The new era of construction, as we all anticipate and are eagerly looking forward to, will rely heavily on use of Technology. Technology in the form of Artificial Intelligence, Robotics, mechanized construction, digital platforms for process management, documentation and communication etc. All these will become the norm and way to work in future, replacing reliance on unorganized and unpredictable processes, and availability of manpower & construction resources. Which will ultimately improving the productivity, efficiency, quality & predictability of delivery along with optimized cost and reduced project risk.
While these technological advancements are yet to be fully explored and implemented in future, there are certain Construction Technologies, which are not fully utilized to their potential.
This pandemic situation due to Covid 19 has led many organizations to think through the Construction process and use of technology from a different perspective. Suddenly, there is a demand of work spaces plan with low density, high flexibility and better efficiency.
Radiant Cooling Technology for Air-conditioning system is one such option to look at as a solution. Using this system, not only the overall operational running cost gets reduced, it also helps in optimizing the space requirement for services.
Radiant System Philosophy
In Radiant cooling system, water is used as a cooling medium (at 17-20°C temperature approx.) directly to cool the indoor air temperature through radiation. Water can carry 3400 times the energy that air can carry for the same volume. Water is a better heating and cooling agent than air, because air would require a much 1000 times larger volume to transport the same amount of heating and cooling capacity. In this system, the radiant cooling tubes (capillary tubes) are embedded inside the Roof/ Floor slabs or Walls or concealed in the Ceiling/ Floor finishes, employs long-wave (infrared) radiation to the cooled surface to remove unwanted heat from the space. Radiant Cooling tubes are laid closed to each other in a grid and concealed.
Cooling in the inside space is achieved when cold surface absorbs the heat radiation generated by people, computers, lighting and other equipment exposed to slab.
Dedicated Outdoor Air System (DOAS) provides ventilation air and dry air to maintain healthy environment, and also to control the moisture inside the space which is addressed as latent load. DOAS unit supplies dehumidified air through its air distribution system. The cooling tubes system separates the task of sensible cooling from those of humidity controlled DOAS with no recirculation of space air. DOAS conveys 100% outside air to each conditioned space via a constant-volume outside air unit (Energy Recovery Ventilator), aside from delivering ventilation air straight to each space. Its outside air unit uses a total energy recovery ventilator, an enthalpy wheel to cool and dehumidify outside air. It can also reduce latent and sensible load with additional cooling coil in the unit.
Advantages of Radiant Cooling System
The cooling and heating medium for radiant systems is typically water that may be conditioned by boilers, heat pumps, chillers, geothermal heat pump, solar thermal panels, etc. There are many advantages to radiant systems over forced air systems, these include:
- Energy savings: Exchanges heat with water rather than air. Water is a better heating and cooling transport agent. Air requires much larger volume (1000 times more) to transport the same amount of heating and cooling capacity. Water uses 30% less energy by reducing 75% motor HP.
- Space saving: Low floor to floor height requirements due to small plenum for ventilation air supply. Equipment room size can be reduced, providing additional rentable space. Approx. 1/3 space required for these equipment is saved.
- Noise reduction: Noise is reduced because much less fan power is required. The radiant panel and capillary tubes are virtually silent. The only noise is created by D.O.A.S. unit (Dedicated outdoor air system) which is normally installed outdoor.
- Human comfort: The space is cooled/ heated evenly due to closed spacing of capillary tubes. The application of radiant cooling significantly eliminates the contamination associated with re-circulated air, improving indoor air quality. DOAS excels at humidity control and thus nearly eradicates microbial problems and related sick-building issues.
- Since cooling relies on radiation from a cooled surface to provide sensible cooling, the cooling tubes system can provide comfort at a higher indoor air temperature than an all air system.
- Maintenance: Lower maintenance is achieved as there are few electrical devices compared to a forced air system (Conventional HVAC System). Sub-stations consist of valves, pump, heat exchanger etc.will require some maintenance. DOAS system will require less maintenance due to equipment capacity and the location.
- Due to the flexibility of the polypropylene tubes, cooling grid might represent the best choice for retrofit or new applications.
- Radiant Cooling system provides an even surface temperature distribution.
- The smaller diameter of the tubes also provides a better homogeneity and higher thermal Efficiency (this efficiency is 98%).
- As air does not play a major role for sensible cooling, so it does not have to be cooled far below the room temperature. This reduces the problems caused by duct leakage and heat loss from ducts.
Disadvantages of Radiant Cooling System
- Limited professionals for design, installation of the system in India.
- Ceiling cannot be punctured (unplanned) if piping is embedded in the ceiling/slab. And once it is punctured, the system becomes redundant; hence services & structural requirements should be designed & coordinated well in advance.
- The system cannot be used in high humid conditions as it will lead to condensation, however it can be controlled with proper humidity control measures.
- Cooling cannot be reduced beyond certain temperature (around 26 +/- 1 deg C) since the slab is cooled at 20 deg C and the temperature has to be maintained below the dew point.
- Not recommended in hospital, hotel or shopping mall due to high variance in air-conditioning requirement, recommended only for IT / office building.
- Zoning cannot be done for small areas.
Building Information Model or BIM as we all know is also one such technology. It is available and in use in construction industry since many years now but still we use it on selective projects. Use of BIM will become an integral part of project management system in future.
Presently, full potential and implementation of BIM is still not common. It is primarily used for 3D visualization and at the max clash detection of services designed. However, it has much advanced usage (4D, 5D, 6D, 7D) & has huge potential which is not limited to Design only. It can be utilized for accurate Quantity Surveying, developing Analytical Models, Scheduling, Progress Monitoring, Cost Management, developing VR models, Facility Management (Inventory management) etc.
Looking at upcoming technologies, use of Drones, 3D Scanning or documentation of building is an interesting technology. It has the potential of documenting and capturing data of any built structure accurately which can be used for review and analysis. Can be effectively utilized in tracking physical progress of the building, as it creates a virtual walkthrough model of the constructed building, which can be used to perform visual inspections to identify visual defects, dimensional correctness etc. from a remote location. It also becomes a record for your progress of work done and complete information can be stored on cloud server accessible to you from any location. It can be integrated with BIM for further design development and evaluation. Also, it would be very helpful on restoration projects, archaeological sites etc.
Power Trowel to achieve better finish
In terms of alternate construction techniques, use of Power trowel floater on casted slab, to achieve uniform level & finish is quite an easy and effective solution in reducing around 50 mm thick cement mortar work floor slab, which is quite laborious, time taking and also increase unwanted load on structure. The finished floor can be used as it is or with tiles laid with adhesive. If planned appropriately during design stage the same can be implemented effectively to optimize time & cost both.
