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Conference papers

Green leasing in theory and practice: A study focusing on the drivers and barriers for owners and tenants of commercial offices
Authors: Publication Year: 2016

Abstract This paper investigates the drivers and barriers for green leasing associated with the relationship between building owners and tenants, whilst also considering the extent to which this should be considered during the life cycle phases of a building. The procurement of appropriate rental property and its services is an important consideration for businesses. In terms of issues associated with this, few are more topical than factoring in sustainability. Emerging from this trend is a leasing product that deals with this directly. This product is a green lease. This not only impacts on the operations associated with a tenancy, but…
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Multilayer glazing technologies: key performance and future perspectives
Authors: Publication Year: 2016

AbstractPrevious studies show that a large part of the net energy demands of an office building is related to window heat loss and cooling demands induced by solar irradiance. Windows with improved thermal transmittance (U-value) and solar heat gain coefficient (SHGC or g-value) are important for reducing the related energy demands.There is a scarcity of available scientific work addressing multilayer window technologies. Hence, in this study, simulations with the aim of identifying the parameters that play a key role in improving thermal performance of multilayer glazing units have been carried out. A state-of-the-art review is presented, alongside an overview of…
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Integrated ground source heat pumps and solar thermal systems for zero energy buildings
Authors: Publication Year: 2016

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Nanoelectrochromics for Smart Windows: Materials and Methodologies
Authors: Publication Year: 2016

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A Review of Research Pathways and Opportunities for Building Integrated Photovoltaics from a Materials Science Perspective
Authors: Publication Year: 2016

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Development of a New Thermally Insulating and Structural Green Concrete for Lean Constructions
Authors: Publication Year: 2016

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Design phase calculation of greenhouse gas emissions for a zero-emission residential pilot building
Authors: Publication Year: 2016

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Simulating switchable glazing with energy plus: an empirical validation and calibration of a thermotropic glazing model
Authors: Publication Year: 2015

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Calcined clay as an alternative binder: A further step towards achieving thermally insulating structural concrete based on aerogel
Authors: Publication Year: 2015

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Energy use consequences of ventilative cooling in a ZEB residential building
Authors: Publication Year: 2015

Abstract New buildings have to satisfy ever-tightening standards regarding energy efficiency and consumption. This results in higher insulation levels and lower air leakages that reduce heating demands. However, even at moderate outdoor temperatures these buildings are easily warmed up to such a degree that in order to ensure acceptable indoor environment quality, removal of excess heat becomes unavoidable. Use of electric energy related to mechanical cooling is considered incompatible with achieving zero energy buildings (ZEB). The use of ventilative cooling (VC) in combination with mechanical cooling means energy consumption reduction due to lower use of mechanical ventilation and cooling system.This…
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Effective ventilation in high performance buildings
Authors: Publication Year: 2015

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Fiber reinforced hollow silica nanospheres for thermal insulation applications
Authors: Publication Year: 2015

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Hollow silica nanospheres as a stepping-stone toward thermal superinsulation materials
Authors: Publication Year: 2015

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Experimental investigations of vacuum insulation panels in an alkaline environment
Authors: Publication Year: 2015

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Sensitivity analysis of the life cycle emissions from an NZEB concept
Authors: Publication Year: 2015

Abstract The net-zero emissions building (nZEB) performance is investigated for building operation and embodied emissions in materials for Norway’s cold climate. An nZEB concept for new residential buildings was developed in order to understand the balance and implications between operational and embodied emissions over the building’s life. The main drivers for the CO2 equivalent (CO2eq) emissions were revealed for the building concept through a detailed emissions calculation.Previous investigations showed that the criterion for zero emissions in operation is easily reached by the nZEB concept (independent of the CO2eq factor considered). Nevertheless, embodied emissions from materials appeared significant compared to operational emissions. It was found that an…
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Solar energy for zero energy buildings - a comparison between solar thermal, PV and photovoltaic-thermal (PV/T) systems
Authors: Publication Year: 2015

