building systems and performance: an introduction to ... · procurement (purchase plan) •...

Building Systems and Performance: an Introduction to Building Operator

Certification –Lesson 15:

Energy Rate Structures and

Data Interpretation

CUNY Institute for Urban Systems Building Performance Lab

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Agenda for Lesson 15• Topic 1: Energy Rate Structures

& Cost Reduction• Topic 2: Demand Response,

Deregulated Markets & Trending Data

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Topic 1: Energy Rate Structures & Cost Reduction

• Consumption and Demand Charges• Base Charges• Fuel Adjustment Charges• Demand-Response Programs

4Energy = $• Utility Rate Structures

• Regulated by the NYS Public Service Commission (PSC), set for each utility service area:

Charge(s) for power are regulated, with rates and changes approved by the Board of Public Utilities (BPU) subject to public comment

• Elements: Consumption and demand are treated separately • Base charge• Consumption (KWH)

• �Declining Block Rate�• Demand (KW) • Power Factor• Fuel Adjustment

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• Energy Consumption vs. Demand Charge• Your building doesn’t consume energy at the same rate all the time. Most facilities

have a greater need for power during the day when lights, AC, computers all operate simultaneously. At other times (weekends or early mornings, etc.) you may be operating some lights and a couple of computers.

• Energy as consumed is measured in kilowatt-hours (kWh)

• When all the equipment is running your facility has a higher rate (volume) of consumption, leading to higher demand. The utility must deliver the volume of energy you require at any time: that volume must provided at any time by any and all customers.

• If demand is large enough, new power plants and larger infrastructure are needed to deliver the power. Demand charges motivate you to manage and reduce your facility’s power consumption.

• The Demand Charge is measured in kilowatts (kW), based on the peak demand: the greatest volume used over any continuous 15 minute in a month. Demand (kW) determines the required size of the wires and transformers needed for your facility. Demand can be up to 40% of billings, at any time of day- not the same as “system peak”-see ‘Demand Response’.

Utility Rate StructuresEnergy = $

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• Electricity Consumption KWH • Declining Block Rate Structure $/kwh

• The more electricity you use, the less it costs -�first 10,000 kwh at $0.10 per kwh�; �next 140,000 kwh at $0.08

per kwh�-�over 150,000 kwh at $0.065 per kwh�

• Average Cost of 250,000 kwh =[(10,000)(.1) + (140,000)(.08) + (100,000)(.06)] / 250,000= [ 1,000 + 11,200 + 6,500 ] / 250,000 = $0.075 per kwh

What you use or save on the margin does not equal the average

Utility Rate StructuresEnergy = $

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• Time-of-Use Rates • Goal of ‘time-of-use’ rates is to shift loads off of system-

wide peaks • Utility offers significantly lower prices for off-peak

electricity• Data captured in time blocks by digital meters• Save $$ (but not energy)• Strategies & Technologies

• Thermal Storage• Change in behavior – do things off peak (at night,

etc.)

Energy = $Utility Rate Structures

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• Power Factor: real/apparent power, KW/KVA • Result of induction loads (coils and windings)• Affects power capacity of a given service • Low PF is corrected by using capacitors• Charges for low PF in some places, not in use by Con Ed (YET)

• Fuel Adjustment • Under certain circumstances, the utility is allowed by

the regulator to pass-along the cost of fuel price increases

Energy = $Utility Rate Structures

9Energy Cost Reduction StrategiesStrategy How it works When to use ?

CHP- Combined Heat & Power

Real-Time monitoring

Thermal Storage

Load Shedding

De-reg market

Greening

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Examples of Energy Strategies

• CHP (Combined Heat & Power) to control demand; and produce their own power when utility rates are high.

• Waste steam from the generation of electricity is used to heat buildings.

• Energy procurement tracks utility rates in real-time to determine when utility rates are high. (Time-of-Use rates)

• Limit Peak Demand with off-peak generation of cooling, done with Thermal Storage of cold water to level demand when our energy needs are high. This is Load-shedding because cooling capacity needed during the day is created at night.

(CASE STUDY: Princeton University)

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Gas Turbine

Power Turbine

Gearbox Electric Generator

Hot exhaust Gas

CO Catalyst

AC Electricity

Steam

Air

Feed Water

Heat Recovery Boiler

Exhaust Gas

Fuel &Water

Combined Cycle �Cogen� to control Demand, Time-of-Use charges

What system do they use, how much electricity do they make, how much heat do they need, what if they need extra heat?

