Uroš StritihUniversity of Ljubljana · Faculty of Mechanical Engineering
Uroš Stritih
Doctor of Engineering
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Publications (56)
Approximately 40 % of the final energy is used for heating and cooling of buildings. Of this, as much as 75 % is used in residential buildings. The proportion of energy needed in buildings is relatively high, so it is necessary to start using technologies that have low energy consumption, use it efficiently or provide it from renewable sources. One...
An active lifestyle is essential for maintaining a healthy heart, body, and mind. To satisfy WHO [1] standards, every fourth adult worldwide does not engage in enough physical exercise. As physical Introduction Air supported halls are buildings that make sure that overpressure is maintained while maintaining the height of a sports venue. These hall...
The present research investigates the active–passive system for cooling application. The Phase Change Material (PCM) plates are applied to the internal wall and ceiling of the PCM modified test cell forming an airgap with its original wall and ceiling which is nocturnally ventilated to decrease the PCM solidification time. The Active–Passive System...
This article presents the use of phase-change material (PCM) thermal storage within the Horizon 2020 HEART project (Holistic Energy and Architectural Retrofit Toolkit), aimed at decarbonising the European building sector through the retrofitting of existing structures into energy-efficient smart buildings. These buildings not only reduce energy con...
Upgrades in building energy efficiency codes led to differences between buildings designed according to outdated codes and those with most recent requirements. In this context, our study investigates the influence of external wall thermal transmittance, thermal inertia, and orientation on energy demand (heating, cooling) and occupant thermal comfor...
The present literature review addresses how to enhance the overall performance of phase change material (PCM) integrated into building elements for cooling with nighttime ventilation. The review consists of the introduction describing the issue of overheating of buildings in summer with possible solutions. The second section gathers the improved PC...
In a larger educational building in Slovenia, we examined the efficiency of ventilation systems by analysing the operation of the heating, ventilation, and air conditioning (HVAC) system in several classrooms. Using the Federation of European Heating, Ventilation and Air Conditioning Associations (REHVA) COVID-19 ventilation calculator, the probabi...
Storage technologies are a central component in energy-efficient buildings which implies also the substitution of fossil energy carriers by low carbon energy and closed carbon cycles, which means less CO2 from fossil fuel power plants and a higher share of renewable generation. By using heat pumps, electric cars, or synthetic fuels based on green h...
Heat pumps are considered as easy to use while utilizing the possibility of bringing low-temperature heat sources to a higher temperature. Thus, low-grade renewable energy sources (such as air, water, ground, solar), as well as waste heat sources, can be used to reduce the demand for fossil fuels and greenhouse gas emissions. Their big advantage is...
In the building sector, 40 % of final energy is used for heating and cooling. Up to 75 % of this is used in residential buildings. It is necessary to take a step forward and reduce this share of energy consumption, in particular through the use of efficient technologies and their integration into the system of renovation of residential buildings, w...
The huge amount of energy consumed by the residential buildings makes the sector one of the principal sources affecting the energy use in the European countries. To face it, the renovation of the building stock is considered one of the key strategies to improve the energy performance of buildings and meet the energy efficiency targets. Thus, a full...
When considering the deployment of renewable energy sources in systems, the challenge of their utilization comes from their time instability when a mismatch between production and demand occurs. With the integration of thermal storages into systems that utilize renewable energy sources, such mismatch can be evened out. The use of phase-change mater...
The trend of lightweight framed building structures is gaining in popularity. Due to lower accumulation capability and thermal stability, buildings might be inclined to higher risk of overheating. The purpose of this study is to investigate overheating in lightweight framed buildings from the aspect of thermal comfort and energy efficiency in cooli...
Prudent and efficient utilization of renewable energy sources is needed in order to achieve clean energy transition. Since energy use in buildings represents around 40% of total energy use in European Union the reduction of energy use in this sector is most definitely needed. One of the great challenges in this sector represents retrofit of residen...
This paper presents seasonal‐energy storage of solar energy for the heating of buildings. We distinguish several types of seasonal storage, such as latent, sensible, and chemical storage, among which the thermochemical storage is used and analysed in this research. In the first part, a laboratory heat‐storage tank, which was made in the laboratory...
