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  • 1. Björn, Lars Olof
    et al.
    Bengtson, Sven-Axel
    Shaoshan, Li
    Hecker, Christoph
    Ullah, Saleem
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nilsson, Annica M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Thermal emissivity of avian eggshells2016Inngår i: Journal of Thermal Biology, ISSN 0306-4565, E-ISSN 1879-0992, Vol. 57, s. 1-5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The hypothesis has been tested that evolution has resulted in lower thermal emissivity of eggs of birds breeding openly in cold climates than of eggs of birds that nest under protective covering or in warmer climates. Directional thermal emissivity has been estimated from directional-hemispherical reflectance spectra. Due to several methodological difficulties the absolute emissivity is not accurately determined, but differences between species are obvious. Most notably, small waders of the genus Calidris, breeding in cold climates on the tundra, and in most cases with uniparental nest attendance, have low directional emissivity of their eggshells, about 0.92 when integration is carried out for wavelengths up to 16 mu m. Species belonging to Galloanserinae have the highest directional emissivity, about 0.96, of their eggs. No differences due to climate or breeding conditions were found within this group. Eggs of most other birds tested possess intermediate emissivity, but the values for Pica pica and Corvus corone cornix are as low as for Calidris. Large species-dependent differences in spectral reflectance were found at specific wavelengths. For instance, at 4.259 mu m the directional-hemispherical reflectance for galliforms range from 0.05 to 0.09, while for Fratercula arctica and Fulmarus glacialis it is about 0.3. The reflection peaks at 6.5 and 11.3 mu m due to calcite are differentially attenuated in different species. In conclusion, the hypothesis that evolution has resulted in lower thermal emissivity of bird eggs being exposed in cold climates is not supported by our results. The emissivity is not clearly related to nesting habits or climate, and it is unlikely that the small differences observed are ecologically important. The spectral differences between eggs that nevertheless exist should be taken into account when using infrared thermometers for estimating the surface temperature of avian eggs.

  • 2.
    Jonsson, Jacob
    et al.
    Environmental Energy Technology Division, Lawrence Berkeley National Laboratory.
    Rubin, Michael
    Environmental Energy Technology Division, Lawrence Berkeley National Laboratory.
    Nilsson, Annica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Environmental Energy Technology Division, Lawrence Berkeley National Laboratory.
    Jonsson, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Optical characterization of fritted glass for architectural applications2009Inngår i: Optical materials (Amsterdam), ISSN 0925-3467, E-ISSN 1873-1252, Vol. 31, nr 6, s. 949-958Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fritted glass is commonly used as a light diffusing element in modern buildings. Traditionally it has been used for aesthetic purposes but it can also be used for energy savings by incorporating it in novel daylighting systems? To answer such questions the light scattering properties must be properly characterized.

    This paper contains measurements of different varieties of fritted glass, ranging from the simplest direct-hemispherical measurements to angle-resolved goniometer measurements. Modeling the light scattering to obtain the full bidirectional scattering distribution function (BSDF) extends the measured data, making it useful in simulation programs such as Window 6 and Radiance. Surface profilometry results and SEM micrographs are included to demonstrate the surface properties of the samples studied.

