12th Envibuild – Buildings and Environment – From Research to Application

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Authors: Enrique Gil, Carlos Lerma, Sara Llop, Ángeles Mas, Jose Vercher
Abstract: A low-cost data acquisition system that records information with K-type temperature probes and Dallas thermometers has been designed to carry out this research. For this, both the software and the hardware have been designed. A specimen was conducted for the thermal analysis of a homogeneous prism of a building wall. Environmental conditions have been controlled in laboratory. Four of the prism faces are thermally insulated with nearly adiabatic conditions. A source of heat is placed on one of the two uninsulated faces of the prism. This induces a temperature gradient in the wall. A sufficient set of thermometers is introduced into the prism to control the temperature gradient. The data acquisition system consists of Arduino-based controllers. The temperature at each moment can be accurately controlled with them. The data generated are saved in a file for later analysis, and to publish them on a web page is possible for real-time queries. These data allow to validate the finite element simulation model which has been carried out for this specimen. Thus, the results of the specimen have been compared with the data obtained from the model, and this allows to extrapolate the model for the thermal analysis of other façades.
Authors: Balázs Nagy, Dóra Szagri, Dániel Bakonyi
Abstract: The paper discusses an experimental hygrothermal analysis of differently constructed additional mineral wool wall and attic insulation of a family house in Hajdúnánás, Hungary. The walls of the building were insulated in two different ways: half of the façade was insulated with Knauf stone mineral wool insulation boards glued to the walls in a continuous mortar bed as recommended, and on the other side of the same façade, the boards were glued only with patches of mortar. In the attic of the same building, one part of the attic was insulated by using Knauf glass mineral wool insulation batts along with vapour permeable underlay membrane as recommended, while the other part was constructed without underlay. Temperature and relative humidity sensors were placed between the layers and heat flux sensors were installed on the internal surfaces of the two differently constructed wall and attic insulations. An external meteorological station was installed on an unused chimney of the building. Besides the structural sensors, temperature and relative humidity sensors were installed in each room, and the energy consumption of the building was also monitored during the measurements. For control values, we monitored the internal hygrothermal conditions and the energy consumption of an identical but uninsulated family house only 8 km away in Hajdúdorog, Hungary. In the article, we analyze the heat and moisture transport through the building constructions and the energy consumption of the family house according to the recorded data of a full heating season.
Authors: Richard Slávik, Miroslav Čekon
Abstract: Building performance simulations and advanced thermal analysis are becoming the basis for a well-established practice of a building sector. This approach requires many input data which are typically not available on site. Apart from already well-practiced climate variable quantities, such as ambient temperature, solar radiation and parameters of wind, more complex data are needed for advanced building thermal analysis. One of those is based on longwave radiation level. A pyrgeometer is a device that measures longwave radiation part of whole thermal radiation phenomena. This can be determined based on sky or effective ambient temperature monitoring. Secondly, both variables might be approximated by infrared sensors as an applicable option in the calculation of longwave radiation heat exchange between the external surface and the ambient building environment. The paper presents data obtained both by pyrgeometer and infrared sensor corresponding to their mutual comparison to demonstrate its application when longwave radiation exchange needs to be calculated or analyzed in advanced. Integrating of the infrared sensor with aim to monitor the effective ambient and/or sky temperature enables its applicability as an alternative, integrated and less cost consuming method towards the monitoring by commercial pyrgeometer.
Authors: Thomas Schoberer, Jan Weyr, Gernot Steindl, Gregor Görtler, Werner Stutterecker
Abstract: For nearly Zero Energy Buildings, it is a challenge to optimize the heat supply of the building based on technologies like heat pumps. Within the project “energy4buildings” a test bench has been realized to create an interface between hardware, located in a laboratory, and a building simulation software. This integrated test bench with a focus on electrical driven heat pumps and chillers can be used to simulate realistic conditions like part load behavior, stand-by-losses, on/off behavior or user-/weather conditions by using different kind of building models. The requirements of the test rig have been realized by using a hardware-in-the loop (HIL) method, which allows real-time tests of embedded devices within a virtual environment under reproducible laboratory conditions. By using the HIL-method, early statements according performance with a reduction of costs under realistic conditions can be made for various devices. This paper describes the implementation of the HIL-interface consisting of hardware, simulation software and data acquisition including an optimization of the behaviour of the control system as well as HIL experiments at varying steady state conditions like temperature tolerance or holding time. Based on the tests both, a comparison of the performance and analyses of deviations between real and simulated value have been made, to make an accurate statement of the behaviour of the system. The knowledge gained in this paper indicates a potential for optimization of the control strategy of some components as well as the improvement of the communication process to make an early estimation regarding performance of the installed device.
