Foundations of Real Estate Management

1
BOMA International

Foundations of Real Estate Management
TM
Module 3 Building Operations I Heating,
Ventilating, and Cooling the Building
2
Objectives

• List the three components of the HVAC system
• List the three tasks of the ventilation system
• Explain why it is important to balance outside
  air and exhaust air pressures, and tell what
  happens in a commercial building if the pressures
  are uneven
• Trace the flow of air through the duct work
  distribution system

3
Objectives

• Describe how electric reheat coils in a VAV box
  provide heat
• Describe how baseboard heating systems provide
  heat
• Describe the refrigeration cycle
• Describe the chilled water cycle
• Describe the condenser water cycle
• List at least five methods to improve efficiency
  of heating and cooling functions

4
HVAC
Heating Ventilating Air Conditioning
5
Ventilation

• Provides outside air
• Removes stale air
• Filters

6
Ventilation

Photo courtesy of PM 101
Outside Air Damper
7
Ventilation

Photo courtesy of Transwestern
Variable Frequency Drive
8
Ventilation
Its a continuum No outside air
100 outside air Maximum energy efficiency
Minimum energy efficiency Minimum IAQ
Maximum IAQ

9
Ventilation
Free cooling Using outside air to condition
the space

10
Ventilation
Exhaust Removing odors and carbon
dioxide

11
Ventilation
Separate exhaust for kitchens and restrooms

12
Ventilation
Ensure restaurant tenants clean their exhaust
system regularly

13
Ventilation

• Plenum Return
• Ducted Return

14
Ventilation

• Partition Walls
• Demising Walls
• Fire Dampers
• Protection

15
Ventilation
Photos courtesy of Transwestern
16
Humidity

• ASHRAE recommends 50 relative
  humidity (range of 30-60)
• Dehumidification
• Humidification (rare)

17
Pressure
The Goal Pressure In Pressure Out
18
Pressure

• Over Pressurization
• More air is brought in than is exhausted
• Inoperable exhaust fan, incorrect VFD settings
• Front doors will not close properly
• People feel pressure (like on airplane)
• HVAC becomes inefficient

19
Pressure

• Under Pressurization
• More air exhausted than brought in
• Inoperable outside air fan, incorrect VFD
  settings
• Front doors hard to open
• HVAC becomes inefficient
• Façade will leak

20
Filtration

• Filters remove dust, debris, insects, and other
  contaminants
• Pleated filters v. fiberglass filters
• HEPA filters
• Charcoal filters for odors
• Changed routinely

21
Air Distribution

• Air Handler
• Trunk Line
• Branch Line
• VAV Boxes/Terminal Units
• Supply Air Diffusers

22
Air Distribution - Zoning

• Areas of the building operate differently from
  one another
• Zones determined by
• Function/Use
• Location

23
Air Distribution

Air Handling Unit (AHU) or Air Handler
24
Air Distribution

VAV Box controlled by a thermostat
25
Air Distribution

Supply Air Diffuser
26
Air Distribution

Trunk and Branch Ducts VAV Boxes and Supply Air
Diffusers
27
Thermostat

• Types
• Pneumatic
• Direct Digital Control (DDC)
• Set point temperature
• Impossible to please everyone
• Location

28
Thermostat

• ASHRAE-recommended set points
• 71o F for heating (68-75o F)
• 76o F for cooling (73-79o F)
• Balance tenant comfort with energy efficiency

29
Thermal Layering

Heat Rises Top 1/3 is warmest
Temperature is measured in the middle 1/3 (On
top of the desk)
Bottom 1/3 is coolest (space heaters)
30
Space Heaters
31
Heating

• Involves adding heat

32
Heating

• Fuel Sources
• Electricity
• Natural Gas
• Heating Oil

33
Heating

• Systems
• Central
• Local

34
Heating

• In most buildings, heating occurs only around
  perimeter not in core
• Air handler provides cooling to entire building
• Electric heaters in perimeter VAV boxes heat
  perimeter as needed

35
Heating

• Baseboard heating
• Electric
• Hot water or steam
• Under floor or sidewalk (radiant)
• Interlock

36
Cooling

• Involves removing heat

37
Cooling

• Just 3 Loops
• Refrigerant Loop
• Chilled Water Loop
• Condenser Water Loop
• The loops do not mix!

