Issue 4/2023

The article introduces the reader to the construction and design of the HVAC systems of the Kotva department store in Prague. The building is located in the historical part of the Old Town, where construction has been going on since the 13th century. Some historical buildings had to be demolished to make room for the building. It is original in its construction design and the concept of a modern department store, including warehouses, employee facilities, and extensive parking areas in its basement. The construction, which was carried out by a Swedish company, was done at a rapid pace from 1972 to 1975, when it was formally opened. The modern concept of the building was matched by the conceptual design of the HVAC systems. The air-handling, cooling, and heating systems were supplied from abroad, and their level of technical excellence exceeded that of domestic products. Therefore, the entire building became a model for the Czechoslovak technical community. In the article, the author introduces the designers to the used heating and cooling systems and appliances. He describes in detail the air conditioning systems (with the original identification) designed for the individual rooms of the department store. From fresh air intake points, location of plant rooms, ventilated areas, to exhaust air outlets. The description also includes emergency ventilation systems for protected escape routes. Finally, the author appeals to the preservation of interesting technical solutions of HVAC technology. Endof-life equipment is usually disposed of and replaced by modern equipment. Preservation and storage are not feasible. As a solution, he suggests to keep a t least the technical documentation.

Monitoring carbon dioxide concentration in indoor environments is the most common method of assessing air quality. CO2 concentration corresponds to occupancy and ventilation intensity. However, carbon dioxide is not the only substance that degrades the indoor environment. When we talk about air quality in terms of odours, we use the term perceived air quality. Higher concentrations of pollutants cause fatigue, headaches, impaired concentration, and reduced cognitive and decision-making abilities. This article describes the relationship between carbon dioxide concentration and perceived air quality, its understanding, and its application within Czech regulations. It outlines the impact of different concentrations of carbon dioxide on human health, either in the form of the gas alone or together with other pollutants produced by people in the indoor environment of buildings. The article also illustrates the use of carbon dioxide concentration as an indicator of air quality and the associated limitations. It is demonstrated in three case studies that include a scenario comparing buildings with natural and forced ventilation, a scenario comparing buildings with single and multiple occupants, and a scenario with different sensor locations in the monitored space. The article confirms the assumption tha t monitoring carbon dioxide concentra tion to determine indoor air quality is appropriate, but that knowledge of the context and limitations is necessary for successful use of a particular a pplication.

The basic means of effectively reducing the heat loss of buildings and various technological devices is the use of suitable thermal insulation materials. In professional literature and other technical documents, it is possible to encounter some inaccuracies, that can be the cause of serious consequences. The article focuses on the frequent duplication of the results of measuring the coefficient of thermal conductivity determined by different methods.

The article deals with the issue of heating systems control. In today’s heating systems, control is an integral, but often neglected, part. For continuous control, which is the subject of the article, the most commonly used controller is the PID controller (the name reflects the fact that it is composed of proportional, integrating and derivative parts). In this paper, the concept of a self-adjusting controller RoboPID , which was developed in the framework of the cooperation between the University Centre for Energy Efficient Buildings of the CTU and the company Energocentrum Plus, s.r.o., will be presented.

The second part of the article about the device used for extracting water from air describes the energy concept for its autonomous operation and the actual testing of the device in real desert conditions. The S.A.W.E.R. prototype consists of two technological containers and a solar roof. The energy supply for autonomous operation is provided by solar photovoltaic, photovoltaic-thermal and photothermal collectors. The facility was tested in during autonomous operation was 85 litres per day.

The paper presents options for building energy systems within the framework of energy flexibility and active demand response strategies. It provides a basic categorization according to types of demand response activation, energy flexibility utilization as well as the new roles of end users, i.e. building owners and operators, in the context of other smart grid stakeholders are introduced. Furthermore, the paper offers a data analysis of the current motivational schemes given by the grid stakeholders, that leads to flexible behaviour considering the future end-user roles. Last, the environmental response potential is evaluated in the frame of the presented market mechanisms.