Introduction
With India growing rapidly in population, mobility, trade and commerce, leisure, healthcare, education, industry and urbanization, demand for built environment is increasing rapidly to take care of the basic human needs of shelter, living, working, care of body & spirits besides travel. Estimates made by McKinsey Global Institute in its report, India’s Urban Awakening: Building Inclusive Cities, Sustaining Economic Growth, April 2010, ‘India would be required to create on annual basis buildings to the tune of 700-900 million sqmts (equal to the built up volume of Chicago City in USA) to meet the needs of built environment of urban India’. Despite huge projected requirements, little priority is being given to building industry to make it more effective and efficient. Buildings continue to be constructed in-situ following the traditional methods, leading to considerable delay in projects completion, inefficiency in construction, cost-overrun and time-overrun etc, leading to widening the gap between demand and supply of built environment.
Traditional on -site construction-Issues
Majority of construction taking place now in India follow the traditional on-site pattern of construction. Traditional on-site construction is described as linear construction, where each individual step is not only constructed entirely/ largely on site, but also needs to be completed before the project can move on to the next phase. Such construction has major implications in terms of time, cost, quality, safety, noise, pollution, manpower etc which can be defined as;
- Majority of building components constructed entirely/ largely on site,
- Linear construction- where each step needs to be completed before taking up next step.
- Considerable time taken for construction- Highly time consuming-time intensive
- Generation of large scale waste- waste intensive
- Construction schedule largely dictated by prevailing weather conditions.- weather dependent
- Generation of lot of pollution, traffic, noise and dust– pollution intensive
- Unsafe for the workers deployed in construction.
- Needs lot of manpower for making and supervision of building operation- manpower intensive
- Large inventory of material- material intensive
- Material storage facilities at site
- Creation of accommodation for workers deployed at construction
- Loss/theft of material from site
- Large variation in quality- largely dependent on work force deployed
- Use of lot of water/energy – resource intensive- Grey Buildings
- Increased initial cost of construction- cost inefficient
Pre- fabrication/Modular Construction
Off-site/modular constructions offers enormous opportunities , which not only overcomes the disadvantage of traditional construction, but also offer distinct advantages in terms of cost, time, quality, safety, environment, materials etc. Off-Site construction is a process that incorporates pre-fabrication and pre-assembly. It involves creating individual building components off site in a designated factory, shipping said parts to the plot of land and installing the components to create a finished structure. Off-site fabrication requires a project strategy that changes the orientation of the project process from construction to manufacture to installation. This method of construction differs significantly from basic methods and offers numerous benefits for both the building owner and the construction agency. Despite distinct advantages prefabrication, as a process, has its limitations also. Prefabrication is bad for making last-minute changes. It’s good for making when project is fine tuned to last detail before starting. When done correctly, off-site construction can benefit a project’s schedule, budget and skilled labour requirements
.Advantages ;
Building in Hazardous Area
Prefabrication has distinct advantages in remote area, areas prone to disasters, areas hit by disasters, where accessibility and availability of manpower, transportation of materials and time available for construction is minimal. In such cases pre-fabrication, offers the best option which can help in creating construction in minimum possible time at minimal cost.
Assured Quality Construction
Since pre- fabrication has genesis in construction of majority of building components in industrial setting, under highly controlled environment, involving lot of quality checks and balances, the components produced are accordingly of assured uniform quality unlike site-built structures which are totally dependent upon varying skill levels and the schedules of independent contractors . Modular buildings are invariably manufactured to code, making owners free from the worry of quality, saving of time and energy involved in supervision, which is a major issue in the traditional method of on-site construction.
Material Efficiency
Prefabricated buildings are known for their material efficiency both onsite and off-site. These buildings do not produce waste, since all the required material for construction arrives in the finished state on site. Since the components are produced in the factory, they leave/ create very little waste during the manufacturing, assembly, disassembly and the construction process which involves just putting together all components as per approved design. Further, since no material is brought to site ,as in the onsite construction, there is no wastage due to human operations and loss of material due to theft etc.
Cost- Efficiency
Greatest advantages of prefabricated construction lies in its capacity to promote economy and cost- efficiency, which is generally achieved through; large discounts received from material suppliers, reduction in construction time, mass
Cost- Efficiency
Greatest advantages of prefabricated construction lies in its capacity to promote economy and cost- efficiency, which is generally achieved through; large discounts received from material suppliers, reduction in construction time, mass production of components and economy achieved through standardisation, repetitive nature of operations and large-scale operations. Reduction of wastage and in-house recycling of the extra materials also lowers down cost of components.
Despite the fact, pieces being custom-made, modular const- ruction remains inexpensive due to lower time frame prefabricated construction takes as compared to traditional construction and the financial advantage made due to saving more money on construction financing.
In addition, factory setting of the prefabrication ,increased controls, better material planning, reduced material surplus calling for less storage cost , less material loss from damage or pilferage; saving on labour hours and manpower cost in construction of building without weather constraints and on-site/off-site work done simultaneously
Green Construction
Though modular buildings, does require a lot of power consumption at the manufacturing site, but compared to traditional constructions, they are lot more eco-friendly, both in the long and short-term. Prefabricated buildings have lower life cycle energy implications as compared to on-site construction due to optimum consumption of materials, assembly, disassembly and recycling of the building components. As they are made inside a factory, any waste or extra material is easily recycled. Prefab buildings have minimum requirement of water due to absence of onsite watering of brick/concrete works, making them least consumers of resources
Flexibility
Flexibility is one of the distinct advantages provided by the modular construction based on easy dismantling and relocation of buildings to different sites, reducing wastage, reduced demand for raw materials, minimum expended
energy and decreased time. Considering the fact prefabricated construction units can be used in different spaces, it can easily blend neutrally in any building typology. Prefabricated structures, being made of numerous individual parts, also permit higher amount of flexibility in building structure/ design by changing the design of the specific prefab component.
