Issue 3/2010

The tendency in designing the HVAC equipment is to apply the below specified aspects: 1) Systems with the controlled capacity according to the demand (DCV – Demand Controlled Ventilation) 2) Evaluation of the specific energy demand of the complete equipment according to the specific power (input) of fans (SFP – Specific Fan Power) 3) Economical cost appraisal as to the equipment lifetime (exploitation time) (LCC – Life Cycle Costs).The application of such conceptions leads to the design of the economic equipment with respect to the operation (as to the energy, by lowering the environmental load due to the CO2 production limiting and the operation cost savings). The situation in the Czech supply market prefers the cheapest equipment as concerns the investment, which however is costly from the view of the operation that is in sharp contrary with tendencies of the development abroad. The author states DCV and SFP characteristics, parameters and conditions enabling the design of DCV systems and the relevant variable quantity values that specify SFP, in his article. He also occupies with causes preventing to push ahead calculations, necessary for the evaluation of costs throughout the lifetime (LCC), or calculations of the designed equipment economic return, which is more costly from the investment point of view but saving from the operation point of view. He does not pay any attention to the legislative questions and the law enforceability; his contribution is solely technical.

The article includes the measurement results of the rotating roof ventilator driven with the wind. There is specified the dependence of the total pressure of the ventilator intake to the air flow rate in the ventilator or to the air velocity inside the ventilator intake duct related to the wind velocity in the scope of 2-13 m/s. Further, there are specified dimensionless characteristics, i.e. the dependence of the ratio of the total pressure in the ventilator to the wind dynamic pressure as to the velocity ratio in the ventilator intake to the wind velocity. The measured characteristics of the rotating roof ventilator are compared with the characteristics of the fixed ventilator of the CAGI type.

Authors describe possible heat consumption energy reduction regarding the heating in a standardized house built from bricks with respect to the night reduction, in their article. Several possible variants of reduction both from views of timing and watching the inner air temperature are examined. Energy balances are calculated in a simulation environment BSim namely in two variants; the original non-insulated house and the entirely insulated house. Results of individual variants as well as recommendations for the operation of the heating system in such types of buildings are summarized in the conclusion of the article.

The assessment of the energy performance (demand) of buildings is currently established on principles required by Directive 91/2002 ES on Energy Performance of Buildings (EPBD), which requires to include the annual demand for the energy for heating, cooling, ventilation, lighting and preparation of hot water in the assessment of the building. The genesis of the implementation of the EPDB in the Czech Republic and the methodology of the calculation of the energy demand focused on the problems of HVAC equipment and building ventilation is described in the article.

The author describes physical and chemical properties of water in the relation to the surroundings temperature in the introduction of his article. Authors attend to treatment and cleaning waste water with utilization of nano-corpuscules of the zero-potent iron during the liquidation of heavy metals above all, in the further part of the article.

TV studios require very special requirements for the air distribution that sometimes get to conflict with technical possibilities. They were successfully achieved with use of textile distribution system in the given case, but the solution needed atypical adjustments and accurate calculations. Important parameters were verified in advance through tests under the simulation of real conditions. The result has served as an example for solution of other similar spaces.

The author comes around to the history of the establishment and used system of air conditioning in the building of former General Pension Institute. This functionalist building was equipped with the relatively perfect air conditioning as the first one in the Czech Republic during the thirties of the last century. There was used the system of firm Carrier according to already implemented foreign buildings. As concerns the present viewpoint, it is somewhat unusual method of the central treatment of inlet air in the long polytrophic washer in which air was heated in the winter and cooled in the summer to the steady temperature +7 °C and then distributed by „the Carrier’s heating and ventilation channel“ to subsidiary machine rooms in individual floors and branches of the building.

In 2006, the technical standard for assessing the annual energy use for cooling and heating of buildings, i.e ČSN EN ISO 15927–4:2006 [1] was accepted in the translation; it states the statistical methodology of creation the hourly data formeteorological elements in the format of a reference year for the specified climatic area. Climatic data provide hourly values of the air temperature and humidity, solar radiation and other meteorological elements in the format of the reference year that represents the typical character of meteorological relations in the said place and region each and every day and hour of the year. The standard is based upon the statistical analysis of the measured climatic data and the selection of typical months and years for the decennium period, at minimum. Climatic hourly data of the reference year created according to the European Standard [2] are currently utilized in EU countries. The meteorological database in the format of the reference year that provides hourly data for the entire territory of the Czech Republic ensues from results of the analysis assignment [10] to the technical standard [1]. The database is needed as the necessary climatologic base for Czech technical standards related to the acceptation of the European Directive on Energy Performance of Buildings EPBD 2002/91/EC and the Amendment of Act No. 406/2000 Coll., on management of energy and further directives regarding the fulfillment of the requirement for the economy improvement in use of energy in buildings.

The reduction of natural ventilation of the environment inside school buildings in the process of replacements old windows with new ones designed tight makes a very topical problem. It concerns of not only apartments but currently of schools. School buildings that were naturally ventilated earlier, achieve almost zero infiltration after window replacements. Concentrations of CO2, dust, chemical substances and smells increase during the education in classes, which result in higher tiredness and lack of concentration both of teachers and pupils as well as small health problems. The volume of humidity that is not taken off increases and school buildings are full of funguses because ventilating through open windows is usually impossible due to pupils’ security reasons.