A PILOT STUDY OF PROMOTING INDOOR THERMAL COMFORTfor High-density Residential Buildings in Hong Kong

1155019830LIANG Guanwen

CATALOGUE• Abstract• Keywords• Introduction• Background• Literature Review• Methods• Case Study• Discussion• Conclusion

ABSTRACT• Thermal comfort is one of the dominant parts of occupants’ living comfort. Due to the

geographical and human factors that form the unique high-density residential architecture style for Hong Kong, the thermal comfort of residents has been ignored. For better residential building design, the issue of indoor thermal comfort should be emphasized.

• This paper reviews extensive literature and background information on earlier indoor thermal comfort studies. It seeks to understand the effects on indoor thermal comfort in three categories: air temperature, air velocity and humidity.

• The paper then tries to find out the determination of the indoor thermal comfort in high-density residential buildings and summarize the key strategies based on the existing cases of current familiar buildings design and standard guidelines.

KEYWORDS• INDOOR THERMAL COMFORT

• HIGH-DENSITY

• RESIDENTIAL BUILDING

INTRODUCTIONThere are several types of comfort, which affect occupants in and around buildings: • Visual comfort• Acoustic comfort• Air quality • Thermal comfort

INTRODUCTIONHistory of thermal comfort research:• In 1900: the thermal stress of miners in Britain by Haldane

• In 1920s: the first thermal comfort measurement “effective temperature”

• The in 1950s: the “wet-bulb globe thermometer index” and “equatorial comfort index”

• In 1970s: the commonly known comfort equations of “predicted mean vote” (PMV) and “predicted percentage dissatisfied” (PPD)

• In 2000: the “adaptive model” of thermal comfort that acts the basis of the new revision of ASHRAE Standard 55-2004

INTRODUCTIONCurrent living situation for normal residents in Hong Kong:• Population density is 6,544 persons per

kilometers• 47.8% of residents live in the public housing

flats and home ownership scheme flats (high housing price)

• Average living space per person of public housing flat is under 12.4m2

INTRODUCTIONThe famous scene of Hong Kong --“wall buildings” • Several high-rise buildings line up like an enormous wall, and cause wall effect and heat

island effect, making negative effects on human thermal comfort.

BACKGROUND

Six primary factors need to be concerned: • Metabolic rate• Clothing insulation• Air temperature• Radiant temperature• Air velocity• Humidity

Definition of thermal comfort by ANSI/ASHRAE Standard 55-2004 • Thermal comfort, demonstrates the condition of mind, which expresses satisfaction with the

thermal environment.

BACKGROUND• The ASHRAE thermal sensation scale, which was developed for use in

quantifying people's thermal sensation, is defined as follows:• +3 hot• +2 warm• +1 slightly warm• 0 neutral• -1 slightly cool• -2 cool• -3 cold

BACKGROUNDReasons why high-density residential buildings exist• High-density population: 7,071,600 • Less than 25% of the territory's landmass is developed

• The land for residential use is just the 6.8% (76 km2) of all.• The government relaxes the restrictions of the plot ratio and the building regulation .• Lack of proper urban planning and supervisions.

BACKGROUNDDefinition of “wall building” by “Greensense” (fulfills 3 of 6):• Distance between buildings is not enough (e.g. less than 15 meters)• The layout of the buildings is linear arrangement• The average floor number of the buildings (include platform) is over 35• The location of the project is special (e.g. seaside, urban center)• The wider side of the buildings face to prevailing winds• Near lower buildings

BACKGROUND• The wall effect stops the natural wind pass in and out, which will reduce the

air circulation of the surrounding area.

• The indoor temperature will rise and air movement will slow down, doing harm to human thermal comfort

LITERATURE REVIEWDue to the limited amount of specifically the same subject in this realm, relative literatures are chosen for reference purpose.• Alfahaid A. F. (2000). Effect of ventilation on human thermal comfort in rooms

• Sreshthaputra A. Building design and operation for improving thermal comfort in naturally ventilated buildings in a hot-humid climate (Thailand)

• Yuen B. and Yeh A. G. O. (2011). High-Rise Living in Asian Cities

• Wang G. and Guan D.S. (2012). Effects of vegetation cover and normalized difference moisture index on thermal landscape pattern: A case study of Guangzhou, South China

• Zhang F. and Xu J. (2012). Identifying Energy Conservation Potentials for Existed Buildings in Terms of Controlling Thermal Comfort: The Case for the Educational Building in Xi'an Colleges and Universities

METHODS• Analysis some typical buildings will be analyzed in terms of air

temperature, air velocity and humidity.

• Compare with familiar cities that confront the same challenge.

• Other than relying on the artificial control, better design of the indoor environment is more suitable for long-term use.

• Summarize critical issues of the solution in a more economical and environmental way.

CASE STUDYThe Festival City, Tai Wai, New Territories, Hong Kong• A large private estates development project on

Hong Kong MTR Tai Wai Station

• 12 buildings

• 46-54 layers

• About 4,328 apartments

CASE STUDYExisting problems:• Separation between continuous is too short.

• Apartments back to the prevailing wind gain poor ventilation .

• Units on upper floor that face to the prevailing winds are sometimes impacted by the draft .

• Rely on air conditions too much, which will reduce the relative humidity significantly.

• Natural sunlight receiving imbalance to individual apartments.

CASE STUDYManhattan, New York, United the States• A population of 1,585,873 living in a land area of

59.5 km2 , 26,924/km² (6,544/km2 in Hong Kong)

• street’s width is 10 meters, the total road area is about 9.74 km2, 16.5% of the administration area

• Use setbacks to ensure that streets and yards are provided more open space and adequate light and air --sky exposure plane

DISCUSSION• The planning and designs of Hong Kong’s built forms in the

direction of high-rise buildings because of the continuously increasing population and limited useful land

DISCUSSION• Climate: hot and rainy in summer and cold and humid in winter

DISCUSSION• Typography: mountainous area with

limited useful land

DISCUSSION• Integration of aforementioned literature reviews,

• ASHRAE standard 55 –Thermal comfort

• BEAM Plus --IEQ14: Thermal Comfort

CONCLUSION• Caring about the living quality of occupants especially on psychological level should be

highlighted in modern architecture design, especially thermal comfort.

• The Hong Kong Government should revise the relevant regulations to restrict the plot area and reduce the exemptible construction area, stopping the developers neglecting the human consideration during the architecture design process.

CONCLUSIONAdvice:• provide shading device;

• increase wall and ceiling insulation;

• increase natural ventilation properly;

• near mountain

CONCLUSIONLimitation• Based on earlier study and empirical literature

• Without numerical analysis support.

• These strategies are just theoretically discussed

• needed to prove by practical measures and simulation