Issue 2/2024

Ventilations of cold storage rooms and freezers have their specific and demanding requirements. It is impossible to design a conventional HVAC duct work solutions that are used in standard building structures. They cannot work due to the fact that structures operating with temperatures deep below the dew point are subject to intense penetration of water vapour through the building with their openings. Vapours often condense where they should not, often the condensate freezes. This article presents a case from practice, where the ventilation was not designed correctly, resulting in failures that were subsequently difficult to remove.

The paper summarizes hands-on experience with cleaning of individual parts of forced ventilation systems with heat recovery in family houses. It draws attention to the necessity of cleaning and discusses design and installation flaws that lead to difficult maintenance. Some principles are mentioned to facilitate the servicing of such systems.

The paper deals with the assessment of the year-round operation of a ventilation system with two-stage heat recovery in a family house. The ventilation unit is equipped with a conventional plate heat exchanger, while for the second stage of heat recovery a heat exchanger with thermoelectric modules is used. It allows cooling or heating of the supplied ventilation air. The assessment was based on the evaluation of a year-round building simulation data. The contribution of the new unit was compared with two other types of ventilation systems for single-family houses: exhaust ventilation without heat recovery and balanced ventilation with heat recovery.

This paper deals with the design and implementation of a master control system for the control of a photovoltaic power plant with battery storage (hybrid photovoltaic power plant). The objective of the master control system is to minimize the operating costs, to comply with the electricity consumption requirements of the facility and not to violate any constraints of the electricity supplier based on the grid connection contract, e.g. overflow or reserved capacity. The master control system is able to operate efficiently with dynamic electricity prices and to optimally buy and sell electricity on the basis of the he operation forecast. The master control system is deployed on a real hybrid photovoltaic power plant project and the results from the operation are presented in this paper.

The paper reflects the increased demand for heating systems combining a heat pump and a biomass combustion source arising from the energy market situation. The paper completely neglects the economic aspects of the above-mentioned heat source combination. It focuses exclusively on the technical solutions of biomass combustion heat sources with a heat exchanger. The paper summarizes the basic characteristics of the hydraulic connection of such a combination and provides some recommendations, especially for the I&C setup, which result from the monitoring of the opera tion of actual installa tions.

The building control system, which usually represents only about 1.5% of the to tal construction costs, has, together with the installed technologies, a major impact on the energy consumption of the building and thus on its operating costs. this paper targets the role of the technology operator in the context of building management, and uses several examples to show where the most common mistakes are made and where to look for potential savings.

This paper focuses on the evaluation of predictive control benefits in district heating systems. The method can be advantageously used in cases where the instrumentation and control system allows real-time aggregation of measurement data from all transfer stations, including heat metering, into one system. In combination with a flow rate and temperature model, temperatures and flow rates in the different sections of the system can be controlled to minimise the sum of the electricity costs of the circulation pumps and the heat losses during heat distribution. In cases where the district heating system has variable heat production costs and a dynamic electricity price is contracted, savings in the order of several percent per year can be achieved by deploying this method.