One of the great challenges in the energy sector represents retrofit of residential buildings where 3/4 of buildings in Europe are residential. To reduce energy consumption and increase the use of renewables in existing residential buildings a holistic approach of retrofit with interconnected technological system is needed. In the present paper ene...
Using thermal energy storage (TES) in phase change materials (PCMs) can reduce energy consumption in buildings. In summer, cold can be stored at night and released during the daytime therefore reducing the temperature while in winter, the system can be connected to a solar air collector that supplies heat. This article presents a paraffin based the...
Heating of ventilation air accounts for a significant part of energy consumption in buildings. The paper presents the use of latent heat thermal energy storage (LHTES) heated with a hot air solar energy collector mounted on the facade of the office building at the Faculty of Mechanical Engineering in Ljubljana where experiments have been carried ou...
Actual national and international energy strategies generally encourage the use of renewable energy sources. Thermal energy storage (TES) offers various opportunities in the design of renewable energy systems. Thermochemical heat storage has gained popularity among researches because of higher energy density and lower heat loss compared to sensible...
Countries with moderate climate have heat gains during the year smaller compared to the heat losses. Therefore,
most of the attention on lightweight prefabricated houses is given for thermal insulation (nZEB). Thermal capacity
of such envelopes is very low, which can result in overheating of the indoor spaces over the summer months. As
a result, th...
In the present paper improvement of the air solar collector ventilation system with latent heat storage (LHS) for the heating period is presented. LHS in phase change materials (PCM) improves effectiveness of the ventilation system and resolves mismatch between obtained heat from the air solar collector and its use for ventilation of the office. Ap...
Actual national and international energy strategies generally encourage the use of renewable energy sources. Improving the energy performance of buildings is the key to achieve goals of the European Union (EU) 2030 Energy Strategy, which is to reduce greenhouse gas (GHG) emissions by at least 30 % compared to 1990 levels, because the buildings are...
The main drawback of renewable energy sources is the variability and intermittence in their availability; causing significant mismatches between the time of energy demand and energy production. To make these future energy sources and conversion technologies a viable solution, it is necessary to use significant levels of energy storage technologies...
Purpose – Bilateral project with Slovenia and Turkey with the title thermal energy storage for efficient utilization of solar energy was the basis for this paper. The paper aims to discuss this issue. Design/methodology/approach – The paper is the review of solar thermal storage technologies with examples of use in Slovenia and Turkey. Findings – T...
In order to reduce energy consumption in buildings, a solution using phase change materials (PCMs) as thermal energy storage (TES) is presented. During summer nights, cold is stored and delivered during the day to reduce cooling load, whereas in winter, heat from solar air collector is stored for heating during morning and evening hours. Proposed i...
In this study, the main goal was to develop an adsorption heat storage system for domestic heating system gained by solar collectors and to indicate a new way of maintaining the energy. Main characteristic of the storage system is to retain the energy for a longer period, as long as the adsorbent and adsorbat are separated. This research analysis t...
Energy storage technologies are a strategic and necessary component for the efficient utilization of renewable energy sources and energy conservation. There is a great technical potential to substitute burning of fossil fuels by using stored heat. Phase change material (PCM) is ideal for energy storage purposes since it can store energy at relative...
One of the technologies which help to reduce energy consumption is the thermal energy storage for cooling applications where the cold is stored in phase change materials (PCMs). Such materials would be suitable for use in buildings because they can store a large amount of cold and phase change occurs at a constant temperature, thereby increasing th...
A lot of research on the topic of energy storage is available, since there are discrepancies between the time when the energy is available and the time when it is needed. One possibility is the latent heat storage. The aim of this study is to determine what the thermal characteristics of the storage unit are and how such a unit could be incorporate...
Alternative solutions for cooling and ventilation of buildings have appeared in practice as a counterweight to energy wasting conventional systems. Free cooling principle with phase change material (PCM) has been used as an alternative method of cooling and ventilating buildings which combines night ventilation and increased thermal mass. A simulat...
This article presents an experimental analysis of cooling buildings using night-time cold accumulation in a phase change material (PCM), otherwise known as the “free-cooling principle”. Studies of the ceiling and floor free-cooling principle, as well as passive cooling, are presented. The free-cooling principle is explained and some of the types of...