  • 3.
    Luthander, Rasmus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nilsson, Annica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Widén, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik, Byggteknik.
    Åberg, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik, Byggteknik.
    Graphical analysis of photovoltaic generation and load matching in buildings: A novel way of studying self-consumption and self-sufficiency2019Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 250, s. 748-759Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For on-site renewable energy supply, such as photovoltaic (PV) electricity generation, an important issue is the daily and seasonal matching between on-site supply and demand. The matching potential is frequently expressed using the load matching indicators such as self-sufficiency and self-consumption. This paper presents the Energy matching chart, which is a novel graphical approach to visualize the PV-load matching. The chart uses self-sufficiency and self-consumption to provide information regarding the matching in both size and time. Using the Energy matching chart, the matching between PV production and load presented in previous studies is graphically analyzed and compared. Furthermore, the potentials for the two most common measures for improving the matching, namely energy storage and load shifting, are investigated. The results show that energy storage has, on average, a significantly higher potential for increasing the PV-load matching than load shifting. The second part of the paper, illustrates the benefits of the Energy matching chart by evaluating the Swedish implementation of the EU legislation on nearly Zero Energy Buildings (nZEBs). The assessment is performed for detached houses and evaluates the feasibility to use PV and battery systems for Swedish nZEBs. The results show that on-site PV production can help buildings to meet the nZEB regulations, but there are limitations due to the poor time-dependent matching. With a combined PV-battery system, the potential to meet the regulation is significantly larger. To summarize, the Energy matching chart has the potential to become a useful tool in the assessment of PV system and the evaluation of load matching measures.

  • 4.
    Monie, Svante
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nilsson, Annica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Lingfors, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Widén, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Åberg, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Thermal Energy Storages in Residential Areas: – a potential to increase renewable power generation?2018Inngår i: 2018 ACEEE Summer Study on Energy Efficiency in Buildings: Making Efficiency Easy and Enticing / [ed] Fred Grossberg, Washington D.C., 2018, Vol. 20, s. 11-1-11-12, artikkel-id 0194_0286_000156Konferansepaper (Fagfellevurdert)
    Abstract [en]

    With an increased ambition of implementing renewable electricity production in our energy systems follows the need of handling the inherent variability from some of these production sources (e.g. wind and solar). This could be via curtailments, infrastructural reinforcements of the power grid, and/or increased utilization of power system reserves. The aim of this study was to investigate if power surplus and deficit due to mismatch between intermittent power generation and power demand could be reduced with electric heat pumps (used for power-to-heat purposes), combined heat and power (CHP) production (for power balancing), and seasonal thermal energy storage (STES) (as buffering capacity). A residential area consisting of buildings refurbished for improved energy performance, roof top solar photovoltaic (PV) systems, a local heat distribution system, a small-scale CHP plant, central heat pumps, and a STES, was simulated. The heat pumps were given priority to use surplus power from roof top PV generation or surplus from the grid (e.g. wind power). The CHP plant produced power during power deficits. Surplus heat from the CHP plant as well as from the heat pumps was stored in the STES. The results showed a reduction of the surplus power from the local PV systems towards the upstream power grid. Also, the possibility to offer regulative service towards upstream power grid by using CHP was demonstrated. The conclusion is that power-to-heat and CHP can significantly reduce the mismatch between variable power generation and power demand.

  • 5.
    Munkhammar, Joakim
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Widén, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nilsson, Annica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Photovoltaic self-consumption potential of alternative year-round daylight savings time2013Inngår i: Proceedings of the 28th European Photovoltaic Solar Energy Conference (EU PVSEC), Paris, France, September 30 - October 4, 2013., 2013, s. 4753-4757Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In a mature photovoltaic (PV) market where feed-in tariffs have declined, managing of the hosting capacity of the distribution grid becomes essential by maximizing the utilization of PV. One way to increase hosting capacity is to increase self-consumption of the self-produced PV power. This paper investigates the effect of an alternative year-round daylight savings time (DST) – where the time of the entire society is changed relative to the sun - on the level of self-consumption in terms of solar fraction and load fraction of PV power both on household- and national level. Household electricity use was modeled with a Markov-chain model, PV power production was modeled from solar irradiance data, and the national level was simulated using national electricity data. Results show that one hour year-round DST shifted ahead might increase self-consumption by a fraction of one percentage point for a net-zero energy household. For a 30 GWp PV installation on a national scale with a 140 TWh annual electricity use one hour DST shift ahead had almost no effect on self-consumption. The optimal self-consumption of PV power on the national level was concluded to be the current DST setup.

