Tilmann E. Kuhn

Tilmann E. Kuhn
Fraunhofer Institute for Solar Energy Systems ISE | ISE · Energy Efficient Buildings

Dr., Dipl. Phys.
Editor Energy and Buildings https://www.journals.elsevier.com/energy-and-buildings/

About

93
Publications
32,643
Reads
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1,612
Citations
Citations since 2017
35 Research Items
1184 Citations
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
Additional affiliations
July 1999 - July 2021
Fraunhofer Institute for Solar Energy Systems ISE
Position
  • Head of Department

Publications

Publications (93)
Article
Full-text available
This paper deals with the state of the art of advanced solar control devices for buildings, with the comparative evaluation of solar-control systems and with guidelines for the development of new solar control systems. It includes multifunctional systems with building integrated photovoltaic (BIPV) and/or building integrated solar thermal (BIST) en...
Article
This study evaluates the performance and robustness of 22 established and newly proposed glare prediction metrics. Experimental datasets of daylight-dominated workplaces in office-like test rooms were collected from studies by seven research groups in six different locations (Argentina, Denmark, Germany, Israel, Japan and the United States). The va...
Article
Full-text available
This paper reviews and analyzes technological design options, which have become available to date for BIPV systems on roofs and facades, independently of specific products or building projects. This means that this survey does not analyze existing products or realized buildings, but provides an overview of the technologies for BIPV. The starting po...
Article
Full-text available
The solar protection feature of shading devices is characterized by the Solar Heat Gain Coefficient (SHGC) or g-value. Given their complex light-scattering properties, it is advisable to test innovative shading devices calorimetrically in a laboratory. In the case of an indoor calorimetric facility, a solar simulator is required as the light source...
Article
The digitalisation of the Architecture, Engineering and Construction domain introduced new methods for digital collaboration, i.e. Building Information Modelling (BIM). While this method focuses on building data, the distribution of digital product models is still problematic, complicating uniform product searches and automated product data process...
Article
Neben der Optimierung von energetischen und elektrotechnischen Leistungseigenschaften sind zur Erfüllung einer sowohl sicheren als auch zuverlässigen Fassadenintegration von BIPV-Modulen für die Produktverwendbarkeit europäische Spezifikationen zu beachten und die Landesbauordnungen. Hinsichtlich Bemessung, Konstruktion und Ausführung sind für die...
Article
Full-text available
Current discomfort glare prediction metrics usually account for at least one of the two categories of effects that induce discomfort glare – the saturation and contrast effects. Saturation-driven metrics (overall illuminance on the eye) are suited for brightly lit scenes in general. On the contrary, contrast-driven metrics (luminance ratio in the f...
Article
Full-text available
We introduce a photonic color concept for integrated photovoltaic modules. Taking up the inspiration from the Morpho butterfly with its brightly colored wings, we developed this photonic concept further to achieve an improved angular independent color effect, suitability for module integration, and compatibility with industrial production processes...
Article
Full-text available
Solar thermal venetian blinds (STVB) pursue the goal of reducing the primary energy demand of buildings with highly transparent façades during operation. They can provide solar control and daylighting functions and at the same time function as a solar thermal collector. A technical overview of STVB based on a design parameter space, which can be us...
Conference Paper
Full-text available
Dieser Beitrag stellt eine zweistufige, wissenschaftliche Methode zur gebäudescharfen BIPV-Potenzialanalyse vor, die in Form einer Vollanalyse des deutschen Gebäudebestands nicht nur Dachflächen, sondern auch Fassaden in die Erhebung mit einbezieht und dabei den Einfluss von Verschattung für jede Teilfläche der Gebäudehülle per Strahlenganganalyse...
Article
Recent improvements in the manufacture of textiles allow enhanced functionality in architectural applications. In this study, a switchable and angle-selective shading system is developed on the basis of a new textile structure. The geometry of the textile structure is optimized through a simulation-based approach. Textiles are characterized by Bi-d...
Technical Report
Full-text available
Task 56 is part of the Solar Heating and Cooling Programme (SHC) of the International Energy Agency (IEA). Within Task 56, Subtask B aims to develop tools and strategies to foster the market penetration for industrialised solar envelope systems. This report outlines strategies for stakeholders of solar building envelopes (SBE) in order to deal with...
Technical Report
Full-text available
Standards are evidence based on science, technology and practice. Test standards are rating procedures designed to give consistent outcomes. They are based on compliance organized and approved by a legally or consensually recognized body. They provide requirements, procedures and guidelines for testing design, installation, use and disposal. Standa...
Article
Rule-based control logics have proven to be efficient for automation of shading and lighting systems. However, successful commissioning of these systems for multiple stores non-residential buildings, regardless of the control logic, requires time-consuming programing and fine-tuning of numerous parameters. In this article, a control approach is sug...
