3
Heating
& Cooling (HVAC)
Page 39
Sustainable HVAC
• Operating motors, fans
and pumps efficiently
• Sustainable HVAC
technologies
• Building system controls
Motors Pages 39-40
Motors
Motors drive fans and pumps in HVAC systems.
Inefficiency can result from:
• Dirty breakers
• Bad connections and
terminations
Voltage drop of more than a
tenth of a volt indicates
connection needs repair.
Bad motor connection:
defective crimp
Motors Pages 39-40
Premium® Energy Efficiency Motors
National Electrical
Manufacturers Association
(NEMA) Premium® Energy
Efficient Motors program
establishes standards for
highly efficient motors.
Motors Page 40
Replacement of Motors and Drives
• “Right-Size” Motors! (see MotorMaster guidelines)
• Undersized motors function poorly
• Oversized motors waste energy and money
• Use variable frequency drives (VFDs), or variable
speed drives (VSDs), to match speeds to loads
Using Variable Frequency Drives for Greater Control Page 40
Variable Frequency Drive (VFD)
VFDs allow for greater control by adjusting the speed of
the motor to match the load.
Circuit Diagram of VFD
Using Variable Frequency Drives for Greater Control Page 40
EXAMPLE: Use VFD to Control Fan Speed
Adjusting fan
speed with a VFD
instead of throttling
the output uses
much less power.
Using Variable Frequency Drives for Greater Control Page 41
Wiring a VFD
• Program can reset when
powered off – controller
programming may be lost!
• Always use VFD on/off
connections
• Don’t put an external switch on
a VFD unless the instructions
explicitly say you can.
Variable Frequency Drive Control
Using Variable Frequency Drives for Greater Control Page 41
Fans: Axial vs. Centrifugal
• Oversized fans waste energy
• Use VFD instead of fan dampers for more energy
efficient control
Axial fan (more efficient)
Centrifugal fan
Fans Pages 41-42
Pumps: Centrifugal vs. Positive Displacement
• Domestic Water Supply
• Hydronic Heat Circulation
Pumps
• Domestic Hot Water
Circulation Pump
Centrifugal Pump
• Oil Burner Pumps and Oil
Circulation Pumps
Positive Displacement
Pump
Pumps Pages 42-43
Component Replacement Plan
• Ensure right sized
equipment is ready when a
component falls apart
• Store spare parts
• Have the piping and
instrumentation diagrams
available
• Discuss plan with building
manager, plumber or HVAC
company
Replacement Parts List
Component Replacement Plan Page 43
Heat Pumps
Moves heat from a heat source to a heat sink
(air conditioner)
Roof mounted air-source heat pump
Heat Pumps Pages 44-45
Heat Pump / Air Conditioner Cycle
Heat Pumps Pages 44-45
Types of Heat Pumps
• Air-source
• Water-source
• Ground-source (GSHP)
Horizontal closed loop GSHP
Heat Pumps Pages 45-46
Upgrading HVAC Systems
• HVAC systems are among the largest users of
energy in buildings
• Buildings often outlive their HVAC systems
• Retrofitting heating and cooling systems can offer
great opportunities for energy savings (and jobs)
HVAC Systems Page 46
Selection of HVAC Systems
• Water carries heat more effectively than air
• In most green HVAC systems, air is only used
for ventilation; all heating and cooling is
carried in circulating water
• Air-and-water systems are more energy
efficient than air-only systems
• Often air-only systems are controlled by
dampers - it’s more efficient to use a VFD
Types of HVAC Systems Page 46
Upgrading HVAC Systems
Electric resistance heating is cheap to install but…
• Expensive to operate
• Inefficient because electricity
is generated from fuel at
30-33% efficiency
Electric Baseboard Heating
Electrical Work in Upgrading HVAC Systems Page 48
Electrical Work in HVAC Retrofits
• Permanent labels on wiring to
simplify troubleshooting in the
future
• Do not strain wire insulation
• Opportunity to correct
mistakes from original
construction
Electrical Work in Upgrading HVAC Systems Page 48
Building Control Systems
Building control systems monitor and control the MEP
systems in a building.
The most common are building management systems (BMS).
Control systems
Temperature sensors
Building Control Systems Pages 48-50
Building Management System (BMS)
A BMS reduces energy use by:
• Scheduling equipment and
operations to meet demand
• Controlling temperature,
pressure, and humidity in the
building, taking weather
conditions into account
• Controlling fans and pumps to
optimize HVAC
• Providing data for analysis
Types of Building Management and Information Systems Pages 48-49
CASE STUDY:
31 Tannery Project, Branchburg, NJ
First Net-Zero Building in U.S.
Building control data,
automation, and control
of energy systems are
key to minimal fuel and
electrical use in this netzero energy building.
31 Tannery Project Page 50
4
Renewable and
Distributed
Energy
Page 51
Where is the Energy Generated?