Abstract In a net zero energy building (nZEB), the energy demand from the operation of the building is met by renewable energy generated on site. Buildings require energy both in the form of heat and electricity, and solar energy utilization is important in order to reach a net zero energy balance. In projects with ambitious energy targets or limited available areas for local energy generation, solar thermal and photovoltaic (PV) installations will eventually compete for space on roofs and facades. Hybrid photovoltaic–thermal (PV/T) modules, in which heat and electricity is generated simultaneously, are therefore an interesting technology for building applications,…
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The ZEB Living Laboratory at the Norwegian University of Science and Techonology: a zero emission house for engineering and social science experiments
Authors: Publication Year: 2015

Summary At the Research Centre on Zero Emission Buildings of NTNU, a new test facility (Living Laboratory) is currently in the final stage of construction and will start its operation in summer 2015. The Living Laboratory was designed to carry out experimental investigations at different levels, ranging from envelope to building equipment components, from ventilation strategies to action research on lifestyles and technologies, where interactions between users and low (zero) energy buildings are studied.The test facility is a single family house with a gross volume of approximately 500 m3 and a heated surface (floor area) of approximately 100 m2. It…
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Building regulations cannot assure ambitious energy upgrading of existing residential buildings according to Norway’s national targets
Authors: Publication Year: 2015

Summary This paper provides a summary of main content and conclusions from a report on evaluation of existing potential and scenario studies concerning renovation of residential buildings. In addition to literature studies there were conducted own calculations adapted from the most important Norwegian scenario model. Also studies addressing design of regulatory requirements for measures with existing buildings were reviewed. The results were discussed in expert workshops. The technical potential for energy upgrade seems to be under- rather than overestimated. On the other hand, the paper substantiates that the renovation rate is lower than assumed in the scenarios, and illustrates that…
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Membrane energy exchangers, evaluation of a frost-free design and its performance for ventilation in cold climates
Authors: Publication Year: 2015

Abstract A frost-free membrane energy exchanger design model is developed combining the conventional ε−NTU method with a frost limit model. A concept of plate performance index is defined to evaluate the net energy saving ability. The frost-free design model and plate performance index are employed for a case study of single-family dwelling with an all-fresh-air air handling unit with a heat/energy recovery exchanger. The membrane energy exchanger, which is able to ensure frost-free operation without extra frost control strategies, is applicable to most cold climates for residential applications. The membrane energy exchanger has a significant energy saving potential compared to…
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Spectroscopic properties of hexagonal sodium tungstate nanorods
Authors: Publication Year: 2015

Abstract Sodium tungstate (Na-WO3) nanorods with typical diameters of 10-200 nm and lengths of several microns were prepared via hydrothermal synthesis. X-ray diffraction showed that the material crystallized in a hexagonal phase (space groupP6/mmm) with unit cell dimensions of a = 7.3166(8) Å and c = 3.8990(8) Å. The as-prepared Na-WO3 nanorods showed a distinctive visible-light-driven photochromism related to a proton-electron double injection process. The involved localstructural evolutions were monitored by Fourier transform infrared (FTIR) and Raman scattering spectroscopy. One diagnostic FTIR absorption at 585 cm-1 and one Raman band at 813 cm-1 were identified and assigned to the O-W-O stretching vibration. These two modes were strongly affected by the…
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Hourly Electricity Load Modelling of non-residential Passive Buildings in a Nordic Climate
Authors: Publication Year: 2015

Abstract Detailed knowledge of electricity demand is essential for power system planning and operation. EUs 20-20-20 targets will increase the development of more energy efficient buildings as all new buildings shall be “nearly zero energy buildings” by 2020. The result from this ambition is that so-called passive buildings and nearly-net-zero-energy-buildings (nZEB), with lower energy demand, or even onsite power generation, will significantly change the way buildings are integrated in the power system. System operators must consequently prepare for changes in load profiles. However, the knowledge on the aggregated impact of nZEBs is so far limited because the actual number of such buildings is still very small. This paper contributes to this knowledge…
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Convective heat transfer between rooms in nordic passive houses
Authors: Publication Year: 2015

Abstract In highly-insulated buildings such as passive houses, the space-heating distribution subsystem can be simplified by reducing the number of heat emitters. In this context, the bi-directional flow through open doorways is known to be an efficient process to support the heat distribution between rooms. This process is therefore investigated using field measurements within a Norwegian passive house. The so-called large opening approximation proves to model fairly the mass flow rate, but also the convective heat transfer if the thermal stratification is accounted for. Furthermore, the discharge coefficient appears to be independent of the heater type and location in the room.
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Ventilative cooling as a solution for highly insulated buildings in cold climate
Authors: Publication Year: 2015

