Issue 2/2016

Diagnosis of air-conditioning units is increasingly evolving field of research and development. However, a common problem is the absence of sensors needed to diagnose the device. This article aims to briefly familiarize the reader with virtual sensors, which can in some cases effectively replace the missing real sensors. The virtual mass air flo w sensor is presented as an example. This article also described an experimental system of an air handling unit, which was created for the purpose of testing and simula tion of various failures typical for air handling units. Diagnostic methods for detecting the failures can be developed and tested based on the da ta obtained from the system.

The paper describes a methodology for the design of ventilation in schools, which serves as a guide to applicants for funding during the realization of energy savings in the buildings used for upbringing and education of children and adolescent, within the Operational Programme Environment. The methodological guidance includes a computational tool for calculation of the CO2 concentration time course during the lessons. The article gives a motivation and description of the proposed guidance, which is based on the design of the fresh air flo w rate and selection of the ventila tion system incl. related aspects.

Nowadays it is very common to use glass facades for high-rise office buildings. The main advantage of the cavity glass facade is the possibility of its use for natural ventilation. The study is targeting the determination of simple and double skin glass facades properties and their effects on the microclimate in the naturally ventilated office space under different boundary conditions. 4 variants of temperature-humidity microclimate behaviour are compared on the basis of the paper [1]. External temperature is identified as one of the most important boundary conditions for the use of natural ventilation in the double skin facades. The positive impact of the cavity facades is clearly demonstrated by CFD simulations of a simplified models of offices on the 25th and 49th floors of a building with a south facing glass fa cade.

The paper describes a system of centralized heat supply implemented as a part of a new residential complex in Sweden, consisting of a family houses and apartment buildings complex, homes for the elderly and nursing home. With regard to the low-energy standard of the buildings, the unconventional solutions to supply heat for heating and hot water preparation was chosen, when the heat transfer medium for the whole district heating system is hot water. The heat for the district heating system is supplied from a wood-pellet burning boiler with an output 250 kW, which is complemented by 700 m2 of local solar thermal systems. The investment costs for the renewable energy source accounted for 1 % of the total budget, which is significantly less than the current level of uncertainty of the final cost for such a large construction project.

The article deals with the testing of solar collectors and application of mathematical models in practice. Solar collectors can not only be tested in laboratory conditions in indoor and outdoor environment, determining the basic parameters necessary for the design of solar systems, but also during operation of the actual installation of a particular solar system. Thus the testing in conjunction with the mathematical modeling can be used to verify the correct opera tion of the collector.

The paper follows up on the specific rules for the use of FMEA in the field of facility management, described in the previous part. It presents to the readers the evaluation of the specific risk priority indicators in the two different groups of criteria. First of them uses a factor of economic assessment of defect’s consequence, the second one monitors the frequenc y of occurrence of particular faults.

This article deals with verification of function of Laddomat 21 (which mixes supply heating water with return water), verification of the time needed to heat up the thermal storage tank when using Laddomat with different thermostatic cartridges (required temperature settings) and effect of using this system on the pollutants emission in the flue gas.

The article is the introduction to a series of artic les whose common denominator is to express the quality of a building as a whole by appropriate aggregated thermal characteristics. These are the characteristics that significantly affect the overall energy balance of a building and will therefore be good predictors of heating or eventually cooling demand of the whole building. Aggregated thermal characteristics of the building are to be numerable on the basis of the information about the building which is commonly known or estimable. In this initial contribution it is deduced which aggregated characteristics of buildings will be subjected to the theoretical analysis in the following papers. The heat balance of the building in the steady and unsteady states will be used for the theoretical derivation. The following papers will include a mathematical analysis of the selected a ggregated variables, analysis of the dependencies and examples of use.