Heating, Ventilating and Air Conditioning
 Introduction to HVAC.
 Cooling load calculations.
 Ventilation calculations.
 DX systems and equipment.
 Chilled water systems and equipment.
 Chilled water plant.
 HVAC ducts & pipes design and air outlets selection.
 Life safety systems and HVAC control.
 HVAC documents and coordination works.
 Case study.
HVAC is the art of treating air to control Temperature, Humidity, Quality,
and Motion of air to achieve thermal comfort and acceptable indoor
environment within reasonable installation, operation, and maintenance costs,
either for human comfort or for industrial applications.
 ASHRAE
American Society of Heating, Refrigerating, and Air-Conditioning Engineers.
 SMACNA
Sheet Metal and Air Conditioning Contractors' National Association.
 NFPA
National Fire Protection Association.
 USGBC
United States Green Building Council.
 Local codes & standards
 ASHRAE Handbook:
➢ ASHRAE Applications.
(2019)
➢ ASHRAE Systems and Equipment.
(2016)
➢ ASHRAE Fundamentals.
(2017)
➢ ASHRAE Refrigeration.
(2018)
One of the four volumes is updated each year.
 ASHRAE Journal :
a monthly magazine published by ASHRAE. It includes peer-reviewed articles
on the practical application of HVAC technology.
 ASHRAE Standards:
➢ Standard 62.1: Ventilation for Acceptable Indoor Air Quality.
(2016)
➢ Standard 90.1: Energy Standard for Buildings.
(2016)
 Standard 189.1: Standard for the Design of High Performance, Green
Buildings.
(2017)
 Hourly analysis program (HAP).
 Autodesk AutoCAD.
 Autodesk REVIT.
 McQuay duct sizer.
 ASHRAE Psychrometric Analysis.
 Equipment selection software.
 The dry-bulb temperature (DBT)
➢ The temperature of air measured by a thermometer freely exposed to the air.
➢ DBT is the temperature that is usually thought of as air temperature.
➢ It indicates the amount of heat in the air.
➢ Temperature is usually measured in degrees Celsius (°C), Kelvin (K), or
Fahrenheit (°F).
 The wet-bulb temperature (WBT)
➢ The temperature of air if it were cooled to saturation (100% relative
humidity) by the evaporation of water into it.
➢ Wet-bulb temperature is largely determined by both actual air temperature
(dry-bulb temperature) and the amount of moisture in the air (humidity).
➢ Read from a thermometer whose bulb is covered by a wet wick.
➢ At 100% relative humidity, the wet-bulb temperature equals the dry-bulb
temperature.
 The dew point temperature (DPT)
➢ The temperature at which the water vapor (moisture) in a sample of air at
constant pressure condenses into liquid water.
 Relative humidity (RH)
➢ A comparison of the amount of moisture that a given amount of air is
holding, to the amount of moisture that the same amount of air can hold, at
the same dry-bulb temperature.
 Humidity ratio
➢ The ratio between the actual mass of water vapor present in moist air - to
the mass of the dry air.
➢ Humidity ratio is normally expressed in kilogram of water vapor per
kilogram of dry air.
 Solar heat gain:
a) for glass :
Q glass = A glass * SHG * SC
Where:
Q glass :
heat gain from glass (btu/hr).
A glass :
glass area (ft²).
SHG :
solar heat gain (btu/hr/ft²). (table 15).
SC
shade coefficient (unit less). (table 16).
:
 Transmission heat gain:
a) for glass :
Q glass = U glass * A glass * ∆T glass
Where:
Q glass
:
heat gain from glass (btu/hr).
U glass
:
glass overall heat transfer coefficient (btu/hr/ ft².°f). (table 33).
A glass
:
glass area (ft²).
∆T glass
:
temperature difference (Fahrenheit). (To- Ti).
To
:
ambient outdoor temperature (Fahrenheit).
Ti
:
required temperature inside conditioned space (Fahrenheit).
 Transmission heat gain:
b) for wall :
Q wall = U wall * A wall * ∆T wall
Where:
Q wall
:
heat gain from walls (btu/hr).
U wall
:
wall overall heat transfer coefficient (btu/hr/ ft².°f). (table 22).