Central vs. Distributed Energy Generation:
• Central Generation: Power is generated at one
central location and transmitted long distances
across a grid to consumers
• Distributed Generation: Occurs close to a load:
• Lower transmission losses
• Lower stress on grid by reducing peak load
Basic Background: Energy Generation Pages 51-52
What is the Energy Source?
Nonrenewable vs. Renewable Energy Generation:
Renewable sources will not be depleted over time.
• Very little CO2 emissions
• Decreased pollution
• Reduced reliance on fossil fuels
• Site energy almost equal to source energy
• Examples:
• Solar thermal
• Wind farms
Basic Background: Energy Generation Page 52
POP QUIZ:
GENERATION:
Central or Distributed?
ENERGY SOURCE:
Renewable or Nonrenewable?
Imperial Valley Solar Project, CA
Rooftop solar PV array
Basic Background: Energy Generation Page 52
POP QUIZ:
GENERATION:
Central or Distributed?
ENERGY SOURCE:
Renewable or Nonrenewable?
Imperial Valley Solar Project, CA
Central Generation
/Renewable Energy
Rooftop solar PV array
Distributed Generation
/Renewable Energy
Basic Background: Energy Generation Page 52
POP QUIZ:
GENERATION:
Central or Distributed?
ENERGY SOURCE:
Renewable or Nonrenewable?
Coal-fired power plant, GA
70 kW microturbine - Cogen
Basic Background: Energy Generation Page 52
POP QUIZ:
GENERATION:
Central or Distributed?
ENERGY SOURCE:
Renewable or Nonrenewable?
Coal-fired power plant, GA
Central Generation /
Nonrenewable energy
70 kW microturbine - Cogen
Distributed Generation /
Nonrenewable energy
Basic Background: Energy Generation Page 52
Radial and Networked Systems
• Radial: Power lines branch out
• Networked: Power lines interconnected
Utility Grid Pages 52-53
Secure Disconnects
A secure disconnect on
a distributed generator
protects utility workers
attempting to restore
power.
Utility Grid Page 53
Selling Energy Back to the Grid
• Net metering
• Find incentives at the
Database of State
Incentives for
Renewables and
Efficiency (dsireusa.org)
Utility Grid Page 53
Standard Energy Generation Wastes Heat
A typical power plant
can lose 67% of its
fuel input to waste
heat.
Cogeneration: Combined Heat and Power Page 54
Cogeneration: Combined Heat & Power (CHP)
Cogen captures and uses “waste” heat.
A CHP
system uses
waste heat
usually lost
to the
environment.
Cogeneration: Combined Heat and Power Page 54
Sizing a Cogen Unit
•
•
•
•
Must be sized to load.
Don't make energy you can't use!
A cogen system needs to run at full
capacity all the time to be cost-effective.
Design it to meet the electric or thermal
base load, whichever is SMALLER.
Cogeneration: Combined Heat and Power Pages 54-55
Sizing a Cogen Unit
Average Electrical
Demand
Actual power
base load is 100 kW
Domestic Hot
Water Consumption
Existing thermal loads of the building
would require only 16 kW unit
Adding hot water storage tanks
increases thermal load to 27 kW
Sizing a Cogen Unit Pages 55-56
Economics of Cogen - Retrofit
Possible deal breakers if the following requirements
are not met:
• The location must allow adequate clearance for
maintenance.
• The location must also be close to gas, electricity, and
waste heat connections.
• There must be adequate natural gas capacity or a
relatively inexpensive way to provide a new gas line.
• There must be an allowance for combustion products to
discharge.
• See cost considerations on page 55 of the manual.
Sizing a Cogen Unit Pages 55-56
Can Cogen be Used as a Backup Generator?
Induction – NO!
•Majority of cogen systems
•Requires voltage from utility to operate
•If utility down, cogen is down
Synchronous – YES!
•Does not require voltage from utility
•Many code restrictions
Sizing a Cogen Unit Page 56
Types of Cogeneration Systems
• Reciprocating Engine: Most common type of cogen
• Microturbine: Smaller-scale, fewer moving parts but
new to market
• Large-Scale Cogen: Gas turbines (industrial
applications only)
• Engine-Driven Chillers: Reciprocating engine
drives standard cooling compressor
• Trigeneration: Produces electricity, heat in winter
and cooling in summer
Cogeneration: Combined Heat and Power Pages 57-58
Fuel Cells
Fuel Cells Page 59
Solar Photovoltaic Power
LI
GH
T
PH A
S
OT
O
NS
SU
N
GRID TO
COLLECT
CURRENT
JUNCTION
P-TYPE
SILICON ( +)
LI
GH
PH A T
OT S
O
NS
N-TYPE
SILICON ( –)
SU
N
• Practical efficiencies
between 8% and 20%
SUN
POSITIVE CURRENT
• PV effect occurs in
semiconductor
materials like silicon
POSITIVE CURRENT
• PV systems convert
sunlight into electricity
via photovoltaic effect
LOA D
–
– ––
–– –– –
––
–
–
–
+ ++
+ ++ + + +
++
+ +
+
HOLE FLOW
ELECTRON FLOW
Solar Photovoltaic Power Page 60
Connections of PV Cells
Parallel
• High current
• Low voltage
Series
• Low current
• High voltage
Electrical Generation and PV Systems Page 61
PV Performance
I-V Curves for a PV module at different levels of insolation.
