Evaporative cooling is a sustainable and energy-efficient technology based on water evaporation to achieve cooling. It uses air (R-729) and water (R-718) as refrigerants, so its effect on global warming is limited. Recent research focuses development of porous heat exchanger surfaces to be used in evaporative cooling technology with intermittent water spray. However, non-porous surfaces were not investigated. Here, we present the possibility of implementing intermittent water spray in a non-porous indirect evaporative cooler. The experimental results show that it increases the cooling capacity when compared to the constant water spray for chosen outdoor air parameters (20–30 °C and 40–50% relative humidity). Also, the time after the outlet air temperature achieves minimum value (4–6 min) is presented for a certain non-porous heat exchanger. The maximum cooling capacity obtained without spraying is 25–64% higher than the cooling capacity in steady-state conditions under constant water spraying. The regression model approach is employed to describe the observation. The results introduce a new path in evaporative cooling technology development. They also create the possibility of improving the effectiveness of existing systems by modifying only the water system management, without any changes in construction or replacing the heat exchanger.

The article presents an optimization calculus of variations of fan energy consumption in ventilation and (or) air-conditioning systems. It defines an air flow rate function that depends on the time of operation in the defined room size, starting conditions and the function of hazardous substances emission rate in the room. The differential form of air flow rate dependence on density of hazardous substances allows to establish a connection between air pollution in the room and a fan air flow rate, i.e. fan energy consumption. Creating a fan energy model experiment in the room in different conditions allows to minimize energy consumption to 5–30% depending on existing conditions.

This study evaluates indoor thermal comfort and the energy performance of HVAC control strategies in the Congo Zone of a zoological facility located in Poland. The main objective in this zone is to maintain adequate relative humidity, which is more critical for plants and animals than the indoor air temperature range. Long-term measurements were carried out to determine the variation of air system heat transfer as a function of outdoor air temperature. To determine the energy demand for heating, cooling, and air transport, eight control algorithms were analysed, each differing in a single detail but potentially affecting overall energy use and thermal comfort. The algorithms combined the following features: maintaining a constant supply or indoor air temperature; operating with a constant or modulated recirculation damper position; maintaining a constant or variable airflow (CAV or VAV); operating within the normal setpoint range or with an extended range of 1 °C; controlling temperature only or both temperature and humidity; and utilising or not utilising free cooling. The control algorithm operating in the facility maintained indoor humidity within acceptable limits for 98% of the year but failed to meet temperature requirements for 28% of the time. Refined strategies achieved energy savings of up to 74% in fan power and 80% in cooling demand, though often at the cost of reduced humidity control.