A wall
:
wall area without glass area (ft²).
∆T wall
:
temperature difference (Fahrenheit). (To- Ti).
To
:
ambient outdoor temperature (Fahrenheit).
Ti
:
required temperature inside conditioned space (Fahrenheit).
 Transmission heat gain:
c) for roof :
Q roof = U roof * A roof * ∆T roof
Where:
Q roof
:
heat gain from walls (btu/hr).
U roof
:
roof overall heat transfer coefficient (btu/hr/ ft².°f). (table 27).
A roof
:
roof area without glass area (ft²).
∆T roof
:
temperature difference (Fahrenheit). (To- Ti).
To
:
ambient outdoor temperature (Fahrenheit).
Ti
:
required temperature inside conditioned space (Fahrenheit).
 Transmission heat gain:
d) for floor:
Q floor = U floor * A floor * ∆T floor
Where:
Q floor
:
heat gain from walls (btu/hr).
U floor
:
floor overall heat transfer coefficient (btu/hr/ ft².°f). (table 29).
A floor
:
floor area (ft²).
∆T floor
:
temperature difference (Fahrenheit). (To- Ti).
To
:
unconditioned space temperature (To- Ti-5). (Fahrenheit).
Ti
:
required temperature inside conditioned space (Fahrenheit).
 Transmission heat gain:
e) for partition:
Q partition = U partition * A partition * ∆T partition
Where:
Q partition :
heat gain from walls (btu/hr).
U partition :
partition overall heat transfer coefficient (btu/hr/ ft².°f). (table 25).
A partition :
partition area (ft²).
∆T partition :
temperature difference (Fahrenheit). (To- Ti).
To
:
unconditioned space temperature (To- Ti-5). (Fahrenheit).
Ti
:
required temperature inside conditioned space (Fahrenheit).
a) for people:
Q people (sensible) = No. of persons * sensible heat\person
Where:
Q people (sensible)
:
sensible heat gain from peoples (btu/hr).
No. of persons
:
number of persons inside conditioned space according
to ASHRAE standard 62.1 (table 6-1) only when actual
occupant density is not known.
sensible heat\person :
sensible heat gain from people inside conditioned
space as per activity level (btu/hr). (table 48).
a) for people:
Q people (latent) = No. of persons * latent heat\person
Where:
Q people (latent)
:
latent heat gain from peoples (btu/hr).
No. of persons
:
number of persons inside conditioned space according
to ASHRAE standard 62.1 (table 6-1) only when actual
occupant density is not known.
latent heat\person
:
latent heat gain from people inside conditioned
space as per activity level (btu/hr). (table 48).
b) for lighting:
Q lighting = No. of lamps * lamp wattage * 3.4 * 1.25
Where:
Q lighting
:
heat gain from lighting fixtures (btu/hr).
3.4
:
factor to convert from wattage to btu\hr.
1.25
:
for florescent light only to include trans heat gain.
c) for appliances:
Q appliances = total appliances wattages * 3.4
Where:
Q appliances
:
heat gain from appliances inside conditioned space (btu/hr).
3.4
:
to convert from wattage to btu\hr.
CFM = No. of persons * CFM / person
Where:
CFM
:
Cubic Feet per Minute.
CFM / person
:
according to ASHRAE standard 62.1 (table 6-1).
Q = m͘ air * CP air * ∆T air
= V͘ air * ρ air * CP air * ∆T air
Sensible ventilation load = CFM * 1.08 * ∆T air
Where:
CFM
:
Cubic Feet per Minute.
1.08
:
ρ air (0.68 ) (pound / ft³) * CP air (0.24) (btu / pound * ft³).
∆T air
:
air temperature difference (Fahrenheit). (To- Ti).
To
:
ambient outdoor temperature (Fahrenheit).
Ti
:
required temperature inside conditioned space (Fahrenheit).
Latent ventilation load = CFM * 0.68 * ∆
Where:
CFM
:
Cubic Feet per Minute.
0.68
:
air density (pound / ft³).
∆
:
humidity ratio (Psychometrics chart).