Time Efficiency
Prefab/ modular construction are known for their time efficiency to build, than on-site construction taking less than half the time when compared to traditional construction, due to better planning, reduced site disruptions and quicker fabrication of multiple components. This permits construction companies to take on multiple projects simultaneously, allowing businesses to grow and make larger profits. Due to reduced on-site construction, requirement of manpower and their supervision is considerably reduced leading to high degree of construction efficiency. Role of experts visiting the site is also minimised leading to higher operational efficiency. In pre-fabrications, building components are produced on a defined schedule, don’t require any operation for finishing on site including watering of concrete/ brick walls, seasoning of wood, painting and polishing of wood/door etc, which minimizes the time span for construction
Safety
Prefab construction is known for overall safety of the building after construction including safety of workers at site during construction. The risks and dangers of outside construction posed by hazardous sites, weather, etc., are mostly neutralized by the fact that the components are mostly manufactured in a controlled and safe environment
Limitations imposed by the Prefab Buildings;
Despite numerous advantages which prefab construction hold, it has few limitations which are enumerated below
Monotony
Limitations imposed by the materials and the process used in the mechanisation of building products, has led to imposing numerous restrictions on the designers in creating state of art buildings. Based on the concept of mass production and standardisation, prefab buildings suffer from lack of design innovations and look monotonous.
Restricting additions and alterations
In addition to being monotonous, prefab buildings don’t provide enough options to owners/tenets to make any change which may be necessitated, considering the changing physical, social and economic conditions. This generally leads to non-acceptability of the prefab buildings.
Reduced Resale Value
Dictated by monotony and limited options for additions and alterations, prefab structures don’t find many buyers in the resale market and accordingly command very low premium. Further the general perception of the people hovering around that pre-fab buildings are of lower quality, also put these them in poor light and reduce their resale value.
High Transportation Cost
Since majority of building components are manufactured off-site in the factory and these components are in the finished mode, having large volume and weight, therefore, they require specialised system of transport-ation to make sure the products don’t suffer any damage during the loading, unloading and transportation.
Accordingly, transportation cost in the prefab buildings is invariably high as compared to traditional buildings where the building materials can be packed more densely. In addition, large prefabricated sections would be requiring heavy machinery involving cranes and precision measurement and handling during loading, transportation and placing them in position, making them cost-intensive and unattractive. Besides high transportation cost, special vehicles are required to transport the building products calling for wide-bodied mobile vans and wide roads to facilitate their movement.
Accuracy and Precision
Prefabricated buildings require high degree of accuracy in manufacturing components besides working out the detailed design. Once the production starts, there are limited option of additions/alterations/changes, which if needed, will require huge cost and dilute all the saving in cost/time which prefab buildings command. High degree of precision is also required in the manufacturing of components because they are all made fit to size. Any variation in size will lead lot of complication/cost/time in replacement. It is rightly said,’ A mistake in the mass production of prefabricated elements ahead of the measurable site work is a serious risk”
Mass Production
Since prefab/modular structure is based on mass production, accordingly it requires an industrial setup with appropriate knowledge, machinery, technical manpower and expertise, which in turn is expensive and requires huge upfront investment. So prefab can only work if the industrial base for mass production is available in place. Creation of such base requires time and resources and a policy framework. Further mass production works on economy of scale and accordingly, for achieving economy, constant flow of order has to be ensured. In the absence of any assured inflow of order no mass production will be feasible and economically viable. However, looking at the entire context there exists dichotomy between industrial production and construction because factory production requires predictable and consistent demand, whereas construction tends to require large numbers at the same time, then none. In addition, mass production will only succeed if there is a constant and adequate demand. Which means they are more viable near large urban centres or where large scale new construction is to come up? Its existence away from small centres, where there is periodic and limited demand – transportation cost may dilute the total process of prefab construction.
Skilled Manpower and Cost
Modular construction requires large skilled manpower, both at production and assembly site, along with machinery and infrastructure to complete the project, which in the developing countries is difficult to find across the board, which limits its application. Cost effectiveness to a large extent may not be achieved always due to additional cost involved in temporary bracing for transportation and/or lifting or permanent framing to support prefabricated assemblies besides cost involved in the pre-assembly in factory prior to dismantling for transport and delivery.
Conclusion
Looking at the fact that India is passing through an era of rapid and massive urbanization coupled with government launching number of missions and yojnas calling for, ‘Housing for all by 2022’; constructing millions of latrines pan India under Swatchh Bharat Mission; creating markets for street vendors and home for houseless in all urban centres under National Urban Skill & Livelihood Mission; promoting rural development under RuUrban Mission; development of 100 cities under Smart City Mission besides taking up development under HRIDAY and AMRUT, demand for building is increasing many fold. In order to achieve defined objectives under these innovative missions, government will have to revitalize and empower the construction industry to make it more vibrant, cost-effective, energy-efficient, qualitative, sustainable, resource-efficient and safe. For this, government has to immediately come out with a well defined and innovative policy to promote state of art construction technologies. Looking at the fact, that pre-fabrication/modular construction has proved its worth globally, it will be appropriate such technology is also made operational in India on large scale. Despite limitations, prefabricated and precast construction methods offer numerous benefits involving optimal materials usage, recycling, freedom from pollution, wind & rain; improved construction safety; year round and fast construction, reduced pilferage; better quality control etc besides providing a real alternative to on-site processes. With improvement in manufacturing technology, prefabricated construction is proving to be an extremely viable option.