Publications
Avoiding snow and ice formation on exterior solar cell surfaces – a review of research pathways and opportunities
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Publication Year:
2016
Authors:
Publication Year:
2016
Abstract Today energy-efficient and energy-harvesting buildings experience an ever-increasing interest and demand. Building integrated photovoltaics (BIPV) may in this respect represent a powerful and versatile tool for reaching the goal of zero energy and zero emission buildings. The BIPV systems replace the outer building envelope skin, thus serving simultanously as both a climate screen and a power source generating electricity. However, snow and ice formation on the exterior solar cell surfaces reduce their performance and may also lead to faster deterioration. Hence, if one could find a way to develop solar cells which were able to avoid snow and ice…
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Journal papers
Building integration of aerogel glazings
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Publication Year:
2016
Authors:
Publication Year:
2016
Abstract The recent building practices have shown that aerogel glazings can be used as a multifunctional building envelope component for different purposes. Nevertheless, the distinctive physical properties and energy performance of aerogel glazings suggest that building integration of aerogel glazings may create architectural challenges, aesthetic problems, as well as concerns on their durability and environmental impact, thus highlighting the importance of developing guidelines to regulate the use of aerogel glazings in the building sector. This study discusses various approaches for the building integration of aerogel glazings by presenting a number of successful examples; the advantages of integration are quantified and…
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Journal papers
Aerogel vs. argon insulation in windows: A greenhouse gas emissions analysis
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Publication Year:
2016
Authors:
Publication Year:
2016
Abstract The scope of this study is a comprehensive analysis of the greenhouse gas emissions from the partial substitution of triple-glazing units with argon gas (U-value of 0.79 W/m2 K) with double-glazing units with either monolithic aerogel (U-value of 0.65 W/m2 K) or granular aerogel (U-value of 0.31 W/m2d K). A residential building located near Oslo and fully upgraded with passive house solutions is used as a case study for this analysis. A cradle-to-site analysis is performed on the facade components. Two replacement schedules and three window-to-wall ratios are used to evaluate the differences in total emissions. Sensitivity analyses based on increasing the fraction of the…
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Kunnskapsstatus – Fuktbufring I materialer og påvirkning på energibehov
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Publication Year:
2015
Authors:
Publication Year:
2015
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Reports
Electrochromic Smart Windows for Dynamic Daylight and Solar Energy Control in Buildings
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Publication Year:
2015
Authors:
Publication Year:
2015
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Books
Nullutslippsbygg er en klimaløsning
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Publication Year:
2015
Authors:
Publication Year:
2015
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Popular Science Articles
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Life cycle GHG emissions from a wooden load-bearing alternative for a ZEB office concept
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Publication Year:
2015
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Publication Year:
2015
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Reports
The suitability of air-heating in residential passive house buildings from the occupant’s point of view
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Publication Year:
2015
Authors:
Publication Year:
2015
Abstract The substantial reduction of required heating load in passive house buildings has led to an integration of heating in the ventilation system by post-heating the supply-air, called air-heating. The incorporation of heating in the ventilation system constitutes a departure from a well-established customary practice of strictly separating heating and ventilation in the indoor climate design. It is therefore imperative to thoroughly investigate and evaluate air-heating with regard to effects on the indoor air quality (IAQ) and thermal comfort. Simulations and laboratory measurements suggest that air-heating has no adverse effects on IAQ and thermal comfort. The purpose of this paper…
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Journal papers
Vinduer i fremtidens kontorbygg – lag på lag og lav vekt på samme tid?
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Publication Year:
2015
Authors:
Publication Year:
2015
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Popular Science Articles
Identifying key design parameters of the integrated energy system for a residential Zero Emission Building in Norway
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Publication Year:
2015
Authors:
Publication Year:
2015
Abstract This study examined an integrated solution of the building energy supply system consisting of flat plate solar thermal collectors in combination with a ground-source heat pump and an exhaust air heat pump for the heating and cooling, and production of domestic hot water. The supply energy system was proposed to a 202 m2 single-family demo dwelling (SFD), which is defined by the Norwegian Zero Emission Building standard. The main design parameters were analyzed in order to find the most essential parameters, which could significantly influenced the total energy use. This study found that 85% of the total heating demand of the…
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Journal papers
Material research for zero emission buildings
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Publication Year:
2015
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Publication Year:
2015
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Conference presentations
Modeling of the Indoor Thermal Comfort in Passive Houses heated by Wood Stoves
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Publication Year:
2015
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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Conference papers
Ombygging av eneboliger
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Publication Year:
2015
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Publication Year:
2015
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Convective heat transfer between rooms in nordic passive houses
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Publication Year:
2015
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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Conference papers
Solutions and technologies for wood stoves in future's energy efficient residential buildings
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Publication Year:
2015
Authors:
Publication Year:
2015
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Conference papers
Vakuumisoleringspaneler i gamla byggnader
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Publication Year:
2015
Authors:
Publication Year:
2015
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Popular Science Articles
The ZEB Living Laboratory at the Norwegian University of Science and Techonology: a zero emission house for engineering and social science experiments
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Publication Year:
2015
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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Conference papers
Dynamic thermal performance of a PCM window system: characterization using large scale measurements
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Publication Year:
2015
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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Experimental synthesis of hollow silica nanospheres for application as superinsulation in the buildings of tomorrow
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Publication Year:
2015
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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Conference papers
Roof-integrated PV in Nordic climate - Building physical challenges
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Publication Year:
2015
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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Conference papers
The utilization of electrochromic materials for smart window applications in energy-efficient buildings
