Fig. 1: summary of final score (GBI, 2010) (Shafii, 2009)

OCCUPANT SATISFACTION IN RESPECT TO INDOOR ENVIRONMENTAL

QUALITY IN ENERGY EFFICIENT CERTIFIED BUILDINGS IN MALAYSIA

Abstract

Malaysia’s Green Building Index (GBI) encourages non-residential building to save energy

and provide a high quality environment to the occupants. The highest point which is 35, will

be awarded for energy efficiency and the second one 21 point, for indoor environmental

quality (GBI, 2009). This challenging task to the building designers is in shaping the

realization of the occupants’ indoor environmental comfort while controlling energy use for

office working space.

This study has been conducted to investigate the occupants’ satisfaction in the working-space

of energy-efficient office building in a tropical country, Malaysia. Two office buildings,

which have been classified as energy efficient buildings in the Klang Valley, Malaysia were

selected for case study. One of them is a Low Energy Office (LEO) Building, designed for low

energy consumption and the other is a Green Energy Office (GEO) Building which was

designed with renewable energy. The results showed that the occupants were satisfied with

their work-space, with “slightly greater satisfaction” in the LEO building than in the GEO

building.

Keywords: Comfort; Satisfaction; Indoor environment; Building Energy Efficiency.

INTRODUCTION

In 2009 The Government of Malaysia launched the formal framework of Green Building

Index (GBI), to provide measurement rating system for the accreditation of green buildings in

Malaysian. Six criteria have been considered for the measurement (Fig.1).

United States Green Building Council (USGBC) classifies green buildings as buildings which

have been designed with consideration of reducing or eliminating negative impacts on the

occupants and environment (USGBC, 2009). Malaysia’s Green Building Index for non-

residential buildings includes indoor environmental quality as the second important aspect to

be measured.

A study conducted by Abbaszadeh (2006), found that the occupants of a building which has

been classified as one of the green buildings in the United States, were dissatisfied with its

lighting and acoustic quality. The occupants have suggested the need of improvements in

controlling the lighting system, and recommended innovative strategies, to accommodate

sound privacy needs in open plan or cubicle office layouts. Another study conducted by

Galasiu (2006) showed that the application of day lighting for office buildings required the

inclusion of energy-efficiency lights, which are suitable to occupants, into the lighting

system. Another study conducted by Hummelgaard (2007) showed results with high degree

of satisfaction among the occupants. The building indoor environment was with natural

ventilated workspace. Similarly, a study showed that a naturally ventilated and passively

cooled buildings can be highly appreciated by occupants if they are designed with proper

indoor climate (Wagner, 2006).

EE Buildings should be energy efficient compared to conventional buildings. In order to

ensure good performance, the architects should take occupants’ interactions with the building

control systems into account at the design stage. This study was conducted to measure and

evaluate the indoor environment quality of the two EE Buildings which looked into the

occupants’ response; such as how energy efficiency buildings are performing from the

occupants’ perspective. If they are performing well, this indicates that the goal is being

achieved. A questionnaire survey requires the occupants to rate their workspace environment

in terms of the most important indoor parameters in the tropics which influence the occupant

satisfaction on the workspace; dry bulb temperature, humidity and air movement (Ariffin,

2002), in addition to lighting. The survey assesses indoor environmental quality (IEQ) in

energy efficient office buildings requiring the occupants to directly respond on their

satisfaction with IEQ in the workspace.

The comfort of building occupants is dependent on many environmental parameters including

air speed, temperature, relative humidity and quality in addition to lighting and noise. The

main physical parameters affecting IEQ are air speed, temperature, relative humidity and

quality (Omer, 2008). The indoor comfort is dependent on several factors that include air

temperature, air humidity and air movement (Zain-ahmed, 2002).

OBJECTIVE

The study aims to investigate how the two energy efficient buildings, LEO and GEO, have

succeeded with their goal as EEB from the occupants’ perspective, bringing User-Centered

Design approach to the energy efficient issue, and the users satisfaction with their workspace;

in terms of thermal comfort, air movement and visual comfort.

The significance of the paper comes from the fact that the imitation of the showcase building

without evaluating, involves the repetition of mistakes. Similarly surveying the occupant

satisfaction in the two buildings would be as occupancy evaluation to upcoming buildings.

Thus the main purpose of this post occupancy evaluation study is to provide recommendation

to improve the indoor environment of upcoming energy efficient building in tropics,

Malaysia.

