ACOUSTICAL EVALUATION OF SIX‘GREEN’OFFICE BUILDINGS

To explain the reactions of the building occupants to their acoustical environments,meetings with the designers,walk-through surveys,and detailed acoustical measurements were done.The objective was to determine how design decisions affect office acoustical environments,and how to improve the acoustical design of‘green’office buildings.Design-performance criteria were established.Measurements were made of noise level,reverberation time,speechintelligibility index(SII),and noise isolation.Noise levels were atypically low in unoccupied buildings with no mechanical ventilation,but excessive in areas near external walls next to noisy external noise sources—especially with windows open for ventilation—and in occupied buildings.Reverberation times were excessive in areas with large volumes and insufficient sound absorption.Speech intelligibility was generally adequate,but speech privacy was inadequate in shared and open-office areas,and into private offices with the doors open for ventilation.Improvement of the acoustical design of‘green’buildings must include increasing the external-internal noise isolation and that between workplaces,and the use of adequate sound absorption to control reverberation and noise.

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’.

PERFORMANCE OF SUSTAINABLE BUIL DINGS IN COLDER CLIMATES

Building performance evaluations(BPEs)were carried out for nine Canadian green buildings using a standardised assessment framework.The aim was to explore and measure the discrepancies between the operational performance of the buildings and their predicted performance,as well as to identify lessons for their owners,design teams and the construction industry.The objective of this paper is not to report individual buildings in detail(we refer the reader to the individual building reports)but to report on some general lessons that came from doing this study.Overall these buildings performed well compared to benchmarks.However,the findings suggest that occupancy is not well understood and often incorrectly predicted during design,and that this affects various aspects of performance,including energy and water use.Also energy and water use modelling is often undertaken principally for building code/green rating compliance purposes and does not necessarily represent an accurate prediction of likely operational use.Combined with variations in occupancy this can lead to considerable discrepancies in performance from the modelled values.This may be understood by experts but is often misleading to building owners and others.Water use is often not well predicted and also not carefully managed in buildings and there is a lack of understanding of what constitutes good water performance.Overall,it is important to recognise that each building has its own individual“story”that provides necessary context for effective management and improvement of the building during its ongoing life.It is proposed that a BPE process allows that context to be better understood,and enables more effective decision making about building management,improvements,occupant satisfaction,energy use,etc.

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.