  • 6.
    Nilsson, Annica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Optical and thermal properties of functional coatings on glass and plastics for energy efficient windows and daylighting2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Over the past couple of decades a number of coated glazing products have appeared on the market, converting the window from an energy drain to a possible resource in the building’s energy supply system. In this paper the light transmittance, total solar transmittance, and thermal conductivity of coated glazing currently available on the market and of future dynamic electrochromic coatings are reviewed and their function in heating or cooling dominated climates discussed. Electrochromic coatings can switch between a transparent state and an absorbing or reflecting state when a small electrical potential is applied, and hence adapt their optical properties to the present condition. Energy balance calculations for the window component stress the importance of selecting the window depending on climate. In a heating dominated climate a low-e coating with a high g-value can result in a net energy gain on a south facing façade and thus be better than an ideal wall.

     

  • 7.
    Nilsson, Annica
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Jonsson, J C
    Lawrence Berkely Nat Lab, USA.
    Light-scattering properties of a venetian bind slat used for daylighting applications2009Konferansepaper (Fagfellevurdert)
  • 8.
    Nilsson, Annica M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Daylighting Systems: Development of Techniques for Optical Characterization and Performance Evaluation2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Successful integration of daylighting systems requires the ability to predict their performance for given climates. In this dissertation, a bottom-up approach is applied to evaluate the optical performance of a selection of daylighting systems. The evaluations are based on the optical properties of the included materials, and part of the dissertation focuses on developing new optical characterization methods.

    The work on characterization techniques uses an integrating sphere method to characterize the transmittance of light scattering samples more accurately. The method's principle is to reduce the discrepancy in light distribution between the reference and the sample scans by using an entry port beam diffuser. For samples exhibiting distinct light scattering patterns, the benefits of improved uniformity outweigh the errors introduced by the diffusing material. The method is applicable to any integrating sphere instrument, and its simplicity makes it suitable for standard measurements.

    In addition to normal-hemispherical properties, many daylighting applications require knowledge of the system's spatial light distribution. This dissertation presents a method combining experimental techniques and ray tracing simulations to assess the light distribution from a Venetian blind system. The method indicates that ray tracing based on simplified optical data is inadequate to predict the light distribution for slat materials exhibiting both specular and diffuse properties.

    Ray tracing is a promising complement to experimental methods used to characterize light guiding or light redirecting systems. Here, spectrophotometric measurements of a scaled mirror light pipe validate a ray tracing model. The model shows excellent agreement with experimental results for both direct and diffuse incident light. The spectral evaluation shows no dramatic color changes for the transmitted light. The ray tracing model is used to evaluate four daylighting systems for a selection of Swedish locations. The percentage of occupied time when the studied systems achieve full design illuminance is relatively low, but the systems provide a valuable contribution to the required illuminance.

    Additionally, this dissertation provides an overview of available energy efficient windows and illustrates the importance of including the solar energy transmittance when evaluating window energy performance.

    Overall, this dissertation presents optical characterization techniques for improved performance evaluations of daylighting systems.

