Heating& Cooling (HVAC)3
Page 39
Sustainable HVAC
• Operating motors, fans and pumps efficiently
• Sustainable HVAC technologies
• Building system controls
Motors Pages 39-40
Motors
Inefficiency can result from:
•Dirty breakers
•Bad connections and terminations
Voltage drop of more than a tenth of a volt indicates connection needs repair.
Motors drive fans and pumps in HVAC systems.
Bad motor connection: defective crimp
Motors Pages 39-40
Motors Page 40
Premium® Energy Efficiency Motors
National Electrical Manufacturers Association (NEMA) Premium® Energy Efficient Motors program establishes standards for highly efficient motors.
Using Variable Frequency Drives for Greater Control 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
Variable Frequency Drive (VFD)
VFDs allow for greater control by adjusting the speed of the motor to match the load.
Using Variable Frequency Drives for Greater Control Page 40
Circuit Diagram of VFD
Using Variable Frequency Drives for Greater Control Page 41
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
Fans Pages 41-42
• Oversized fans waste energy
• Use VFD instead of fan dampers for more energy efficient control
Axial fan (more efficient) Centrifugal fan
Fans: Axial vs. Centrifugal
Pumps Pages 42-43
Pumps: Centrifugal vs. Positive Displacement
Centrifugal Pump
Positive Displacement Pump
• Domestic Water Supply
• Hydronic Heat Circulation Pumps
• Domestic Hot Water Circulation Pump
• Oil Burner Pumps and Oil Circulation Pumps
Component Replacement Plan Page 43
• 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
Roof mounted air-source heat pump
Moves heat from a heat source to a heat sink
(air conditioner)
Heat Pumps Pages 44-45
Heat Pumps
Heat Pump / Air Conditioner Cycle
Heat Pumps Pages 44-45
Horizontal closed loop GSHP
Heat Pumps Pages 45-46
• Air-source• Water-source • Ground-source (GSHP)
Types of Heat Pumps
HVAC Systems Page 46
• 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)
Upgrading HVAC Systems
Types of HVAC Systems Page 46
• 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
Selection of HVAC Systems
Electric Baseboard Heating
Electrical Work in Upgrading HVAC Systems Page 48
Electric resistance heating is cheap to install but…• Expensive to operate• Inefficient because electricity
is generated from fuel at
30-33% efficiency
Upgrading HVAC Systems
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
Building Control Systems Pages 48-50
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
Types of Building Management and Information Systems Pages 48-49
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
CASE STUDY: 31 Tannery Project, Branchburg, NJFirst Net-Zero Building in U.S.
31 Tannery Project Page 50
Building control data, automation, and control of energy systems are key to minimal fuel and electrical use in this net-zero energy building.
4 Renewable andDistributedEnergy
Page 51
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
Where is the Energy Generated?
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 farmsBasic Background: Energy Generation Page 52
POP QUIZ: GENERATION: Central or Distributed?
ENERGY SOURCE: Renewable or Nonrenewable?
Basic Background: Energy Generation Page 52
Imperial Valley Solar Project, CA Rooftop solar PV array
POP QUIZ:
Central Generation /Renewable Energy
GENERATION: Central or Distributed?
ENERGY SOURCE: Renewable or Nonrenewable?
Basic Background: Energy Generation Page 52
Imperial Valley Solar Project, CA Rooftop solar PV array
Distributed Generation /Renewable
Energy
POP QUIZ: GENERATION: Central or Distributed?
ENERGY SOURCE: Renewable or Nonrenewable?
Basic Background: Energy Generation Page 52
Coal-fired power plant, GA 70 kW microturbine - Cogen
POP QUIZ: GENERATION: Central or Distributed?
ENERGY SOURCE: Renewable or Nonrenewable?
Central Generation / Nonrenewable energy
Distributed Generation / Nonrenewable energy
Basic Background: Energy Generation Page 52
Coal-fired power plant, GA 70 kW microturbine - Cogen
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
• Net metering • Find incentives at the
Database of State Incentives for Renewables and Efficiency (dsireusa.org)
Utility Grid Page 53
Selling Energy Back to the Grid
A typical power plant can lose 67% of its fuel input to waste heat.
Cogeneration: Combined Heat and Power Page 54
Standard Energy Generation Wastes 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.
• 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
Domestic Hot Water Consumption
Sizing a Cogen Unit Pages 55-56
Sizing a Cogen Unit
Actual power base load is 100 kW
Existing thermal loads of the building would require only 16 kW unit
Adding hot water storage tanks increases thermal load to 27 kW
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
Economics of Cogen - Retrofit
Sizing a Cogen Unit Page 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
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 Page 59
Fuel Cells
• PV systems convert sunlight into electricity via photovoltaic effect
• PV effect occurs in semiconductor materials like silicon
• Practical efficiencies between 8% and 20%
Solar Photovoltaic Power Page 60
Solar Photovoltaic Power
Connections of PV Cells
Electrical Generation and PV Systems Page 61
Parallel•High current•Low voltage
Series•Low current•High voltage
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
PV Performance
Stand-alone PV system with battery storage.
PV Performance Page 62
Storing Solar Power
PV wiring with AC conversion for grid connection.
PV Performance Page 62
Storing Solar Power
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
Additional Components of PV Systems
DC to AC PV system string inverter
Outdoor connection requires:• Protection from corrosion• Sufficient slack to allow for
thermal expansion and contraction
• Allowance for the removal and replacement of modules
Inverters
Additional Components of PV Systems Pages 62-63
Roof mounted PV system
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
Types of PV Systems Page 63
Building-Mounted Systems
Types of PV Systems Pages 63-64
Large-Scale Systems
• 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
New PV Technologies are Reducing Costs
New PV Technology Page 64
Simple Payback Analysis
Analysis Categories CostPV 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
• 50 kW rooftop solar PV system
• National certification:
Solar Photovoltaic Power Page 65
PV Installer Certification
Underwriters Laboratory
• Regional Certification
• Manufacturer Certification
Wind farm near Tehachapi, CA
• Off-shore wind farms
• Mountain ranges
• Great Plains
Wind Power Pages 66-67
Wind Power: Utility-Scale
Effectiveness depends on wind speed and consistency.
Brooklyn Navy Yard, Brooklyn, NY
Concerns:
• Not cost-effective
• Less consistent
• Stresses to existing building
• Machine failure in densely populated environments
Wind Power Pages 66-67
Wind Power: Building-Mounted Systems
East River Turbine, RITE Project, New York, NY
Tidal Turbines
Harvest energy in the tides.
Tidal Turbines Page 68
Electric vehicle charging system, Syracuse, NY
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 Systems Pages 68-69
CLASSROOM EXERCISE #2
BASIC PV DESIGNA 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 DESIGN4. 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