floor of the building that were conducted in ANSYS Fluent software. Three types of solutions were selected for the tests: air inflow into the room through the air intake located at the basement level, air inflow through the window ventilator (although no longer used, this solution can be found in many existing residential buildings) and the natural ventilation system supported with the so-called “solar chimney” that is usually a glass superstructure, located on the roof of the building above the ventilation ducts. All simulations were conducted with an outdoor temperature of +3 degrees C. The indoor temperature is + 20 degrees C, considered to be the minimum thermal comfort level. The simulations concerned such issues as: pressure system inside the room and in the exhaust duct, distribution of air temperatures in the room, vector direction of air flow through supply and exhaust ducts and in the room. Tests conducted using a computer method of air flow analysis in ducts and in the analysed room indicate that the developed natural balanced ventilation system is a good solution, especially when building sealing is so common. In all cases presented, it meets the normative regulations and requirements for the ventilation air stream and the air exchange rate in the room. The paper (second part) describes test results concerning the room located on the upper floor of the building, i.e. with a long 9-meter long supply duct and a short 3-meter long exhaust duct.