The cogeneration plant contains one European Gas Turbines package 15MW General Electric LM-1600 gas turbine operating at a heat rate of 9,750 Btu/kWh: 52,000 pounds of steam is generated with the turbine exhaust in a Heat

Recovery Steam Generator (HRSG). With auxiliary firing, the HRSG can produce 182,000 lb/hr of steam. Augmenting the HRSG are two Indeck/IBW/Volcano 150,000 lb/hr boilers.

The units burn #2 oil or natural gas. Peak summer steam production is approx. 180,000 lb/hr. Winter demand can reach 244,000 lb/hr.

Non-operating boilers are kept warm and pressurized using main steam in lower drum heaters (another energy saving strategy so boiler water is warm but the boiler is not running and cycling)

Energy StrategiesCHP – Combined Heat & Power

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Buildings Heated by CHP Plant

Energy StrategiesCHP – Combined Heat & Power

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Thermal Storage Tank Stratification (at Princeton)

Energy StrategiesLoad-Shedding using Thermal storage to control Peak Demand & Time-of-Use

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Procurement (purchase plan)• Electric – market based

• We operate our equipment based on the market price

• Grid price changes constantly

• Saves $2 to $3.5M per year

• Gas – Transparent pricing system for daily gas• We pre-purchase our gas

and cut out the middle-man• Saved $50K in gas costs in

November• New legislation has approved

the Pre-purchase of gas

Regulatory (new utility rules)• New electric wheeling bill passed in Trenton

– Annual savings around $200K.

Energy StrategiesReal-time monitoring of electric rates to determine Time-of-Use cost

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Electric price rises & turbine output goes up

Princeton buys lots of grid power when it is cheap and make its own power when grid power is expensive

Energy StrategiesTime-of-use & demand are controlled by turbine use

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Topic 2: Demand Response, Deregulated Markets & Trending Data

• Managing Electrical Demand• Deregulated Markets• Interpreting Data Trends/Diagnostics• Occupancy Scheduling & Short-

Cycling

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Managing Electric Demand

• What causes high electric demand?• Large but steady load (pretty flat load profile)• Short-duration peaks of 30 minutes or longer• 30 minutes will register with the utility for demand• Different strategies for each type of demand • Identify unnecessary simultaneous operation of

equipment

• BUT NOT SIMULTANEOUS MOTOR STARTING -starting spike is in mili-seconds, too short to register in the demand.

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Managing Electric Demand

• What causes high electric demand?• What kinds of equipment

• Lighting• Refrigeration• Motors (fans, pumps, burners) • Air Conditioning

• Improved efficiency of equipment will reduce demand: you can implement “load-shedding” to reduce demand

(turn off certain equipment on a prioritized basis)

19Managing Electric Demand• When do we most often see high electric demand? • May - June - (July - August - ) September • What actions can you take with your motors?

• Control equipment – Avoid running large motors simultaneously:

• Burners for hot water – avoid firing during peak AC use • Ventilation fans – cycle off during peak AC use

• Duty-cycling - On and Off cycling of equipment to meet loadsMorning “pull down” “cool down”

• Pre-cool using pre-occupancy operation of ventilation fans

20Managing Electric Demand• Limiting Demand vs “Demand-Response Program”• What is it?

• Short duration CURTAILMENT (1-4 hrs.) by bldg. operator• Utility requests load reductions at times of severe system

peak; usually no more than 3 - 4 days per year, hottest days

• Can be Voluntary or Contract-Commitment How? Notification by utility (in advance), either;-Load-shedding by staff, IMPLEMENT A PRIORITIZED LOAD

SHED-Remote (by utility)-Back-up generators (sched. times)

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• The De-Regulated Market (electricity and gas)• Transmission & Distribution (�wires�or gas

transportation pipeline) still regulated • Commodity (�electrons� or gas) de-

regulated

The De-Regulated MarketWhy the Energy Sector has the structure it does

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• Buying Energy (electricity and gas)• �Commodity� can be purchased through

Energy Service Companies ESCOs, or from the Utility (Con Ed)

• Fixed Price vs Monthly-variable• ESCO usually offers a fixed price

• Fixed Price includes projected demand, in price-per-kwh (no separate billing of demand)

The De-Regulated Market

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• More on ESCO’s• Energy service companies more than help you

negotiate energy pricing.• ESCO’s can help you build and fund projects

• An ESCO will install an ECM and guarantee its performance: the guarantee can help you obtain funding.

