Issue 4/2024

The transmission of impact sound in prefabricated apartment buildings is a frequent cause of complaint. Often there are only thin floor layers on the load-bearing panels, which may be the only preventive measure of the ceilings in terms of sound insulation. The difference between the use of different floor layer materials can be surprisingly significant from an acoustic point of view. The paper presents a series of measurements in a specific a partment building. Both suitable as well as completely unsuitable solutions are pre sented.

Museum storage spaces are specifically designed for long-term storage of valuable collections, in controlled and stable environment. This paper addresses the feasibility of maintaining internal environmental conditions exclusively by passive methods. The hygro-thermal performance of the model depository is modelled by dynamic hygro-thermal simulation, considering weather data for Prague. Despite allowing for seasonal fluctuations of temperature and relative humidity within the relatively wide range of 18 to 25 °C and 40 to 60 % RH, achieving the required internal climatic conditions solely through passive methods, such as good thermal insulation, high thermal capacity of the building enclosure, and high airtightness, was not feasible. It was found that, in colder days, the required conditions inside the model depository can be maintained by heating and humidification, assuming a high air circulation, with a minimum supply of fresh outdoor air. Notably, the depository building did not require cooling and dehumidification during the warmer period of the year.

The article describes a sensitive renovation of the heating and cooling system of an architectural landmark in the centre of prague. For heating and cooling of the bui lding, an energy-efficient VrV system with water loop energy recovery was selected. it is a water-to-air heat pump in a three-pipe design allowing energy recovery in two stages. the first stage of energy recovery takes place on the refrigeration circuit among the indoor units, i.e. the indoor units in cooling mode transfer energy to the units that are in heating mode. the second stage of energy recovery takes place on the water loop between the individual heat pumps. the units that are designed for commercial application provide cooling all year round. the recovered energy is transferred to the wa ter loop. the heated water is then used by the hea t pumps for hea ting of the office spaces.

The paper describes the design of a multi-zone single-channel variable air volume (VAV) air conditioning system. The aim of the paper is to introduce this unconventional air-conditioning system in more detail to the professional community and to highlight some problematic issues related to the design and subsequent operation of the system. Practical experience with the design and operation of similar systems is taken into account.

The aim of the paper is to present the characteristics of individual pneumatic conveyor feeders, to evaluate their energy consumption and to compare them. The feeders under comparison are used as pressure relief valves for pneumatic conveying in suspension. These include vessel feeder, rotary feeder, flow feeder, screw feeder and venturi feeder.

The utilization of solar energy to produce renewable heat to supply a low-temperature district heating network is compared on two solar system concepts, a solar thermal system with flat plate collectors and a system combining photovoltaic modules and air-to-water heat pumps. The systems are operated with seasonal heat storage and both the heat production efficiency of each system and the seasonal heat storage efficiency are compared. Initial analyses indicate that a system based on heat pumps powered by electric energy from photovoltaics alone shows about 10 to 20 % higher production and delivery of heat than a solar thermal system with the same area covered by collectors.