District Cooling System
District Cooling System: Greater Human Comfort at Lower Costs
Human comfort is a major aspect of developed space and impacts the reputation of a developer. A developer whose buildings provide enhanced human comfort experiences an increase in prestige and can easily charge a premium which customers, in most cases, are happy to pay.
Space cooling is a key component that determines human comfort in any built environment, especially in our country. Indoor thermal comfort is essential for the physical as well as psychological wellbeing of people. It is provided by heating or cooling or combination of both based on local weather of the location.
Increased demand for better indoor climate and comfort in buildings has been a driving force in enhancement in air conditioning technology. It is well known that in any built environment 45 to 50% energy is used for this need, that is why HVAC Systems are labeled as power guzzlers universally.
DCS vs Conventional HVAC systems:
To get the maximum energy efficiency, District Cooling System or DCS is the preferred choice over local systems for each building. This generates cost savings as well as environmental benefits. District Cooling/heating Systems are being used globally for community or as part of mixed-use area at the city level.
With DCS, cooling is centrally produced with large HVAC equipment and distributed to each user / buildings through a network of underground insulated piping network with one supply pipe and other return pipe. The supply pipe is used to circulate chilled water at a temperature of 6–7degree C. Sometimes a glycol mixture at 0 degree C is also used. At the user building the supplied chilled water absorbs heat in the process of cooling indoor air resulting in the temperature of return pipe being 12-17 degree C. This water is again chilled at the DCS plant and re-circulated in the network.
DCS offers operating flexibility if used in mixed used buildings built over a large area. Energy efficiency can be maximized if Absorption Type Chillers are used to produce chilled water or with the use of thermal storage systems to cater to part loads.
The key parameters to be analyzed before designing a DCS to meet economic & critical demand are as follows:
# Detailed assessment of demand
# Flexibility in plant design
# Co-ordination with city level planning authorities
# Ease in expansion on infrastructure in future requirements
# Optimization of main plant energy used by implementing latest technologies
DCS is completed with following Primary Components.
- Central Cooling Plant with Chillers, Pumps, Cooling Towers, central command station etc.
- Chilled water Piping Network through overground or underground Utility Tunnels
- Energy Transfer Stations, metering station at each user building
- Chilled Water Vertical Piping with control valves etc within the buildings
- Air Handling units / Fan Coil Units / Radiant Cooling Systems in user buildings
The first major district cooling system was installed in Hartford, Connecticut, in 1962.
In India, the first DCS plant was installed at Gift City, Gujarat. Implementation of DCS has increased due to an increase in demand of stopping the usage of CFC refrigerants which led to ozone depletion in the atmosphere.
Benefits of District Cooling
Benefits to Society/Community:
- Highs energy-efficient with energy saving potential of 45 to 50% compared to conventional systems.
- Environment friendly as it consumes less energy which generates less greenhouse gases
- Eliminates noise, vibrations & thermal plume in end user buildings thereby reducing overall heat generation
- Area spared on roof can be utilized for solar power plant or green roofs for greater sustainability
- Reduced grid power demand
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