FACTORS AFFECTING VENTILATION,INDOOR-AIR QUALITY AND ACOUSTICAL QUALITY IN‘GREEN’AND NON-‘GREEN’BUILDINGS:A PILOT STUDY

This paper discusses a pilot project involving the direct monitoring of ventilation,indoor-air quality and the acoustical conditions in selected nominally‘green’and non-‘green’buildings located on a university campus.The objectives were to measure parameters quantifying these three aspects of indoor environmental quality,determine the relationships between them and the building-design concepts,and evaluate the implications of the results for ventilation-system design,especially in‘green’buildings.Measurements were made in rooms,with and without acoustical treatment,in buildings with natural ventilation or mechanical(displacement and/or mixed-flow)ventilation systems.Measurements were made of ventilation rates(air changes per hour),indoor air quality(respirable-fibre,total-VOC and ultrafine-particulate concentrations),and the acoustical conditions(noise levels and reverberation times).Correlations between the environmental results,the building concept,the ventilation concept and the building window status were explored.In rooms with natural ventilation,low-frequency noise and total sound-pressure levels were lower;however,the rooms had higher ultrafine-particulate counts and lower ventilation rates.Rooms with mechanical ventilation had higher low-frequency and total sound-pressure levels,higher ventilation rates and fibre concentrations,but lower concentrations of ultrafine particulates.It was concluded that,in general,mechanical ventilation can provide better indoor air-quality,but that HVAC noise is an issue if the system is not properly designed.In‘green’buildings,noise levels were acceptable when the windows were closed,but increasing the ventilation rate by opening the windows resulted in higher noise levels.The results suggest that the acceptability of environmental factors in buildings depends on the degree of compliance of the design and its implementation with standards and design guidelines(i.e.for ventilation,air quality,thermal comfort,etc.),whether the original design concept is‘green’or non-‘green’.

ACOUSTICAL IMPROVEMENTS WITH NATURAL AIR VENTILATION IN THE LIU INSTITUTE FOR GLOBAL ISSUES AT THE UNIVERSITY OF BRITISH COLUMBIA

Low speech privacy in shared and private offices in one of the early generation of a“green”building resulted in occupants’dissatisfaction.This problem is experienced in Liu institute with a natural-ventilation system.Such a system requires low air-flow resistance which is achieved by large openings which will result in noise transmission between various spaces within the building.The poor acoustical quality in this building resulted in occupants’noise complaints which were further investigated by way of relevant acoustical measurements.CATT-Acoustic software was utilized to modify the acoustical quality of the building without any disturbance to the occupants.The optimized design of the transfer box above the office door was selected based on CATT-Acoustic predictions.The acoustical measurements were conducted after installation of the transfer box above the office door.The measurements’results agreed with the predictions which led to improved speech privacy to an acceptable level between the office and the corridor in Liu Institute.More work should be done to improve the acoustical quality of natural-ventilated building to conform to ANSI standards.1 The results of this study strongly support including acoustics in“green”building designs with natural ventilation to avoid users’complaints.