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Abstract The paper presents the experimental measurements and numerical simulation of a ground source heat exchanger operating at a cold climate for a passive house ventilation system. The investigated passive house is a detached single-family house without a basement, occupied by a four head family, located in the South of Poland. The measurements cover over one year period and CFD (Computational Fluid Dynamics) simulations are reported for February when system operates at typical for this period and location cold climate conditions. The calculations were made with the CFD ANSYS FLUENT software package. The house and its components are fitted with a data acquisition system that is operational from 2011 and records 139 points at an interval of 1 min. The data reported in the paper were recorded during winter in the year 2011/2012 by an onside located meteorological station and temperature sensors placed at different depths in the ground and at the outlet of the ground heat exchanger.

Abstract The objective of this article is to improve diagnosing and data availability for all stakeholders, including building operators, planners, inhabitants and utility suppliers. This paper presents the results concerning the demand for final and primary usable energy. For each of the buildings a preliminary energy audit was prepared and this was the basis for comparison between the estimated energy consumption in the buildings before and after thermal upgrading. The research was carried out mainly in buildings belonging to the Department of Public Utilities and Housing in Zielona Gora. The group of selected buildings consisted mainly of traditional technology buildings having different functions, i.e. residential, residential-commercial, commercial, and other buildings (schools and boarding houses). Forty buildings were selected for analysis. They were built in different years and had different functions, i.e.: 23 residential buildings, 6 residential commercial buildings, 7 commercial buildings, and 4 buildings had other functions (schools). They are the main energy consumers, which has a considerable impact on the environment.

A new kind of longitudinal flow spiral recuperator for the heat recovery in ventilation systems of buildings was studied experimentally and analytically. The aim of this work is to analyze the possibility of using air handling units with new type of spiral recuperator in order to recover heat in ventilation systems of buildings. For the reason that the air flows are parallel to the symmetry axis of the longitudinal flow spiral recuperator, in this unit pressure drops are smaller than in commonly known spiral exchangers. Because of the counter flow, a greater value of thermal effectiveness ɛ is reached for the same value of the number of transfer units in comparison to cross-flow recuperators. The exploitation of the new type of spiral recuperator in winter periods brings significant savings. The results obtained from computations are very encouraging for a widespread use of these devices.

Abstract This paper highlights the potential of adapting the energy profile of conventional office buildings in Southern Europe into a profile of Balanced Energy Buildings. The proposed energy adaptation does not only aim to satisfy the electricity consumption on an overall annual basis using intermittent renewable energy sources (RES), but seeks for a better instantaneous match of the on-site demand of the building with the production from RES. The self-consumption of locally generated clean electricity shall be maximized and peaks in energy transactions between building and grid are to be reduced. The aforementioned targets are pursued with the utilisation of intermittent RES (mainly solar PV systems in Southern Europe), active energy-saving techniques supported by ICT (Information & Communication Technology) technologies and energy storage systems. Beyond this, attention is given to the indoor climate comfort.

The radiant floor heating/cooling systems are more often used in new designed and modernized buildings, what renewed the interest in the study of the characteristic parameters, which are taking in to account by dimensioning or detailed scientific analyzes of such a systems. Very important and fundamental characteristic parameters for radiant floor are heat transfer coefficients. This article presents the results of experimental research on heated/cooled radiant floor conducted in the laboratory room in the climatic chamber, which aim was to estimate experimentally the values of heat transfer coefficients for the surface of cooled/heated radiant floor. The values of radiant, convective and total heat transfer coefficients were developed on the basis of the amount of heat emitted from the radiant surface and by the use of proper and clearly defined reference temperature depending on the kind of heat transfer coefficient. It was noticed, that the values of heat transfer coefficients for heated/cooled radiant floor, which are commonly used in practice, are overestimated, even in the range of 10–30%.

Abstract This paper presents an evaluation of energy-related and economic aspects of production of thermal energy to heat a family house with wood briquette. The object of the study was a detached house with an area of 247 m 2 , situated in Olsztyn, in the north-east of Poland. The study lasted three years, from October 2006 to September 2009. The highest monthly consumption of wood briquette for thermal energy production: heating water for the central heating system and hot utility water production were recorded in January (1052–1333 kg/month). The average annual briquette consumption ranged from 6.36 to 6.72 t/year. With the mean lower heating value of briquette of 17.99 GJ/t, the mean consumption of energy in the fuel ranged from 114 to 121 GJ/year. The annual cost of heat production for a family house with briquette as fuel ranged from €572 to €651, during the 2006/2007 and 2008/2009 seasons, respectively. It would have been cheaper by €187–228 year −1 to heat the house with seasoned willow chips, whereas using alternative fuels, such as hard coal (fraction 0.5–2.5 cm) oak pellets, natural gas and heating oil would have increased the cost of heat production. If the last of those fuels had been used, it would have increased the cost 3.5-fold as compared with wood briquette.

Abstract The article applies the global costs calculation method with regard to the energy assessment of the selected solutions for the technical equipment of buildings, depending on the purpose and function of the building. The global costs were calculated by means of the net present value method in accordance with the cost-optimal draft regulation. In order to determine the sensitivity of the optimal ratio of primary energy to the adopted initial data, the total cost of the building, which is the sum of the investment and operating costs in the assumed operating period, was analyzed. The procedure takes into account the variability of the thermal envelope of the building, the ventilation requirements and the macroeconomic parameters. Primary energy includes all energy used for heating, ventilation, hot water and auxiliary energy and depends on the adopted macroeconomic parameters. In the region lacking economic stability, such as Eastern Europe, the sensitivity analysis is important for the process of establishing thermal requirements of the building and the energy supplied. In those countries, the economic changes will lead to changes in requirements over time.

Abstract With a large number of factors affecting the energy efficiency of buildings, the importance of analyzing the growing amount of data becomes important. The aim of this research is to check whether the use of Self-Organizing Maps will allow the indication of the relationships between building features which are considered important from the point of view of their energy performance. The research was carried out on a sample of 5040 randomly generated variants of single-family buildings with a fixed volume and location. These models were next subject to clustering, based on selected features, with the use of Self-Organizing Maps. The results prove the suitability of the method used. Grouping analysis shows the dependencies between particular parameters, confirming the importance of the U-value of partitions, the thermal mass of the building and its air-tightness for energy efficiency, while discovering unexpected relationships such as the irrelevancy of a building's orientation. In addition to expanding knowledge about the relationships between building features affecting their energy performance, it may allow optimal parameters for the given initial conditions to be found.

Abstract Simple models used for the simulation of the thermal performance of buildings usually assume constant (time-invariant) values of their parameters. This paper presents the simple and efficient solution for the simulation of the thermal performance of the building with the time-varying parameters of its thermal network with the use of the Matlab/Simulink. The lumped parameter thermal model taken from EN ISO 13790 was used to build the simulation model in the state space. Then it was validated for two different ventilation schedules, each for 20 European cities. Reference results of the annual heating and cooling needs were taken from the EnergyPlus detailed simulation, showing satisfactory accuracy of the developed model. An error analysis of the hourly indoor air temperature prediction was also performed. For this purpose, statistical goodness-of-fit criteria were used: the Mean Square Error (MSE), Mean Absolute Error (MAE), Root Mean Square Error (RMSE), Mean Absolute of Percentage Error (MAPE) and coefficient of determination (R2). These metrics showed a very good quality of prediction of the presented model.