RESEARCH METHODOLOGY

A three phases of methodology are adopted in this study. The first phase was to define the

area of the study; local climate and building description. The second phase of the study is

based on physical measurement of the buildings environment. Finally, the third phase of the

study relied of questionnaire survey to collect responses from building occupants and this

constitute a source of data to declare the occupants’ perspective on their satisfaction at their

workplace.

The study was carried out in the months of September and October 2009. A direct survey was

conducted in the two chosen buildings. This is to evaluate the important parameters of indoor

environment quality, that might be influenced the satisfaction of occupants on the workspace.

Whilst the physical measurement is to compare the responses of the occupants to the same

environment judged against the Malaysian Standard (MS 1525).

100 responders were selected from the two EE buildings were collected. The sample size is

50 responders per building. In addition to more general questions, the questionnaire address

directly related to the workspace indoor environmental quality parameter such as;

temperature, humidity (dampness), air movement and lighting,. The questionnaire survey

collected have been evaluated together with measured data; outdoor/indoor temperatures, day

lighting, air-velocity and humidity from SKYE and BABUC/A data loggers. The survey took

one week to make reliable evaluation for indoor environment quality in the two buildings.

Local Climate

As Malaysia is an equatorial country (Kula Lumpur 3.13°, 348 km north), therefore its

climate characteristics are relatively uniform throughout the year (Fig. 2). There are no large

variations in temperature, relative humidity, and solar radiation during the daytime of the

year, the variation significantly accurse throughout the day. The mean monthly temperature

vary not more than 1.40C. From the mean average of 27

0 C was found in November to 28.4

0

C in May. The average mean temperature in a day ranges from 31.580 degree Celsius during

the daytime to 24.56 0 C during the night.

The monthly average of solar radiation in Kula Lumpur; Subang station is 3.71-4.89 kWh/m²,

with monthly sunshine duration ranging from 9 to 13 hours. The high solar radiation arises

during August to November, (the survey and field measurement of this study contacted

within this period), and January to February, while the low solar radiation occurs in April and

May with 13.72 and 13.04 respectively.

Fig.3: Monthly average of Relative Humidity and

its relation to average max. and mean

Temperature. (source: author besed on 10 years

Subang J. station)

Fig.2: Stereographic diagram to Kuala

Lumpur, Malaysia Latitude: 3.10

(12 Sep., 14:00hr)

Also the humidity is uniformly high all through the year due to the large body of water

surrounding the peninsular Malaysia. The mean monthly relative humidity over the period

was 82 % found in August and never falls below 75.79 % in November.(data based on 10

years 1999 to 2008, Subang Station) (Fig. 3).

Buildings and Experimental Settings

In Malaysia about 70% of energy consumption is used for cooling the environment (Abdul

Rahman, 2006), this is why passive strategies is so important to efficiency reducing energy

consumption in office buildings. The two office buildings LEO building and GEO building

were selected to represent an energy efficient office building in the region and are built to be

a showcase to the public. The LEO building (Fig 4) was awarded the ASEAN Energy Award

in 2006 (Hong, 2007). It was built with ambitious goal of energy saving more than 50%

compared to conventional new office building in Malaysia, with energy index of

114 kWh/m2 year compared to typical conventional of 275 kWh/m2 year (Lau, 2009).

Whereas, the GEO building, (Fig. 5), has been stated in Malaysian’s GBI as a showcase to

Green Energy Office and the details of the building is cited on GBI website (GBI, 2009). The

GEO building energy index of 65 kWh/m2 year compared to typical conventional of 250 to

300kWh/m2year (Lau, 2009).

Fig. 6: (a) Setting up the indoor data logger, (LEO building; (b) setting up the indoor data

logger, GEO

(a) (b)

Fig.4: Low Energy Office (Wagner)

Building, Putrajaya. (Source PTM)

Fig. 5: Green Energy Office Building (PTM),

Bandar Baru Bangi. (Source PTM)

Instrumentation

“Babuc /A” data logger for indoor and “Skye” data logger for outdoor logging with a number

of sensors (outdoor/indoor temperature, air movement, lighting, and RH sensors) were

connected to the data logger, (Fig. 6-a&b). The outdoor temperature sensor was placed in a

balcony in, LEO, at about 2m away from the building façade whereas placed on the roof in

GEO case. The indoor temperature, air movement and RH sensors were stationed on a tripod

located at about 1.0 m above the floor level. The readings of each sensor were recorded by

the logger at 5 minutes interval for twenty-four hours duration in two weeks.