Room Sensible Heat (RSH) =  Q sensible
Room Latent Heat (RLH) =  Q latent
Total Heat Gain (THG) = TSH + TLH
TR = GTH (btu/hr) / 12000
 Outside conditions (ASHRAE Climatic Design Information).
 Required inside conditions (ASHRAE Applications).
 Arc. drawings (areas and height).
 Type of walls, roof and glass (ASHRAE Fundamentals - chapter 26).
 Building orientation (north direction).
 Building application.
 No. of people inside each space (ASHRAE Standard 62.1).
 Lighting power (ASHRAE Fundamentals - chapter 18).
 Equipment power or heat dissipation (ASHRAE Fundamentals - chapter 18).
 An evaporator is a device used to turn the liquid form of a chemical into its
gaseous form. The liquid is evaporated into a gas.
 The evaporator is a finned tube coil used to cool air or water.
 Warm air flows across the finned tube arrangement and refrigerant flows
through tubes.
 The refrigerant absorbs heat
from the warm air causes the
liquid refrigerant to boils.
 The resulting low pressure
refrigerant vapor is drawn to
the compressor.
 A compressor is a mechanical device that increases the pressure of a gas by
reducing its volume.
 The compressor raises the pressure of the refrigerant vapor to a pressure and
temperature high enough so that it can reject heat to another fluid, such as
ambient air or water.
 The hot high pressure refrigerant vapor
then travels to the condenser.
 A condenser is a device or unit used to condense a substance from its




gaseous to its liquid state, by cooling it.
The condenser is a heat exchanger used to reject the heat to another
medium.
The hot high pressure refrigerant flows through the tubes of the condenser
and the cooler ambient passes
through the condenser coil.
The heat content of the refrigerant
vapor is reduced, it condense into
liquid.
The pressure liquid refrigerant
then travels through the
expansion device.
 Expansion valves are flow-restricting devices that cause a pressure drop of
the working fluid.
 A large pressure drop occurs leads to reduce the refrigerant pressure and
temperature.
 To air-condition an area, let’s assume that the temperature inside it shall be
24°c, we have to introduce the cold air to the room at a temperature of
between 12 to 14°c.
 Accordingly, the cooling medium temperature would have to be lower than
12°c by about 5°c, i.e. 7°c as per the following drawing:
AIR @ 24°C
FREON @ 7°C
AIR @ 12°C
 In order to complete the loop of the refrigerant, it is evaporated in the
AIR @ 24°C
COMPRESSOR
FREON @ 7°C
MIXED STATE
FREON @ 7°C
EXPANSION
VALVE
EVAPORATOR
AIR @ 12°C
VAPOR STATE
AIR @ 40°C
FREON @ 80°C
LIQUID STATE
FREON @ 50°C
CONDENSER
SUPERHEATED STATE
evaporator, then compressed to the condenser thus raising its pressure and
temperature to about 50°c, then condensed to liquid in the condenser, and at
last its pressure is decreased back to that of the evaporator by means of the
expansion valve as per the drawing:
 DX system (Direct Expansion).
➢ Window unit.
➢ Split unit.
➢ Package unit.
➢ Split system.
➢ VRF system.
 Chilled water system.
➢ Air cooled system.
➢ Water cooled system.
 Window unit.
 Split unit.
a.
Cassette type.
b.
Ducted concealed.
c.
Decorative.
➢
Wall mounted.
➢
Ceiling mounted.
➢
Floor mounted.
➢
Free stand.
 Package unit.
a.
Vertical.
b.
Roof top.
• Distance between the outdoor unit &
indoor unit is restricted.
• Condensing unit shall be outdoor located.
(elevation & roof space is required).
• Low cooling capacity.
• Low cost, easy installed & high
electrical consumption.
• Outdoor located. (outdoor space is required).
• Limited cooling capacity.
• Medium cost & high electrical consumption.
 Split System.
a.
AHU
with condensing unit.
 VRF system.
• Air handling unit shall be indoor or
outdoor located. (roof space or
mechanical room is required).
• Condensing unit shall be outdoor located.
(outdoor space is required).
• Large cooling capacity.
• Medium cost & high electrical
consumption.