    Delarbeid
    1. Method for more accurate transmittance measurements of low-angle scattering samples using an integrating sphere with an entry port beam diffuser
    Åpne denne publikasjonen i ny fane eller vindu >>Method for more accurate transmittance measurements of low-angle scattering samples using an integrating sphere with an entry port beam diffuser
    2011 (engelsk)Inngår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 50, nr 7, s. 999-1006Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    For most integrating sphere measurements, the difference in light distribution between a specular reference beam and a diffused sample beam can result in significant errors. The problem becomes especially pronounced in integrating spheres that include a port for reflectance or diffuse transmittance measurements. The port is included in many standard spectrophotometers to facilitate a multipurpose instrument, however, absorption around the port edge can result in a detected signal that is too low. The absorption effect is especially apparent for low-angle scattering samples, because a significant portion of the light is scattered directly onto that edge. In this paper, a method for more accurate transmittance measurements of low-angle light-scattering samples is presented. The method uses a standard integrating sphere spectrophotometer, and the problem with increased absorption around the port edge is addressed by introducing a diffuser between the sample and the integrating sphere during both reference and sample scan. This reduces the discrepancy between the two scans and spreads the scattered light over a greater portion of the sphere wall. The problem with multiple reflections between the sample and diffuser is successfully addressed using a correction factor. The method is tested for two patterned glass samples with low-angle scattering and in both cases the transmittance accuracy is significantly improved.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot fasta tillståndets fysik
    Identifikatorer
    urn:nbn:se:uu:diva-149785 (URN)10.1364/AO.50.000999 (DOI)000287851800019 ()
    Tilgjengelig fra: 2011-03-23 Laget: 2011-03-23 Sist oppdatert: 2017-12-11bibliografisk kontrollert
    2. Transmittance characterization of anisotropically light scattering samples using an integrating sphere with an entry port beam diffuser
    Åpne denne publikasjonen i ny fane eller vindu >>Transmittance characterization of anisotropically light scattering samples using an integrating sphere with an entry port beam diffuser
    (engelsk)Inngår i: Optical materials (Amsterdam), ISSN 0925-3467, E-ISSN 1873-1252Artikkel i tidsskrift (Fagfellevurdert) Submitted
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-183304 (URN)
    Tilgjengelig fra: 2012-10-24 Laget: 2012-10-24 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    3. Light-scattering properties of a Venetian blind slat used for daylighting applications
    Åpne denne publikasjonen i ny fane eller vindu >>Light-scattering properties of a Venetian blind slat used for daylighting applications
    2010 (engelsk)Inngår i: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 84, nr 12, s. 2103-2111Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The low cost, simplicity, and aesthetic appearance of external and internal shading devices, make them commonly used for daylighting and glare-control applications. Shading devices, such as Venetian blinds, screens, and roller shades, generally exhibit light scattering and/or light redirecting properties. This requires the bi-directional scattering distribution function (BSDF) of the material to be known in order to accurately predict the daylight distribution and energy flow through the fenestration system. Acquiring the complete BSDF is not a straightforward task, and to complete the process it is often required that a model is used to complement the measured data. In this project, a Venetian blind slat with a white top surface and a brushed aluminum bottom surface was optically characterized. A goniophotometer and an integrating sphere spectrophotometer were used to determine the angle resolved and hemispherical reflectance of the sample, respectively. The acquired data were fitted to a scattering model providing one Lambertian and one angle dependent description of the surface properties. These were used in combination with raytracing to obtain the complete BSDFs of the Venetian blind system.

