Conference Agenda

Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

Session Overview
Session 15: RES (Renewable energy systems)
Wednesday, 25/Aug/2021:
4:00pm - 5:30pm

Session Chair: Prof. Dariusz Gawin, Lodz University of Technology
Location: Room 4 - Room 015, Building: 116

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4:00pm - 4:15pm

A bi-directional approach to building-integrated PV systems configuration

Ardeshir Mahdavi, dawid wolosiuk, Christiane Berger

Department of Building Physics and Building Ecology, TU Wien, Austria

The configuration of local building-integrated photovoltaic (PV) installations can benefit from effective and reliable computational support. Especially in cases where a high degree of energy self-sufficiency is desired, it is important to optimally match the temporal profiles of the building's energy demand and the available solar radiation intensity. In many instances, such a matching is conducted in a mono-directional manner. As such, the building's demand profile is taken as given, which is treated as the basis for the sizing and configuration of the PV installation. The computational framework introduced in this paper facilities this type of matching, but it is intended to offer additional functionalities. Specifically, the developed computational platform is conceived to facilitate a bi-directional approach to supporting the design and configuration of PV installations meant to be integrated in new building projects. Thereby, the idea is to probe pertinent building design variables such as orientation, transparent envelope elements, thermal mass, daylight use, and indoor climate control systems (for heating, cooling, ventilation, and lighting) in terms of the magnitude and temporal distribution of the resulting building energy demand. The proposed bi-directional iterative approach not only informs the configuration of PV system based on the building's demand profile, but also allows for the exploration of the consequences of the magnitude and temporal profile of the PV's energy supply potential for the aforementioned relevant building design variables. We present, in detail, the structure and elements of the developed computational platform and demonstrate its functionality in terms of a number of realistic application cases.

4:15pm - 4:30pm

Numerical assessment of self-sufficiency of residential buildings in Belgium by using heat pumps, photovoltaic panels and energy storages

Katarina Simic, Klaas Thiers, Hugo Monteyne, Jan Desmet, Michel De Paepe

Ghent University, Belgium

Pressing targets set by the policymakers of the European Union require serious changes in the current resulting trends of energy use indicators. With every new energy-saving policy, increasing the use of renewable energy sources and more efficient energy use of installed equipment remain to be the main goals. Residential buildings claim a significant share of the total energy use worldwide. In order to have a more realistic energy performance predictions, increased attention is paid to the analysis of the buildings energy use through comprehensive, transient detailed numerical simulations. In particular, part-load operation, optimal controlling principles and integration of renewable energy resources are being investigated. In this article, self-consumption and self-sufficiency of three detached energy residential buildings are assessed through numerical models made in programming language Modelica and software tool Dymola. The three buildings have the same structure and different space heating energy demand of 15kWh/m2year, 30 kWh/m2year and 45 kWh/m2year. The energy use of the buildings coincides with the occupancy profile of a family with four members with the dominating domestic hot water use over the space heating demand. The designed building systems are consistent out of the low-temperature underfloor heating system and domestic hot water demand provided by an air to water heat pump. The discrepancy between the optimal energy generation and the energy consumption is mitigated by means of thermal load shifting and electrical energy storage. The research aims to analyze the potential reach of self-consumption and self-sufficiency for the studied buildings as a function of economically favourable energy storage sizing. For the use of an electrical battery with the installed capacity of 2.5kWh and thermal energy storage of 250L, the self-sufficiency results to be 40%, 38.5% and 37% for the building energy demand of 15kWh/m2year, 30 kWh/m2year and 45 kWh/m2year respectively for the specific energy demand conditions.

4:30pm - 4:45pm

Thermal performance of ETICS, energy activated with PCM and PV

Martin Talvik1, Simo Ilomets1, Targo Kalamees1, Paul Klõšeiko1, Dariusz Heim2, Anna Wieprzkowicz2, Dominika Knera2

1Tallinn University of Technology, Estonia; 2Lodz University of Technology, Poland

Installing photo-voltaic (PV) panels on building façades is a growing tendency that helps to achieve both newly built and renovated nearly zero energy buildings. A novel approach to building active facades is to use a phase change material (PCM) behind the flexible PV. The PCM stabilises the PV’s temperature which can lead to an increase in energy production and cuts down the temperature peaks to avoid damage. In this study, Delphin 6 was used to model the thermal performance of an En-ActivETICS wall in three different locations across Europe. The model was validated against on-site temperature measurements and the results were compared to those from Delphin 6 simulations. The efficiency of the PV was calculated and an optimal PCM thickness and melting temperature were selected. The results show that annual energy production of the PV panel could increase between 2% (in Łodz) to 5% (in Madrid) using a 40mm-thick PCM. The maximum peak PV temperatures could be reduced by ca. 20°C.