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Publication Year:
2015
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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Building regulations cannot assure ambitious energy upgrading of existing residential buildings according to Norway’s national targets
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Publication Year:
2015
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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Conference papers
Development of Nano Insulation Materials for Building Constructions
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Publication Year:
2015
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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Conference papers
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
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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Conference papers
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
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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Conference papers
Hourly Electricity Load Modelling of non-residential Passive Buildings in a Nordic Climate
Authors:
Publication Year:
2015
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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Conference papers
Energy use consequences of ventilative cooling in a ZEB residential building
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Publication Year:
2015
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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Conference papers
Silver nanoparticles as low-emissivity coating materials for window glazing applications
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Publication Year:
2015
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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Conference papers
Spectroscopic properties of hexagonal sodium tungstate nanorods
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Publication Year:
2015
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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Conference papers
Convective heat transfer between rooms in nordic passive houses
Authors:
Publication Year:
2015
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…
Published in
Conference papers
Ventilative cooling as a solution for highly insulated buildings in cold climate
Authors:
Publication Year:
2015
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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Conference papers
Analysis of grid interaction indicators in net zero-energy buildings with sub-hourly collected data
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Publication Year:
2015
Authors:
Publication Year:
2015
Abstract This paper aimed to contribute to the discussion about the role of net zero-energy buildings (ZEBs) or nearly ZEBs in future energy systems, from the perspective of the resulting import/export interaction with the surrounding energy grid (commonly named grid interaction (GI)). This investigation analyses three buildings with measured data at sub-hourly time resolution. The goal of this paper was to quantify the effect of using high-resolution data (one or a few minutes) versus hourly resolution in the GI analysis of buildings with an on-site generation system. A limited set of quantitative GI indicators have been selected: the generation multiple,…
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Journal papers
Vi ville at miljøhensynet skulle være en livsstil – ikke bare en hobby
Publication Year:
2015
Publication Year:
2015
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Media contributions
Vi ville at miljøhensynet skulle være en livsstil – ikke bare en hobby
Publication Year:
2015
Publication Year:
2015
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Media contributions
Vi ville at miljøhensynet skulle være en livsstil – ikke bare en hobby
Publication Year:
2015
Publication Year:
2015
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Media contributions
Intelligente bygninger kan løse klimautfordringer. Fremtidens smarte bygninger.
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Publication Year:
2015
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Publication Year:
2015
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Media contributions
Slik blir fremtidens byggematerialer
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Publication Year:
2015
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Publication Year:
2015
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Membrane energy exchangers, evaluation of a frost-free design and its performance for ventilation in cold climates
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Publication Year:
2015
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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Conference papers
Norske skole kan bli verdens beste klimabygg
Publication Year:
2015
Publication Year:
2015
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Media contributions
Spectral and angular solar properties of a PCM-filled double glazing unit
Authors:
Publication Year:
2015
Authors:
Publication Year:
2015
Abstract: Background Phase change materials (PCMs) have been proposed as a means to increase the thermal inertia of glazing systems. These materials have optical features that need to be investigated and characterised in order to better understand the potential of these systems and to provide reliable data for numerical simulations. Methods The spectral and angular behaviour of different PCM glazing samples, characterised by different thicknesses of PCMs, were investigated by means of commercial spectrophotometer and by means of a dedicated optical test bed that includes a large integrating sphere with a diameter of 0.75 m. Such equipment was necessary because…
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Journal papers
Fremtidige krav til utforming av bærekraftige bygninger og energiforsyning
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Publication Year:
2015
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Publication Year:
2015
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New solutions for facade energy insulation. Examples from some research projects
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Publication Year:
2015
Authors:
Publication Year:
2015
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ByBo vil bygge 800 nullutslippsboliger i Bergen
Publication Year:
2015
Publication Year:
2015
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Media contributions
Intelligente bygninger kan løse klimautfordringer
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Publication Year:
2015
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Publication Year:
2015
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Media contributions
Snart har vi solceller i taket og nano i veggen
Publication Year:
2015
Publication Year:
2015
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Media contributions
Spectral and angular solar properties of a PCM-filled double glazing unit
Authors:
Publication Year:
2015
Authors:
Publication Year:
2015
Abstract Background Phase change materials (PCMs) have been proposed as a means to increase the thermal inertia of glazing systems. These materials have optical features that need to be investigated and characterised in order to better understand the potential of these systems and to provide reliable data for numerical simulations. Methods The spectral and angular behaviour of different PCM glazing samples, characterised by different thicknesses of PCMs, were investigated by means of commercial spectrophotometer and by means of a dedicated optical test bed that includes a large integrating sphere with a diameter of 0.75 m. Such equipment was necessary because of…
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Journal papers
Thermal performance of in-between shading systems in multilayer glazing units – Hot-box measurements and numerical simulations
Authors:
Publication Year:
2015
Authors:
Publication Year:
2015
Abstract Shading systems are widely used, also in Nordic climates, in conjunction with glazed facade in office buildings. The primary functions of the solar shading devices are to control solar gains leading to cooling needs during operational hours and reduction of discomfort caused by glare. A secondary property of shading devices incorporated in glazing units is that they can be utilized as an additional layer in the glazing unit when the shading device is deployed. This can improve the thermal transmittance value (U-value) of the windows. It can be deployed during night-time or in periods when a blocked view does…
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