Publications
Membrane energy exchangers, evaluation of a frost-free design and its performance for ventilation in cold climates
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2015
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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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Zero Emission Buildings Use and Operation
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2015
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2015
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The ZEB Research Centre and Pilot Buildings
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2015
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2015
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Spectroscopic properties of hexagonal sodium tungstate nanorods
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2015
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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
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2015
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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
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2015
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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
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2015
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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
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2015
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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
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…
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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
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Publication Year:
2015
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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
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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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Dynamic thermal performance of a PCM window system: characterization using large scale measurements
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Publication Year:
2015
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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
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Publication Year:
2015
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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
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2015
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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
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2015
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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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All buildings are solar buildings – Zero energy and zero emission buildings
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2015
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Publication Year:
2015
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The Research Center on Zero Emission Buildings
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2015
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2015
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Snart har vi solceller i taket og nano i veggen
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2015
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2015
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Low-emissivity materials for building applications: a state-of-the-art review and future research perspective
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Publication Year:
2015
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Publication Year:
2015
Abstract Low-emissivity (low-e) materials can be used in order to reduce energy usage in both opaque and transparent areas of a building. The main focus for low-e materials is to reduce the heat transfer through thermal radiation. Furthermore, low-e materials will also influence on the daylight and total solar radiation energy throughput in windows, the latter one often characterized as the solar heat gain coefficient (SHGC). This work reviews low-e materials and products found on the market, and their possible implementations and benefits when used in buildings. The SHGC is often left out by many countries in energy labellings of…
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Solutions and technologies for wood stoves in future's energy efficient residential buildings
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2015
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2015
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Vinduer i fremtidens kontorbygg – lag på lag og lav vekt på samme tid?
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2015
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2015
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Silica aerogels - A multifunctional building material
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2015
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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
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2015
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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
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2015
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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
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2015
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2015
Co-publication with StableWood
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Ombygging av eneboliger
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2015
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2015
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The suitability of air-heating in residential passive house buildings from the occupant’s point of view
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Publication Year:
2015
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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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Phase Change Materials for Building Applications: A State-of-the-Art review and Future Research Opportunities
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Publication Year:
2015
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2015
Abstract Phase change materials (PCM) have received considerable attention over the last decade for use in latent heat thermal storage (LHTS) systems. PCMs give the ability to store passive solar and other heat gains as latent heat within a specific temperature range, leading to a reduction of energy usage, an increase in thermal comfort by smoothing out temperature fluctuations throughout the day and a reduction and/or shift in peak loads. The interest around PCMs has been growing significantly over the last decade. Hence, several commercial products have arrived on the market with various areas of use in building applications. This…
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Hybrid photovoltaic-thermal systems in buildings a review
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2015
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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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Intelligente bygninger kan løse klimautfordringer. Fremtidens smarte bygninger.
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2015
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2015
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Intelligente bygninger kan løse klimautfordringer
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2015
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2015
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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
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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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Transparent facades in low energy office buildings Numerical simulations and experimental studies
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2015
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Publication Year:
2015
Windows are a key component in the building envelope. They are often, thought of as energy drains and something associated with excessive energy demands in a building. However, in order to assess the energy performance of a window, several factors must be addressed. The most important issues to consider are energy losses due to heat transmission through windows, energy gains from solar radiation as well as transmitted visible light and the influence on artificial lighting demands. Factors like thermal and visual comfort in buildings are additional factors that need to be assessed and addressed. Existing work that has been carried…
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Reports
The legal dwelling: how Norwegian research engineers domesticate construction law. Engineering Studies
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2015
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Publication Year:
2015
Abstract The considerable amount of energy spent on the construction, maintenance, and demolition of buildings draws attention to sustainable development in the construction sector. Regarded as both tools and frameworks, laws are expected to sustain and speed technological innovation. With the STS (Science and Technology Studies) theory of domestication and in-depth interviews with building researchers studying zero emission buildings in Norway, I discuss the role of research engineers in the domestication of law, that is, the translation of European Directives for building codes and technical requirements, and the mediation of these legal frameworks for industry and practitioners. I classify two…
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Vi ville at miljøhensynet skulle være en livsstil – ikke bare en hobby
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2015
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2015
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Vi ville at miljøhensynet skulle være en livsstil – ikke bare en hobby
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2015
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2015
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Vi ville at miljøhensynet skulle være en livsstil – ikke bare en hobby
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2015
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2015
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Material research for zero emission buildings
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2015
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2015
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Material research for zero emission buildings
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2015
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2015
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Vakuumisoleringspaneler i gamla byggnader
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2015
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2015
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New solutions for facade energy insulation. Examples from some research projects
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2015
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2015
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New solutions for facade energy insulation. Examples from some research projects
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2015
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2015
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Experimental Investigations of Aerogel-Incorporated Ultra-High Performance Concrete
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Publication Year:
2015
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Publication Year:
2015
Abstract Improvements to concrete will have a large impact in the construction and building sector. As the attention is drawn towards energy-efficient and zero emission buildings, the thermal properties of concrete will be important. Attempts are being made to decrease the thermal conductivity of concrete composites while retaining as much as possible of the mechanical strength. In this study experimental investigations of aerogel-incorporated mortar (AIM) with up to 80 vol% aerogel are prepared utilizing a reduced ultra-high performance concrete (UHPC) recipe. It was found that at 50 vol% aerogel content, the AIM sample possessed a compressive strength of 20 MPa and a thermal…
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Norske skole kan bli verdens beste klimabygg
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2015
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2015
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ByBo vil bygge 800 nullutslippsboliger i Bergen
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2015
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2015
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Fremtidige krav til utforming av bærekraftige bygninger og energiforsyning
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2015
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2015
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Fremtidige krav til utforming av bærekraftige bygninger og energiforsyning
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2015
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2015
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