Indoor environment quality and occupant - DRO - Deakin University

Indoor environment quality and occupant - DRO - Deakin University

Deakin Research Online Deakin University’s institutional research repository DDeakin Research Online Research Online This is the published version: ...

737KB Sizes 0 Downloads 9 Views

Deakin Research Online Deakin University’s institutional research repository

DDeakin Research Online Research Online This is the published version:

Paevere, P., Brown, S., Leaman, A., Luther, Mark and Adams, Rob 2008, Indoor environment quality and occupant productivity in the CH2 building, in SB08 : Proceedings of the 2008 International Scientific Committee World Sustainable Building Conference, [ASN Events], [Balnarring, Vic.], pp. 222-229.

Available from Deakin Research Online: http://hdl.handle.net/10536/DRO/DU:30018085 Every reasonable effort has been made to ensure that permission has been obtained for items included in DRO. If you believe that your rights have been infringed by this repository, please contact [email protected] Copyright : 2008, ASN Events

INDOOR ENVIRONMENT QUALITY AND OCCUPANT PRODUCTIVITY IN THE CH2 BUILDING Phillip PAEVERE Stephen Brown 1 2 Adrian Leaman Mark Luther43 Rob Adams

1 2

!

1

CSIRO, Sustainable Ecosystems, Melbourne, Australia, [email protected] Building Use Studies, United Kingdom, [email protected] Deakin University, Geelong, Australia, illJhe~akin.edu.au City of Melbourne, Australia, [email protected]

Keywords: Indoor environment quality, occupant productivity, sustainable office buildings

Summary This paper presents a summary of the results from a post-occupancy evaluation study on indoor environment quality (lEO) and occupant health, wellbeing and productivity in the Council House 2 (CH2) building, which is owned and occupied by the City of Melbourne. This case study has highlighted that the productivity of office building occupants can potentially be enhanced through good building design, and provision of a high quality, healthy, comfortable and functional interior environment, that takes account of basic occupant needs.

1. CH2 Building Council House 2 (CH2) is a 10-storey office building which houses around 500 City of Melbourne staff, and some ground-floor retail space. CH2 was officially opened in August 2006 and occupied by staff in October 2006. CH2's gross floor area of 12,536m2 comprises: • •

Nine floors of office space (9,373m2 total; 1,064m2 per floor typically) 1,995m 2 of basement areas



500m 2 of ground floor retail

CH2 was conceived, designed and built with a SUbstantial focus on setting a new standard for ecologically sustainable office buildings. It has a raft of sustainable technologies and design philosophies incorporated throughout the entire building, services and fit-out. Key sustainability-related features of CH2 include: •

Low energy, passive cooling systems



Low energy, integrated electric lighting and daylighting systems



Co-generation, photo-voltaic cells, and wind-driven turbines



Active louvres on West facade and vertical garden on North facade



Sewer mining, water recycling, rainwater collection



Use of recycled materials



Extensive facilities for cyclists

A key element of the business case for CH2 was that provision of high levels of lEO, along with other design features, would result in significant benefits to City of Melbourne through improved health, wellbeing and productivity of staff in the building. Key lEO features of CH2 include: •

100% fresh air ventilation is introduced at floor level, and is then exhausted at ceiling height using natural convection.



Radiant cooling is provided by the thermal mass of concrete ceiling panels, and also through chilled panels which use a mechanical chiller in combination with phase change material stored in the basement, to charge the coolant. Night purging of the building is used to store the night 'coolth' in the concrete ceiling which is then released during the day. Evaporative cooling through shower www.sb08.org

From the Proceedings of the World Conference 5B08 - 15BN 978-0-646-50372-1

<: Back



Home



Contents



Authors Index



Program Index

>

Forward

towers on south face is used to cool the retail areas on the ground floor, and to remove some heat from the coolant used in the chilled ceiling panels. •

Lighting is provided through a mix of high-efficiency recessed luminaries in the ceiling, suspended strip lighting, daylight penetration, and extensive task lighting.