This article presents an experimental analysis of cooling buildings using nighttime cold accumulation in a phase change material (PCM), otherwise known as the “free-cooling principle”. Studies of the ceiling and floor free-cooling principle, as well as passive cooling, are presented. The free-cooling principle is explained and some of the types of...
The article presents a short review of electricity production from renewable energy sources in Slovenia. In Introduction the term of "green electricity" is defined. Comparison of structures of electricity production is presented for the years 1990 and 2003. The main part of the article presents an approximate data for technical and theoretical pote...
This paper presents a combined heat and power (CHP) unit using wood biomass to provide an energy supply for housing. The Stirling engine is used as a CHP-producing technology for which a thermodynamic analysis was carried out. The thermodynamic values were mathematically calculated and a computer program for the CHP simulation was written. A parame...
This paper presents an experimental and numerical analysis of building cooling using night-time cold accumulation in phase change material (PCM), otherwise known as the "free-cooling" or "passive-cooling" principle. The phase change materials were used in ceilings and floors. The free-cooling principle is explained and some of the types of PCMs sui...
The performance of a boiler with a built-in thermal storage unit is presented. The thermal storage unit is an insulated water tank that absorbs surplus heat from the boiler. The stored heat in the thermal storage unit makes it possible to heat even when the boiler is not operating, thus increasing the heating efficiency. A system with three compone...
The heat-transfer characteristics of a latent-heat storage unit with a finned surface have been experimentally studied in terms of the solidification and melting processes by comparing them with those of a heat-storage unit with a plain surface. Paraffin with a melting point of 30 °C was used in the investigations because it is appropriate for ther...
Podzemno shranjevanje toplotne energije ali na kratko UTES (Underground Thermal Energy Storage) je zanesljiva in energetsko varčna tehnologija shranjevanja toplote in je namenjena hlajenju in ogrevanju v stavbnih objektih in industrijskih procesih ter je sedaj že široko razširjena po celem svetu. V zadnjih dvajsetih letih je bila ta metoda aplicira...
In the paper we present a method of seasonal heat storage with boreholes and thermal response test for determination of ground parameters. Analysis methods for concrete calculations of thermal conductivity as well as error determination are explained. In the continuation measurements made in research of the ground in Turkey and situation in a field...
In this article a review of heat storage technologies with phase change materials (PCMs) is given. In addition, we present paraffin as phase change material in solar heat storage wall with proposals of heat transfer enhancement. The mathematical model for heat transport in heat storage is made. The results obtained with the simulation gives the tim...
Tendencies towards rational energy use have been appearing for the last decades due to the fact of limited quantities of fossil fuels and increased ecological awareness. Also the rising prices of all fuels should be taken into account. Since energy consumption will increase in the future, the possibility of using renewable energy resources and rati...
In this paper a model is presented and its operation of a cooling process that uses air as the cooling medium. In the introduction, conventional refrigerants are compared with an alternative refrigerant - air. The system construction and the thermodynamic model are presented. The model is used to study the performance of a CFC-free air-conditioning...
This paper presents simulations of heating and cooling loads for different types of building with the TRNSYS programme package. We present seven different building types and four different weather conditions in the European Union. Altogether we made 28 simulations and the results for an office building are shown in this paper.
In this article we present a solar wall, which absorbs solar energy into black paraffin wax which is an example of phase change material (PCM). The stored heat is used for heating the air for the ventilation of the house. Experimental results for prototype of the solar wall are presented and operation of the wall in the heating season is calculated...
In this paper we present data on phase change materials (PCM) for the storage of solar energy and list their physical characteristics. A wall section with all elements was developed in the Laboratory for Heating, Sanitary and Solar Technology at the Faculty of Mechanical Engineering in Ljubljana. A mathematical model of paraffin wax melting as an e...
Building envelope, especially wall, has been used for energy storage in many ways. The review of those methods are presented with special emphasis on phase change material utilisation. In the article we present a solar wall, which absorbs solar energy into black paraffin wax as an example of phase change material (PCM). The stored heat is used for...