Power output is zero when V = 0 or I = 0,
maximum on the shoulder of the curve.
Solar Photovoltaic Power Pages 61-62
Storing Solar Power
Stand-alone PV
system with
battery storage.
PV ARRAY
+
FUSE/ CIRCUIT BREAKER
OR DISCONNECT
CHARGE
CONTROLLER
+
CLASS T
FUSE
D.C. OUTPUT
-
+
BATTERY(S)
PV Performance Page 62
Storing Solar Power
PV wiring with AC conversion for grid connection.
DC
AC
PV ARRAY
BUILDING
LOADS
PV
POWER
OPTIMIZER
GROUND
FAULT
PROTECTOR
CIRCUIT
BREAKER
INVERTER
CIRCUIT
BREAKER
UTILITY
SWITCH
MAIN
SERVICE
PANEL
WITH METER
ELECTRIC
UTILITY
PV Performance Page 62
Additional Components of PV Systems
DC to AC Conversion:
• PV cells provide DC power
• Building systems are AC
• Inverter converts DC power to AC power
Solar Photovoltaic Power Pages 62-63
Inverters
Outdoor connection requires:
• Protection from corrosion
• Sufficient slack to allow for
thermal expansion and
contraction
• Allowance for the removal
and replacement of modules
DC to AC PV system string inverter
Additional Components of PV Systems Pages 62-63
Building-Mounted Systems
Maximize on-building systems:
• Orientation: Perpendicular to
the sun, facing south at an angle
to the horizontal, slightly
shallower than the angle of
latitude
• Shading: Avoid shading!
Reduces output of whole cell
string
• Placement: Avoid
overshadowing
Roof mounted PV system
Types of PV Systems Page 63
Large-Scale Systems
Types of PV Systems Pages 63-64
New PV Technologies are Reducing Costs
• Amorphous thin film technologies have lower efficiency but
may provide lower overall cost
• HIT PV cell development may also lead to lower PV cost
Solar Photovoltaic Power Page 64
Simple Payback Analysis
• 50 kW rooftop solar PV system
Analysis Categories
Cost
PV panel cost with installation
$300,000
Federal tax credit (one-time)
- $90,000
State energy program incentive
- $95,000
Net invested capital
= $115,000
Anticipated operated savings/year
+ $15,000
Payback period
$115,000 / $15,000 =
8 YEARS
New PV Technology Page 64
PV Installer Certification
• National certification:
Underwriters Laboratory
• Regional Certification
• Manufacturer Certification
Solar Photovoltaic Power Page 65
Wind Power: Utility-Scale
Effectiveness depends on wind speed and consistency.
• Off-shore wind farms
• Mountain ranges
• Great Plains
Wind farm near Tehachapi, CA
Wind Power Pages 66-67
Wind Power: Building-Mounted Systems
Concerns:
• Not cost-effective
• Less consistent
• Stresses to existing
building
• Machine failure in densely
populated environments
Brooklyn Navy Yard, Brooklyn, NY
Wind Power Pages 66-67
Tidal Turbines
Harvest energy in the tides.
East River Turbine, RITE Project, New York, NY
Tidal Turbines Page 68
Electric Vehicle Charging Systems
Electric vehicles are
cleaner to run than
internal combustion
vehicles.
As they become more
common, electricians will
find more opportunities in
EVSE (Electric Vehicle
Service Equipment).
Electric vehicle charging system, Syracuse, NY
Electric Vehicle Charging Systems Pages 68-69
CLASSROOM EXERCISE #2
BASIC PV DESIGN
A homeowner is considering installing PV panels on an
existing roof. See details on page 70.
1. What size array can be installed? How many panels can be
included and what is the total area?
2. If the peak power available at this roof angle is 93 W/sf,
what is the peak output of the array?
3. What is the total installation cost? The cost after incentives?
Pages 70-71
CLASSROOM EXERCISE #2
BASIC PV DESIGN
4. Using the map on the page 71, how much energy do the PV
panels produce in a year?
5. How much is saved in energy costs per year?
6. How long is the payback period? (See Figure 4.20 in manual
for Simple Payback Analysis)
7. Give two or three reasons for converting electricity from the
PV panels to AC, rather than leaving it as DC and storing the
energy in batteries for back-up during power outages.
(Compare to using a fuel powered generator during the
outage.)
Pages 70-71