The satisfactory level of occupants was tested and obtained with a questionnaire and rate their

satisfaction perceptions on their workplace environment covering most factors influencing

the IEQ (Ho et al., 2009), they are lighting:( glare, brightness), thermal comfort (

temperature, dampness, and air movement). The satisfaction level evaluated at two different

locations of working space which is near window within less than 3 meter distance and away

from window which is more than 3 meter distance. The questionnaires were given to 50 staff

of each building. The number of responses was 40 (80%) in the GEO office, and 30(60%) in

the LEO office. A likerts 5-point scale was used to range the level of satisfaction with

endpoints from -2“very dissatisfied” to 2“very satisfied” level 0 of satisfaction is considered

as positive or satisfied as the occupants who claim that were not complaining on any

advantage or disadvantage.

RESULTS

Measurements

The finding shows (Fig. A-1, Appendix), the workspace air temperature and the relative

humidity in LEO building and GEO building measured during the sunny 7 days, the same

days as the questionnaires were administered. LEO building showed the peak temperatures

average of the 5 working days at 15:00h with 21.97 °C. While in the GEO it was 23.75 °C at

16:00h. The difference of indoor air temperatures between the two buildings were

approximately 1.78 °C higher in GEO than in LEO. Differently on the off days the peak

temperatures at 16:00h were approximately 0.75 °C higher in LEO than in GEO. The Figure

A-1 shows also that the indoor temperature in the two buildings were lower than outdoor

temperature before the office core hours. At 08:00h. the difference in LEO between indoor

and outdoor was 23.40 °C and 25 °C respectively with 1.60 °C lower on indoor. In GEO

indoor was lower with 1°C, as 24/25 °C indoor/outdoor. The measured relative humidity

varies 60.03 % at 08:00h to 58.94 % at midday in LEO. Likewise in GEO relative humidity

varies with 59.83 at 08:00h to 55.33 at midday. The indoor air movement in both buildings is

approximately zero; with maximum average recorded were 0.01m/s.

The illuminance level of both buildings shows (Fig. A-2, Appendix) at distance less than 3m

from the window and height of 0.75 m from the floor reaches to 300 lux, in LEO open plan

workspace, before 09:00 a.m. and after 05:00 p.m. and never reaches to 400lux. For GEO the

illuminance was 300lux after 10:00 a.m. and before 05:00 p.m., and exceeds 400 lux at

01:00p.m.

Questionnaire

Comparing the results of surveys in the two EE buildings, showed the occupants in LEO

building are more satisfied in the following areas (Fig. 7): Air movement; humidity,

temperature and; overall satisfaction with workspace, whereas the occupants in GEO building

are quite more satisfied in lighting than in LEO building. In both building away to window

the study (Fig. 8) found that the occupants are more satisfied with two indoor parameters:

temperature and; lighting than those near the window. Similarly the figure 9 shows the

occupants in GEO express dissatisfaction with day lighting and they prefer to work with

artificial light. Whilst in LEO the occupants state their satisfaction to the mixed-mode with

slightly more preference to day ligting.

Fig.7: Illustrate the responses of occupants in the two buildings to all indoor environment

parameters.

Fig.8. Illustrates the occupants’ preference to workspace location with respect to the

distance from the window

Figure 10 shows the votes in both of EE buildings, within the category “_2 to 2”. the survey

found that the occupants in LEO are largely satisfied with their workspace, only less than 5%

rating it as unsatisfied and 95% of them felt satisfied in their workspace with the thermal

aspects, and 93% satisfied with visual aspects. Whereas in GEO about 58% of occupants

stated a satisfaction to the thermal comfort parameters, and there are about 41% of the

occupants are unsatisfied. On the contrary, the occupants in GEO show positive response to

the visual comfort with 93% are satisfied.