Low toxicity materials used for all furnishings and finishes



Extensive use of indoor plants

The Interior design was also intended to produce productivity benefits through increased communication and collaboration between staff. The fit-out of CH2 is based on a modern open-plan philosophy, with no enclosed offices and low adjustable partitions between workstations. There are relatively unobstructed lines of sight throughout each floor, with the only enclosed spaces being the formal meeting rooms. Informal meeting and social spaces are provided throughout the building. Occupants also have access to external balconies, a winter garden, a summer terrace and a rooftop garden. An external view of the CH2 building is shown in Figure 1, and some interior views are shown in Figure 2.

Figure 1

Exterior views of CH2

www.sb08.org

From the Proceedings of the World Conference 5B08 -15BN 978-0-646-50372-1

<

Back



Home



Contents

•. Authors Index



Program Index

>

Forward

Figure 2

Interior views of CH2

1. Methodology Evaluation of lEO and productivity is based on a program of physical lEO measurements, occupant questionnaires, focus group interviews, and sick leave and staff turnover data. A three page modified 'Building Use Studies' (BUS) occupant questionnaire was conducted in both CH2 and in a 'baseline' City of Melbourne building located next door (CH1). More than 260 responses were received in each building. Assessments for CH2 are compared against Australian and international benchmarks and against the CH1 baseline for productivity assessments. Physical measurements and spot health-symptom questionnaires were also conducted in summer and winter seasons. Measurements and occupant responses are averaged over spatial and organisational boundaries to allow overall assessments to be made. The impact of the lEO on occupant productivity is determined through a single question on the occupant questionnaire which uses a discrete nine-point scale, and asks the respondent to estimate how productivity at work is decreased or increased by the environmental conditions in the building. Although this may not necessarily translate directly to an equivalent increase in work output, it is the most appropriate way to measure the building's impact on productivity in a diverse organisation like City of Melbourne, which encompasses a wide range of job-types which have context-specific productivity dependencies that cannot be clearly defined or measured. The BUS self-assessment methodology has been widely used in Australia and internationally as it provides a consistent measure which enables comparison and benchmarking of productivity effects within and between buildings. Additional questions were added to the standard BUS questionnaire to obtain extra data on wellbeing, indoor plants, and other contextual factors which may impact on productivity assessments. Further details on the methodologies used are given in a separate report (Paevere & Brown, 2008)

2. Summary of Measurements and Questionnaire Findings CH2 occupants are highly satisfied with the building overall, and its facilities, furnishings and fit-out. More than 80% of occupants prefer CH2 to their previous accommodation. A broad summary of the data collected is shown in Figure 3. Full details of the measurements and questionnaires used in the evaluation are given in a separate report (Paevere & Brown, 2008). Thermal comfort is generally good in CH2 based on both physical measurements, and also occupant perceptions for all variables except ventilation, as a result of the airflow being perceived to be too still. The monitoring of center 'building core' comfort levels over the course of a three day period on three different floors of the building was extraordinary in terms of its consistency during both winter and summer periods. This indicates the building's capabilities to provide outstanding, continuous and a consistent level of thermal comfort. (see Figures 4 & 5). This is a good outcome given the relatively complex and inter-connected nature of the various cooling and ventilation systems, and the fact that the systems were being tuned during the period of the study. Further tuning may result in better performance in the future, but diligent management of the systems must be continued. Air quality in CH2 is excellent in terms of measured pollutant levels, and is good based on occupant perceptions. Formaldehyde concentrations in CH2 were much lower than normally found in office buildings. This result can be primarily attributed to the use of 100% fresh air ventilation, and low emission furnishings and finishes throughout the building. Air quality was identified by many occupants as having a positive effect on their productivity. Measurements of ambient noise levels and reverberation times were considered ideal in CH2, however occupant satisfaction ratings for noise are average to poor and are generally worse than benchmarks. The low satisfaction scores are primarily due to unwanted interruptions and distractions from other people in the building. The hindrance of noise from interruptions must be contrasted against the potential productivity enhancement due to the open plan layout, as improved communication has been reported by some occupants and managers. Satisfaction with speech privacy in CH2 may be improved through tuning of the

