Most HVAC systems are designed to supply air based on assumed (usually maximal) rather than actual occupancy, therefore often resulting in over-ventilation. The concept and theories of demand-controlled ventilation (DCV), which are to find better ventilation strategies according to actual occupancy, have been developed for more than two decades and have been applied to many situations. However, a certain type of room (i.e. short-term occupied room) seems to have been neglected in the literature of DCV.

Durability of the building envelope is important to new homes that are increasingly built with improved levels of airtightness. It is also important to weatherized homes such that energy savings from retrofit measures, such as air sealing, are persistent. This paper presents a comparison of air leakage measurements collected in November 2013 through March 2014, with two sets of prior data collected between 2001-2003 from 17 new homes located near Atlanta, GA, and 17 homes near Boise, ID that were weatherized in 2007-2008.

Old buildings that represent and maintain historic values often have poor indoor conditions and energy efficiency. The aim of this work was to evaluate the influence of building structures on airtightness and energy performance of certain historic building types. In this study on-site measurements, dynamic simulation and questionnaires were used. Significant differences between the levels of the airtightness of the historic houses exist in the studied region. No statistically significant correlation was found between the structure types and the envelope tightness.

This research aims at quantifying the leakage occurring in Under Floor Air Distribution (UFAD) systems and Over Head Air Distribution (OHAD) systems. The study also classifies the leakage occurring in the different systems into Category 1 leakage and Category 2 leakage. The study was performed between a plenum supply UFAD system (having a maximum flow rate of 1272 m3/h), a ducted supply UFAD system (having a maximum flow rate of 286 m3/h) and an OHAD system (having a maximum flow rate of 2004 m3/h).

House dust contamination has recently become an important issue in the residential indoor environment. This study evaluated ventilation systems for removing house dust efficiently in a full-scale residential room. Experiments and simulations were performed to investigate diffusion and deposition of house dust by different ventilation systems. Riboflavin particles were used as the house dust. Two kinds of ventilation systems were considered, namely ceiling exhaust and slit exhaust.

The impact of clothing, breathing and body posture on the thermal plume above a thermal manikin was investigated. Measurements of air velocity and temperature above the manikin were performed at four different heights above a sitting and a lying manikin. The results obtained from tests above the sitting manikin show an inverse proportion between the thermal insulation of clothing and the air velocity in the thermal plume. Air velocity in the thermal plume with the breathing function switched on equalled 90-98% of the values obtained for non-breathing experiments.

The effects of vent configuration and span number on the microclimate in multi-span greenhouses were investigated. A three-dimensional (3-D) computational fluid dynamics (CFD) model was constructed based on an 11-span plastic greenhouse cultivated with 0.2 m-high lettuces. The model was verified with the temperature profile measured in the greenhouse. Then, it was used to explore the effects of vent configuration and span number on greenhouse climate. Simulations show that different vent configurations result in very different microclimate fields.

In the present study microclimate and airflow patterns in a real operating theatre (OT) under effective use conditions are investigated. Surgical staff movements and sliding door opening/closing effects on the air thermal distribution and velocity fields are considered. Experimental measurements and numerical simulations are carried out for the “at rest” and “operational” conditions of the OT. Two “operational” use conditions are considered: “correct” and “incorrect” during a simulated hip surgery.

A specific type of centrifugal fan named the "squirrel-cage" is broadly used in parallel configurations within an evaporator unit of HVAC systems for public transport. In these units, interaction effects arise, both between fans themselves and between fans and the structural elements. Blockage effects, such as the electrical motor, the evaporator gate and some aesthetic covering may also appear when these external elements are located very close to the fans aspiration nozzles.

The air tightness of ventilation ductwork was measured in two recently built low-energy houses and in two conventionally built houses in the summer of 2013. The ducts and components were metal in three houses and plastic in one house. The air tightness of the ductwork had been checked by an installation survey after construction. The measured leakage airflows corresponded to air tightness class A or lower, therefore did not satisfy the minimum requirement set for class B regarding the air tightness of ventilation ductwork.