English

The governing equations in duct system flow analyses are nonlinear, and iterative solution methods must be used. A suitable initial flow rate guess may be needed to start the calculations so that a converged solution can be finally achieved. A method to obtain a reasonably accurate initial flow rate guess is presented. In it the duct system is analyzed first in a strongly simplified setting assuming a linear (imaginary laminar) duct flow problem. The continuity equations at the junctions are satisfied.

Aerosol detection in HVAC duct components is a critical component of contaminant detection and analysis. Incorrect placement of a sensor inlet within the ductwork can have a significant, deleterious effect on capture efficiency and sample accuracy. Computational fluid dynamics studies were conducted of straight rectangular cross-section ductwork and a 90° bend to determine flow patterns and simulations of particulate injections were made at various locations across the inlet. The resultant particle distributions were analyzed to determine the optimal placement for a sensor inlet.

There is a need to improve the accuracy of infrared thermography for measuring the temperature distribution of building exterior surfaces. Thermography is useful for building ventilation and thermal analysis, as well as understanding city ventilation and the urban heat island phenomenon. The key in correcting infrared images is to quantify accurately the reflected infrared contribution of surrounding surfaces as well as that of the atmosphere. Two new methods are proposed here for correcting measured temperature distribution of building exterior surfaces by infrared thermography.

Windcatchers are roof mounted devices that use the action of the wind to provide top down natural ventilation to a room. Here, fresh air is channelled into a room while, at the same time, stale air is drawn out. This provides a simple but attractive natural ventilation methodology that is increasing in popularity in U.K. schools. However, an analysis of system performance has largely been limited to laboratory based measurements and the use of CFD to generate predictions.

In this paper, a review is made of the adaptive thermal comfort model. This is then applied and compared with the performance of the conventional thermal comfort model for a school located in a Mediterranean weather environment. Measurement data, combined with a building thermal response numerical model, are used to define the comfort performance under ambient natural ventilation and passive conditions for various classrooms. These results can then be used to identify the locations that require further measures to improve comfort, such as extra passive heat load and shading measures.

Hybrid ventilation represents an interesting option both to guarantee good air quality for indoor environments and to reduce the energy consumption related to the mechanical motivation of the air.

Nowadays many people spend most of their time indoors, so the quality of indoor air has significantly impacted human health and comfort. The purpose of the present work was to determine the thermal comfort and suitable air intake rate for Thai people in air-conditioned buildings. A field study was conducted in three types of building from six provinces of Thailand; 698 occupants responded to the questionnaire while simultaneous indoor air quality measurements were taken.

Stratum ventilation is a recently proposed air distribution system. It works by creating a layer of fresher air in the occupants' breathing zone. This is achieved by placing large supply inlets along the side-walls of the room just above the height of the occupants. Fresh air is emitted into the room and gradually loses momentum. The supply velocity is sufficiently strong to provide fresh air directly to the occupants without space mixing.

Ventilation systems are primarily designed for ensuring good indoor air quality (IAQ). However, building energy requirements tend to put demand on reducing air change rates. The assessment of the performance of ventilation systems over long periods has thus become a subject of importance. In this framework, five ventilation systems were investigated for a heating period in a single-family house using a representative occupancy and pollution schedule. This was undertaken using SIMBAD, a combined mass and heat transfer toolbox. This paper compares the different results.

Hybrid ventilation systems combine the superior properties of natural and mechanical ventilation systems to reduce energy consumption. In this study, hybrid ventilation simulations were performed for several cities in Turkey, which have different climate conditions. Matlab/Simulink was utilized to perform the simulations. The results of these simulations were compared with that of regular air conditioning units in terms of energy consumption.