From the Proceedings of the World Conference 5B08 -15BN 978-0-646-50372-1

"<

Back



Home



Contents



Authors Index

www.sb08.org ." Program Index

>

Forward

white noise system installed in the building. Trials in which white noise levels were increased on one Level in the building resulted in better satisfaction scores for noise when compared to the rest of the building (1018% better for relevant noise variables), however this result is not conclusive, given that satisfaction ratings for most other variables were also higher on this Level. Careful consideration of workgroup layout, circulation routes, and the separation of quiet and noisy activities may also lead to improvements in occupant satisfaction with noise. Lighting is considered to be satisfactory in CH2 overall with some question marks against task lighting and satisfaction with daylight levels. The integration of task lighting into the overall lighting strategy, with lower general illuminance levels, as is the philosophy in CH2, is considered good practice from both a sustainability and user control perspective, however the initial configuration for the CH2 lighting resulted in some complaints about the building being too dark. Measurements shown in Figure 6 indicate that the lux levels for desktop illuminance often fall below the desired level. The background luminance (brightness) was thought to be problematic due to large variations between the electric light sources and the adjacent darkertoned ceiling surfaces, which results in a 'starry-night' effect where a dark surface background prevails against a bright source. These issues were addressed by building management during the study period by incorporation of additional direct/indirect lighting in several places, providing better light diffusion and reducing this problem, although the effect of the changes on occupant satisfaction are not clear. Grey concrete ceilings and darker-toned furnishings and plants are a part of the interior design of CH2 and these may have an impact on occupant perceptions of lighting. Given the improvements and adjustments made to the lighting systems during the study, further assessment of the lighting is warranted. Perceived user control over lEO was rated poorly by occupants in CH2, but only a small portion of occupants indicated this as important to them, and hence for this study, this is not considered as a major factor in assessment of the lEO. CH2 is rated very highly by it's occupants for perceived healthiness, and is considered to have low levels of occupant-reported rates for building-related health symptoms, when compared to levels in the general population. Absenteeism and staff turnover have not changed significantly during the first 12 months of occupation of CH2, compared to previous years, however given the year-to-year variability, and the possibility that organisational restructuring may have had some impact, a longer period of monitoring is required before any solid conclusions can be made about the effects of the building on absenteeism and staff turnover. Satisfaction

lEO - Physical Measurements Sum mary

IEQ - Occupant Satisfaction Summary

100% ,--------------=BU,;;-S;;-Be-:-nchC"Cm-Cack-cmgC"","'®~Go-'-od::-Orc:;cTyC""picCC"al"~'-;:P:C-oo-r-, 80%+-------------=~----------------~~ 60% 40%

20% -r--1'.".i~-Y.·

Temp

Temp

Air

Air

Lighting

Noise

Comfort

Indoor Air

Thermal

Thermal

Winter

Summer

Winter

Summer

Overall

Overall

Overall

Quality

Comfort

Comfort

Winter

Summer

Lighting

Noise

Building Overall

Satisfaction

Productivity Satisfaction

FililCH1 QCH2

100%

Loss/Gain

rolCH1 UCH2

80% +---------,-----,-,-,---60%

+--------1:'

20%

Building Image

Design Overali

Figure 3

Needs

Preferred Accomodation

0%

Summary of key findings on lEO and Occupant Productivity

3. Impact of Building on Occupant Productivity Based on the first 12 months of CH2 occupation, there has been a significant improvement in perceived health and productivity when compared against the CH1 baseline. Given the importance of health and productivity in the business case for sustainable buildings, it is useful to examine the differences between CH2 and CH1, as perceived by the occupants, to try and gain some insights into the impact that different aspects of the building have had on the positive productivity ratings for CH2. It ~ust be noted how~v.er that it is not possible to make quantitative conclusions about the impact that any particular aspect of bUilding design will have on health and productivity based on a study of only two buildings, in which many variables have been changed simultaneously. The results and analysis presented herein apply only to the context of CH2 compared to CH1. www.sb08.org

