• Energy Research

Abstract This paper shows the investigation of the features of facade greening, concerning the reduction of heat demand in the winter. Supporters of facade greening claim that their systems can reduce the heat demand in the winter. But so far, there is no proof for that and each greening system is different. Two greened facades have been researched and measured for one heating season. The measurements were compared with parts of the same buildings which are not greened. So far there does not exist a general method, how to calculate the U-value at greened facades. The method which is developed in this paper makes the comparison between the greened part of the facade and the not greened part possible. It turned out that there is a difference of the thermal resistance between greened and not greened parts of the facades in winter. It is between 0,31 m 2 K/W and 0,68 m 2 K/W depending on the greening system and its location.

Strategies to mitigate urban heat islands are a recent issue in the Austrian capital, Vienna. In this study, the uhiSolver-v2106-0.21 software was used to evaluate the summer cooling effects and humidity production of small-scale facade greening and a green pergola located in two schools within the city. Based on on-site measurement data, the study revealed that small-scale greening measures are not able to substantially reduce ambient air temperature. On a hot summer day, at 3 p.m. local time (CEST), the maximum decrease amounted to 0.3 °C at 0.1 m from the facade greening as well as inside the green pergola. As for the apparent (perceived) temperature, a reduction of up to 4 °C was observed under the green pergola compared to the unshaded roof terrace. Hence, the simulation results show that, within urban areas, a significant improvement of thermal comfort in summer can only be achieved through large-scale greenery that provides shade for pedestrians.

Abstract Sustainability and energy efficiency in buildings are currently evaluated not only based upon thermal insulation thickness and heating demand, but also according to primary energy demand, CO2 reductions, and ecological properties of the building materials. These properties are essential for a holistic assessment. To meet the requirements which are increasing in rigor, the demand for ecological building materials is growing dramatically, particularly insulating materials from renewable resources. Ecological insulation materials have been available on the market for a long time; however, conventional materials are still predominantly used. Most builders are unsure whether the alternative materials meet the same performance requirements as conventional building materials and supporting scientific research and publications are difficult to find. In a joint project of the Brno University of Technology and Vienna University of Technology, the thermal insulation from sheep wool has been tested under various conditions. The building physics and acoustic properties were specifically tested which are important for durable and undamaged applications. The tests results show that the thermal insulation from sheep wool has comparable characteristics with mineral/rock wool, and in some applications even performs better. Additionally, in comparison to mineral wool, sheep wool is more ecological and has fewer damaging health aspects.

Abstract Testing of the actual properties of insulation materials is usually connected with the actual situation when measurement realization requires suitable weather conditions, for instance the winter time. The previous research [6] , in which measurements of polystyrene were conducted, was testing its thermal properties under actual conditions every 30 min, being directly dependent on the building environment where the insulation material was tested. Laboratory simulation of the actual application on the outside of the building to test the thermal properties of insulation materials can circumvent the dependency on the actual environmental conditions during the experiment. Here the actual thermal conductivity through the material of a specific thickness was tested using a new experimental measuring method. The method is based on generating an outside temperature of −18 °C using the Peltier module on one side of the block-shaped piece of insulation material. The methodology also enables testing of the internal thermal behavior of the material with the proper thickness as well as the shape of the material. The research results are especially useful when deciding on the effective thickness of the building’s insulating material; using statistical methods. The analytical expression of the insulation properties inside the material would also serve for that purpose.

Abstract Recent years have witnessed growing concern about climate change's impact upon office buildings’ performance in regard to energy consumption and indoor thermal comfort. A vicious circle of raising outdoor temperatures and consequently increasing CO2 emissions associated with raising energy demands for cooling during summer heat waves is anticipated in this respect. This paper builds upon regionally downscaled weather data from future climate scenarios and applies these to dynamic thermal simulation of nine sample office buildings in Vienna, Austria. Values of both heating and cooling demands under current and future conditions are calculated and compared: while heating demands slightly diminish, cooling requirements generally rise significantly. Distinct differences in energy performance of buildings from different periods of construction can be observed. Due to the buildings’ respective constructions its overall energy demand raise, stagnate or even slightly decrease under conditions of climate change.

The paper describes the experiences with passive houses that have been built and operated in Vienna during the last years. The first part of the paper is the description of the projects; the second part presents measurement results during the first years of operation regarding indoor climate and energy consumption. The third and main part describes the lessons learnt regarding the necessary accuracy of calculations in the design phase with special focus on solar shading, internal loads, thermal bridges, and the distribution losses of hot water and the heating systems. ASHRAE Buildings XI Conference paper #61

The building sector is one of the highest energy consumers in Austria. The potential to save energy in existing buildings is very high. Current Austrian policy incentives encourage home owners to renovate buildings to meet the European requirements, reduce energy consumption, and reduce CO2 emissions. Nevertheless, there are often discrepancies between the measured and calculated energy consumption results despite efforts to take parameters into account such as the exact geometry and thermal properties of the building, energy demand for hot water, heating, cooling, ventilation systems, and lighting in the planning phase for selecting the best reconstruction option. To find the answer to this problem, many buildings are carefully investigated with the help of measurements, interviews, and simulations. This paper presents the analysis and results of the investigation of the impact of lifestyle on the energy demand of a single family house. The impact on energy performance of the most important parameters was observed by systematically changing parameters such as changing from a decentralized to a centralized heating system, considering various technologies and fuels for producing electricity and heat, use of renewable energy sources. Different occupant behaviours were changed systematically. The effects of these measures are analysed with respect to primary energy use, CO2 emissions and energy costs. The results of these investigations show that the lifestyle and occupants’ living standard is mainly responsible for the differences between the calculated and measured energy consumption.

Façade greening at the intersection between buildings and urban space offers an optimal opportunity to integrate greenery into increasingly dense cities and influence the microclimate and contribute to high quality of life in urban areas. Despite proven numerous positive effects, there is still a lack of implementation and practical relevance is low until now. To integrate existing greening systems directly into future planning processes and thus keep up with the advancing digitalization in the building sector, an integration of these systems into Building Information Modeling (BIM) is urgently needed and in connection to this, the implementation of an automated planning process to support easier realization of greening projects contributing to a sustainable urban development. Therefore, BIM objects were created for five façade greening systems after analyzing the necessary basic data. Subsequently, an automated process was used to optimize the time-consuming conventional planning process of façade greening, with the aim of evaluating the simulated greening variants based on defined parameters. A case study presents the application of the prototypes and the possible calculations over the life cycle of the building. This development holds great potential by simplifying the process of decision-making and placing façade greenery on buildings.

With the introduction of energy-efficient buildings, the importance of embodied energy in new buildings has become increasingly relevant to minimising the impact of climate change. This study compares two existing four-storey residential buildings: one building has a reinforced concrete (RC) structure and the other has a timber structure. The study’s aim is to find out which building components are responsible for the largest embodied impacts and whether there are differences between the two construction methods. The specificity of the wooden building is the combined use of solid and lightweight timber elements. The methodology consists of a general life cycle assessment (LCA) and a more detailed analysis of the product stage using the eco2soft software. The heating and cooling energy demand was calculated using the WUFI Plus software with recent regional climate data sets. The results show that for both types of construction in multi-storey buildings, it is not only the superstructure that needs to be considered, but also the floor structures, which have a major influence on the embodied impact. The timber building requires less energy to maintain the indoor climate within the set temperatures. As climate change has progressed rapidly in Austria in recent years, it is recommended that the standards for climate models be updated more quickly to allow realistic prediction of thermal comfort at the design stage.