Conference Paper
DC-DC power optimizers present a promising approach to minimize losses in photovoltaic systems integrated into buildings (BIPV). Compared to free-standing PV plants, BIPV systems are often geometrically very complex, leading to a more complicated electric circuit and effects like partial shading and hot spots. We addressed the complex electrical de...
Conference Paper
Full-text available
To reach future Net-Zero Energy Buildings as requested by the "Energy Performance of Buildings Directive" (EPBD, [1]) the integration of systems for harvesting of renewable energy is decisive. Building integrated solar thermal (BIST) collectors can play an important role in this paradigm shift. In the R&D projects ArKol and TABSOLAR multidisciplina...
Article
In this contribution, a new model of switchable insulation element is introduced. This element essentially consists of a double glazing unit with a translucent insulating panel mounted inside. Switching of the U-value is achieved by control of an internal convective flow around the insulation panel. The element can be in an insulating state with a...
Chapter
Full-text available
Relatively recent cultural and technological changes, particularly in Westernized societies, have led to habitat and lifestyle shifts that have gradually estranged us from daylight. Although human beings are resilient and appear able to cope with extreme variations in environmental and living conditions, this process of separation can have negative...
Article
A new controller for office spaces with venetian blinds has been developed to explicitly address both daylight maximization and glare control. Conventionally, systems that operate on these principles require numerous sensors to monitor the visual conditions in the room, leading to expensive, complicated and impractical installations. To address thi...
Conference Paper
Full-text available
Photovoltaic systems that are integrated into buildings face several challenges compared to free-standing PV plants. Besides their multi-functionality and a more complex construction process with the constraints given by a building and its facades and roof, BIPV systems are often geometrically very complex, leading to a more complicated electric ci...
Conference Paper
Full-text available
In order to support acceptance and attractivity of building integrated PV (BIPV), there is a rapidly increasing demand for coloured PV modules. Especially, architects and building planners wish an individual colour choice, saturated colors, a homogeneous appearance for all angles of incidence and at the same time a high module efficiency. Furthermo...
Article
This paper presents a method to evaluate the thermal impact of complex fenestration systems on the energy balance of a building zone based on Directional Solar Heat Gain Coefficients (DSHGC) and Bi-directional Scattering Distribution Functions (BSDF). The proposed methodology is presented as an alternative to layer-by-layer heat transfer models. An...
Article
Based on an analysis of building processes to date, this paper proposes two ways to make Building Information Modelling (BIM) and with it complex building processes less expensive and more reliable. First, existing experience with building processes that include building-integrated solar systems is analysed, as they are one example for buildings wi...
Article
In this paper, the potential of a facade element with switchable U-value and g-value is investigated. This new switchable facade element consists of a series of air-filled cavities separated by opaque films, that can be rolled up or down between two fixed layers, thus switching the thermal and optical properties from a thermally insulating state to...
Conference Paper
Full-text available
Although fabrics are widely used as shading devices, reliable simulation models are rather rare and therefore the choice of a fabric with appropriate material characteristics is difficult. This paper presents a simulation model, which can be applied to most of the common available fabric shading materials. Furthermore a comprehensive simulation stu...
Article
Full-text available
Solar building envelopes are attracting increasing interest. Building-integrated solar thermal (BIST) systems are one of the subgroups of solar building envelopes. This paper summarizes the most important contributions of recent years and extends them. First, BIST elements are defined and available BIST elements are presented. Then, the general fun...
Article
Full-text available
Active building envelopes have provided cost reductions of 40% compared to the separate installation of solar collectors on a building envelope. However, solar building envelopes are more complex than conventional building envelopes due to their additional solar function. Firstly, the paper explains this complexity before describing methods of hand...
Conference Paper
Full-text available
Über eine Fläche von etwa 70 m² ist eine architektonisch integrierte BIPV-Anlage seit Oktober 2015 in der Kaltfassade eines Laborbaus am Fraunhofer-Institut für Solare Energiesysteme ISE im Betrieb. Von einer ersten Installationsphase speisen zehn der BIPV-Module schon seit Ende August 2013 Strom ins Netz. Für die gesamte BIPV-Anlage wurden 70 rand...
Technical Report
Full-text available
The report has the following permanent identifier: urn:nbn:de:0011-n-4190528 Please use this number if you cite the document. This report is partly based on the results of task 1.1 ‘Identification of requirements for the building from the point of view of architects, photovoltaic (PV) producers, plant manufacturers and construction companies. Bas...
Article
The generated electricity of a rather complex building-integrated photovoltaic system, installed in the main building of the Fraunhofer Institute for Solar Energy Systems, is analyzed in detail. For this purpose, the measured irradiance on the tilted surface, the temperatures of the PV modules, the DC power and the AC power are compared with the re...
