2012年12月29日星期六
Elemental Cost analysis
- Used for similar previous project as basic for estimated
- The cost is completed on a superficial or floor area basis but the overall superficial unit costs is broken down into elements and sub-elements
- It is possible to make cost adjustment for variations in design in new projects as compare with previous scheme .
- Necessary to updatae the cost to take into account of increased cost which occurred sinder tender date for the cost analysis is available .
S. H
*Storey height of the building are determined by the client requirement
* The construction items that may influence by the variantion in storey height will be :
- Longer waste pipe and cables
- Higher construction cost for wall paritions
- Longer waste pipes for sanitary appliances
- More costly foundation to support the increased load .
- More cost to construct the staircase and lift
- Larger volume for the air-conditioning services
-Higher cost for construction of roof due to hoisting
Storey Height
- Storey height of the building are determied by the client requirement
- The construction items that will affected by the variation in storey height would be :
* Walls , partitions , and associated finishing work
* Longer waste of pipes for sanitary appliances
* Higher construction cost of roof due to hoisting
* Longer waste for pipes and cables
* Increase volume for air-conditioning
* More costly foundation to support the increased load .
* Increase cost for construction for staircase and lift
Storey height
- The storey height of building are determined by the clients requirements
- The construction items that are affected by the variations in storey height would be :
*Longer length for pipes or cables
* Higher construction cost for roof due to hoisting
* Increase cost of constructing staircase and lift
* More costly foundation due to increased load
* Wall , partitions and their associated finishing work
* Increase volume to be air - conditioning
* longer waste pipes to sanitary appliances
C. S
- An economical layout will have a main aims to reduce in circulation space because :
* Circulation area such as entrance , lift lobby , staircase and corridor etc cannot use for profitable purpose .
- The percentage allocated of circulation space vary in type of building :
* office 23 %
Circulation space
-An economical layout will have one of its main aim to reduce the circulation space because :
* circulation space such as corridor , lift lobby , entrance and staircase etc cannot use as profitable purpose .
* The proportion of floor space allocated to circulation space vary between the types of building .
* office 23 %
Circulation space
- An economical layout will have a main aim of reduce in circulation space because :
* circulation space such as lift lobby , entrance , staircase , and corridor etc cannot used for profitable purpose .
- The proportion of floor space allocated to circulation purpose vary between different types of building .
wall / floor ratio
- wall/ floor area ratio is calculate by dividing of external wall area ( inclusive window and door ) by gross floor area .
- Wall/ floor area ratio expressing the planning efficnecy of building and influenced by shape , and storey height of building .
- The lower wall / floor are ratio the more economical will be the proposal
- The best floor / wall ratio is produced a circular building but the cost is offset by a higher circular work .
Wall / floor area ratio
- Wall / floor area ratio expressing the planning effiency of a building and influnced by size , plan shape and storey height of the building .
- Ratio is calculated by diving the external wall are ( inclusive door and window ) by gross floor area .
- The lower the wall . floor area ratio , the more economical will be the proposal .
- The best wall / floor area ratio is produced by circular building but the cost is offset by a higher circular work .
Wall / floor area ratio
- Wall / floor area ratio mean of expressing the planning efficiency of a building and influenced by the plan shape , size .and storey height
- Ratio is calculate by dividing the external wall area by gross floor area .
- The lower the wall / floor area ratio the more economical will be the proposal
- The best wall / floor area ratio is produced by a circular building
Size of building
*Larger project is less costly to built as wall / floor area reduce .
* Advantage of building will be accure due to lift serving a large space of plan and number of occupant will increase with plan size .
*General rule is cost does not rise proportionaly with increase the size of building because :
- Fixed cost such as : temporary road , temporary supply of water , temporary material storage does not increase with extension of building .
Size of building
* The larger the project ,the less costly to build as wall / floor area reduces .
* Cost advantage of high-rise building may accure due to lift serving a large floor area and greater number of occupant with increase plan area .
* General rule is increases in size of building will produce reductions in unit costs
* Cost do not rise proportionaly with increase in plan size of a building because :
- Fixed costs .i.e. temporary water supply , temporary storage of material , transport does not rise with increase size of building .
Shape of the building
* General rule is the simpler the shape of the building , the lower will be the unit cost .
* When building becomes more complicated , the perimeter / floor area ratio will increase accompanied with a higher unit cost .
* Rectagular shape building is more expensive than square one because of smaller perimerter / floor area ratio
Factor of reliability of cost information and practical limitation .
- Main sources of cost data are obtain from the contractor price which is subject to consideration variables
* From contractor to contractor
* Project to project
* District to district
* Over a period of time
* Lack of concidence between the unit production cost and unit design cost account
* Difficult of predicting operational times , regional different and etc .
* Additional cost due to specific design , abnormal requirement are forecasting stage .
* Factor of consideration
-Type of contract
-Project location
-Size of project
- Availability of labour
-Stability of material prices
-Whether fixed price tender
- Method of pricing
- Special requirement as to speed
* Must interpret the cost appropriate before use .
* Cost information used by QS obtained from price BQ and is advisable to use average price rather than lowest .
* Prices different in billes rate are not necessary due to mistakes in estimating .
* * Unit cost is made up of standard of within determinable parameter
Factor of reliability of cost implication and practical limitation
- Main source cost data are obtain from contractor prices which is subject to consideration variable
* from contractor to contractor
* Project to project
* district to district
* Over a period of time
* Lack of concidence between the unit of productioc cost and unit of design cost account .
* Skilled judgement is neccessary when extracting the cost data from price BQ
* Cost information used by the QS is advisable to use average price rather than the lowest
* Additional cost due to specific design and abnormal requirement are in forecasting stage
* Difficult of predicting operatinal cost , and regional different ,etc
* Unit cost is made up of standard cost within determinable parameter .
* Factor of consideration :
- Type of project
- Size of project
- Location of project
- Stability of material
- Availability of labour
- Fixed price tender
- Method of pricing preliminaries
- Climate of the industry
* Necessary to know the condition of the prices
- Price different in billes rate are not neccessary due to mistake
Reliability of Cost Information
- Main Cost imformation is obtain from the contractors prices which is subjected to consideration variables :
* From Contactor to contractor
* Project to project
* District to district
* Over a period of time
- Must interpret the cost in appropriate context before use
- Necessary to know condition surrounding the prices
Factors for consideration
* Size of project
* Climate of industry
* Stability of material prices
* Availability of labour and material
* Whether fixed price ender
* special requirements as to speed
* Method of pricing preliminaries
* Location of project
* Type of contract
- Cost information used by Qs is obtained from price BQ and it is advisable to use average prices rather than lowest tender .
- Skilled judgement is necessary when extracting and using cost information
- Lack of coincidence between the unit of production cost and design cost account
- Prices different in bills rates are not neccessary due to mistake s in estimating
- Dicculty of predicting the operational times , and regional difference and etc .
- Unit cost is made up by standard cost within determine parameter
- Additional cost due to specific design and abnormal requirement are in forecasting stage .
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