From the Proceedings of the World Conference 5B08 - ISBN 978-0-646-50372-1

<

Back



Home

• Contents



Authors Index



Program Index

>

Forward

The following categories have been adopted to represent the broad range of factors which could potentially have an impact on occupant productivity: Building Overall; Furnishings, Facilities, Fit-out & Equipment; IEQ (Thermal Comfort, Air Quality, Lighting, Noise); Health Symptoms; Other Factors When the major variables from the occupant questionnaires are categorised in this manner, it can be seen which aspects of CH2 stand out as the biggest perceived improvement, relative to the CH1 baseline. Table 1 outlines the variables that are assigned to the different categories, the satisfaction differences between CH2 and CH1, and the correlation coefficient of each variable with Perceived Productivity in CH2. Figure 7 shows the averaged difference in satisfaction ratings between CH2 and CH1 for these different categories of variables. The main conclusion that can be drawn from this analysis, is that in the case of CH2 compared to CH1, the 'Building Overall' category of variables is likely to be the most significant, in terms of impact on Perceived Productivity. All of the variables under this category correlate better with Perceived Productivity, in relative terms, than all of the other variables in all of the other categories (although it should be noted that the correlations are not very strong in absolute terms, with R in the range 0.5 to 0.6). This category also exhibits the largest difference in satisfaction ratings between CH2 and CH1. Other variables and categories in Table 1 which show a relatively stronger correlation with Perceived Productivity are Thermal Comfort (summer more than winter), Noise Overall, Air Quality, Space Layout, Workstation Usability and Privacy, although none of these are as strongly related to the Perceived Productivity rating as the 'Building Overall' variables. Interestingly, if the averaged satisfaction differences for each category are summed together (they add to 36.5%), this value is very close to the difference in the Perceived Productivity satisfaction rating (which is 36%). Although this is most likely a coincidence, it demonstrates conceptually how different aspects of the building and its design may either enhance or hinder productivity depending on whether they are perceived as satisfactory, or not by occupants. The analyses presented herein cannot be used to prescribe quantitative relative importance or weightings for the impact of individual variables (or categories of variables) on perceived productivity. However, they reinforce the notion that occupant productivity is likely to be dependant on a range of factors related to the overall building and it's fit-out, the different aspects of IEQ, and possibly other contextual factors which may not be related to the building itself, such as experiences in previous accommodation. In the case of CH2, it would seem that satisfaction with the 'building overall' is likely to have had a greater impact on occupants perceived productivity than any specific aspects of the IEQ. As far as the IEQ impact on perceived productivity is concerned, when the data is considered in light of occupant comments, it is likely that air quality and thermal comfort have enhanced productivity, whereas some issues with lighting and noise due to interruptions may have had a hindering effect Assessment of various contextual indicators shows that there has been a reduction in perceived workgroup morale due to workplace restructuring, but there have not been any major contextual shifts in terms of happiness, autonomy and communication during the study period. It is therefore concluded that contextual changes are unlikely to have resulted in any 'false-positive' effect on perceived productivity ratings. Further analyses of the productivity findings are given in a separate report (Paevere & Brown, 2008)

4. Business Case for CH2 In setting up the original Business Case for CH2 and convincing the Council to provide the necessary finance for sustainability and productivity enhancing features, there were two distinct components: 1) The energy and water savings which were conservatively measured at $330,000 per annum and; 2) Productivity and wellbeing of staff again conservatively measured at 4.9% and valued at $1.12M per annum. These components were significant for reasons beyond the simple financial model to prove to the wider industry, the viability of CH2. By placing the emphasis on sustainability and IEQ, the Council was strategically targeting the occupants of future buildings as the most important change agents. Developers would naturally argue to minimise costs, and given they had no long term stake in the completed building, its running costs and occupant conditions, it became evident that if the Council was to promote change it would need to be via an education process of future tenants. This strategy has proved to be effective in that high profile tenants like the National Australia Bank and the ANZ Bank are now insisting on 5 and 6 star buildings with an emphasis on good IEQ. The conclusion of this study has indicated that the productivity and wellbeing in CH2 is in fact 10.9% higher than the baseline building CH1.This represents a $2.4M per annum benefit to Council and reduces the payback time of the sustainability and IEQ features of the building ($11 M) to around 5 to 6 years. Given the life expectancy of the Building, 50-100 years, this study has demonstrated that the business case for incorporating these features is compelling.