AbstractNew and refurbished buildings have to relate to ever increasing standards regarding energy efficiency and energy consumption. This results in well insulated building envelopes with low air leakages offering reduced heating demands. One of the downsides of this is that these buildings are easily warmed up to such a degree that in order to sustain an acceptable indoor climate, removal of excess heat becomes a necessity. The removal of surplus heat is often done through means of mechanical cooling. However, energy consumption related to mechanical cooling is considered incompatible with achieving zero energy buildings (ZEB). As a response, the use…
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Silver nanoparticles as low-emissivity coating materials for window glazing applications
Authors: Publication Year: 2015

Abstract The potential of silver (Ag) nanoparticles as low emissivity (low-e) coating materials for window glazing applications has been discussed. Ag nanoparticles were prepared via a wet chemical method and applied on the surface of flat glass through spin coating. A mild heat treatment at 200°C was employed to achieve the low-e effect, which results in a total surface emissivity of about 0.015, compared to about 0.837 of the plain glass substrate. By applying such low-e coatings, the heat loss through a single-glazed window pane could be reduced by about 45% (U-value from 5.75 to 3.18 W/(m2K)).
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Convective heat transfer between rooms in nordic passive houses
Authors: Publication Year: 2015

Abstract In highly-insulated buildings such as passive houses, the space-heating distribution subsystem can be simplified by reducing the number of heat emitters. In this context, the bi-directional flow through open doorways is known to be an efficient process to support the heat distribution between rooms. This process is therefore investigated using field measurements within a Norwegian passive house. The so-called large opening approximation proves to model fairly the mass flow rate, but also the convective heat transfer if the thermal stratification is accounted for. Furthermore, the discharge coefficient appears to be independent of the heater type and location in the…
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Impact of opaque building envelope configuration on the heating and cooling energy need of a single family house in cold climate
Authors: Publication Year: 2015

Abstract The building envelope plays a crucial role in reducing operational energy demand. In particular, the two main properties of the building envelope to look at in this perspective are thermal transmittance (U, W/m2K1) and thermal inertia, which is often expressed by a metric called periodic thermal transmittance (Yie, W/m2K1). These two properties are also traditionally connected to two different energy demands: while thermal transmittance is crucial to reduce heating energy demand, thermal inertia has an impact on energy demand for cooling. However, a question may rise about the impact of each property on the other demand – i.e. the…
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Impact of opaque building envelope configuration on the heating and cooling energy need of a single family house in cold climate
Authors: Publication Year: 2015

Abstract The building envelope plays a crucial role in reducing operational energy demand. In particular, the two main properties of the building envelope to look at in this perspective are thermal transmittance (U, W/m2K1) and thermal inertia, which is often expressed by a metric called periodic thermal transmittance (Yie, W/m2K1). These two properties are also traditionally connected to two different energy demands: while thermal transmittance is crucial to reduce heating energy demand, thermal inertia has an impact on energy demand for cooling. However, a question may rise about the impact of each property on the other demand – i.e. the…
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Dynamic thermal performance of a PCM window system: characterization using large scale measurements
Authors: Publication Year: 2015

Abstract Introduction of more dynamic building envelope components have been done throughout the last decades in order to try to increase indoor thermal comfort and reduce energy need in buildings for both temperature and light control. One of these promising technologies is phase change materials (PCM), where, the latent heat storage potential of the transition between solid and liquid state of a material is utilized as thermal mass. A PCM layer incorporated in a transparent component can increase the possibilities to harvest energy from solar radiation by reducing the heating/cooling demand and still allowing the utilization of daylight. The introduction…
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Roof-integrated PV in Nordic climate - Building physical challenges
Authors: Publication Year: 2015

Abstract Use of photovoltaics (PV) is key remedies in buildings where a large part of the energy supply should be based on renewable energy. PV in Nordic climate can be challenging because of snow, wind and temperatures below zero. The aim of this research work has been to provide a state-of-the art overview of recent experiences and challenges for building physical conditions related to the use of roof-integrated PV in Nordic climate. The study has identified practical guidelines for installation and ventilation of the roofing as challenges to be solved for extensive use of such systems in Nordic climate.
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The utilization of electrochromic materials for smart window applications in energy-efficient buildings
Authors: Publication Year: 2015