    Emneord
    ABg-model, BSDF, Raytracing, Venetian blinds
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-139621 (URN)10.1016/j.solener.2010.09.005 (DOI)000285125900013 ()
    Tilgjengelig fra: 2010-12-28 Laget: 2010-12-28 Sist oppdatert: 2017-12-11bibliografisk kontrollert
    4. Spectrophotometric measurements and ray tracing simulations of mirror light pipes to evaluate the color of the transmitted light
    Åpne denne publikasjonen i ny fane eller vindu >>Spectrophotometric measurements and ray tracing simulations of mirror light pipes to evaluate the color of the transmitted light
    2014 (engelsk)Inngår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 124, s. 172-179Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Tubular daylighting systems are designed to guide light to the building's core using a highly reflective pipe. The intensity of the transmitted light is essential for the performance of the system. For the qualitative perception of the provided illumination, the color of the delivered light is also an important aspect. For highly reflective mirror light pipes, spectral variations are generally assumed not to affect the color of the transmitted light. Here, spectrophotometric measurements and ray tracing simulations of mirror light pipes are used to verify this commonly made assumption. The characterization methods employ spectral evaluations for both direct and diffuse incident light. The color properties are evaluated for mirror light pipes with a length to diameter aspect ratio of up to 16, using the CIE chromaticity diagram and CIELAB coordinates. For the xy chromaticity diagram, a larger color shift was noted for different illuminants than as a result of the optical properties of the reflective material. Using the CIELAB coordinates, a small color shift was noted for light incident at low solar altitudes. Overall, highly reflective films with spectral variations of a few percent do not markedly affect the color of the transmitted light.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot fasta tillståndets fysik
    Identifikatorer
    urn:nbn:se:uu:diva-183305 (URN)10.1016/j.solmat.2014.01.049 (DOI)000335111000024 ()
    Tilgjengelig fra: 2012-10-24 Laget: 2012-10-24 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    5. Evaluation of optical and thermal properties of coatings for energy efficient windows
    Åpne denne publikasjonen i ny fane eller vindu >>Evaluation of optical and thermal properties of coatings for energy efficient windows
    2009 (engelsk)Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, nr 10, s. 3173-3177Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Over the past couple of decades a number of coated glazing products have appeared on the market, converting the window from an energy drain to a possible resource in the building's energy supply system. In this paper the light transmittance, total solar energy transmittance, and thermal transmittance of coated glazing currently available on the market and future dynamic electrochromic coatings are reviewed and their function in heating or cooling dominated climates discussed. Electrochromic coatings can switch between a transparent state and an absorbing or reflecting state when a small electrical potential is applied, and hence adapt their optical properties to the present condition. Energy balance calculations for the window component stress the importance of selecting the window depending on climate. In a heating dominated climate a low-e coating with a high g-value can result in a net energy gain on a south facing facade and thus be better than an ideal wall.

    Emneord
    Coated glazing, Climate, Energy efficiency, Electrochromics
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-139620 (URN)10.1016/j.tsf.2008.11.083 (DOI)000265178700031 ()
    Tilgjengelig fra: 2010-12-28 Laget: 2010-12-28 Sist oppdatert: 2017-12-11bibliografisk kontrollert
    6. Optical and thermal properties of functional coatings for future high performance windows
    Åpne denne publikasjonen i ny fane eller vindu >>Optical and thermal properties of functional coatings for future high performance windows
    2008 (engelsk)Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    With modern society facing the task of reducing energy consumption in all areas of life, modern windows provide an enormous potential to reduce energy consumption for the heating, cooling and lighting of buildings. For future buildings and for the retrofitting of older buildings the window is more and more becoming an integral part of the building’s energy system. In this paper we present the optical properties for a selection of different window coatings and discuss their impact on the performance of the window. Special emphasis is put on switchable glazing. Optimum performance for switchable glazing is often a trade off between minimum energy consumption for cooling heating and lighting. This can sometimes be in conflict with occupancy preferences. As an example we show how different control strategies for electrochromic windows can influence the energy balance of the window, and that small variations in the control algorithm can lead to improvements. The results were obtained by using the WinSel window simulation tool.

     

    Emneord
    Switchable glazing, control strategies, energy balance calculations
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-125235 (URN)
    Konferanse
    EuroSun, Lisbon, Portugal, 7-10 October, 2008
    Tilgjengelig fra: 2010-05-11 Laget: 2010-05-11 Sist oppdatert: 2016-04-13bibliografisk kontrollert
  • 9.
    Nilsson, Annica M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Laborationsupplägg för främjande av studentaktivitet vid datorbaserade laborationer2012Konferansepaper (Fagfellevurdert)
  • 10.
    Nilsson, Annica M
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Jonsson, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Jonsson, Jacob C
    Environmental Energy Technology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Method for more accurate transmittance measurements of low-angle scattering samples using an integrating sphere with an entry port beam diffuser2011Inngår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 50, nr 7, s. 999-1006Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For most integrating sphere measurements, the difference in light distribution between a specular reference beam and a diffused sample beam can result in significant errors. The problem becomes especially pronounced in integrating spheres that include a port for reflectance or diffuse transmittance measurements. The port is included in many standard spectrophotometers to facilitate a multipurpose instrument, however, absorption around the port edge can result in a detected signal that is too low. The absorption effect is especially apparent for low-angle scattering samples, because a significant portion of the light is scattered directly onto that edge. In this paper, a method for more accurate transmittance measurements of low-angle light-scattering samples is presented. The method uses a standard integrating sphere spectrophotometer, and the problem with increased absorption around the port edge is addressed by introducing a diffuser between the sample and the integrating sphere during both reference and sample scan. This reduces the discrepancy between the two scans and spreads the scattered light over a greater portion of the sphere wall. The problem with multiple reflections between the sample and diffuser is successfully addressed using a correction factor. The method is tested for two patterned glass samples with low-angle scattering and in both cases the transmittance accuracy is significantly improved.