38
Cooling

• The Refrigeration Loop/Cycle
• Refrigerant
• Compressor
• Condenser
• Expansion Valve

39
Cooling

• Refrigerant
• Fluid that absorbs heat
• Moves from liquid to gas (add heat) and back to
  liquid (remove heat) easily
• Boiling point is low 50-60o F
• Gas at room temperature

40
Cooling

• Compressor
• Applies pressure
• Changes refrigerant from low pressure gas to a
  high pressure, super-heated vapor

41
Cooling

• Condenser
• Rejects heat outside building
• Either air cooled or water cooled
• Enters as a super-heated vapor
• Leaves as a high temperature, high pressure
  liquid

42
Cooling

• Expansion Valve
• Sprays liquid into a fine mist
• Reduces pressure and cools refrigerant

43
Cooling

• Evaporator
• Transfers heat from building to refrigerant
• Heating the refrigerant causes it to boil
• Heated refrigerant then passes to compressor and
  the cycle continues

44
Cooling

• The refrigeration cycle is nothing more than
  changing the refrigerant from a liquid to a gas
  and back to a liquidover and over again
• Its a closed loop system

45
Cooling

• The Refrigeration Cycle

46
Cooling
Heat always moves from higher to lower
temperature
47
Coils and Bundles

• Coils
• Transfer heat between air and refrigerant
• Bundles
• Transfer heat between liquid and refrigerant

48
Coils and Bundles

• Photo courtesy of PM 101

Coils
49
Coils and Bundles

Shell and Tube Bundles
50
Moving Heat from Inside to Outside

• Chilled Water Loop
• Rejects heat from occupied spaces to the
  refrigerant
• Condenser Loop (air-cooled) or Condenser Water
  Loop (water-cooled)
• Rejects heat from the refrigerant to outside of
  the building

51
Cooling

• Chilled Water Loop
• Water treatment is critical
• Picks up heat in evaporator coil (in AHU) and
  takes heat to refrigerant loop
• Cooler chilled water returns to evaporator coil
  to start process over again
• As heat is removed, cooler air is blown through
  duct system by the AHU

52
Cooling

• Condenser Water Loop
  (water-cooled)
• Water treatment is critical
• Picks up heat in refrigerant
  loop loop and takes heat to
  heat to cooling tower

53
Cooling

• Cooling Tower
• Condenser water pipes bathed in cool water
  sprayed inside cooling tower. Large fans also
  help transfer heat
• Heat is transferred to outside
• Cooler condenser water is pumped back inside to
  start cycle again

54
Cooling

• Condenser Loop (air-cooled)
• Air is blown over refrigerant loop to reject
  heat

55
Cooling

• Water- or Air-Cooled Systems
• Chillers
• Self-Contained Units (SCUs)
• Air-Cooled Systems
• Rooftop Units (RTUs)
• Split System
• Heat Pump

56
Cooling

Chiller
Photo courtesy of PM 101
57
Cooling

Self-Contained Unit (SCU)
Photos courtesy of PM 101
58
Cooling

Rooftop Unit (RTU)
Photo courtesy of Thomas J. Easley
59
Cooling

Split System
Photo courtesy of Thomas J. Easley
60
Cooling

Heat Pump
61
Piped Systems

• Types
• 2 Pipe
• 4 Pipe
• Fan coil units

62
Free Cooling
Rejecting heat without using the
compressor Flat plate heat exchanger
Photo courtesy of Transwestern
63
Control Systems

• Building Automation System (BAS)
• Energy Management System (EMS)

64
Controlling HVAC Costs

• Optimize EMS
• Use free cooling
• Pay attention to weather
• Coasting
• Check temperatures with hand-held thermostat
• Control tenant adjustment abilities
• Aggressive water treatment
• Keep all components clean