English

Describes method which permits long term tracer gas measurements in several separate rooms simultaneously. The method employs a fully automated constant concentration system developed at the laboratory for building physics at the Swedish Institute for Materials Testing. Describes measurement principles andpractice.

Over 200 reports of health hazard evaluations are available of sealed, air-conditioned buildings, requested by occupants who believe their buildings to be hazardous to their health. Describes a computer based building information system developed to extract relevant information about internal environmental measures, disease characteristics and history of occupants, as well as relevant features of the architecture and ventilation conditions of buildings.

Data collected in a LBL study on ventilation in four public buildings includes sensory evaluations of indoor environment and of physical and chemical properties of indoor air. Analyzes database to establish how the indoor odour acceptability criterion (acceptability by 80% of individuals entering theoccupied space) depends on other qualities of the indoor air. Finds that the staleness freshness rating correlates to the odour acceptability better than odour intensity alone. At low concentrations formaldehyde or aldehydes increase odour intensity but also improve odour acceptability.

Compares measured hourly data on indoor humidity with data obtained by calculative values for NBS Houston test houses and for the high mass test building in an environmental chamber. Measured values are usually very different from the calculated values if no considerations are given to moisture absorption and desorption phenomena that take place at the interior surfaces. Introduces the Tsuchiya model that permits the evaluation of room surface moisture absorption capability.

Looks at ventilation requirements for both odour and physical acceptability and pays particular attention to the differences between smoking and non smoking occupancy in an environmental chamber. Results imply that under non smoking conditions and with moderate humidity, between 5 and 10 cfm of fresh air per occupant should satisfy 75% of visitors, but that under smoking conditions, many times as much fresh air is needed for both odour acceptability and compliance with customary criteria values for smoke.

Describes a series of experiments to determine the ventilation performance of 2 different models of wall or window mounted heat exchangers. Determines their nominal efficiency by the measurement of tracer gas decay rates at several indoor locations. Notes significantly higher local ventilation efficiencies in rooms where heat exchangers are operating. Some preliminary tests indicate that internal leakage between the air streams contribute significantly to the ventilation inefficiency of these systems.

Air change rate is often reported as a single number, with no attention paid to different values of air change rate in different zones of a building. This may affect air quality evaluation as there may be undetected zones where air change rate is too small, resulting in localized pollutant concentrations. Describes a multi-point tracer gas technique used to quantify air change ratein different zones of various residential buildings. Defines and calculates zonal ventilation efficiency terms, and proposes a criterion for analysis of the results for indoor air quality evaluation.

Uses a two-zone model to describe the concept of and to define the effectiveness of ventilation. Deals with multiroom aspects and procedures for measuring ventilation effectiveness. The simple two-zone model predicts generally high effectiveness for ventilating systems using the displacement principle, taking advantage of stratification. Reviews tests using thisprinciple in an office room for 1-3 people (28 sq.m., 2.8m ceiling height).

The concept of age, or residence time is applicable to characterize both how the supplied air or a contaminant is spread within an enclosed space and how quickly a contaminant is removed. Discusses the application of the concept toany enclosed space with air intakes and extracts. Establishes a direct relationship between the age concept, exposure to contaminants, and equilibrium concentrations. Treats different tracer gas techniques for measuring the age distributions and derived quantities.

Correlates hourly infiltration in 3 adjacent unoccupied test houses to determine the relative contribution of wind and stack effects. The database, obtained using tracer gas techniques over 2000 hourly readings in each house, is sorted to a single 45 degree sector. Different weather sealing techniques give mean infiltration rates of 0.19, 0.45, and 0.59 ach for the 3 houses. Addition of independent wind and temperature induced pressures correlate only part of the weather induced data variability leaving a residual RMS scatter of about 0.004 ach.