  • 11.
    Nilsson, Annica M.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Jonsson, J. C.
    Light-scattering properties of a Venetian blind slat used for daylighting applications2010Inngår i: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 84, nr 12, s. 2103-2111Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The low cost, simplicity, and aesthetic appearance of external and internal shading devices, make them commonly used for daylighting and glare-control applications. Shading devices, such as Venetian blinds, screens, and roller shades, generally exhibit light scattering and/or light redirecting properties. This requires the bi-directional scattering distribution function (BSDF) of the material to be known in order to accurately predict the daylight distribution and energy flow through the fenestration system. Acquiring the complete BSDF is not a straightforward task, and to complete the process it is often required that a model is used to complement the measured data. In this project, a Venetian blind slat with a white top surface and a brushed aluminum bottom surface was optically characterized. A goniophotometer and an integrating sphere spectrophotometer were used to determine the angle resolved and hemispherical reflectance of the sample, respectively. The acquired data were fitted to a scattering model providing one Lambertian and one angle dependent description of the surface properties. These were used in combination with raytracing to obtain the complete BSDFs of the Venetian blind system.

  • 12.
    Nilsson, Annica M.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Jonsson, Jacob C
    Lawrence Berkeley National Laboratory, CA, USA.
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Spectrophotometric measurements and ray tracing simulations of mirror light pipes to evaluate the color of the transmitted light2014Inngår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 124, s. 172-179Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tubular daylighting systems are designed to guide light to the building's core using a highly reflective pipe. The intensity of the transmitted light is essential for the performance of the system. For the qualitative perception of the provided illumination, the color of the delivered light is also an important aspect. For highly reflective mirror light pipes, spectral variations are generally assumed not to affect the color of the transmitted light. Here, spectrophotometric measurements and ray tracing simulations of mirror light pipes are used to verify this commonly made assumption. The characterization methods employ spectral evaluations for both direct and diffuse incident light. The color properties are evaluated for mirror light pipes with a length to diameter aspect ratio of up to 16, using the CIE chromaticity diagram and CIELAB coordinates. For the xy chromaticity diagram, a larger color shift was noted for different illuminants than as a result of the optical properties of the reflective material. Using the CIELAB coordinates, a small color shift was noted for light incident at low solar altitudes. Overall, highly reflective films with spectral variations of a few percent do not markedly affect the color of the transmitted light.

  • 13.
    Nilsson, Annica M.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Evaluation of optical and thermal properties of coatings for energy efficient windows2009Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, nr 10, s. 3173-3177Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Over the past couple of decades a number of coated glazing products have appeared on the market, converting the window from an energy drain to a possible resource in the building's energy supply system. In this paper the light transmittance, total solar energy transmittance, and thermal transmittance of coated glazing currently available on the market and future dynamic electrochromic coatings are reviewed and their function in heating or cooling dominated climates discussed. Electrochromic coatings can switch between a transparent state and an absorbing or reflecting state when a small electrical potential is applied, and hence adapt their optical properties to the present condition. Energy balance calculations for the window component stress the importance of selecting the window depending on climate. In a heating dominated climate a low-e coating with a high g-value can result in a net energy gain on a south facing facade and thus be better than an ideal wall.

