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Skaugen T.,Norwegian Water Resources and Energy Directorate | Weltzien I.H.,Norwegian Water Resources and Energy Directorate | Weltzien I.H.,University of Oslo | Weltzien I.H.,Norconsult AS
Cryosphere | Year: 2016

Snow is an important and complicated element in hydrological modelling. The traditional catchment hydrological model with its many free calibration parameters, also in snow sub-models, is not a well-suited tool for predicting conditions for which it has not been calibrated. Such conditions include prediction in ungauged basins and assessing hydrological effects of climate change. In this study, a new model for the spatial distribution of snow water equivalent (SWE), parameterized solely from observed spatial variability of precipitation, is compared with the current snow distribution model used in the operational flood forecasting models in Norway. The former model uses a dynamic gamma distribution and is called Snow Distribution-Gamma, (SD-G), whereas the latter model has a fixed, calibrated coefficient of variation, which parameterizes a log-normal model for snow distribution and is called Snow Distribution-Log-Normal (SD-LN). The two models are implemented in the parameter parsimonious rainfall-runoff model Distance Distribution Dynamics (DDD), and their capability for predicting runoff, SWE and snow-covered area (SCA) is tested and compared for 71 Norwegian catchments. The calibration period is 1985–2000 and validation period is 2000–2014. Results show that SD-G better simulates SCA when compared with MODIS satellite-derived snow cover. In addition, SWE is simulated more realistically in that seasonal snow is melted out and the building up of "snow towers" and giving spurious positive trends in SWE, typical for SD-LN, is prevented. The precision of runoff simulations using SD-G is slightly inferior, with a reduction in Nash-Sutcliffe and Kling-Gupta efficiency criterion of 0.01, but it is shown that the high precision in runoff prediction using SD-LN is accompanied with erroneous simulations of SWE. © Author(s) 2016.

Halling C.,University of Stockholm | Wikstrom S.A.,University of Stockholm | Wikstrom S.A.,AquaBiota Water Research | Lillieskold-Sjoo G.,University of Stockholm | And 3 more authors.
Journal of Applied Phycology | Year: 2013

Seaweed farming has a crucial role in the development of future sustainable mariculture. In the same time, spreading of introduced species or genotypes from farms may threaten local ecosystems. We analyzed a molecular marker (mitochondrial cox2-3 spacers) from cultivated and wild specimen of the widely farmed seaweeds Eucheuma and Kappaphycus, collected in Zanzibar on the African east coast where commercial farming was introduced in 1989. Genotypes of presumed Asian origin were found growing on coral reefs and drifting in seagrass meadows, indicating that genotypes introduced for farming have established successfully in the wild in Zanzibar. Only a very low number of genotypes, all of Asian origin, were found in the farms. This indicates a low accessible gene pool, which can limit the capacity for adaptation to changed conditions and disease resistance in the farming system. African genotypes were found in a few sites, showing the potential for future farming of native strains. The ecological effects of the Asian genotypes introduced to coral reefs should also be further investigated in order to evaluate the risk connected with further introductions of new foreign strains. © 2012 Springer Science+Business Media B.V.

Nord N.,Norwegian University of Science and Technology | Qvistgaard L.H.,Norconsult AS | Cao G.,Norwegian University of Science and Technology
Renewable Energy | Year: 2016

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 SFD was covered by renewable energy. The results showed that the solar energy generated by the system could cover 85-92% and 12-70% of the domestic hot water demand in summer and winter respectively. In addition, the solar energy may cover 2.5-100% of the space heating demand. The results showed that the supply air volume, supply air and zone set point temperatures, auxiliary electrical volume, volume of the DHW tank, orientation and tilt angle and the collector area could influenced mostly the total energy use. © 2015 Elsevier Ltd.

Kjorlaug R.A.,Norconsult AS | Kaynia A.M.,Norwegian University of Science and Technology | Kaynia A.M.,Norwegian Geotechnical Institute
Earthquake Engineering and Structural Dynamics | Year: 2015

The dynamic response of a wind turbine on monopile is studied under horizontal and vertical earthquake excitations. The analyses are carried out using the finite element program SAP2000. The finite element model of the structure is verified against the results of shake table tests, and the earthquake response of the soil model is verified against analytical solutions of the steady-state response of homogeneous strata. The focus of the analyses in this paper is the vertical earthquake response of wind turbines including the soil-structure interaction effects. The analyses are carried out for both a non-homogeneous stratum and a deep soil using the three-step method. In addition, a procedure is implemented which allows one to perform coupled soil-structure interaction analyses by properly tuning the damping in the tower structure. The analyses show amplification of the ground surface acceleration to the top of the tower by a factor of two. These accelerations are capable of causing damage in the turbine and the tower structure, or malfunctioning of the turbine after the earthquake; therefore, vertical earthquake excitation is considered a potential critical loading in design of wind turbines even in low-to-moderate seismic areas. © 2015 John Wiley & Sons, Ltd.

Mjos T.,Norconsult AS | Larsen P.,Norconsult AS | Larsen P.,Norwegian University of Science and Technology
Light and Engineering | Year: 2012

The paper gives a quick introduction to European norm EN 15193 "Energy Performance for Buildings - Requirements for Lighting". It introduces and explains the influences of the different parameters to the annual energy consumption of the installation. More in detail, based on full scale implementation and on site metering, the different implemented measures and technologies and their respective influences are illustrated. The case study is the 17.000 m2 head office building of Norconsult, Norway, which over the past three years has implemented Energy Efficiency measures.

