write up on under floor air distribution system

8/8/2019 Write Up on Under Floor Air Distribution System

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UNDER FLOOR AIR DISTRIBUTION

Flexibility in services is a major concern in todays industry and has to be compromised because of the rigidconventional systems.

Flexibility in air distribution is now possible in India by incorporating Under Floor Air Distribution (UFAD) systembrought to you by AET Flexiblespace (I) Pvt. Ltd. a joint venture between United Insulations India and AdvancedErgonomic Technologies United Kingdom. AET has installed over 65 million Sq. ft. of UFAD systems worldwide. UFADsystem along with raised access floor, under floor service distribution and totally demounted partitions helps in creatinga green and flexible environment.

Underfloor Air Distribution (UFAD) is a method of delivering space conditioning in commercial buildings that isconsidered as an alternative to conventional ceiling-based air distribution systems because of the significant benefitsthat it can provide.

By combining a building's HVAC system with all major power, voice, and data cabling into one easily accessibleservice plenum under the raised floor, significant improvements can be realized in terms of increased flexibility andreduced costs associated with reconfiguring building services. These raised floor systems are particularly appropriate

for office buildings housing today's businesses with their typically extensive use of information technologies and highchurn rates.

UFAD TechnologyUFAD technology uses the underfloor plenum between the concrete slab and the underside of a raised access floorsystem to deliver conditioned air directly into the occupied zone (height of 1.8 to 2 mtrs) of the building. Thisconditioned air is delivered into the space using active or passive terminals mounted on the raised access floor. Byinduction effect of these terminals, the temperature as per the set point is maintained in the occupied or breathingzone. The occupants experience a better indoor air quality compared to the overhead system as the conditioned air isdirectly delivered in the breathing zone.

AET can offer the following systems for comfort application1) PleinAir System Manufactured by AirFixture USA

In this system the Conditioned Air is introduced from the floor and the return is taken high from the ceiling.

2) Hivar System In this system the Conditioned Air is introduced from the floor and the return is taken high from the ceiling.3) CAM System

In this system the Conditioned Air is introduced from the floor and the return is also taken from the floor.

Description of the System

1) PleinAir system manufactured by AirFixture from USAThis system uses passive terminals to deliver conditioned air into the Breathing zone. A central air handling unitdelivers conditioned air into the plenum created between the top of the slab and the bottom of the raised access floorat about 16 18 degree C. By maintaining a static pressure of about 12.5 pascals in the plenum the air is deliveredthrough the terminals to maintain desired room conditions in the breathing zone. The conditioned air is deliveredthrough constant volume or variable air volume (VAV) terminals using time modulation. These terminals are availablein square and round shape having the load bearing capacity of the raised access floor and in various color shades to

match the interiors. Some constant volume and VAV terminals can offer directional adjustments or individual controls.

Constant Volume terminals Variable Air Volume Terminals with Time Modulation


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The space can be either conditioned with constant volume terminals as shown in fig 1 or by VAV terminals with timemodulation as shown in fig @ or it can have constant volume terminals in the internal area and the VAV on theperimeter as shown in fig 3.

Figure 1

Figure 2


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Figure 3

The hot air stratifies and is taken back to the central unit using terminals located high in the ceiling.

2) Hivar SystemThis system uses active terminals to deliver conditioned air into the Breathing zone. A compact central unit i.e Hivarunit delivers conditioned air into the plenum created between the top of the slab and the bottom of the raised accessfloor at about 14 15 degree C. By maintaining a static pressure of about 5 pascals in the plenum the air is delivered

through the active fan assisted Fan Tile Units FTU to maintain desired room conditions in the breathing zone. Thereturn air can be taken through the return grills or directly from the space.

3) Cam SystemThis also system uses active terminals to deliver conditioned air into the Breathing zone. A compact central unit i.e.Cam unit delivers conditioned air into the plenum created between the top of the slab and the bottom of the raisedaccess floor at about 14 15 degree C. By maintaining a static pressure of about 5 pascals in the plenum the air isdelivered through the active fan assisted Fan Tile Units FTU to maintain desired room conditions in the breathing zone.The plenum is divided into supply and return zone by an impervious material such that each room has both the zones.The active supply FTU terminals are located in the supply zone and the return passive grills are located in the returnzone. The return air is taken back to the Cam unit through the return grills located on the floor.