• Outdoor unit shall be outdoor located.
(elevation & roof space required).
• Lower electrical consumption than split
units.
• Refrigerant piping length can be longer
than split units.
Average dimensions
1000 x 700 x 700 mm
Up to 2 TR
Condenser
Expansion valve
Compressor
Evaporator
Average dimensions
900 x 350 x 750 mm
Up to 5 TR
Condensing unit
Outdoor unit
Compressor
Expansion valve
Average dimensions
1500 x 300 x 350 mm
Evaporating unti
Indoor unit
600 x 600 x 300 mm
950 x 950 x 400 mm
Average dimensions
900 x 800 x 1,100 mm
Up to 25 TR
Evaporator
Expansion
valve
Condenser
Compressor
Average dimensions
3,600 x 2,200 x 1,800 mm
Up to 80 TR
Evaporator
Expansion
valve
Condenser
Compressor
The main difference is in
the shape of the condenser
fan which is axial instead of
centrifugal.
AIR COOLED
CONDENSING UNIT
AIR HANDLING UNIT
Up to
120 TR
From: 2,100 x 1,300 x 1,600 mm
To:
5,000 x 2,500 x 2,000 mm
From: 4,000 x 2,000 x 700 mm
To: 11,000 x 4,000 x 2,500 mm
 Air cooled system.
 Water cooled system.
a.
Electrical chiller.
b.
Gas chiller (absorption chiller).
 Air cooled chillers adopt the same concept of the air-conditioning cycle, except that
the evaporator cools water instead of air.
 The chilled water then pumped to the loads (Air handling units OR fan coil units)
through a piping network.
 Air cooled chillers have a cooling load up to 500 TR.
 Dimension of a 500 TR chiller is 14 m L x 2.25 m W x 2.5 m H.
 Air cooled system shall be located at open area.
 Area required for air cooled system plant is about 1 m² per each 2.5 TR.
 Power consumption for air cooled system is about 1.9 kW per TR for all system
components.
CH.W @ 6°C
CH.W @ 12°C
LIQUID STATE
FREON @ 50°C
CH.W PUMP
SUPERHEATED STATE
FREON @ 80°C
AIR @ 40°C
EXPANSION
VALVE
VAPOR STATE
FREON @ 2°C
MIXED STATE
FREON @ 2°C
CONDENSER
COMPRESSOR
EVAPORATOR
LOAD
 Same concept as air cooled chillers, except that the condenser is cooled with water
instead of air.
 This cooling water after gaining heat from the condenser is then cooled in a cooling
tower.
 Water cooled chillers have cooling loads up to 3000 TR.
 Dimension of a 1000 TR chiller is 5 m L x 2.25 m W x 2.5 m H.
 Dimension of a 1000 TR cooling tower is 3.6 m W x 6.7 m W x 7 m H.
 Cooling towers shall be located in open area.
 Make-up water tank may be provided.
 Area required for water cooled system plant is about 1 m² per each 5 TR.
 Power consumption for water cooled system is about 1.4 kW per TR for all system
components.
CH.W @ 6°C
CH.W @ 12°C
CH.W PUMP
SUPERHEATED STATE
FREON @ 70°C
LIQUID STATE
FREON @ 40°C
CONDENSER
EXPANSION
VALVE
VAPOR STATE
FREON @ 2°C
MIXED STATE
FREON @ 2°C
WATER @ 35°C
WATER @ 30°C
C.W PUMP
COMPRESSOR
EVAPORATOR
LOAD
 Factors affecting air distribution:
➢ Throw
➢ The horizontal distance that air stream travels from the outlet.
➢ Throw is directly proportional to supply velocity, supply temperature,
ceiling effect.
➢ Throw is reversely proportional to aspect ratio , angle of spread.
 Factors affecting air distribution:
➢ Drop
➢ The vertical distance that the air travels till it reaches the end of it’s throw.
➢ Drop = room height – 1.8 m
➢ Drop is reversely proportional to the supply temperature.
 Factors affecting air distribution:
➢ Spread angle
➢ The angle of divergence of the air stream that leaves the outlet.
➢ if the spread angle increased → throw decreased , drop increased.