Article
Since summer 2013, 15 m2 of angle-selective PVShade® glazing in the spandrel zone of a seminar room at the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg has provided seasonal solar control and selective visual contact and generated electricity photovoltaically (PV). The PVShade® element was invented and patented by one of the author...
Article
This paper addresses the definition of a new criterion Raout−in to evaluate the color rendering of objects in a room viewed by an observer who is outdoors. This is not only relevant when outdoor observers are viewing persons in the room. It is also frequently taken into account when the color of internal solar-control or glare protection systems is...
Technical Report
Full-text available
The full set of information on the study "Flexibility concepts for the German power supply in 2050. Ensuring stability in the age of renewable energies" can be found on http://www.acatech.de/de/aktuelles-presse/dossiers/dossier-stromversorgung-2050.html and the main document with the study in English is available on http://www.acatech.de/de/publika...
Article
The indoor environment in retrofitted pilot demonstration offices, equipped with advanced radiant ceiling panels that were used for heating and cooling, is evaluated in the paper. Comprehensive analyses based on various sets of real case measurements were carried out in order to assess the efficiency and adequacy of the proposed retrofitting concep...
Conference Paper
Colored photovoltaic modules with high angle tolerance can be achieved using the photonic Morpho butterfly effect. Mimicking this effect, we achieved various saturated colors and demonstrated the technology on large area module glass.
Conference Paper
Full-text available
Building-integrated photovoltaic thermal collectors (BIPVT) can provide an increased PV performance and renewable low temperature heat at the same time. Building-integrated solar thermal systems (BIST) offer lower costs and higher performance than building-added collectors. However, active building skins are more complex than conventional building...
Article
Full-text available
In order to achieve significant savings in energy and an improved level of thermal comfort in retrofitted existing buildings, specific retrofitting concepts that combine new technologies and design need to be developed and implemented. Large radiant surfaces systems are now among the most promising future technologies to be used both in retrofitted...
Article
Abstract Building-integrated solar thermal systems (BIST) outperform building-added solar thermal systems (BAST) due to smaller heat losses at the back of the collector. BIST offer economic advantages, too. The insulation behind the collector can be used to reduce the heating demand of the building as well as to increase the solar thermal yield. Th...
Article
This study presents and demonstrates a methodology for calculating the economic potential of photovoltaic installations in urban areas including the previously often disregarded potential on building façades. The analysis of a 2 km2 urban area has shown that building façades there provide almost triple the area of building roofs. However due to non...
Article
Full-text available
Within the Aktifas project, a road map is being developed for research and development of façade-integrated solar thermal systems. The road map is based on an analysis of the barriers for façade-integrated solar thermal systems as well as a market overview of existing components. This paper presents the methodology for creating the road map as well...
Article
A new Radiance-based modelling approach called Fener is presented. The motivation is to be able to perform detailed analyses of complex fenestration systems (CFS) from the energetic and daylighting points of view in a computationally efficient manner, so the benefits of innovative products can be easily quantified. The model couples daylighting and...
Article
To prevent the overheating of a well-insulated building in summer, facade elements with switchable U-value are a possible solution. A new translucent element with switchable U-value is presented. The convection around a translucent insulation panel is controlled by moving this panel vertically within the double glazing unit. Measurements of such el...
Article
Full-text available
A field of transparent solar thermal façade collectors (TSTC) was installed in a pilot building in Ljubljana, Slovenia. This paper presents the first measurement results from the installation. During the heating season, the transparent façade collectors contribute to the heating of the pilot building, while they provide heat to an adsorption chille...
Article
Abstract: The paper describes procedures for the direct calorimetric measurement of the solar heat gain coefficient g in detail. g is also called SHGC, solar factor, g-value or total solar energy transmittance TSET. All these terms are used synonymously in this document although there are some differences in the details of the definitions of these...
Patent
The present invention relates to a construction element (1) having a controllable heat-transfer coefficient U, comprising - a frame (7), - a first panel (3) and a second panel (5), which are opposite each other and which are arranged at a distance A from each other in the frame (7), wherein a closed volume V that is filled with at least one gas is...
Conference Paper
Full-text available
Within the European research project RETROKIT (http://www.retrokitproject.eu) and supported by a partner network all over Europe, a low-cost building-integrated photovoltaic thermal (BIPVT) component was developed. This component is part of a prefabricated façade that can be easily retrofitted on old residential buildings with little or no energy e...
Conference Paper
Full-text available
While thermal insulation of a building is always beneficial in the cold season and in constantly hot conditions, it inhibits beneficial night-time heat loss of buildings in conditions with hot day temperatures and cool nights. This leads to accumulation of heat and additional need for active cooling in the building. A concept to overcome this probl...
