Due to the global warming and resulting problems, attention has been paid to greenhouse gases released into the atmosphere since the 1980s and 1990s. For this reason, the Montreal Protocol and the Kyoto Protocol have tightened regulations on the use of gaseous refrigerants in both HVAC systems and industrial refrigeration. Gradually, new generations of gaseous refrigerants, that theoretically have much less negative environmental impact than their predecessors, are introduced into the market. The key parameter describing environmental impact is the GWP index, which is most often defined on a time horizon of 100 years. The long-term use of new generations of gaseous refrigerants in HVAC systems reduces CO₂ emissions into the atmosphere; however, given that new generation gases often have a short lifetime, it seems that the adopted assessment may not be applicable. The aim of the article was to show how emissions of CO₂ equivalent to the atmosphere differs in the short and long time horizon. The article presents the results of calculations of equivalent CO₂ emissions to the atmosphere caused by the operation of compressor cooling devices used in HVAC systems, where cooling is done with the use of water or a water-glycol solution. The analysis was carried out for 28 commonly used devices on the world market. The analyzed devices work with refrigerants: R513A, R454B, R290, R1234ze, R32, R134a, R410A. The equivalent emissions values for GWP 100 and GWP 20 were analyzed in relation to the unit power of the devices depends on refrigerant mass and number of fans. The study showed that in the case of new generation refrigerants with a very short lifetime, the use of GWP 100 indicators is misleading and does not fully reflect the effects of environmental impact, especially in the area of refrigeration equipment application. The article shows that the unit value of the cooling load related to the number of fans or the unit would be helpful in assessing the environmental impact of a cooling device.

This article is an attempt to estimate concentration of bacteria and fungi in characteristic places in two air handling units. The research was conducted with the units equipped with heat recovery exchanger and recirculation of exhaust air. Additionally, microbiological analysis was done for indoor and fresh air. We performed measurements regarding supply and exhaust air volume. This means that the air velocity inside ventilator chamber was known. The mean concentration of bacteria and fungi was specified for air filters on the supply and exhaust side. The efficiency of air filters was verified by the concertation of bacteria and fungi in fan chamber. This article confirms that bacteria content in supply air is always lower than in exhaust air despite air recirculation. In this work we proved that the position of Petrie plate is essential for bacteria and fungi measurement.

The knowledge about dynamic changing heating and cooling load in existing building is essential for proper energy management. Whenever existing building is analyzed or ventilation system is going optimized, it’s essential to estimate temporary sensible and latent heat based on historical data. The basic conditions for heat calculations are quasi-stable thermal conditions. If supply air temperature significantly varies in short time, what happens very often, the calculations can give untrue results. The procedure described in this article improves usability of measured data affected by rapid supply air temperature changing. Therefore real sensible and latent heat can be calculated, what it is important for future optimization process. Specified, on the basis of varying supply and exhaust air temperatures, thermal loads range from -55.8 kW to 40.7 kW was substitute to more authentic range from -14.1 kW to 51.2 kW received from the conducted simulations. In addition, the data obtained from the simulation showed that latent heat gains were associated with the air temperature in the room, and not with the operation mode of the ventilation unit (day/night) as observed on the basis of historical data.

Celem artykułu jest analiza złożonych uwarunkowań projektowania instalacji HVAC w pracowniach diagnostyki obrazowej i medycyny nuklearnej. Artykuł przedstawia analizę aktualnego stanu prawnego i technicznego w Polsce, w tym przepisów Prawa atomowego oraz rozporządzeń Ministra Zdrowia. Ze względu na brak szczegółowych krajowych wytycznych technicznych dla systemów ogrzewania, wentylacji i klimatyzacji (HVAC) w tych obszarach, przeprowadzono analizę porównawczą międzynarodowych standardów: niemieckiego (DIN 1946-4), amerykańskiego (ASHRAE 170), szwajcarskiego (SWKI VA105-01) oraz francuskiego (NF S90-351), a także polskich wytycznych branżowych. Analiza wykazała, że polskie regulacje definiują bezpieczeństwo radiologiczne, ale nie określają konkretnych parametrów technicznych dla HVAC, takich jak krotność wymian powietrza czy klasy filtracji. Wskazano, że pomieszczenie diagnostyczne jest integralnym elementem technologicznym aparatury, a systemy HVAC są kluczowe dla jej niezawodności. Projektowanie tych przestrzeni wymaga zintegrowanego podejścia łączącego wiedzę inżynierską z fizyką procesów medycznych oraz wymaganiami ustawowymi. Ze względu na luki w krajowych przepisach, niezbędne jest opieranie się na standardach międzynarodowych i wytycznych producentów sprzętu.