Comparison of high-performance and conventional internal insulation materials based on hygrothermal analysis using in situ measurements and simulation

in Bauphysik (2022), 1

Following the European directive to reduce CO2 emissions of existing buildings by improving energy efficiency, internal insulation systems play a central role in the renovation of historically valuable ... [more ▼]

Following the European directive to reduce CO2 emissions of existing buildings by improving energy efficiency, internal insulation systems play a central role in the renovation of historically valuable buildings which cannot be insulated from the outside for reasons of monumental protection, or in cases where no additional exterior space is available. However, besides the thermal property of insulation systems, there are other relevant properties to be considered before choosing an internal insulation system, such as the hygrothermal behavior which plays a particularly important role in diffusion-open interior insulation systems. As the internal insulation layer reduces the temperature of the existing wall during the heating season, its drying potential after rain events is considerably reduced. In addition to the effects of moisture from the outside (mainly wind driven rain), the entry of humidity from the inside through diffusion plays an important role. In the presented study, high performance insulation materials with nanostructure based on silicon dioxide and polyurethane are compared to conventional material based on wood fiber from a hygrothermal point of view by analyzing in situ measurements and simulations. [less ▲]

Measured and perceived indoor comfort versus energy efficiency and users‟ control in Luxembourg‟s new school buildings

Scientific Conference (2013, September)

Room climate can be evident for job productivity and individual ́s health. Its realisation is often of high relevance for the building ́s energy consumption e.g. air conditioning vs. natural ventilation ... [more ▼]

Room climate can be evident for job productivity and individual ́s health. Its realisation is often of high relevance for the building ́s energy consumption e.g. air conditioning vs. natural ventilation. New school buildings in Luxembourg differ significantly regarding to energy consumption, heating, air-conditioning technology and technical control as well as interaction means given to the user. Several studies have shown that personal control plays an important role for the satisfaction with the room climate. Central research question was, how the technological control has to be designed that energy is used efficiently and users are still satisfied with the room climate. In this study technical features to control the room climate e.g. features for ventilation, opening windows and heating systems were summarized to an overall control factor to be compared with perceived control by the users. Physical room climate and its users ́ satisfaction level were measuredas well as the buildings ́ individual energy consumption levels were taken into account. 342 Teachers were asked by a standardised questionnaire during winter 2010/2011 in 31 new school buildings in Luxembourg, in 17 schools technical devices for air temperature, quality and humidity were installed. The results show a strong correlation between perceived control and room climate satisfaction as well as a significant correlation between the technical control factor and perceived control. Further results will be examined. [less ▲]

Energieeffizienz neuer Schul-und Bürogebäude in Luxemburg basierend auf Verbrauchsdaten und Simulationen

Doctoral thesis (2011)

In Luxemburg, energy consumption in the building and housing sector has been significantly increasing over the last years. An assessment of the energy saving potential of buildings requires a ... [more ▼]

In Luxemburg, energy consumption in the building and housing sector has been significantly increasing over the last years. An assessment of the energy saving potential of buildings requires a comprehensive data basis with real consumption figures that are not yet available. One focus of this study was to create a priori a detailed energy consumption database for new “School and Administrative Buildings” for Luxembourg. These are both groups cover a major part of the building and housing sector in Luxembourg besides residential buildings. Based on the samples collected, it was able to expand the figures to the entire country using mathematical methods and the medium heat and electricity consumption of these two types of buildings could determined. After collecting some details about each object, it was able to analyze the influence of different parameters, such as building age, size, type, glass fraction etc., on energy consumption using multivariate statistical methods. A posteriori, the results from the database were verified using parameter studies to existing objects and one object still under construction. Based on this, important key parameters relevant for both energy savings and thermal comfort could be found. This knowledge are necessary to understand energy flows within buildings better and, based on this, to be able meeting the nearly zero energy buildings requirements as set out by the EU Directive in the years to come. As conclusion, the central-European climatic zone provides opportunities to design energy-saving office and school buildings (primary energy consumption < 100 kWh/m2a) without mechanical cooling and ventilation systems that still guarantee appropriate degrees of thermal comfort. Unfortunately, the real average primary energy consumption figures of new school (187 kWh/m2a) and office buildings (677 kWh/m2a) in Luxemburg are still significantly higher. [less ▲]

Thermal comfort of a new university building in Luxembourg with passive cooling

in Thermal comfort of a new university building in Luxembourg with passive cooling (2010)

The new Luxembourgish university buildings should comply with a low energy standard, which was defined for typical offices and smaller lecture rooms by a thermal end-energy lower than 14 kWh/m3a and an ... [more ▼]

The new Luxembourgish university buildings should comply with a low energy standard, which was defined for typical offices and smaller lecture rooms by a thermal end-energy lower than 14 kWh/m3a and an electricity use for HVAC and lighting of max. 6 kWh/m3a. Consequently it was necessary to find ways to avoid the need for mechanical ventilation and air-conditioning. The heat consumption was minimized by an air-tight and well insulated building envelope. A difficulty was posed by special outside façade elements which were set-up as a grid over the complete outer surface as an architectural element. To prevent the risk of overheating during summer, it is necessary to reduce the solar gains by optimizing the window sizes and the glazing types, as well as through the installation of movable indoor shading elements. Nevertheless enough daylight should enter the rooms to limit the consumption of electricity for artificial lighting. Hence detailed dynamic simulations were performed using TRNSYS and TRNFLOW to ensure thermal comfort without active cooling. The effective electricity consumption of a newly installed state-of-the-art lighting system, including presence detectors and daylight controllers for dimming, was measured in a test installation to determine the internal loads by lighting. Radiation and illuminance measurements were performed on sample elements of the façade grid. The results were used to verify the daylight simulations and to analyze the benefits of daylight controllers. Several iterative steps were taken to gradually improve the building by introducing different modifications, e.g. reduction of the window sizes, installation of a lighting control system, improving the night ventilation and effective use of the thermal inertia of the building. [less ▲]