Tomaz Suklje | University of Ljubljana (original) (raw)
Phone: +386 1 4771 236
Address: Askerceva 6, 1000 Ljubljana, Slovenia
less
Uploads
Papers by Tomaz Suklje
Vertical greenery systems (VGSs) are becoming a common architectural element in urban environment... more Vertical greenery systems (VGSs) are becoming a common architectural element in urban environments. In addition to the aesthetics of VGSs, impacts on building's energy demand and heat island mitigation in cities has been identified. In the present study, experimental results of thermal response and properties of VGSs with vertical leaf area index (LAIV) equal to 6.1 and 7.2 are presented. Experimental results show that VGSs can impact up to 34 K lower surface temperatures of a façade, while maintaining air temperatures in the VGSs' canopies close to ambient temperatures. Properties of the VGSs were used as a basis as well as an input for a detailed mathematical model of the thermal response of a building envelope with a VGS. The validated mathematical model was used for parametrical analysis of the impact of thermal resistance of a building envelope on the cooling potential of the VGSs. The results show that the cooling effect is more significant for less insulated façades, and that a VGS can be modelled as an independent urban cooling element. Finally, a parametrical model of the latent heat flux of a VGS was developed and can be used as a boundary condition in urban heat island studies.
A microclimatic layer of the green façade is proven to have specific temperature and flow conditi... more A microclimatic layer of the green façade is proven to have specific temperature and flow conditions on the building envelope. Lower temperatures and wind velocities, and higher relative humidity in the microclimatic layer are the characteristics
of vertical greenery systems, which cause lower energy consumption for the cooling and heating of buildings. Despite innovative
architectural solutions, there are some drawbacks to applying vertical greenery on building envelopes. In this study, a bionic
façade that mimics the positive effects and eliminates the disadvantages of green façades is presented. The bionic façade consists
of bionic leaves, which are made of photovoltaic cells and evaporative matrices. A real scale experiment was carried out in the summer to evaluate the potential of the cooling efficiency of the microclimatic layer and a new photovoltaic cooling technique.
The results show a good agreement of the thermal performance between the bionic and the green façade and up to 20.8 K lower
surface temperatures of photovoltaic cells, which increase the daily electricity yield by 6.6%.
This paper presents a study of the thermal characteristics of a concentric-tube heat exchanger th... more This paper presents a study of the thermal characteristics of a concentric-tube heat exchanger that is a key element in local ventilation device. The inner tube of the concentric-tube heat exchanger has a sinusoidal, wavy surface in the longitudinal direction, which enables heat transfer enhancement. The tube can be stretched to a certain extent and thus change the corrugation of the heat-transfer surface area. We designed an experiment in which we used the Wilson-plot method to separately determine the convective heat-transfer coefficient on the inside and outside of the inner tube of the concentric-tube heat exchanger with different corrugation ratios. Based on the measurements correlation equations were developed to calculate the convective heat-transfer coefficient for any corrugation ratio, which allows us to simplify the design of local ventilation devices. Performed studies showed that, compared to a smooth tube, the convective heat-transfer coefficient increased only in the case of corrugated tubes with a corrugation ratio of less than 1.648, but the heat transfer was more intense for all considered corrugated tubes by 65% to 90% due to the increased heat-transfer surface area. The highest heat transfer rate was observed for the case of the maximum-stretched tube with a corrugation ratio of 1.401, which is advantageous also in terms of material consumption.
Conference Presentations by Tomaz Suklje
Green façades are becoming an important architectural element in an urban environment. Regarding ... more Green façades are becoming an important architectural element in an urban environment. Regarding the technology of the installation of green façades, one can distinguish between direct and indirect green façades, living walls and double skin façades with foliage. In addition to aesthetics of green façades, an impact on the outdoor and the indoor comfort has been proven. That is due to changed temperature and air flow conditions at the building envelope boundary. It has been proven that green façades impact lower surface temperatures of a building envelope and enhance thermal insulation properties of a building envelope, thus reduce energy demand of a building. Based on results from green façade thermal response research and growing interest in local ventilation systems one can conclude that there is potential for a free cooling of a building. Therefore, this paper presents the design and the preliminary experimental research of a local ventilation system coupled with an indirect green façade. Based on the experimental work it has been ascertained that the indirect green façade can impact a 5 K lower inlet air temperature for the local ventilation system compared to the one at the traditional façade.
