The performance of a newly designed corner impinging jet air distribution method with an equilateral triangle cross section was evaluated experimentally and compared to that of two more traditional methods (mixing and displacement ventilation). At nine evenly chosen positions with four standard vertical points, air velocity, turbulence intensity, temperature, and tracer gas decay measurements were conducted for all systems. The results show that the new method behaves as a displacement ventilation system, with high air change effectiveness and stratified flow pattern and temperature field. Both local air change effectiveness and air exchange effectiveness of the corner impinging jet showed high quality and promising results, which is a good indicator of ventilation effectiveness. The results also indicate that there is a possibility to slightly lower the airflow rates for the new air distribution system, while still meeting the requirements for thermal comfort and indoor air quality, thereby reducing fan energy usage. The draught rate was also lower for corner impinging jet compared to the other tested air distribution methods. The findings of this research show that the corner impinging jet method can be used for office ventilation.Energies 2019, 12, 1354 2 of 15 the average IAQ in the occupied zone, and the results showed that there was a 35-50% improvement in the breathing zone due to the buoyancy effect around the mannequin body [4]. In a more recent publication, four different ventilation systems were compared in terms of ventilation efficiency, thermal comfort and energy-saving potential by using numerical simulations. The four systems compared were DV, mixing ventilation (MV), wall confluent jets ventilation (WCJ), and impinging jet ventilation (IJV). The comparison was done for an office environment. The results showed that DV was better than the other air delivery systems in all areas except when evaluating the vertical temperature gradient between ankle and neck levels for a standing person [5]. Other research groups have also concluded that DV is more suitable for cooling by exhibiting higher ventilation and energy effectiveness. It also creates a temperature stratification which facilitates the concentration of pollutants in the lower strata of the occupied space [6][7][8].Another type of air distribution system is IJV, which has been the subject of much research [9-13]. However, very few studies have examined multiple inlet devices based on IJV. In an early study, Karimipanah and Awbi [14] compared IJV to wall displacement ventilation in a laboratory classroom. They tested several key parameters such as ventilation efficiency, local mean age of air, and other characteristic parameters both experimentally and by numerical simulations. One of the conclusions of their research was that the IJV system showed a slight improvement in mean age of air and velocity distributions due to a better balance between buoyancy and momentum forces. Similarly, Koufi et al. [15] also reached the conclusion that IJV ha...

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A vital requirement for all-air ventilation systems are their functionality to operate both in cooling and heating mode. This article experimentally investigates two newly designed air distribution systems, corner impinging jet (CIJV) and hybrid displacement ventilation (HDV) in comparison against a mixing type air distribution system. These three different systems are examined and compared to one another to evaluate their performance based on local thermal comfort and ventilation effectiveness when operating in heating mode. The evaluated test room is an office environment with two workstations. One of the office walls, which has three windows, faces a cold climate chamber. The results show that CIJV and HDV perform similar to a mixing ventilation in terms of ventilation effectiveness close to the workstations. As for local thermal comfort evaluation, the results show a small advantage for CIJV in the occupied zone. Comparing C2-CIJV to C2-CMV the average draught rate (DR) in the occupied zone is 0.3% for C2-CIJV and 5.3% for C2-CMV with the highest difference reaching as high as 10% at the height of 1.7 m. The results indicate that these systems can perform as well as mixing ventilation when used in offices that require moderate heating. The results also show that downdraught from the windows greatly impacts on the overall airflow and temperature pattern in the room.

Low-emissivity (low-E) window films are designed to improve the thermal comfort and energy performance of buildings. These films can be applied to different glazing systems without having to change the whole window. This makes it possible to apply films to windows in old and historical buildings for which preservation regulations often require that windows should remain unchanged. This research aims to investigate the impacts of low-E window films on the energy performance and thermal comfort of a three-story historical stone building in the cold climate of Sweden using the simulation software “IDA ICE”. On-site measurements were taken to acquire thermal and optical properties of the windows. This research shows that the application of the low-emissivity window film on the outward-facing surface of the inner pane of the double-glazed windows helped to reduce heat loss through the windows in winter and unwanted heat gains in summer by almost 36% and 35%, respectively. This resulted in a 6% reduction in the building’s annual energy consumption for heating purposes and a reduction in the percentage of total occupant 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 rather long payback period of around 30 years. Thus, the films seem scarcely attractive from a purely economic viewpoint, but may be warranted for energy/environmental and thermal comfort reasons.

This is the accepted version of a paper published in Energy. This paper has been peerreviewed but does not include the final publisher proof-corrections or journal pagination.