4:45pm - 5:00pm

Energy demand for roof mounted heating snow load mitigation systems.

Thomas Thiis1, Iver Frimannslund1, Louise Viketun Skjøndal1, Thomas Marke2

1Norwegian University of Life Science, Norway; 2University of Innsbruck, Austria

Roof mounted solar PV systems have become a widespread use of roof surfaces on existing buildings. Particularly flat roofs on existing storage buildings and warehouses is a secure alternative to install PV panels out of reach to the public. Such solar power plants add significant load to the roof, which uses some of the load capacity originally designated for snow load. To allow for installing roof mounted solar systems on existing buildings without compromising the structural reliability of the building, one strategy is to run the solar PV panels in “reverse mode” i.e. to use electric power to generate heat and further melt away snow from the solar panels. The success of this strategy relies on several parameters, such as the amount of snow which needs to be melted, the solar radiation, the air temperature and wind velocity i.e. the turbulent surface heat transfer. All these parameters determine the electricity demand for melting enough snow to sustain the reliability of a roof in different climates. In this study, a point-scale, physically based energy balance snow model (ESCIMO) is used for simulating snow accumulation and ablation on a roof with variable installed power for snow melting. Different strategies for when to melt snow are tested and the energy demand for different situations is investigated. The study describes which melting strategies are suitable for different climates and quantifies the required energy demand for keeping the snow load under a target lever for buildings with added solar PV panels or roof mounted heating systems for mitigating snow load. The results show that the average melting energy is between 2-25 kWh/m2 depending on the climate and the melting strategy and that a melting system requires more than 100/m2 kWh to have significant effect

5:00pm - 5:15pm

System-Scale Modeling of a Building Envelope-Integrated, Transparent Concentrating Photovoltaic and Thermal Collector

Nick Novelli1, Justin Shultz2, Mohamed Aly Etman1, Kenton Phillips3, Melanie M Derby4, Peter R H Stark5, Michael Jensen6, Anna Dyson1

1Yale University, New Haven, CT, USA; 2EYP, Washington DC, USA; 3Buro Happold, New York, NY, USA; 4Kansas State University, Manhattan, KS, USA; 5Harvard University, Cambridge, MA, USA; 6Rensselaer Polytechnic Institute, Troy, NY, USA

The buildings sector is a principal contributor to global greenhouse gas emissions, but consistently trails other sectors in innovations for harnessing climatic energy resources (such as solar) that could support net-zero and even net-positive operation. New building technologies could trigger disruptive strides towards the resilience, self-sufficiency, and health of the built environment, but if the integration and effects of these technologies are not understood in the multiple contexts in which they operate and against all relevant criteria, their potential is difficult to project. To explore the value of the built environment’s capacity to metabolize solar energy, a previously-developed analytical model of a Building Envelope-Integrated, Transparent, Concentrating Photovoltaic and Thermal collector (BITCoPT) was parameterized to project electrical and thermal energy and exergy production (cogeneration) over a range of orientations and operating temperatures. Simulated annual cogeneration efficiency was noted at 27% (exergy) at an operating temperature of 55°C, and up to 55% (energy) at 25°C. It was noted that exergetic efficiency remained nearly constant as operating temperatures increased through 75°C, indicating the thermal energy collected would be suitable for driving heat engine processes such as adsorption chilling. Although the scope of this study doesn’t include the system’s projected broader (building-scale) benefits of daylighting (lighting load reduction), and reduction of solar gains (cooling loads) in occupied spaces, these efficiency results suggest BITCoPT is worth further investigation for on-site net-zero and energy-positive commercial building design, and might contribute to expanding opportunities for net-zero and energy-positive architecture.

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