Recently Central Public Works Department made news when it employed ‘Dry Construction Technology’ to build two office buildings in Delhi. This may be a major milestone in Indian construction sector as the government’s premier construction agency is employing modern technology and setting an example for others to follow. In this project, prefabricated building components are being brought from factories located at Indore, Haridwar, Bawal and Palwal for assembling at the sites. Hence, more than 80 per cent of the project work is done in factories, away from the project site, thus reducing pollution and heavy water consumption, as is the case in RCC construction. The combined built-up area of the two complexes will be 92,000 sq metres and will be completed in a flat 240 days, which is one-third of the time taken compared to conventional buildings that use reinforced cement concrete (RCC) technologies.
It takes at least two years to construct such a building complex using conventional technologies. This does not need water for curing of any concrete or cement plaster work and hence, a lot of water is saved. More importantly, there will be less work at the project site as precast components are manufactured elsewhere resulting in less air and noise pollution.
The World Health Organisation (WHO) recognises air pollution as the world’s biggest environmental and health threat. Each year, approximately 3.7 million people die premature deaths globally due to outdoor air pollution.
Construction is a major polluter
It’s a common knowledge that use of construction materials such as concrete, wood, cement, silica and stone often contributes to dust. Diesel engines used on sites to run various equipment also emit poisonous gases such as carbon monoxide, nitrogen oxides, hydrocarbons and carbon dioxide, which significantly result in air pollution. Besides, other hazardous chemicals such as thinners, oils, glues and paints also release toxic fumes into the environment that pose serious health hazards to not only workers at the construction sites but also the residents in the neighbouring areas. Typically, dust and noise generated at construction sites travel larger distances and leave harmful effects all around. No wonder then last couple of years when air pollution in Delhi and NCR region had peaked construction activities had to be temporarily suspended to avoid further air pollution. However, suspension of construction activities to avoid air pollution is like throwing baby along with bathwater as the decision causes economic loss and unemployment. Therefore, promoting adoption of environment-friendly construction practice is the way out.
Construction being one of the major activities carried out both in urban and rural areas and is also a major contributor to air, noise and water pollution, the type of construction technology we employ is becoming extremely important nowadays. Keeping this fact in mind, recent decision of the CPWD to go for prefab construction seems to be timely. “Off-site, modular construction practices can be preferable due to lower volume and more controlled dust production,” says World Green Building Congress.
Ministry of Urban Development makes it mandatory
In May 2016, the Ministry of Urban Development issued an Office Memorandum making the earlier suggestion made by CPWD mandatory for CPWD, DDA and NBCC. According to CPWD recommendation, adoption of the following three technologies have several benefits:
- Monolithic concrete construction system using aluminium formwork
- Industrialised 3-S system using cellular light weight concrete slabs & precast columns (precast/prefab)
- Monolithic concrete construction system using plastic- aluminium formwork
According to CPWD, adoption these technologies will result in significant reduction in air and noise pollution and construction waste, optimise the use of water in construction, ensure increased labour productivity due to working in controlled environment and also will result in quality and durable construction. Above all, it also helps to keep the work site neat and clean thereby preventing air pollution.
Emphasis on offsite production of modules
In modular construction approach, a building’s large-scale modularized components are prefabricated in an offsite manufacturing facility for rapid assembly onsite. Modular construction has been shown, in a majority of cases, to result in a higher-quality building delivered in a shorter time frame with more predictable costs. Apart from curbing noise and air pollution and saving costs, modular construction also has the potential to help the building industry meet its sustainability goals. It can deliver greater environmental and social sustainability benefits than conventional construction can through reduced material waste, reduced disruption to the building site and surrounding community, safer working conditions and reduced operational energy.
However, modular construction has its own set of challenges too, logistics related being the major one. Transportation may pose a major challenge if the construction involves movement of bulky and heavy modules, especially in case of crowded cities. Such modules may have to be moved during off peak hours for which special permission may be required to be obtained. In such cases fabrication location has to be decided after considering the logistics constraints. Further, front-loaded design process forces buyers and owners to make final selections on things like finishes and appliances so they can be purchased well before the work even begins. This also results in heavy investment in initial stages of the project execution. Also, aesthetics may take a back seat in modular construction as the production of most of the modules are standardised.
While modular construction is beneficial in certain circumstances, it’s not without challenges and isn’t the answer for every project. Despite these challenges, modular construction should be the first choice considering some of the benefits it offers vis-à-vis pollution and conservation of resources. In some cases, urgency of the situation, as in the case of Covid-19 pandemic, may also favour the modular construction technology.