foundations of real estate management boma international ® module 3: building operations i heating,...

Foundations of Real Estate Management

BOMA International®

Module 3: Building Operations I

Heating, Ventilating, and Cooling the Building

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Foundations of Real Estate ManagementModule 3: Building Operations I 2

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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


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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


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HVAC

Heating

Ventilating

Air Conditioning


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Ventilation

Provides outside air

Removes stale air

Filters


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Ventilation

Outside Air DamperPhoto courtesy of PM 101


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Ventilation

Variable Frequency DrivePhoto courtesy of Transwestern


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Ventilation

It’s a continuum

No outside air 100% outside air

Maximum energy efficiency Minimum energy efficiency

Minimum IAQ Maximum IAQ


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Ventilation

Free cooling

Using outside air to condition the space


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Ventilation

Exhaust

Removing odors and carbon dioxide


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Ventilation

Separate exhaust for kitchens and

restrooms


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Ventilation

Ensure restaurant tenants clean their exhaust system regularly


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Ventilation

Plenum Return

Ducted Return


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Ventilation

Partition Walls

Demising Walls

Fire Dampers

Protection


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Ventilation

Photos courtesy of Transwestern


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Humidity

ASHRAE recommends 50% relative humidity

(range of 30-60%)

Dehumidification

Humidification (rare)


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Pressure

The Goal:

Pressure In = Pressure Out


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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


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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


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Filtration

Filters remove dust, debris, insects, and other contaminants

Pleated filters v. fiberglass filters

HEPA filters

Charcoal filters for odors

Changed routinely


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Air Distribution

Air Handler

Trunk Line

Branch Line

VAV Boxes/Terminal Units

Supply Air Diffusers


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Air Distribution - Zoning

Areas of the building operate differently from one another

Zones determined by:

Function/Use

Location


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Air Distribution

Air Handling Unit (AHU) or Air Handler


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Air Distribution

VAV Box – controlled by a thermostat


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Air Distribution

Supply Air Diffuser


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Air Distribution

Trunk and Branch Ducts

VAV Boxes and Supply Air Diffusers


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Thermostat Types

Pneumatic

Direct Digital Control (DDC)

Set point temperature

Impossible to please everyone

Location


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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


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Thermal Layering

Temperature is measured in the middle 1/3 (On top of the desk)

Bottom 1/3 is coolest (space heaters)

Heat Rises – Top 1/3 is warmest


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Space Heaters


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Heating

Involves adding heat


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Heating

Fuel Sources

Electricity

Natural Gas

Heating Oil


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Heating

Systems

Central

Local


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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


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Heating

Baseboard heating

Electric

Hot water or steam

Under floor or sidewalk (radiant)

Interlock


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Cooling

Involves removing heat


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Cooling

Just 3 Loops

Refrigerant Loop

Chilled Water Loop

Condenser Water Loop

The loops do not mix!


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Cooling

The Refrigeration Loop/Cycle

Refrigerant

Compressor

Condenser

Expansion Valve


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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


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Cooling

Compressor

Applies pressure

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


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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


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Cooling

Expansion Valve

Sprays liquid into a fine mist

Reduces pressure and cools refrigerant


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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…


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Cooling

The refrigeration cycle is nothing more than changing the refrigerant from a liquid to a gas and back to

a liquid…over and over again

It’s a closed loop system


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Cooling

The Refrigeration Cycle


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Cooling

Heat always moves from

higher to lower

temperature


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Coils and Bundles

Coils

Transfer heat between air and refrigerant

Bundles

Transfer heat between liquid and refrigerant


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Coils and Bundles

Photo courtesy of PM 101

Coils


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Coils and Bundles

Shell and Tube Bundles


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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


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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


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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


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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


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Cooling

Condenser Loop (air-cooled)

Air is blown over refrigerant loop to reject heat


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Cooling

Water- or Air-Cooled Systems Chillers

Self-Contained Units (SCUs)

Air-Cooled Systems Rooftop Units (RTUs)

Split System

Heat Pump


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Cooling

ChillerPhoto courtesy of PM 101


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Cooling

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


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Cooling

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


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Cooling

Split SystemPhoto courtesy of Thomas J. Easley


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Cooling

Heat Pump


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Piped Systems

Types

2 Pipe

4 Pipe

Fan coil units


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Free Cooling

Rejecting heat without using the compressor

Flat plate heat exchanger

Photo courtesy of Transwestern


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Control Systems

Building Automation System (BAS)

Energy Management System (EMS)


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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

foundations of real estate management boma international ® module 3: building operations i heating,...

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