Deficiencies of redevelopment
Government's redevelopment programs have the following deficiencies:
Migration of vast number of people is a complicated process requiring detailed planning, monitoring and documentation. A high percentage (up to 40%) of Hong Kong population is housed in Public Housing Estates. An extensive re-housing and redevelopment program is required, which exerts heavy pressure on manpower, time and money.
Demolition of a building is a costly process. Moreover it creates construction waste undesitably unavoidably. The waste, if unsuitably reused, can result in pollution of the environment and depletion of resources. Also noise and visual pollutions can become nuisances to nearby residents.
New estate designs are often based on economic values. Also, cost efficiency and high practicality had been the approach adopted in the new developments, lacking in the encouragement of communal interactions. The new estates have more monotonous and self-enclosed living environment.
Significances and Advantages of Maintenance
According to David Highfield (2000) defined that the cost of refurbishing and re-using and existing building is generally considerably less than the cost of demolition and new construction since many of the building elements are already constructed.
One of the principles advantages of opting of refurbishment and re-use of existing building - rather than demolition and construction - is that, in he majority of cases. The renewed or redeveloped accommodations will be available in a much shorter time. And the shorter contract duration reduces the effects of inflation on building costs, also the overall development period could be shorter and reduces the cost of financing the scheme
The work required refurbishing and existing building would normally take considerably less time than the alternative if demolition, site clearance and the construction of a new building. Time savings, during the pre-contract design, planning permission and building works phases of development.
The client obtains the building sooner and therefore begins the earn reveue from it (e.g. rentals, retail sales of manufacturing profits) at an earlier date.
With the increasing cost of new-build work, effective maintenance of existing building stock is become more important and building maintenance now represents a significant proportion of construction output.
About unstable supply of construction works, according to Patricia Hillebrandt (2000) stated that the determination of demand for construction activity is a very complex affair and heavily depends on the policy of government either directly through its intervention in the public sector, or through its influence on the general level of economics activity in the private sector.
The standard of maintenance achieved has an important influence on the quality of the built environment and there seems little doubt that society will continue to expect higher standards in new and existing buildings. Nowadays, maintenance is a significant and important part of the work of the constrctuion industry.
The environmental advantages, one of the many ways in which energy consumption can be reduced is to recycle and re-use exising resouces as much as possible, in preference to consuming even more energy by replacing them. E.g. when major alterations are made, will generally use less energy than demolition and new build.
Housing Authority stressed that maintenance can facilitate early defect deteration and rectifection. This canavoid the additional expenses arising from further deterioration and it enables building elemets and services installations to be replaced at the optimum time in order to achieve the maximum serviceable life (Press Release: Home CARE Maintenance for Public Housing Estate, 1 March,2001)
Disadvantage of Maintenance
Although maintenance is beneficial to the aged building and many articles are supporting this view, but there are no perfect views of any matter, so in this part, the disadvantage of maintenance is shown as the follows:
The resultant standard of living may not live up to contemporary expectations.
Very limited potential for positive impact with regard to lad use and building performance.
The current mismatch in housing type supply and demand and the general inefficient layout of the site would remain.
This approach dose not count for the relatively short life span of the existing housing.
Deterioration and Obsolescence
The life cycle analysis by Flanagan (1989), which includes the following items:
Physical deterioration; economic obsolescence; functional obsolescence; technological obsolescence; social obsolescence; location obsolescence; legal obsolescence; aesthetic and visual obsolescence; image obsolescence; and environmental obsolescence.
Base on Aikivuori (1995) asserts that the defects of building are relative, not absolute and therefore difficult to measure objectively. The replacement due to obsolescence is not technically rational since it does not optimize the use of structures until the end of their durability. Since corrective replacement is defined as the project aimed at deteriorated structures in unacceptable physical condition.
According to Taylor (1980) proposes that deterioration has no part in the accumulated inferiority caused by obsolescence and the deterioration and obsolescence are 2 separable issues. Both Taylor (1980) have categorized the causes of replacement into these 2 classes, e.g. deterioration and obsolescence.
Thus, Aikivuori (1995) view the reasons for the decision to initiate a redevelopment project as a basis of the demand. The phenomena causing redevelopment are classified into 5 categories in his study as follows: failure in the building due to deterioration: change in use: optimization of economic factors: subject features of the decision maker: and the change of circumstances.
Life Span of Building Components
Base on the main theme of this study, the life span of building components is a very critical part to provide the sustainable development environment and enhance the value and practicability of the aged building. Also, it is a critical part to affect the decision between maintenance and redevelopment, so the building components should be coordinate with the methodology to present result that meet the international standard, the methodology is really simple to included multifarious application and give a suitable advice of the analysis or review for different type of building in Hong Kong or other country.
According to the related RICS journals "Assessing the Life Expectancies of Building for Life Cycle Costing" by Ashworth (1996) bring up the idea is about the rate of depreciation of building components depend on different information or data supporting and the selection of relevant life span reviews. Base on the theory from this journal, the expectancies may be uncertain, due to a proper design and maintenance arrangement or physical deterioration and obsolescence affect or the quality of refurbishment phase. Anyhow, different types or use of building have different refurbishment lives and the argument of expectancies incidence is important than overall building life span.
Macdonald (2003) indentified the building requirement and intention of life is at least 50 years or above, if there is good workmanship in construction stage and arrange inspection and maintenance work on cycle. Actuality, most of the building may be demolished before the end of time and rebuild, if there is any economical profit of that place or may be change the use of building to meet the new requirement.
Base on the information from RICS, the serviceable life span of aged public housing can be extending about 10-15 years, due to a systematic and cycle maintenance arrangement. Therefore, the aged public housings are structurally safe, that mean it is unnecessary to demolish and redevelopment.
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The life span components of public housing estates as follow:
Building Components
Life Span (year)
Window glazing
20
Plumbing
25-30
External wall tile
20-25
Vinyl sheet or tile
20-30
External paint
5-10
Internal wall paint
5-10
Waterproofing, bituminous coating
10
Wooden door
20-30
Hence, there are many factors affecting the life expectancy of building components and need to be considered when making replacement decisions, including the quality of the components, the quality of the installation, level of the maintenance, weather and climatic conditions and intensity of their use. Some components remain functional but become obsolete because of changing styles and styles and taste or because of product improvement.
RICS defined that the building structure may be designed using materials, components and technology that may last for about 100 years or more, depending on the quality and standards expected from users.