Abstract Electrochromic materials (ECM) and windows (ECW) are able to regulate the solar radiation throughput by application of an external electrical voltage. Thus, ECWs may decrease heating, cooling, lighting and electricity loads in buildings by admitting the optimum level of solar energy and daylight at any given time, e.g. cold winter climate versus warm summer climate demands. It is crucial to be able to compare the dynamic solar radiation control for different ECWs and hence require specific ECW properties. The solar radiation control for ECWs may readily be characterized by several solar radiation glazing factors, where a comparison for various ECW configurations enables one to select the most appropriate ones for specific smart…
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Moisture in Multi-Layer Windows
Authors: Publication Year: 2015

Abstract There is an increasing interest in development of coupled multi-layer window structures. This is to optimize thermal properties and to develop systems with a better climate protected solar shading system. The risk of condensation on the inside of the exterior glass layer in a multi-layer window structure might be a challenge and is often questioned. The risk of condensation will depend on both window properties and indoor and outdoor climate conditions. The air gap between the inner and outer part have to be ventilated with outdoor air to give the window a "drying out" capacity. The U-value of the…
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Solutions and technologies for wood stoves in future's energy efficient residential buildings
Authors: Publication Year: 2015

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Silica aerogels - A multifunctional building material
Authors: Publication Year: 2015

Abstract Silica aerogels are a nanoporous material with extremely high porosity (up to ~99.8 %), low density (as low as ~0.005 g/cm3), and low thermal conductivity (~0.010–0.020 W/(mK)). Aerogels can also be made with a translucent or transparent state. These structural and functional features make aerogels a multifunctional material for many important applications. In this work, we discuss the perspective of aerogels as super insulation materials and window glazings in the building and construction sector. It shows that different research and development (R&D) strategies of aerogels shall be considered when aiming for different applications; reducing the manufacture cost, improving the…
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Development of Nano Insulation Materials for Building Constructions
Authors: Publication Year: 2015

Abstract The application of superinsulation materials (SIM) reaching thermal conductivities far below 20 mW/(mK) allows the construction of relatively thin building envelopes while still maintaining a high thermal resistance, which also increases the architectural design possibilities for both new buildings and refurbishment of existing ones. To accomplish such a task without applying vacuum solutions and their inherit weaknesses may be possible from theoretical principles by utilizing the Knudsen effect for reduced thermal gas conductance in nanopores.This study presents the attempts to develop nano insulation materials (NIM) through the synthesis of hollow silica nanospheres (HSNS), indicating that HSNS may represent a promising candidate or stepping-stone for achieving SIM. Furthermore, initial…
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Organo Nanoclays as Insulating Materials in Alternative Concrete
Authors: Publication Year: 2015

Abstract Calcined marl was identified as an insulating binder substituent mate-rial for aerogel based mortars. Further synthesis of insulating organo-nanoclays through the incorporation of polyethylene glycol (PEG) or in situ polymerisation of polystyrene (PS) in clays displayed greater promises for further reduction of thermal conductivity independent of the compressive strength, unlike more con-ventional aerogel-incorporated concrete. The organo-nanoclays were characterized by Hot Disk thermal analyzer measurements. The results so far indicated the for-mation of organoclay particles from both ideal systems of bentonite and calcined marl with lowered thermal conductivities. The calcined clay appeared to maintain its binding properties, suitable for gelling…
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The process of batch combustion of logs in wood stoves – Transient modelling for generation of input to CFD modelling of stoves and thermal comfort simulations
Authors: Publication Year: 2015

Co-publication with StableWood
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Hybrid photovoltaic-thermal systems in buildings a review
Authors: Publication Year: 2015

Abstract This paper presents a review of projects where hybrid photovoltaic-thermal (PV/T) systems are used in buildings. PV/T systems convert solar radiation to electricity and heat simultaneously, in one module. The output of both electricity and heat suggests that the technology can be suited for use in buildings, especially when the available area for installation is limited. The market and research activities related to PV/T technology has increased in recent years. This article adds to existing reviews on PV/T technology by focusing on the building perspective. Different strategies for the use of PV/T in buildings are discussed, and examples of…
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Experimental synthesis of hollow silica nanospheres for application as superinsulation in the buildings of tomorrow
Authors: Publication Year: 2015