  • 14.
    Nilsson, Annica M.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Optical and thermal properties of functional coatings for future high performance windows2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    With modern society facing the task of reducing energy consumption in all areas of life, modern windows provide an enormous potential to reduce energy consumption for the heating, cooling and lighting of buildings. For future buildings and for the retrofitting of older buildings the window is more and more becoming an integral part of the building’s energy system. In this paper we present the optical properties for a selection of different window coatings and discuss their impact on the performance of the window. Special emphasis is put on switchable glazing. Optimum performance for switchable glazing is often a trade off between minimum energy consumption for cooling heating and lighting. This can sometimes be in conflict with occupancy preferences. As an example we show how different control strategies for electrochromic windows can influence the energy balance of the window, and that small variations in the control algorithm can lead to improvements. The results were obtained by using the WinSel window simulation tool.

     

  • 15.
    Nilsson, Annica M.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Wilson, Helen Rose
    Homogenisation or scattered transmitted light in an integrating sphere using a highly diffusing film on the entry port2014Konferansepaper (Fagfellevurdert)
  • 16.
    Nilsson, Annica
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Optical characterization of a tubular daylighting system for evaluation of its suitability for Swedish climates2011Inngår i: CISBAT 2011: CleanTech for sustainable buildings from nano to urban scale, 2011Konferansepaper (Fagfellevurdert)
  • 17.
    Nilsson, Annika M
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Optical and thermal characterisation of functional coatings on glass and plastics for energy efficient windows and daylighting2008Inngår i: Proceedings, 2008, s. 355-360Konferansepaper (Fagfellevurdert)
  • 18.
    Roos, Arne
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Jonsson, Andreas
    Nilsson, Annica M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Applications of coated glass in high performance energy efficient windows2009Inngår i: Glass Performance Days, 2009Konferansepaper (Fagfellevurdert)
  • 19.
    Wang, JunXin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nilsson, Annica M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Fernandes, Daniel L. A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Angle dependent light scattering by gold nanospheres2015Inngår i: INERA Conference: Book of Abstracts, 2015, s. 71-, artikkel-id 012018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Gold nanocrystals exhibit unique optical properties in enhanced light absorption and scattering owing to their extremely large scattering/absorption cross. sections and large electric field enhancements generated by localized surface plasmon resonance. In this work, the optical properties of gold nanospheres with diameters of 60 nm and 200 nm with remarkable uniformity in size were studied both numerically and experimentally. The total transmittance and reflectance as well as the angle. resolved light scattering intensities of the gold nanospheres were measured. The absorption and scattering coefficients were obtained by fitting the experimental data to the two. flux theory and were in qualitative agreement with single. scattering calculations using the Mie theory.

  • 20.
    Wang, JunXin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nilsson, Annica M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Light Scattering by 2D- and 3D- Angle-Resolved Spectroscopy2016Inngår i: INERA Conference: Vapor Phase Technologies for Metal Oxide and Carbon Nanostructures, 2016Konferansepaper (Fagfellevurdert)
  • 21.
    Wang, JunXin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Xu, Changgang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Xian Univ Sci & Technol, Sch Mat Sci & Engn, Xian 710054, Shaanxi, Peoples R China.
    Nilsson, Annica M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Fernandes, Daniel L. A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    A novel phase function describing light scattering of layers containing colloidal nanospheres2019Inngår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, nr 15, s. 7404-7413Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Light scattering from small particles exhibit unique angular scattering distributions, which are strongly dependent on the radius to wavelength ratio as well as the refractive index contrast between the particles and the surrounding medium. As the concentration of the particles increases, multiple scattering becomes important. This complicates the description of the angular scattering patterns, and in many cases one has to resort to empirical phase functions. We have measured the angle dependence of light scattering from a polymer layer containing sub-micron metallic and dielectric particles. The samples exhibited strongly forward and backward peaked scattering patterns, which were fitted to a number of empirical approximative phase functions. We found that a novel two-term Reynolds-McCormick (TTRM) phase function gave the best fit to the experimental data in all cases. The feasibility of the TTRM approach was further validated by good agreement with numerical simulations of Mie single scattering phase functions at various wavelengths and sizes, ranging from the Rayleigh scattering regime to the geometrical optics regime. Hence, the widely adaptable TTRM approach is able to describe angular scattering distributions of different kinds of nanospheres and nanocomposites, both in the single scattering and multiple scattering regimes.