Borgstrom R.,Norwegian University of Life Sciences | Isdahl T.,Norwegian University of Life Sciences | Isdahl T.,Norconsult AS | Svenning M.-A.,Norwegian Institute for Nature Research
Polar Biology | Year: 2015

Although landlocked Arctic charr, Salvelinus alpinus, occur in a large number of High Arctic lakes and often as the only fish species, knowledge of densities and resource use is limited. An allopatric landlocked population of Arctic charr in the 1.47 ha Lake Nordre Borgdam on Svalbard (78°3′N, 13°5′E) was studied during the period 1998–2004. Population abundance was estimated by mark–recapture in July–August 2001. The population was dominated by small individuals with lengths below 16 cm. In 2001, the total number of charr in the length-class 6.0–15.9 cm corresponded to 1,920 individuals/ha or 20.7 kg ha−1. They were mostly feeding on chironomid and trichopteran larvae. The few larger charr seem to feed mainly on smaller conspecifics, and these cannibals probably control the population structure and the abundance of smaller fish. Due to low total number of prey fish in the lake, few individuals are likely to become piscivores. © 2014, Springer-Verlag Berlin Heidelberg.

Rohde T.,Sintef | Martinez R.,Norconsult As
Journal of Healthcare Engineering | Year: 2015

This article presents a study of how equipment is used in a Norwegian University hospital and suggests ways to reduce hospital energy consumption. Analysis of energy data from Norway's newest teaching hospital showed that electricity consumption was up to 50 % of the whole-building energy consumption. Much of this is due to the increasing energy intensity of hospital-specific equipment. Measured power and reported usage patterns for equipment in the studied departments show daytime energy intensity of equipment at about 28.5 kBTU/ft2 per year (90 kWh/m2 per year), compared to building code standard value of only 14.9 kBTU/ft2 (47 kWh/m2 per year) for hospitals. This article intends to fill gaps in our understanding of how users and their equipment affect the energy balance in hospitals and suggests ways in which designers and equipment suppliers can help optimize energy performance while maintaining quality in the delivery of health services.

Lothe A.E.,Norconsult AS | Musch O.F.R.,Norconsult AS
Proceedings of the International Conference on Port and Ocean Engineering under Arctic Conditions, POAC | Year: 2015

A study has been carried out to determine likely extreme wave conditions at 6 locations with active or abandoned communities with port structures at Svalbard; Longyearbyen, Barentsburg, Pyramiden, Ny-Ålesund, Svea and Coles Bay. The work was originally initiated as part of a survey of historical ports commissioned by the Governor of Svalbard/Svalbard Environmental Fund and carried out by SINTEF. In a revision of the previous study, the effect of ice cover (the period during which no or negligible waves may occur) is examined by excluding input from wind and ocean wave data months where it is assumed that ice-cover exists at each site. In addition, the impact of deviation in ice-cover is examined by progressively shortening the ice-cover period. This revision of the data may be applied in two areas of interest. 1. For design purposes, it will lead to a reduction of the design wave heights for those sites where it can be demonstrated that ice-free conditions never occur. 2. In the context of climate change effects, the average wave loading on beaches and glacier fronts will increase if there is a reduction in the period of ice-cover in a typical winter. This may have a significant effect on the numerous shale and gravel beaches on Svalbard, presumably increasing the risk of erosion. In addition this may also have an adverse effect on existing port structures at the chosen locations.

Harsem T.T.,Oslo University College | Harsem T.T.,Norconsult AS | Grindheim J.,Norconsult AS | Borresen B.A.,Norconsult AS
Procedia Engineering | Year: 2016

The purpose of the research was to examine the savings potential and verify how to reduce the energy consumption in new hospitals by about 50%. Our results are also very relevant in other buildings complex with surplus heating, cooling and thermal storage. Conversion and utilization of surplus heat sources represent well known technologies and are under constant development. In large building complexes there is a potential for coordinated production, storage, and distribution of energy. Heat pump, chiller and thermal storage technologies enable re-use of surplus heat/cool energy throughout the year. Energy supply and demand are typically modelled with separate tools and timescales. Through our study new methods are developed for operation of interacting simulating models. These methods provide tools to step into optimization of combinations of integrated energy systems. The main issues focus on hydraulic water flow and storage systems as a basis. The layout is important not only with regards to utilize the energy quality, i.e. The temperature. In addition, control strategies are shown to have a highly relevant impact on the possible savings. Some details of new hydraulic layout and control design will be described and discussed in the paper. Both in combination with heating, cooling and storage system. Our research indicates that it is possible to save between 20-50% of the energy consumption with optimizing the technical installations in Oslo area. Another benefit of integrated thermal modelling is to reduce the risk of permafrost in ground source heat pump installations. This risk is relevant for large buildings in northern Norway, at annual mean temperatures are below 0°C. This paper shows how integrated simulation and design can be used to avoid permafrost. © 2016 Published by Elsevier Ltd.

Lothe A.E.,Norconsult AS | Vold S.,Sintef | Eliassen J.,Public Roads Administration
Coasts, Marine Structures and Breakwaters 2013: From Sea to Shore - Meeting the Challenges of the Sea | Year: 2014

This paper presents the investigations, including laboratory testing, carried out to design a wide berm and low-crested breakwater that aims to absorb the wave energy and prevent overtopping of an exposed section of the E10, National Tourist Road, near Reine, Norway, using graded rock from a nearby tunneling project. The study concludes that low-crested structures are a realistic alternative to high-crested berm structures at sites where scenic qualities are important, and may also be viable from an economic point of view if the bathymetry in front of the breakwater is favorable.

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