➢ if the spread angle decreased → throw increased , drop decreased.
 Ceiling diffusers.
➢ Square ( 4 way – 3 ways – 2 way ).
➢ Round.
➢ Rectangular.
 Slot diffuser.
 Side grilles.
 Floor grilles.
 Jet nozzles.
 Swirl diffusers.
 Perforated diffusers.
 Plaque diffusers.
4 way square diffuser
Air grill
3 way square diffuser
Jet nozzle
Round diffuser
Swirl diffuser
Chilled water pipe material: Seamless black steel Sch 40.
 Pipe sizing classification
Closed cycle: chiller.
Open cycle: cooling tower.
 Steps for pipe sizing:
➢ Determine water flow rate in each branch.
GPM = 2.4 x T.R (for chilled water temp. difference of 10 F )
➢ From chart get the pipe diameter with to conditions.
Maximum friction rate = 4 ft.w/100ft (400PA/M)
Maximum water velocity = 1.2 m/s for pipes smaller than 50 mm
Pumps type:
•
Positive displacement pumps.
•
Centrifugal pumps. (used in HVAC systems).
•
Primary pumps: overcome friction loss on return line.
•
Secondary pumps: overcome friction loss on supply line.
➢ Given by HVAC:
 Shafts dimensions.
 Concrete pads locations.
 Main HVAC equipment weight.
 Any opening in shear walls, beams & slabs.
➢ Required from Structure:
 Concrete beams & drop panels location and dimension.
 Expansion joint location.
➢ Given by HVAC:
 Interface points.
➢ Motorized damper (MD).
➢ Smoke detector (SD).
➢ Control module (CM).
➢ Monitor module (MM).
 HVAC equipment location.
 BMS points schedule.
 Fire case scenario.
 HVAC outlets distribution on ceiling.
➢ Required from Communication:
 Communications rooms heat dissipation.
 Communications rooms conditions (temperature & humidity).
 Computer room air handling unit location.
➢ Given by HVAC:
 HVAC equipment location & electrical consumption.
➢ Required from Electrical:
 Electrical, Transformer, Generator, MCC, Medium voltage, Low voltage, UPS,
Battery, RMU & MDP rooms heat dissipation.
 Lighting fixture distribution on ceiling excluding pharmaceutical factories &
hospitals operating rooms.
 Lighting density (w/m²).
 Task lighting wattage if any.
 Electrical rooms conditions (temperature & humidity).
 Generator exhaust & make up air.
 HVAC electrical wiring diagram.
 Load estimation. (HVAC load & electrical load).
➢ Given by HVAC:
 HVAC outlets distribution on ceiling.
 HVAC equipment location for equipment drain & floor drain.
 HVAC equipment needs water supply (humidifier).
 Make up water tank capacity & location.
 Steam & hot water flow rates if any.
➢ Required from Plumbing & Fire Protection:
 Fire Fighting gases suppression rooms. (Co2, FM200, Novec & Argonit).
 Main drain pipe location.
 Water pump rooms location. (water softeners & dosing pumps).
 Pumps power consumption.
 Supply & drain points for each HVAC room & server rooms.
 Vertical & horizontal drain.
 Compressors, diesel pumps, vacuum pumps and medical equipment
exhaust & make up air.
 Cooling towers make up pump.
➢ Given by HVAC:
 Shafts dimensions.
 HVAC rooms dimensions.
 HVAC equipment location.
 Concrete pads locations.
 Louvers size & location.
 Air outlets distribution on ceiling.
 Access doors & maintenance areas.
 Raised floor height at server rooms.
➢ Required from Architecture :
 Project location & true north direction.
 Architecture plans (space usage & furniture) .
 Reflected ceiling plans.
 Elevations & sections.
 Wall & roof types (thickness, density, specific heat & R-value).
➢ U value (wall, roof, ceiling, floor and partition).
 Glass & sky light types ( U-value & shade coefficient).
 Changing in spaces area & usage.
 Changing in reflected ceiling.
 Above ceiling clear height.
 Above ceiling coordination.
 Equipment locations.
 Shafts locations.
 Sound level in critical areas.
 Ducts size.
Thank You