  • 22.
    Widén, Joakim
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nilsson, Annica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Wäckelgård, Ewa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    A combined Markov-chain and bottom-up approach to modelling of domestic lighting demand2009Inngår i: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 41, nr 10, s. 1001-1012Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Detailed simulations of distributed generation in residential areas   have prompted the need for improved models of domestic electricity   demand that are able to reproduce important features of real household   loads. The high share and temporal variability of the lighting demand   make it of special interest, in particular when the models are to be   used in simulations of distributed photovoltaics (PV), which to a high   degree is negatively correlated with the lighting demand. In this   paper, a stochastic bottom-up model based on domestic occupancy   patterns and data on daylight availability is presented. A threestate   non-homogeneous Markov chain is used for generation of occupancy   patterns and a conversion model transforms occupancy patterns to   lighting demand, with respect to the daylight level. Markovchain   transition probabilities are determined from a detailed set of time-use   (TU) data in Swedish households and the parameters in the   occupancy-to-lighting conversion model are adjusted to make the   resulting load curves fit recent measurements on aggregate population   level. The performance of the model is analysed by comparison of   simulated demand to measured lighting demand. It is concluded that for   both individual households and aggregate demand, all relevant features   of measured demand are realistically reproduced.

  • 23. Wilson, Helen Rose
    et al.
    Nilsson, Annica M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Bretschneider, Joachim
    Hoffmann, Thomas
    Hutchins, Michael G.
    Jonsson, Jacob
    Kremel, Christine
    Marenne, Ingrid
    Roos, Arne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    van Nijnatten, Peter A.
    Transmittance of patterned solar glass panes results of a measurement roud-robin by ICG TC10.11th ESG Conference2012Konferansepaper (Fagfellevurdert)
  • 24.
    Åberg, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Carlsson, Jonas
    ekoPerspektiv AB.
    Nilsson, Annica M
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Improved efficiency for distribution and use of district heating: A simulation study of retrofitting a Swedish apartment complex from the 1970's2018Inngår i: Journal of Building Engineering, ISSN 2352-7102, Vol. 20, s. 559-568Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Important features of the next generation of district heating systems are low distribution heat losses and low distribution temperatures. The purpose of this transition is to compensate for reduced heat demand densities caused by increased energy efficiency in buildings. In Sweden a majority of multi-family residential buildings are connected to district heating networks that are up to 50 years old. This study investigates the possibility to improve building energy efficiency and simultaneously reduce distribution temperatures and losses for a Swedish apartment complex built in the 1970's. The results show that a combination of better insulated building envelopes and ventilation heat recovery can reduce the heat demand in the studied apartment complex by 53%. The improved building energy performance significantly reduces the required supply temperatures for space heating and reduces heat distribution losses to some extent. The heat distribution losses can be reduced further (up to 49%) by replacing central hot water preparation with apartment based heat exchangers. This eliminates heat losses from pipes for domestic hot water supply and hot water circulation. The study concludes that a potential cost-synergy occurs when a holistic strategy is adopted and conventional energy efficiency measures are combined with reduced distribution losses.

  • 25.
    Åberg, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Fälting, Lars
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Ekonomisk-historiska institutionen.
    Carlsson, Jonas
    ekoPerspektiv.
    Johansson, Lars
    EC-Power.
    Forssell, Anders
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Företagsekonomiska institutionen.
    Widén, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nilsson, Annica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Munkhammar, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Lingfors, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Nya lösningar för fjärrvärme i miljonprogramsområden2017Rapport (Annet vitenskapelig)
1 - 25 of 25
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