ABSTRACT The path toward energy-efficient buildings with a low or zero carbon footprint, e.g. zero energy and zero emission buildings, involves the development of high-performance thermal insulation, aiming at reaching thermal conductivities far below 20 mW/(mK). Applying such superinsulation will allow the construction of relatively thin building envelopes yet maintaining a high thermal resistance, thus also increasing the architectural design possibilities. A vacuum insulation panel (VIP) represents a stateof-the-art thermal insulation solution with a thermal conductivity of typical 4 mW/(mK) in the pristine and non-aged condition. However, the VIPs have issues with fragility, perforation vulnerability, increasing thermal conductivity during time…
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Synthesis and characterization of aerogel glass materials for window glazing applications
Authors: Publication Year: 2015

Summary This chapter reports an approach to enhance the mechanical strength of silica aerogels via densification. Although the loss of porosity and consequently the increase of thermal conductivity of silica aerogels represent drawbacks related to the densification process, a combination of enhanced mechanical performance and optical transparency indicates that the densificated silica aerogels may be used as new glass material for window glazing application. Preliminary experimental results indicate lightweight (density 1.8 g/cm3, compared to 2.5 g/cm3 for float glass) and thermal insulating (thermal conductivity k ≈ 0.18 W/(mK), compared to about 0.92 W/(mK) for float glass) aerogel glass materials with high visible transparency…
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Modeling of the Indoor Thermal Comfort in Passive Houses heated by Wood Stoves
Authors: Publication Year: 2015

ABSTRACT Space-heating using wood stove is a popular solution in many European countries. Nevertheless, nominal powers of state-of-the-art stoves are oversized compared to the needs of highly-insulated building envelopes, such as passive houses. In this respect, a simplified wood stove model has been developed in order to investigate the thermal comfort using detailed dynamic simulations (e.g. TRNSYS) at an acceptable computational cost. A specific experimental setup has been developed to validate this modelling procedure, especially as regards the interaction between the stove and the building. The largest source of error appears to be the thermal stratification in the room where…
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The Norwegian zero emission neighbourhood Aadland
Authors: Publication Year: 2014

Abstract The ambition level for the zero emission neighbourhood Aadland is that the area will be self supplied with both thermal and electric energy. This paper presents how emissions from operation of the 500 dwellings are offset by on-site renewable energy production. The paper also describes a procedure for how to deal with embodied emissions from materials in an early stage design phase. The study verifies that it is possible to reach a zero emission balance for the neighbourhood. Zero emission from operation is achievable as an average for the neighbourhood. For individual zero emission buildings this also includes embodied emissions from materials and construction in…
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Design strategies for low embodied energy and greenhouse gases in buildings: analyses of the IEA Annex 57 case studies
Authors: Publication Year: 2014

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Optimal investments in Zero Carbon Buildings
Authors: Publication Year: 2014

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Synthesis, characterization and durability of self-cleaning antireflection coatings for glazing applications
Authors: Publication Year: 2014

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Synthesis and Thermal Conductivity of Monodisperse Hollow Silica Nanospheres
Authors: Publication Year: 2014

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Treated aluminum as highly reflective facade material for energy-efficient buildings
Authors: Publication Year: 2014

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Simulation and evaluation of CO2 heat pump system with energy storage for ZEB
Authors: Publication Year: 2014

Abstract Reduced energy consumption is one of the most cost effective ways of reducing CO2 emissions for combustion of fossil fuels. Residential buildings must become more energy efficient according to the Energy Performance in Buildings Directive (EPBD). The demands for domestic hot water have become more significant. Therefore the share of domestic hot water (DHW) in high insulated houses constitutes an increasing share of total heating demand. For DHW and space heating purpose CO2 tripartite gas cooler heat pumps are among the most efficient systems. Due to heat rejection at different temperature levels a large enthalpy difference and low compressor…
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Life cycle assessment integrated in the design of a new nano insulation material
Authors: Publication Year: 2014

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The high performance thermal building insulation materials of beyond tomorrow – from consept to experimental investigations
Authors: Publication Year: 2014

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State of the art and the path to the building integrated photovoltaics of tomorrow
Authors: Publication Year: 2014

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