| 1. |
- Kabanshi, Alan, et al.
(författare)
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Window size optimization and shading with photovoltaic panels: Simulation of cooling energy demand in the tropics in the southern hemisphere
- 2021
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Ingår i: 13th International Conference on Sustainable Energy and Environmental Protection: Solar Energy. September 13-16, 2021, Vienna, Austria.. - 9783900932879
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Konferensbidrag (refereegranskat)abstract
- Window size and orientation of holding façade influences the quantity of solar insolation into buildings and consequently the heating/cooling demand and occupant thermal comfort. In cold climates, window optimization (size and the orientation) can reduce the heating requirements if well integrated into the building envelope. However, in hot climates window sizing and orientation poses challenges as it only adds to the cooling energy demand. In addition to design strategies like window size and orientation, passive strategies like blinds or shades are recommended to reduce and control the solar insolation. The current study, through IDA-ICE building simulations, explores optimization of window size, orientation and shading configurations (internal blinds and PV as external shades) and its influence on the cooling energy demand in Harare, Zimbabwe, located in the tropic of Capricorn in the Southern Hemisphere. The results shows that cooling demand and occupant thermal comfort was sensitive to the North facing facades, and slightly on the west, but not on the South and west oriented windows. Shading reduced the cooling demand and use of PV panels proved equally effective although only a slight improvement in thermal comfort level was obtained compared to using internal blinds. However, PV panels produced electricity that could help offset the cooling demand by powering a heat pump or reduce the imported power for other building services. Implications of the results on building design and operation are discussed.
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| 2. |
- Moghaddam, Saman Abolghasemi, et al.
(författare)
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Low‐Emissivity Window Films as an Energy Retrofit Option for a Historical Stone Building in Cold Climate
- 2021
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 14:22
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Tidskriftsartikel (refereegranskat)abstract
- Low‐emissivity (low‐E) window films are designed to improve the thermal comfort andenergy performance of buildings. These films can be applied to different glazing systems withouthaving to change the whole window. This makes it possible to apply films to windows in old andhistorical buildings for which preservation regulations often require that windows should remainunchanged. This research aims to investigate the impacts of low‐E window films on the energyperformance and thermal comfort of a three‐story historical stone building in the cold climate ofSweden using the simulation software “IDA ICE”. On‐site measurements were taken to acquirethermal and optical properties of the windows. This research shows that the application of the lowemissivitywindow film on the outward‐facing surface of the inner pane of the double‐glazedwindows helped to reduce heat loss through the windows in winter and unwanted heat gains insummer by almost 36% and 35%, respectively. This resulted in a 6% reduction in the building’sannual energy consumption for heating purposes and a reduction in the percentage of totaloccupant hours with thermal dissatisfaction from 14% (without the film) to 11% (with the film).However, the relatively high price of the films and low price of district heating results in a ratherlong payback period of around 30 years. Thus, the films seem scarcely attractive from a purelyeconomic viewpoint, but may be warranted for energy/environmental and thermal comfort reasons.
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| 3. |
- Yamasawa, Haruna, et al.
(författare)
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Applicability of Displacement Ventilation and Impinging Jet Ventilation System to Heating Operation
- 2021
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Ingår i: Japan Architectural Review. - : John Wiley & Sons. - 2475-8876. ; 4:2, s. 403-416
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to acquire an understanding of the fundamental feature of IJV and DV under heating operation. Full‐scale experiments were conducted under these two different systems and supply air conditions along with temperature distribution and ventilation effectiveness. A wall surface of the test room was cooled as a heating load, and heating elements simulating occupants were located as internal heat load and contaminant emission source. Three cases of supply temperature were tested and the flow rate was also varied correspondingly. The position of the supply terminal was also changed to see its effect on heating performance, that is, mounted on the interior/exterior wall. For DV, the temperature/contaminant distribution differed significantly depending on the supply conditions, while that of IJV remained almost the same as a perfect mixing condition. Generally, IJV can achieve better temperature distribution compared to DV; however, the ventilation effectiveness of DV was superior to that of IJV with large supply flow rate. The correlation between the Archimedes number based on supply conditions and indices expressing local temperature and ventilation effectiveness is obtained. For IJV, the position of the terminal was found to have a larger impact on air distribution than the supply flow rate, while the opposite feature was obtained for DV.
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| 4. |
- Yamasawa, Haruna, et al.
(författare)
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Effect of supply velocity and heat generation density on cooling and ventilation effectiveness in room with impinging jet ventilation system
- 2021
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Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 205
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to understand the effect of supply momentum and heat generation density on the cooling and ventilation effectiveness in a room with an impinging jet ventilation system (IJV). A parametric study was conducted by CFD analysis, and the number of supply terminals and occupants were varied as parameters. CFD validation was conducted before the parametric study by comparing the experimental and analytical results. RNG k-ε and SST k-ω model showed almost the same accuracy for simulating, and SST k-ω model was chosen to be used for the parametric study. It is shown that the larger number of terminals and/or occupants leads to the air distribution to be displacement flow, whereas the smaller number leads to that of mixed condition. The ventilation effectiveness and cooling effectiveness within the room could be kept higher by locating the supply terminal at the centre of the walls than at the corner of the room. When the supply velocity was smaller than 0.833 m/s, the draught rate (DR) at ankle level in the central cross-section could keep lower than: 20% in the region farther than 0.5 m horizontally away from the terminals, and 15% in the region farther than 1.0 m away from the terminals. Finally, the cooling and ventilation effectiveness is expressed as the function of Archimedes number (the balance between supply momentum and buoyancy) in the specific studied cases. The asymptotic values for both large and small Archimedes numbers are obtained for each index expressing cooling and ventilation effectiveness.
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