Technical Report
Full-text available
This report presents a current overview of available technologies for facade-integrated solar thermal systems. First, glazings are anaylised, followed by available absorber technologies. Then, available collectors and systems are presented, fluid-based ones as well as with air as heat transfer medium, vacuum tubes as well as semitransparent collect...
Article
Fener, a new Radiance-based building energy model, is presented. The motivation is to be able to perform detailed analyses of complex fenestration systems (CFS) from the energetic and daylighting points of view. The model couples daylighting and thermal simulations in a time-step basis, so that shading control strategies that depend on thermal vari...
Conference Paper
Full-text available
Innovative building-integrated components provide solar heating, solar control and visual contact to the exterior. However, their contributions to the building are challenging to predict. This paper presents the results of a detailed physical model which show that the g value depends not only on the position of the sun, but also on the collector op...
Article
Full-text available
New facades of high-rise buildings often include renewable energy converters to allow “green building” operation. At the same time, numerous tenants value visual transparency. Transparent solar thermal collectors (TSTCs) aim at decreasing the non-renewable primary energy demand and increasing the visual transparency at the same time. On the one han...
Conference Paper
Full-text available
This paper presents a simplified model for Transparent Solar Thermal Collectors (TSTC). An existing, validated detailed model was used to identify the formula’s coefficients by comparing the simulation results of both models. The accuracy of the simplified model as well as the influence of the set of simulations used to establish the model has been...
Conference Paper
Full-text available
1. Einführung Bei der Integration von Fassadenkollektoren in den Sichtbereich des Innenraums spielen nicht nur energetische Aspekte, sondern auch der visuelle Komfort eine Rolle. Dabei ist darauf zu achten, dass sowohl eine Durchsicht nach draußen als auch ein Blendschutz gewährleistet ist. Eine Röhre eines fassadenintegrierten Vakuumröhrenkollekto...
Article
Full-text available
Transparent façade collectors can provide solar heating and cooling and lead to primary energy savings even compared to an opaque wall. They can be simulated with a detailed physical model based on laboratory measurements. The demonstration installation in Ljubljana will provide extensive measurement data of transparent façade collectors in an outd...
Article
The authors investigate the effect of the coating of various internal blinds on the operative room temperature in an office space. It is very important to correctly evaluate the impact of solar protection and daylight/glare systems on building comfort, and the resulting influence on human behaviour. Many building energy simulation programmes consid...
Article
Transparent solar thermal collectors (TSTC) represent a new development. An adequate model is needed to predict their performance. This paper presents a collector model with an advanced calculation of the transmission of diffuse radiation and a connection to the building which allows analysis of the collector gains and of the g value, also called “...
Conference Paper
Full-text available
The Energy Performance of Buildings Directive requires all new buildings to be nearly zero-energy buildings by 2020. In order to achieve this goal, energy efficiency measures have to be combined with on-site renewable energy production. Especially for high-rise buildings with large façade areas, the installation of a building-integrated photovoltai...
Article
Die wissenschaftlich-technischen Arbeitsziele dieses vom Bundesministerium für Wirtschaft (BMWi) geförderten Projektes wurden in fünf Teilen erarbeitet. Die einzelnen Themen resultieren aus aktuellen Fragestellungen; sie haben dennoch einen allgemein anwendbaren Charakter. Das Konsortium hat die folgenden Teilprojekte bearbeitet: (1) Aufbau einer M...
Conference Paper
Full-text available
Transparent solar thermal collectors (TSTC) as presented by Figure 1 indicate primary energy savings – even in comparison with an opaque wall [1, 2]. Figure 1 Schematic drawing of a TSTC. An absorber with openings and slats is mounted inside of three glass panes. [2] While conventional collector measurements focus on predicting the collector gain,...
Conference Paper
Full-text available
In this paper a BIPV façade and a conventional façade are compared in terms of economic profitability (life-cycle cost assessment) and ecological impact (electricity yield and C02 emissions saved by the photovoltaic generation of electricity) The analysis considers different cell technologies, different module sizes, German, French and Italian feed...
Conference Paper
Full-text available
New façades of high-rise buildings often include renewable energy converters to allow " green building " operation. At the same time, numerous tenants value visual transparency. Transparent solar thermal collectors (TSTC) aim at decreasing the non-renewable primary energy (NRPE) demand and increasing the visual transparency at the same time. On the...
Conference Paper
Full-text available
Since transparency is a major trend in modern high-rise architecture, transparent solar façade collectors seem to be promising for primary energy reduction with their combination of visual transparency, shading and collection of solar energy. But the prediction of the annual gains of transparent solar façade collector proves to be a serious scienti...
Article
Full-text available
This paper describes a new general method for building simulation programs which is intended to be used for the modelling of complex facades. The term ‘complex facades’ is used to designate facades with venetian blinds, prismatic layers, light re-directing surfaces, etc. In all these cases, the facade properties have a complex angular dependence. I...