Authors: Enrique Gil, Fernando Gómez, Ángeles Mas, Jose Vercher, Carlos Lerma, Jorge Lopez
Abstract: A reasonably accurate, low-cost system for the monitoring of strains in simple physical models within the field of Structural Engineering, based on Internet of Things, is presented, calibrated and discussed. The system only requires average, economic devices as Arduino microcontroller and strain gauges. Several tests on a case study of a scaled-cantilevered aluminium beam with different loading are conducted. Governing parameters are calibrated aimed at an optimization when benchmarked against theoretical and experimental results obtained with a reference device. Results show great accuracy; however, the need of setting of the parameters campaign-by-campaign, especially aimed at dealing with thermal drift, becomes a shortcoming. Still, its minimum cost and user-friendly management makes it a suitable solution for different applications.
Authors: Matthias Schuss, Farhang Tahmasebi, Ardeshir Mahdavi
Abstract: Buildings are responsible for a major amount of the annual energy consumption. A detailed recording and evaluation of building data could provide a deeper understanding of building operation schemes and the corresponding performance. This could help building owners and operators to evaluate and better understand the actual situation. Based on this (real-time) data an optimized operation scheme can be designed and implemented for future time steps. Additionally, a more detailed understanding of the impact of previous building systems interactions will be possible. The building automation industry and the related service provider sector are actually providing proprietary solutions for data logging, visualization and energy optimization. Such solutions are regularly integrated into their own specific software of the used proprietary building management solutions. As an alternative, we suggest an Internet of Things (IoT) and web services inspired concept for the implementation of a generic web service for building diagnostics. Our suggestion encompasses a holistic performance evaluation that considers both the energy consumptions and delivered building service. In this contribution, a general design of a web service based solution is presented and the future possibilities for data access from various sources are discussed. Furthermore, details of actually developed and demonstratively implemented software components for data preprocessing are presented. Data processing examples for different types of data are included and highlight the potential of such web-based approaches. Moreover, possibilities for improved building control by the use of web services for operation schedule generation or model predictive control are illustrated and critically debated.
Authors: Christoph Moser, Gerald Englmair, Hermann Schranzhofer, Andreas Heinz
Abstract: A TRNSYS model of a novel PCM heat storage, utilizing stable supercooling of Sodium Acetate Trihydrate (SAT), is presented. To achieve high solar fractions in heat supply of single family houses, the necessary integration of big water volumes is challenging. To evaluate its functionality, a system model of a solar thermal combisystem for space heating and domestic hot water supply for dynamic system simulation was built. The key component is a PCM volume for long term heat storage. While conventional heat storage concepts with SAT release the latent heat a few degrees below the melting temperature, with the concept of stable supercooling latent heat can be stored for long periods of time at ambient temperature. This allows the design of a partly loss-free storage. Solar fractions were evaluated for simulation runs with two building variations. Annual specific space heating demands of 15 and 30 kWh/(m2a) and a domestic hot water demand of a typical single family house were considered. A sensitivity analysis on solar fractions of domestic heat supply was performed by variation of the collector field and the PCM volume. While the increase of the PCM volume from 4.5 m3 to 9 m3 shows moderate effects in all simulation runs, an increase of the collector area has substantial effects on the share of solar heat on the total energy demand of the building.
Authors: Werner Lerch, Richard Heimrath, Andreas Heinz, Thomas Mach, Christian Fink, Thomas Ramschak
Abstract: The Austrian project “solSPONGEhigh” [1] examines the use of thermal activation of building components in order to increase the solar fraction of the heat demand of buildings. The aim of the project is to evaluate, under which conditions a high solar fraction of a single family house (low energy building) can be achieved with solar technologies (PV and solar thermal, in this paper the focus is on solar thermal). Different heat supply systems based on solar thermal energy (basic or complex supply systems) have been defined. The systems were modeled in the simulation environment TRNSYS [2], analyzed concerning their system behavior and further developed. The investigated systems range from classical monovalent heat supply systems, systems combined with solar thermal up to complex integrated hydraulic solutions. The heating of the building via concrete core activation was compared with a conventional underfloor heating system. A detailed analysis of the dynamic system and building simulation results shows that the system efficiency can be significantly increased, if solar heat is used to charge the storage capacity of the building structure directly. A further advantage when activating the building structure (primarily concrete) is the less rapidly changing room air temperature with strongly fluctuating environmental conditions.
Authors: Ondřej Šikula, Pavel Charvát, Lahouari Adjlout, Omar Ladjedel
Abstract: The topic of the contribution can be included in computer modeling of the thermal behavior of radiators for heating of buildings. Control of heaters leads to dynamic phenomena affecting the final thermal state of the heated room and heating energy consumption. The paper focuses on modeling of radiator quantitative control method using thermostatic valve. The objective of the paper is to show a quality of controlling and to compare an energy consumption when various thermostatic radiator valves time delay are set. The models of control, radiator, and a room are implemented in software TRNSYS. The results show significant differences in energy consumption.

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