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Fan Tile UnitThe Fan Tile Unit (FTU) is an active terminal. The fan tile unit has a blower, on off damper, temperature sensors,optional heater and a smart controller. The operating modes of the FTU are as per the figures. The FTU has twotemperature sensors one of the sensor monitor the room temperature and the second sensor monitors the supplytemperature. Based on the set point for the room the fan tile unit opens the damper and introduces supply air into theroom to maintain the set temperatures. When the temperature in the room has been achieved the FTU will close thedamper and would re circulate the air in the room. Note that in the recirculation mode the unit always takes someamount of supply air having fresh air continuously.

Fig I Fig II


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UFAD Technology Benefits

1. Improved thermal comfort: - By allowing individual occupants to control their local thermal environment, theirindividual comfort preferences can be accommodated.

2. Improved ventilation efficiency and indoor air quality: - Improvement in ventilation and indoor air quality atbreathing level can be expected by delivering the fresh supply air at floor level near the occupants and returning atceiling level.

3. Reduced energy use: - Energy saving for UFAD system over conventional overhead system can be associatedwith cooling and fan energy saving.

4. Better flexibility for reconfiguration of building services: - By integrating a building HVAC and cable managementsystems into easily accessible under floor plenum, in-house maintenance personnel can carry out reconfigurationsat significantly reduced cost using simple tools and hardware.

5. Reduced floor-to-floor height in new construction: - Buildings using UFAD systems have potential to reduce floor-to-floor heights compared to projects with conventionally designed ceiling based system.

6. Improved occupant satisfaction and productivity: - Research evidence suggests that occupants satisfaction andproductivity can be increased by giving individuals greater control over their local environment and by improvingthe quality of indoor environment.

7. Reduction in project completion schedules: - Projects with UFAD system have potentials to be completed in lesstime compared to conventional system.

8. Better conformance to LEED and Green Building Requirements: - Significant progress towards the USGBC LEED

2.2 (IGBC 1.0) requirements can be made with RAF and UFAD. A Green Building has been shown to give the

owners a higher Return On financial Investment (ROI).

This concept has helped lot of developer to construct the required number of floor in a reduced height or to constructextra floors in the same height. Some of the projects are listed below. By not needing the 600 800 mm of ventilationzone, the slab to slab dimensions can be brought down by about 300 400mm per floor retaining the same headroom.In a building height of about 10 floors the developer can construct about 11 floors or in a small building the developercan construct a mezzanine floor.


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THE CENTER FIRST POINT, BAA TELECOM TOWERHONG KONG GATWICK MALAYSIS

HEIGHT SAVING 35 MTRS 6000 M2 BECAME 7500 M2 HEIGHT SAVING 30 MTRS

The evaluation of lifecycle cost of a building is not a simple thing. It is particularly difficult to forecast life cycle costaccurately because so many forward looking assumptions must be made. One of the most studied aspects of this isenergy consumption. UFAD will usually provide significantly lower operating cost when compared to systems withsimilar operating conditions. The bottom line with RAF and UAFD is lower life cycle cost and better Return OnInvestment (ROI) for investors.

UFAD is now well established in many parts of the World (USA, Northern Europe and Hong Kong). In some areas it isthe system of first choice. As we continue to develop new markets, the same questions and concerns about the newstrategy are asked. We would be concerned if good engineers were not asking these questions. Hopefully now theanswers are available.

This is a viable Mainstream technology. UFAD has come a long way in the last 10 to 15 years. Consider it with carefor every project. Listen to a broad array of experienced professionals when designing and executing a UFAD/ RAFproject.

ExistingbuildingswithUFADsystemsMultiTenantBuildings

AmericanWaterworksBldg.St.Louis,MOOneCenturyPlaceNashville,TNFoundrySquareSanFrancisco,CA160KingStreetSanFrancisco,CAMissionBayCatellusSanFrancisco,CATheSofferTechOfficeBldg.Pittsburgh,PADataCenter/TelecomBuildings

AT&TVarioussitesGTEVarioussitesGlobalCrossingVarioussitesINFLOWDataCentersVarioussites


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Level3CoLoCentersVarioussitesMCIWorldcomVarioussitesNYNEXVarioussitesSprintPCSVarioussitesCall

Center

Buildings

AmericanExpressVarioussitesBlueCrossBlueShieldVarioussitesBritishAirwaysNewYork,NYDellComputersVarioussitesHewlettPackardVarioussitesIBMVarioussitesMotorolaVarioussitesUnitedParcelServiceOakland,CAFinancialBuildings

JackHenry&AssociatesVariousSitesCapitalOneTampa,FLChaseFinancialServicesVarioussitesCitibank VarioussitesLloydsofLondonLondon,EnglandMorganStanleyDeanWitterVarioussitesShearsonLehmanAmericanExpressVarioussitesWorldBankHeadquartersWashington,DC

write up on under floor air distribution system

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