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
Poster introductions 18: Solar radiation and energy
Thursday, 26/Aug/2021:
11:35am - 12:00pm

Session Chair: Gregers Reimann, IEN Consultants Sdn Bhd
Location: Room 3 - Room 013, Building: 116

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11:35am - 11:38am

Study of the impact of the type, orientation and temperature of solar panels on their actual efficiency in the Latvian climate conditions

Daniels Marks Heincis, Andris Jakovics, Jevgenijs Telicko

University of Latvia, Institute of Numerical Modelling, Latvia

As solar panel technologies become more and more popular and are increasingly used nearly zero energy building solutions, it is necessary to make sure that the panels are able to achieve performance indicators such as those established by manufacturers under standard test conditions in real-life conditions. Standard test conditions are: 25°C ambient temperature, 1000 W/m2 solar radiation intensity. In real operating conditions without geographical location, cloudiness factor also plays an important role in solar panels efficiency. In order to determine the efficiency of poly- and monocrystalline panels, depending on their spatial orientation, a set of test panels was installed in Riga in Latvia in 2018 for the long-term monitoring of the energy produced. The panel system consists of 10 solar panels set up in five different orientations such that panels of either type, polycrystalline or monocrystalline, are tested for every orientation. The panels have been set up on the roofs of the buildings to reduce shading by surrounding objects such as trees. This article summarizes the results for the first two years. In the autumn of the second year of monitoring, temperature sensors were installed on solar panels to study the effects of temperature on panels efficiency. We analysed the amount of energy that solar panels can potentially produce by assessing the incidence angle of solar radiation and its intensity (W/m2). The data show that the panel's spatial position plays a major role in the amount of energy produced. The efficiency of the panels varied strongly over the various months of the year, but overall, in the Latvian climate, only a small share of total energy is produced during the autumn and winter months. To make a generalization of the results possible it is planned to continue the monitoring for several years.

11:38am - 11:41am

Comparing statistical modeling techniques for heat loss coefficient estimation using in-situ data

Xiang Zhang, Katia Ritosa, Dirk Saelens, Staf Roels

KU Leuven, Department of Civil Engineering, Building Physics Section, Kasteelpark Arenberg 40 Bus 2447, 3001 Heverlee, Belgium

The combination of in-situ collected data and dynamically statistical modelling techniques have shown to be a promising approach in ‘real’ building energy performance assessments. Solar gains, generally indicating the overall indoor energy gains supplied by solar radiation, play a vital role in the energy performance assessment. Thus, a precise estimation of solar gains can considerably contribute to reduce the assessment uncertainties on building energy performances, such as the actual overall heat loss coefficient, or to enhance the accuracy of prediction models as in model predictive control (MPC). Nevertheless, current data-driven approaches often oversimplify solar gains and in-depth knowledge of dynamic solar gain estimation is lacking.

In this study, two candidates of statistical modelling techniques, grey-box and autoregressive with exogenous terms (ARX) models, are developed to fill this gap. To be trustworthy, the statistical estimating outcomes are verified by full building energy simulation results. Moreover, the pros and cons of those two modelling techniques in solar gain estimation are compared.

Based on field data of a portable site office (PSO), it is concluded that both grey-box and ARX modelling can not only reflect the key dynamic information of solar gains but also only require a limited-size low-frequency dataset. The dynamic models merely ask no more than a one-week-long hourly dataset with 5-7 parameters (e.g. indoor/outdoor temperature, heating input, solar radiation, and wind speed). By contrast with ARX model, grey-box modeling demands more expertise and is harder to apply, but delivers better physical interpretations on estimation outcomes. Oppositely, the ARX models are relatively weaker at the interpretation of parameters, but easier on the implementation.

11:41am - 11:44am

Innovative approaches to thermochromic materials for adaptive building envelopes

Gloria Perez1, Valentina Serra2, Samira Garshasbi3, Fabio Favoino2, Paloma Sirvent1, Kwok Wei Shah4, Pablo La Roche5, Isabel Galán6, Mattheos Santamouris3

1Institute of Construction Science Eduardo Torroja, Spain; 2Politecnico di Torino, Italy; 3University of New South Wales, Australia; 4National University of Singapore, Singapore; 5California State Polytechnic University Pomona, USA; 6Graz University of Technology, Austria

Thermochromic (TC) materials are characterized by a change of their optical response at a specific temperature. They can work based on both, the alteration of solar reflection by temperature, or the change of photoluminescence intensity. In building applications, this type of smart materials enhances the rejection of solar heat for high temperatures to favour cooling of the envelopes and reduces this rejection for low temperatures to improve surface heating. This adaptive optical response improves energy efficiency and reduces environmental impact of urban areas. Most of the current advances in this area are related to TC glazing based on Vanadium oxide, while opaque TC materials have been developed as based on Leuco dyes. The main drawback of these last materials is their significant aging in outdoor applications due to a photo-degradation process. The present work shows the recent results of a multidisciplinary and multinational consortium for research on innovative approaches to thermochromic materials for adaptive building envelopes. Next steps will be focused on building simulation to evaluate material choices across different performance aspects, while physical prototypes will be used for inter-laboratory evaluation of such performance and material durability.

11:44am - 11:47am

Control-oriented model for air-based BIPV/T systems

Anna-Maria Sigounis, Efstratios Dimitrios Rounis, Andreas Athienitis, Charalampos Vallianos

Concordia University, Montreal

This study presents the development of a control-oriented model for Building Integrated Photovoltaic Thermal (BIPV/T) systems. Model-based control strategies could optimize their coupled operation with the building Heating Ventilation and Air-Conditioning (HVAC) system and maximize the heat utilization. Two transient simulation models (1st order and 2nd order) are developed using Python, validated with experimental data and compered to each other. Finally, simulation results are presented where the range of possible outlet air temperatures for different mass flow rates are identified.

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