Reducing the airflow and heat input rates of a furnace that is connected to a duct system in thermal contact with unconditioned spaces can significantly reduce thermal distribution efficiency. This is a straightforward theoretical calculation based on the increased residence time of the air in the duct at

The airflow rate in heating and cooling equipment has major implications for the performance of the system. Improper flow across air conditioner and heat pump coils degrades the capacity of the coil, low flow across the heat exchanger in furnaces can cause the system to cycle on the high-temperature limit switch, and the flow rate has major implications for the efficiency of the duct system. The primary method for measuring the airflow through an air handler uses the change in temperature between the return and supply side of the air handler.

Many energy codes require that ductwork installed outside of the conditioned space be sealed. Prescriptive codes have no performance standard for what constitutes an acceptable level of duct sealing. Testing and anecdotal evidence indicate that many new homes have extensive leaks on both the supply and return sides of the heating system. A field study of 29 recently built homes was conducted in the Spokane, Washington, area. Systems were visually inspected; all defects were

The purpose of continuous fan operation is to bring in fresh outdoor air to the conditioned space in order to maintain acceptable indoor air quality. Ventilation not only uses more energy, but it also impacts air distribution system efficiency.This is partially due to various system interactions. The objective of this paper is to quantify the impact of continuous fan operation on energy use and distribution efficiency by introducingtwo new parameters: energy use ratio (EUR) and distribution efficiency ratio (DER).

Using a newly developed simulation model for electricpowered compression heat pumps, ventilation modules with an integrated exhaust air heat pump for supplying heat for passive solar houses are studied. New units are tested in the conception and design phase. Different designs can be compared before readings are taken from the first prototype. The capacity of the method is tested and the simulation model is validated on the example of a simulated integrated ventilation and heat supply unit for passive solar houses that is intensively measured.

Leakage data for ducted air terminal connections are reported. The leakage flow rate generally varied from 1% to 8% of the total approach flow rate. Leakage was found to increase with the increase in the static pressure adjacent to the terminal for the unsealed condition. With marginal sealing of rigid ducts, leakage was found to be less than half that of the unsealed connection. The use of drawbands to mount air terminals to flexible ducts can reduce leakage at the collar to virtually

An experimental study was conducted to estimate the leakage through air terminal connections to rigid duct and flexible duct. Air terminals from three different manufacturers were tested under different sealing conditions, namely, unsealed, marginally sealed, and fully sealed. Diffusers and supply grilles were tested in a blow-through test setup, whereas return grilles were tested in a draw-through test setup. The experimental procedure and data reduction are described.

Velocity and turbulence intensity profiles of the airflow inside a section of a narrow body (737) aircraft cabin were measured using the particle image velocimetry (PIV) technique.In this paper the measurement technique is described and the results are presented and discussed. The purpose of this study was to provide accurate experimental data for validation of the computational fluid dynamics (CFD) codes developed for this application.

This paper gives an overview of sources of indoor particulate matter (PM) and its effects on occupants. Studies indicate that outdoor PM contributes to indoor PM, yet a large fractionof indoor PM is generated indoors. The ratio of indoor to outdoor PM concentrations (I/O ratio) varies substantially due to different indoor conditions and PM spatial distributions.Real-time investigation using multiple point sampling technique is needed for better understanding of PM spatial distribution.

Past research that has evaluated the association between student performance and some change variable (building renovation, room temperature, curriculum, teacher involvement, etc.) has focused on student-level data and has not adequately accounted for regression artifacts (regression to