• The contract with the ESCO can stretch over 20 years, which can make contracts with longer payback more attractive.

• Contracts with a performance guarantee give the installer incentive to do a good job and not over exaggerate savings.


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Greening by Certificate • All electrons are same color • Separate market for �green production

attribute�• Wind farm sells its electricity into the grid at bid-

prices just like any other generator- wind farm gets added payment for what it produces, �the green attribute�

• Certification process for how much electricity is produced and where it goes

• When you enter into a contract for �Green Power�, you are purchasing the certified attribute for that amount of power.


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Feedback: Monitoring Energy Project Performance

• Create a baseline from historical use data• characterize the relationship between

energy use and an independent variable (weather, production)

• Use the baseline characterization to calculate what would have happened under original operating conditions

How We Use Energy Data - Trends

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Economizer Operation: Example use of Graphs – 1 Day

Outdoor/Return/Mixed/Discharge vs. Time

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10

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60

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3/12/077:12 PM

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3/13/074:48 AM

3/13/079:36 AM

3/13/072:24 PM

3/13/077:12 PM

3/14/0712:00 AM

3/14/074:48 AM

Time

Tem

pera

ture

(oF)

Outdoor Retrun Mixed Discharge

Return

Discharge

Outdoor

Mixed

Trends for Data Driven Diagnostics

Source: PNNL Building Re-tuning Program

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Economizer Operation : Example use of Graphs – 1 Day • Outdoor-Air Damper Stuck Fully Open• Example of Bad Operation


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3/12/077:12 PM

3/13/0712:00 AM

3/13/074:48 AM

3/13/079:36 AM

3/13/072:24 PM

3/13/077:12 PM

3/14/0712:00 AM

3/14/074:48 AM

Time

Tem

pera

ture

(oF)

Outdoor Return Mixed Discharge

Return

Discharge

Outdoor

Mixed



Heating waste

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Economizer Operation: Example use of Graphs – 1 Day• Outdoor-Air Damper Stuck Fully Closed• Example of Bad Operation


0

10

20

30

40

50

60

70

80

3/12/077:12 PM

3/13/0712:00 AM

3/13/074:48 AM

3/13/079:36 AM

3/13/072:24 PM

3/13/077:12 PM

3/14/0712:00 AM

3/14/074:48 AM

Time

Tem

pera

ture

(oF)

Outdoor Return Mixed Discharge

Return

Mixed

Discharge

Outdoor


Outdoor air temperature is perfect for economizer


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Occupancy Scheduling

Equipment Use should match Occupancy

• Match operations of equipment & systems to actual need• Turn off, or turn down, equipment & systems during

unoccupied hours. • AHU’s & Lighting are a major energy users• Graphs can be simple – Use vs Time

31Occupancy Scheduling - AHU Static Pressure Control


• Continuously Operation, 24 hours a day, 7 days a week• Operating Hours are 6am – 6pm, Mon-Fri

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• Equipment with Night and Weekend Setback• Easy to see the energy savings

Occupancy Scheduling - AHU Static Pressure Control

33Occupancy Scheduling - AHU Static Pressure

Control

34Occupancy Scheduling – Electric Load Profile


• 1 Day / 24 Hours of Energy Meter Data - Electric Load Profile• How does our Energy Use match our Occupancy Schedule

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• Occupancy 6am –6pm

• Baseload is high• Weekend load

Increases • Shutdown period long

Occupancy Scheduling – Electric Load Profile

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Source: PNNL Building Re-tuning Training

• Baseload reduced / Peak load reduced

• Weekend load flat

• Shutdown period matches occupancy

Occupancy Scheduling – Electric Load Profile

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Equipment Short-Cycling


Identify & Correct – Compressor cycling – short cycling

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Equipment Short-Cycling


Identify & Correct – Compressor cycling – correct

39Equipment Short-Cycling

• Chiller – Cycling On during Unoccupied hours• Chiller Operation, 24-hour Period

Source: Virtjoule.com company blog, 10/13/11

12am 5am

10am 3p

m

8pm

12am

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Class Review and Reading Assignment• Energy Rate Structures• Cost Reduction Strategies: Case Study• Demand Response and De-regulated Markets • Trending Energy Data• Occupancy Scheduling• Equipment Short-Cycling

• Reading Assignment for Class 16: • Herzog Chap. 3

building systems and performance: an introduction to ... · procurement (purchase plan) •...

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