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