Fig. 9. Perceives the votes of occupants in both buildings to their preference with respect to

lighting and temperature control

Fig. 10. Relationship between overall satisfaction in LEO and GEO. As the “0” is

considered positive the chart shows that the occupants are satisfied with their workspace in

both buildings with “slightly more” satisfaction in LEO than in GEO

DISCUSSION

Based on field measurements, energy efficient buildings are perceived to be satisfied for their

occupants. For thermal comfort the ideal conditions for Malaysian has been found to be

between 22°C to 26°C (Zain-Ahmed, 1998) (Ministry of Science, 2007). Another studies

presented the variation of thermal comfort in Malaysia of about 24°C to 28°C (Abdul

Rahman, 2006) (Lee Chung Lau, 2009). The analysis of the two buildings (Fig. A1&7),

shows that introducing air-con to sustain the indoor environment will increase the occupant

satisfaction as occupants in LEO building show more satisfaction to temperature 22°C, than

those in GEO with 23.75 °C, after employs air conviction system to indoor environment.

However, physical measurement found that the indoor temperature lies on comfort range of

Malaysian standard, which is below 24 °C; the mean recommendation of MS1525. However,

the indoor temperature in the two buildings was found lower than outdoor temperature before

the office core hours, 08:00h. Nevertheless, the occupants show desire to implement

additional mechanical controlling to maintain their indoor environmental quality. Linked to

this and more highlighting on occupant judgment the study found that the occupants in both

buildings away to window are more satisfied than those near the window. This proposes that

the amount of heat gain and glare are still a problem near the window in these two energy

efficient buildings.

The results also showed that the workspace lighting of the two buildings lies in an acceptable

range for most of the time, complying the Malaysian Standard (2007) which recommends that

the interior lighting for offices should be between 300 and 400 lux. The difference in the two

buildings is that the occupants in LEO building show the occupants’ preference are in mixed-

mode, where it should be consistent with what was proposed at its design stage, to attain

reduction in energy consumption of 18% for lighting when this data compared to other

government buildings (Lee Chung Lau, 2009). In GEO the day lighting was implemented

with almost 100% (PTM, 2009), however the impact showed the occupants in GEO are less

satisfied with its lighting system due to the brightness and glare, the LEO occupants shows

their preference to use blinds with artificial light to get a satisfied luminance level and avoid

the glare.

The ideal comfortable thermal environment for Malaysia is to have a sufficient air movement

and a cool surrounding (Abdul Rahman, 2006). The recommended air movement to obtain

satisfaction in workspace is varied from 0.15 to 0.7 m/s (Ministry of Science, 2007). This

study showed occupant’s judgment was negative to the air movement in the workspace. This

confirms the result from measurement that found the air movement in two buildings is

(0.01m/s maximum), which is lower than the air movement recommended to air-conditioning

office in tropics (Ministry of Science, 2007).

According to ASHRAE when 80% of occupants are satisfied, this indicates to be an

acceptable environment for building (ASHRAE, 1992). With respect to this concept, the

survey found that the occupants in LEO are largely satisfied with their workspace, this due to

implementing additional affective mechanical cooling and controllable interior blinds. In

GEO building about 58% of occupants stated a satisfaction to the thermal comfort

parameters. This is probably due to the orientation and their workspace position against the

windows. A study suggested providing each occupant a flexible adjustment to their personal

working space indoor comfort with for example, ceiling fans and open-able window (Nicol,

2007). For tropical climate as in Malaysia the reduction of thermal condition by passive

design in where the average air temperature is about 33°C with relative humidity of about

80% is not enough to reach to the occupants comfort without the additional of active systems

(Abdul Rahman, 2006), particularly for introducing the ample air movement to control the

high humidity of tropical climate.

CONCLUSION

The study examines satisfaction at the two EE buildings, in Klang-Valley, Malaysia, in the

context of occupants. The study found, in general, that the occupants are in satisfaction with

indoor environment quality of their workspace in the two buildings with preference to LEO

building where implementing air-con. The study concluded that the strategies employed in

energy efficient buildings have been, on average, effective in improving occupant satisfaction

by eliminating air movement that was seen by not to their satisfaction. This position was

confirmed from measurement was registered on workspace.

Comparing the measurement and occupants’ responses of environmental quality in the

workspace of the energy efficient buildings in Klang-Valley, Malaysia, revealed that

responses were based on the occupant’s experience with the questionnaire surveys.

Therefore, it is important to take occupant’s interactions with the control systems into

account when designing EE buildings, especially within tropical climate.

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APPENDIX

Fig. A-1. Illustrate the main indoor thermal comfort parameters: Air Temperatur; Relative Humidity; and Air

Movement to workspace of Energy Efficient, LEO building & GEO building.

Fig. A-2. Illustrate the indoor Lighting of workspace during working Hours to Energy Efficient Buildings; LEO

& GEO.