air conditioning

The paper presents a way of producing an algorithm for the automated construction of mathematical models of air conditioning and ventilating systems with branched air duct networks. The use of mathematical modelling in making aerodynamic calculations of air duct networks allows us to determine the actual value of air flow in network elements. It also permits us to achieve the required air flows effectively in the adjustment of a system.

There are important benefits to come from using passive techniques as opposed to artificial cooling. They may not be sufficient to provide thermal comfort throughout the year in wet tropical areas, however. Few experiments have been performed on the thermal performance of buildings using a mixed-running strategy in warm-humid climates. The paper attempts to demonstrate that a possible dual-mode integrated operation can be used for such locations.

Investigates the possibility of limiting ventilation in archival storage areas when the outside conditions would have a detrimental effect on the humidity. Conducted measurement-based simulations on the Vaud state archives in Lausanne, Switzerland, with a continental mild climate. Recommends good insulation and high thermal mass.

Describes a project which aimed to develop strategies to improve and control the performance of HVAC systems for incorporation into codes and guidelines. One subtask of the project was an investigation of maintenance procedures, including a literature review, the definition of cleanliness for the major components and a 'new maintenance guideline'.

Air conditioning equipment commissioning adjusts the variables of air diffusion, induction ratio and Coanda effect to optimise comfort. Outlines the author's views on employing suitably qualified persons for commissioning, and in the case of larger projects, a commissioning manager. Recommends the use of a hood factor for air balance and system leakage diagnosis. Lists methods available for balancing water based systems, with index balancing being the most cost effective. Recommends also conducting pre-commissioning checks.

Analyses the operation and life cycle costs of industrial buildings using an energy and environmental auditing process. The results will be used in the design of optimized HVAC systems for the future.

Mycological investigations were performed on a modern multistorey office building in the southeastern coastal US. Extensive colonization was found in the air handling units and fibreglass duct liner of the HVAC system. Concentrations in air samples were low however. Removal of colonized insulation material reduced indoor air quality complaints.

Describes a project to examine the secondary air filters in the air handling units on four floors of a multi-storey office building which had a history of fungal colonization of insulation in the air distribution system. Fungi were observed throughout the system. Lower concentrations of volatile organics were emitted from fungal affected air filter medium. Concludes that the growth of fungi in air distribution systems may affect the content of volatile organics in indoor air.

Describes a study of 424 homes in USA to analyse the presence of dust mite allergens. Seasonal fluctuations were identified. Air conditioning was found to reduce allergens. States that the findings imply that differences in the microclimate within homes may have a dramatic effect on mite populations.

The effect of residential central air conditioning on indoor spore counts was investigated. Six pairs of residential buildings were monitored for three days. The homes were both air conditioned and non-air-conditioned. An Andersen sampler was used and outdoor measurements were also taken. Kitchens and bedrooms of air conditioned homes revealed significantly lower spore counts. The study used multiple regression analysis to show that the lower spore counts were associated with lower relative humidity.