From the Proceedings of the World Conference SB08 -ISBN 978-0-646-50372-1

<

Back



Home

.~ Contents



Authors Index

www.sb08.org •

Program Index

>

Forward

hot

warm

Level 6

Level 8

Level 2

slightly warm

....

$SOu

slightly cool

cool

80% Satisfied

1.0 CLO

90% Satisfied

1.2 MET

eVote

cold

Figure 4 Continuous thermal comfort measurement during a winter period - MABEL

ISO 7730 (Fanger) Comfort Model CH2 Summer Continuous Comfort Cart (6,8,2) 3

Ot

2

warm Level 8

Level 6

.

Level 2

~

slightly warm

....0

Q)

> <:

co Q)

E

0

"0

• c:ag eutCill'

7

.....~...."

lUi

2<)

r £

slightly cool

'6 -1 f!

0.5 CLO

80% Satisfied

Co

cool

-2

1.2 MET

90% Satisfied

III Vote

cold

-3



"-I

"-I

"-I

-.j

-.j

"-I -.j

2> "-I 2> 2> ~ "-I "-I

"-I

0

0

I

"-I

"-I

"-I

"-I

"-I "-I 0

"-I "-I "-I

a a..... 2>

0



"-I

..... ..... ..... ..... ..... (II a> 0 "-I :..;. c;., c;., """ c;., c;., (II

I

"-I

0

00

c;.,

0

-.j

-.j

2>

I

I

"-I

~

"-I 0

c;., c;., c;., 0

0

0

1

1

"-I

~

0 "-I "-I

c;.,

0

'

I

Iii

I

"-I

"-I 00

N

N

N

N

"-I 03

"-I .....

"-I .....

"-I .....

2> ~ "-I

"-I

a>

c;., c;., """ 0

0

I

I



I

I

I

'

aa~ a ~ :;f ~ : (II

(II

(II

i



"-I

iii

"-I 00

~

2>

0 "-I

"-I

.....

......

a>

00

"-I

~

0 "-I "-I 0

I

I

"-I 00

2> "-I "-I "-I

:.;.. :.;.. :.;.. :.;.. (II

(II

(II

iii

.....

2> w 0

:.;.. (II

iii.

..... 2> w "-I

:.;.. (II

i



2> w

2> w

2> w

a>


(II

0

""":.;.. :.;..

(II

(II

...2>

iii

..... ..... ..... 0

I

Iii

..... .....

w

2> w

0

0

..... ...... 0

I

2> W

...w ... (II

0

0 0

time [hh:mm]

Figure 5 Continuous thermal comfort measurements during a summer period - MABEL

From the Proceedings of the World Conference SB08 - ISBN 978-0-646-50372-1

<

Back



Home

• Contents



Authors Index

www.sb08.org • Program Index

>

Forward

4): .. i1:{tH{ () nii.{-<.t ,*"'i( < ,

.tro&"

,***

() ~)\t-~ ~.t.~~;

<0

~)'J*1I

.. ::loj,H~n~

kH.::#tlt<1l

tln~

Figure 6: Level 2 - Horizontal Lux and Colour Temperature at Workplaces (Summer) - MABEL

Difference in Satisfaction Ratings Between CH2 and CH1 for Different Categories of Variables

% Difference CH2·CH1

40% , - - - - - - - - - 30% 20%

10%

-10%

2%

2%

Other

Health Symptoms

+-----------------= Productivity

Figure 7

Building Overall

Air Quality

Thermal Comfort

Noise

Lighting

Furniture & Fitout

Difference in satisfaction ratings between CH2 and CH1 for specific categories of variables.

