O&SB2010 “Open and Sustainable Building” – Chica, Elguezabal, Meno & Amundarain (Eds.) © 2010, Labein -TECNALIA. ISBN 978-84-88734-06-8

OCCUPANT SATISFACTION IN RESPECT TO INDOOR ENVIRONMENTAL QUALITY IN ENERGY EFFICIENT CERTIFIED BUILDINGS IN MALAYSIA

Qahtan, Abdultawab; Keumala, Nila I. M. & Rao,S.P. Department Of Architecture, Faculty of the Built Environment, University Of Malaya, Kuala Lumpur, 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 .

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

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

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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 270 C was found in November to 28.40 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 1.39-1.83 kWh/m², with monthly sunshine duration ranging from 9 to 13 hours. The high solar

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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.

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.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)

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

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.

Fig.4: Low Energy Office (Wagner) Building, Putrajaya. (Source PTM)

Fig. 5: Green Energy Office Building (PTM), Bandar Baru Bangi. (Source PTM)

 

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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.

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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

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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

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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.

REFERENCES

Abbaszadeh, S. (2006.) Occupant Satisfaction with Indoor Environmental Quality in Green Buildings, Proceedings of Healthy Buildings. Lisbon, Vol. III, 365-370.

Abdul Rahman, A. M., And Rodzi-Ismail, Mohd. (2006) Future design in an energy efficient building as an identity ofa Malaysian tropical architecture with emphasis on photovoltaic technology and passive solar building design elements IN MOKHLIS, H. (Ed. 4th international conference 2006 (MRG-AIC). United Kingdom.

Ariffin, A. R., Rao S.P. , Inangda Nila (2002) Thermal comfort and evaporative cooling of external walls in an equatorial climate. IN RAHMAN, A. M. A. (Ed.) Development of passive solar design and technology in tropical climate. Pulau Pinang, Penerbit University Sains Malaysia.

Ashrae, (1992). Thermal environmental conditions for human occupancy.

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Galasiu, A. D., & Veitch, J. A. (2006) Occupant preferences and satisfaction with the luminous environment and control systems in daylit offices: a literature review. Energy and Buildings. Energy and Buildings, 38, 728-742.

GBI, (2010) Green Building Index (GBI), rating system. Kula Lumpur, http://www.greenbuildingindex.org/rating_system.htm.

Ho, S. H., Rosario, L. & Rahman, M. M. (2009) Thermal comfort enhancement by using a ceiling fan. Applied Thermal Engineering, 29, 1648-1656.

Hong, W., M. S. C., Ruth A. Shapiro, Mark L. Clifford. (2007) Building Energy Efficiency, Why Green Buildings Are Key to Asia’s Future. Hong Kong: the Asia Business Council., Hong Kong, Asia Business Council.

Hummelgaard, J., Juhl, P., Saebjornsson, K. O., Clausen, G., Toftum, J., & Langkilde, G. (2007) Indoor air quality and occupant satisfaction in five mechanically and four naturally ventilated open-plan office buildings. Building and Environment, 42, 4051-4058.

Lau, L. C., Tan, K. T.,Lee, K.T. And Mohamed, A. (2009) A comparative study on the energy policies in Japan and Malaysia in fulfilling their nations’ obligations towards the Kyoto Protocol. Energy Policy.

Lee Chung Lau, K. T. T., Keat Teong Lee , Abdulrahman, M.(2009) A comparative study on the energy policies in Japan and Malaysia in fulfilling their nations’obligations towards the Kyoto Protocol. Energy Policy.

Ministry Of Science, T. A. I. (2007) Malaysia Standard,MS1525, code of practice on energy efficiency and use of renewable energy for non-residential buildings. IN MALAYSIA, D. O. S. (Ed. Putra Jaya.

Nicol, F. A. R., Susan (2007) Progress on passive cooling: Adaptive thermal comfort and passive architecture IN SANTAMOURIS, M. (Ed.) Advances in passive cooling London Earthscan in the UK & USA.

Omer, A. M. (2008) Energy, environment and sustainable development. Renewable and Sustainable Energy Reviews 12 2265–2300.

PTM, P. T. M., GEO BUILDING (2009) Green Energy Building Features. Kuala Lumpur, http://www.ptm.org.my/PTM_Building/Geo.html.

Shafii, Faridah, (2009). Malaysia Green Building Confederation. Institute Sultan Iskandar Universiti Teknologi Malaysia.

USGBC, U. S. G. B. C. (2009). http://www.usgbc.org/.

Wagner, A., Gossauer, E., Moosmann, C., Gropp, T., & Leonhart, R. (2006) Thermal comfort and workplace occupant satisfaction - Results of field studies in German low energy office buildings. Energy and Buildings, 39, 758-769.

Zain-Ahmed, A. (1998) the bioclimatic design approach to low-energy buildings in the klang valley. Malaysia. Renewable energy i5, 437-7440.

Zain-Ahmed, A., Sopian,K., Othman,M., Sayigh,A., & Surendran,P. (2002) Daylighting as a passive solar design strategy in tropical buildings: a case study of Malaysia. Energy Conversion and Management, 43 1725–1736.

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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.

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