Vertical greenery systems (VGSs) are becoming a common architectural element in urban environment... more Vertical greenery systems (VGSs) are becoming a common architectural element in urban environments. In addition to the aesthetics of VGSs, impacts on building's energy demand and heat island mitigation in cities has been identified. In the present study, experimental results of thermal response and properties of VGSs with vertical leaf area index (LAIV) equal to 6.1 and 7.2 are presented. Experimental results show that VGSs can impact up to 34 K lower surface temperatures of a façade, while maintaining air temperatures in the VGSs' canopies close to ambient temperatures. Properties of the VGSs were used as a basis as well as an input for a detailed mathematical model of the thermal response of a building envelope with a VGS. The validated mathematical model was used for parametrical analysis of the impact of thermal resistance of a building envelope on the cooling potential of the VGSs. The results show that the cooling effect is more significant for less insulated façades, and that a VGS can be modelled as an independent urban cooling element. Finally, a parametrical model of the latent heat flux of a VGS was developed and can be used as a boundary condition in urban heat island studies.
A microclimatic layer of the green façade is proven to have specific temperature and flow conditi... more A microclimatic layer of the green façade is proven to have specific temperature and flow conditions on the building envelope. Lower temperatures and wind velocities, and higher relative humidity in the microclimatic layer are the characteristics
of vertical greenery systems, which cause lower energy consumption for the cooling and heating of buildings. Despite innovative
architectural solutions, there are some drawbacks to applying vertical greenery on building envelopes. In this study, a bionic
façade that mimics the positive effects and eliminates the disadvantages of green façades is presented. The bionic façade consists
of bionic leaves, which are made of photovoltaic cells and evaporative matrices. A real scale experiment was carried out in the summer to evaluate the potential of the cooling efficiency of the microclimatic layer and a new photovoltaic cooling technique.
The results show a good agreement of the thermal performance between the bionic and the green façade and up to 20.8 K lower
surface temperatures of photovoltaic cells, which increase the daily electricity yield by 6.6%.
This paper presents a study of the thermal characteristics of a concentric-tube heat exchanger th... more This paper presents a study of the thermal characteristics of a concentric-tube heat exchanger that is a key element in local ventilation device. The inner tube of the concentric-tube heat exchanger has a sinusoidal, wavy surface in the longitudinal direction, which enables heat transfer enhancement. The tube can be stretched to a certain extent and thus change the corrugation of the heat-transfer surface area. We designed an experiment in which we used the Wilson-plot method to separately determine the convective heat-transfer coefficient on the inside and outside of the inner tube of the concentric-tube heat exchanger with different corrugation ratios. Based on the measurements correlation equations were developed to calculate the convective heat-transfer coefficient for any corrugation ratio, which allows us to simplify the design of local ventilation devices. Performed studies showed that, compared to a smooth tube, the convective heat-transfer coefficient increased only in the case of corrugated tubes with a corrugation ratio of less than 1.648, but the heat transfer was more intense for all considered corrugated tubes by 65% to 90% due to the increased heat-transfer surface area. The highest heat transfer rate was observed for the case of the maximum-stretched tube with a corrugation ratio of 1.401, which is advantageous also in terms of material consumption.
Green façades are becoming an important architectural element in an urban environment. Regarding ... more Green façades are becoming an important architectural element in an urban environment. Regarding the technology of the installation of green façades, one can distinguish between direct and indirect green façades, living walls and double skin façades with foliage. In addition to aesthetics of green façades, an impact on the outdoor and the indoor comfort has been proven. That is due to changed temperature and air flow conditions at the building envelope boundary. It has been proven that green façades impact lower surface temperatures of a building envelope and enhance thermal insulation properties of a building envelope, thus reduce energy demand of a building. Based on results from green façade thermal response research and growing interest in local ventilation systems one can conclude that there is potential for a free cooling of a building. Therefore, this paper presents the design and the preliminary experimental research of a local ventilation system coupled with an indirect green façade. Based on the experimental work it has been ascertained that the indirect green façade can impact a 5 K lower inlet air temperature for the local ventilation system compared to the one at the traditional façade.