HVAC SYSTEMS

TYPES

HOW AS AN ARCHITECT TO MAKE A CHOICE FIT FOR THE

PROJECT TYPE

ARCHITECTURAL THUMB RULE1 TON IS THE AC LOAD REQUIREMENT FOR A SPACE OF

100 SFT.

10’0”

10’0”

PRICINPLES OF AIR CONDITIONINGTHE AIM IS TO KEEP IT MORE COMFORTABLE INSIDE

THE BUILDING THAN IT IS OUTSIDE

A simple stylized diagram of the refrigeration cycle: 1) condensing coil, 2) expansion valve, 3) evaporator coil, 4) compressor

The refrigeration cycle uses four essential elements to cool.The system refrigerant starts its cycle in a gaseous state. The compressor pumps the refrigerant gas up to a high pressure and temperature.From there it enters a heat exchanger (sometimes called a condensing coil or condenser) where it loses energy (heat) to the outside, cools, and condenses into its liquid phase.An expansion valve (also called metering device) regulates the refrigerant liquid to flow at the proper rate.The liquid refrigerant is returned to another heat exchanger where it is allowed to evaporate, hence the heat exchanger is often called an evaporating coil or evaporator. As the liquid refrigerant evaporates it absorbs energy (heat) from the inside air, returns to the compressor, and repeats the cycle. In the process, heat is absorbed from indoors and transferred outdoors, resulting in cooling of the building.

PRICINPLES OF AIR CONDITIONINGTHE AIM IS TO KEEP IT MORE COMFORTABLE INSIDE

THE BUILDING THAN IT IS OUTSIDE

TYPES OF AC SYSTEMS

TYPES OF AC SYSTEMS

WINDOW AC

SMALL SCALE PROJECTS

PROVIDES HIGH REDUDANCY DOESN’T LOOK GOOD AESTHATICALLY

WINDOW AC

SMALL SCALE PROJECTS

PROVIDES HIGH REDUDANCY DOESN’T LOOK GOOD AESTHATICALLY

WINDOW AC

HIGH WALL AC

SMALL SCALE PROJECTS

PROVIDES HIGH REDUDANCY LOOK’S BETTER AESTHATICALLY

HIGH WALL AC

CASSETE AC OR CEILING MOUNTED AC

SYSTEM COMPARISON FOR SERVICES APARTMENTS, RESTAURANTS AND FOOD COURT PROJECT: CONSCIENT ONE DATED: 15 JULY 2013

S No PARAMETER AIR COOLED SPLIT SYSTEM WATER COOLED SPLIT SYSTEM AIR COOLED VRV SYSTEM AIR COOLED SCREW CHILLER WATER COOLED SCREW CHILLER

1 COMPONENTS

Indoor unit. Indoor unit. Indoor unit. Aircooled screw chillers. Watercooled screw chillers.

Aircooled outdoor unit. Watercooled condensing unit. Aircooled outdoor unit. Chilled water pumps. Chilled water pumps.

Refrigerant piping. Refrigerant piping. Refrigerant piping. Chilled water piping. Condenser water pumps.

Cooling towers. Electronic controls. Airhandling units / Fan coil units. Chilled water piping.

Condenser water pumps.  

Condenser water piping.

Condenser water piping. Cooling towers.

Air Handling units / Fan coil units.

2 PHASE WISE INSTALLATION Possible Possible Possible Not Possible Not Possible

3 CAPITAL COST L1 L2 H H L3

4POWER CONSUMPTION HIGH LOW LOW Higher at full load LOW

IKW [Full Load] 1.35 kW/TR 1.1 kW/TR 1.2kW/TR 1.6 kW/TR 1.1 kW/TR

5 OPERATING COST

ICooling Requirement at 80% diversity 382 Tons 382 Tons 382 Tons 382 Tons 382 Tons

IIPower consumption 516 420 459 611 420

6 SPACE REQUIREMENT

IOPEN SPACE for ODUs Required Not Required Required Not Required Not Required

IIOPEN SPACE for PLANT Not Required Not Required Not Required Required Not Required

IIIOPEN SPACE for COOLING TOWERS Not Required Required.[for condenser pumps

also] Not Required Not Required Required

IVBASEMENT SPACE for PLANT Not Required Not Required Not Required Not Required Required

7 REFRIGERANT PIPING Length less than 15 m. Required Length 50m-100m. NA NA

8 BILLING Easiest Easy, only cooling towers and pumps are common.

Easy, in case of separate system for each user. Difficult due to common plant Difficult due to common plant

9 DERATION High in peak ambient conditions Low in peak ambient conditions High in peak ambient conditions High in peak ambient conditions Low in peak ambient conditions

10

SOFT WATER REQUIREMENT NA 8LPH/TR NA NA 8LPH/TR

TOTAL WATER REQUIREMENT/DAY (12 HOURS)

NA 36710 LITRES/DAY NA NA 36710 LITRES/DAY

11 RECOMMENDATIONSNot recommended due to non availability of open spaces for ODUs

Recommended for best efficiency and low capex if water is not scarce.

Not recommended due to non availability of open spaces for ODUs

Recommended due to water scarcity and good performance on part loads.

Recommended for best efficiency and low capex if water is not scarce.

CENTRALISED AC SYSTEM

ROOM FITTED WITH

DUCTS

EACH ROOM HAS FCU

EACH FLOOR HAS AHU

EACH BUILDING HAS COOLING TOWERS MOSTLY ON ROOFS

EACH BUILDING HAS CHILLERS MOSTLY IN

BASEMENTS

CENTRALISED AC SYSTEM

ROOM FITTED WITH

DUCTS

EACH ROOM HAS FCU

EACH FLOOR HAS AHU

EACH BUILDING HAS COOLING TOWERS MOSTLY ON ROOFS

EACH BUILDING HAS CHILLERS MOSTLY IN

BASEMENTS