English

Distributed demand control ventilation (DDCV) has shown potential for improving both indoor air quality (IAQ) and energy consumption over conventional ventilation systems. However, ventilation strategies based on measurements of CO2 concentrations suffer from several shortcomings due to issues related to accuracy and drift of off-the-shelf CO2 sensors as well as the highly non-uniform distribution of CO2 in typical office environments.

Mixing and displacement ventilation are common systems in commercial buildings, while mixing ventilation is used in residential buildings. Displacement ventilation provides fresh air to the occupied zone in a more efficient way than mixing ventilation but it is important to know how well it works with a floor system for heating or cooling. Can, for example, a floor heating system warm up the supply air too fast and destroy the displacement effect?

Nowadays, the ceiling slot diffuser is very popular in offices. However one of the problems, for the producer and designer of linear diffusers, is to determine and specify correctly the throw-length data, in order to achieve optimal air movement in the occupied zone. Here, experimental studies were conducted to identify the variation characteristics in jet behaviour for ceiling slot diffusers. Nine cases, covering different aspect ratios, were measured under isothermal conditions in two test rooms using traversing measurement systems.

There are various demands for air-conditioning in each office space resulting from the variability of thermal distribution caused by a bias of heat sources. Furthermore, individual demands on the thermal environment are diverse. Therefore, it is difficult to satisfy all demands using conventional air-conditioning systems since these assume perfect mixing. Instead, demand may vary with the result that some spaces could be excessively or unnecessarily cooled. This paper examines an airflow and temperature control for personal air-conditioning.

This work investigates the impact of space planning, interior porosity and variable occupancy on the energy use in offices that is attributable to ventilation/infiltration and air movement. TAS, Lightscape, and Excel software packages were used to simulate and analyse airflow and thermal loads in different office layouts. These layouts were created by varying the internal configurations of a base case shell.

The gradual shift from the traditional approach of outdoor processes of habitation in Ghana to the indoor, coupled with an ingress of solar radiation, liberates excess heat into buildings and makes occupants feel uncomfortable. A straightforward response has been the adoption of air conditioners. This has resulted in high peak electricity demand and excess emissions of greenhouse gases into the atmosphere.

This paper presents the influence of air blown through an injection nozzle in a circular section induction box on the axial jet and air induction. The effect of the turbulent jet on the axial mean streamwise velocity decay, turbulence characteristics, mass entrainment and temperature distribution in the near flow field of an enclosed numerical space is investigated. Convergence of the steady state simulations is achieved by using the RNG kappa-epsilon turbulence model.

The fan is one of the major noise sources of an air conditioner. Because of the presence of other components in the fan assembly, such as the bell-mouth, outlet grille and compressor chamber, the ingested and discharged flow fields around the fan impellers are distinctly different from those in a free field. Therefore, the noise generation mechanisms become much more difficult to analyze and model. This paper concentrates on understanding the generation mechanism and evaluating the noise in the fan system of a split-type air conditioner.

The ventilation of underground car parks is important to avoid health problems associated with the inhalation of combustion products released by car engines, in particular carbon monoxide CO (which is commonly used as the indicator of car park indoor air quality). In recent years, a new mechanical ventilation system has appeared, based on the use of axial ventilators (jet fans) suspended under the car park ceiling. In this paper the flow generated by jet fans and their effects on pollutants are studied.

Wind is an important factor that should be considered in the process of urban design. It is particularly important for natural ventilation design as well as providing guidance on heat transfer, the dispersion of air pollution, wind loading and pedestrian exposure.  This article introduces a set of graphs produced by the author to estimate the wind speed around low rise buildings at heights of less than 10 metres above ground level.