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In recent years, residential energy conservation research has focused attention on heating system distribution efficiency. Several field studies in the Pacific Northwest have found forced-air heating systems which have a majority of ducts located in unheated buffer spaces can lose as much as 3 0% of the equipment's heating output to duct air leakage and conduction loss. The magnitude of loss can be equivalent to the combined improvements in building shell insulation levels due to updated energy codes.

The primary purpose of a laboratory exhaust system is to remove and convey fumes from the fume hoods and laboratory spaces to an area for safe discharge. This requires discharge conditions that allow good dispersion and prevent re-entrainment. Since laboratories are usually designed for once through air ( 100% makeup air with no recirculation), a secondary purpose is energy recovery from the exhaust stream. Laboratory exhaust systems have typically one of two arrangements.

This paper describes the wind tunnel study conducted on behalf of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to evaluate and quantify the effect of architectural screens on rooftop concentration levels due to effluent from short stacks. An equivalent stack height (ESH) concept is introduced, which is used to develop a stack height reduction (SHR) factor that may be used in conjunction with existing stack design procedures found in the 1997 ASHRAE Handbook-Fundamentals to account for the presence of architectural screens.

Laboratory exhaust stacks should be designed with sufficient height and exit momentum to avoid re-entry of exhaust and possible air quality problems, and the design should be evaluated before construction. One evaluation method is presented in this paper that combines dilution prediction equations from the 1997 ASHRAE Handbook-Fundamentals (1997} and a dilution criteria of Halitsky (1988). This method is less conservative than a geometric method in the ASHRAE Handbook and is less costly than wind-tunnel modeling.

While there is no convincing technical basis for current code requirements for crawl space ventilation, most codes still require operable vents and the practice is well established among builders and architects . While the evidence against venting is compelling to many if not most in the research community builders and code officials apparently want to see hard evidence. In this research project I measured weekly energy consumption for space heating for a 1150 square foot home in a climate with 5900 heating degree days.

Ventilation systems for residential buildings can be generally categorized as supply, exhaust, or balanced systems. Subcategories include: integration into central air distribution ducts, or single- or multipoint air distribution; This effort focused on establishing a design methodology for central-fan-integrated supply ventilation systems using an outside air duct to the return side of a central air distribution fan, with a specialized fan recycling control.

Containment of hazards in a laboratory chemical hood is based on the principle that air drawn through the face area of the hood is sufficient to overcome the many challenges at or near the opening. Challenges to overcome include, but are not limited to, air velocities near the hood, movement of the researcher, people walking past the hood, location of equipment inside the hood, size of the sash opening, and the shape and configuration of entrance conditions. To overcome these challenges, a sufficient face velocity must be maintained.

The heating, ventilating, and air-conditioning (HVAC) system for a laboratory must be designed with consideration for safety, air cleanliness, and space temperature. The primary safety concern is to ensure proper coordination between fume hood exhaust and makeup air supply. Air cleanliness is maintained by properly filtering supply air, by delivering adequate room air changes, and by ensuring proper pressure relationships between the laboratory and adjacent spaces. Space temperature is maintained by supplying enough cooling air to offset the amount of heat generated in the room.

Current model building codes require attic ventilation in all U.S. climates. Originally, these requirements were strictly based on concerns for condensation in attics during winter in cold climates, and they were based on limited technical information. Nevertheless, attic ventilation has become the uncontested strategy to minimize condensation and ice dams during winter and extreme attic temperatures during summer. However, other strategies exist that address each of these problems as well as or better than attic ventilation.

The goal of this work was to assess the performance of two common ventilation systems, an exhaust and an exhaust supply system, in Swedish apartment buildings. Since correct air-exchange and interzonal airflows are important for removing contaminants and improving indoor air quality, these airflows were analyzed by systematic computer calculations when selected input parameters were varied around their default values.