5. Acknowledgements This paper draws on a range of coordinated studies as follows: •

• • •



Occupant Surveys of CH1 and CH2: Conducted by Adrian Leaman of Building Use Studies Ltd. in association with Leena Thomas, University of Technology, Sydney, and Monica Vandenberg, Encompass Sustainability. Indoor Environment Quality Monitoring of CH2: Conducted by Mark Luther and the MABEL team (Mobile Architecture & Built Environment Laboratory), Deakin University. Indoor Air Quality Monitoring of CH2: Conducted by Stephen Brown of CSIRO. Focus Group Interviews of CH2 Occupants: Conducted by Monica Vandenberg, Encompass Sustainability and Leena Thomas, University of Technology, Sydney in association with Adrian Leaman, Building Use Studies Ltd. A research project commissioned by the Cooperative Research Centre for Construction Innovation, 'Regenerating Construction to Enhance Sustainability'

The authors would also like to gratefully acknowledge the following people and organisations for their valuable contributions to this study. Shane Power from City of Melbourne and Adam Leggett (ex City of Melbourne) for their support and assistance in arranging all of the data collection. Austin Ley (City of www.sb08.org

From the Proceedings of the World Conference SB08 - ISBN 978-0-646-50372-1

<

Back



Home



Contents



Authors Index



Program Index

>

Forward

Melbourne) and Peter Newton (Swinburne University of Technology) for their assistance in establishing various components of the studies. Dianna Snape Photography for the photographs in the paper. Finally and most importantly, a big thanks to all of the staff from City of Melbourne who willingly and enthusiastically participated in the study, and tolerated a host of measurements and questionnaires.

6. References Paevere, P. and Brown, S. 2008, Indoor Environment Quality and Occupant Productivity in the CH2 Building, CSIRO Report No. USP2007/23, CSIRO Sustainable Ecosystems. Australia.

Table 1 - Difference in satisfaction ratings between CH2 and CHi, and correlations with Perceived Productivity in CH2 for different categories of variables Correlation With Productivity in CH2

36%

1.00

Comfort Overall Design ImaQe Facilities Meet Needs Perceived Healthiness Space use in the building Comparison with Prevo Accommodation Furniture I Workstation Meeting Room Availability Plants Space at Desk Space Layout StoraQe Health Symptoms: Summer Health Symptoms: Winter Air Freshness: Summer Air Freshness: Winter Lighting: Artificial LiQhting: Overall Lighting: Natural

13% 20% 47% 16% 35% 12% NA 13% 22% 8% -10% -6% 12% 4% 0% 15% 18% -16% -18% -17%

0.61 0.53 0.54 0.53 0.59 0.47 0.65 0.42 0.32 0.19 0.30 0.42 0.25 NA NA 0.36 0.40 0.15 0.32 0.38

Noise: Overall

-10%

0.40

Thermal Conditions Overall: Summer Thermal Conditions Overall: Winter Temperature: Summer Temperature: Winter Cleaning Communication Happiness IT Privacy Autonomy Morale

17% 13% 13% 8% 13% 6% -6% 15% -12% -2% 0%

0.48 0.42 0.47 0.39 0.40 0.18 0.31 0.25 0.42 0.23 0.24

Variable

Productivity (36% Betterj

Perceived Productivity

Building Overall (23.8% Better; R=0.56)

Furniture & Fit-out (6.5% Better R=0.32) Health Symptoms (1.9% Better) IEQ: Air Quality (16.5% Better; R= 0.38) IEQ: Lighting (17% Worse; R=0.28) IEQ: Noise (10% Worse; R=0.4) IEQ: Thermal Comfort (12.8% Better; R=0.44)

Other (2% Better; R=0.29)

"~v

Satisfaction CH2-CH1

% Difference

Category (Avge % Diff; Avge Rprod)

,"

'

www.sb08.org

From the Proceedings of the World Conference 5B08 -15BN 978-0-646-50372-1

<

Back



Home



Contents



Authors Index



Program Index

>

Forward