Building Systems and Performance: an Introduction to Building Operator

Certification –Lesson 13:

Weather Normalization and

Interpretation

CUNY Institute for Urban Systems Building Performance Lab

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Topic 1: Weather Normalization & Load Profiles• Understanding energy accounting, data sources and data

visualization• Normalizing building energy performance for weather and

climate• Interpreting spreadsheets and graphics of energy data

Topic 2: Load Profiles & End Use

Agenda for Lesson 13

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Energy AccountingThe cornerstone of good energy efficiency practices, energy accounting is a method for tracking energy usage and applying the information gained to control and manage energy usage and resulting costs.

It involves collecting and recording a facility’s fuel and electrical consumption over various periods to build standardized indices of consumption.

Further data analysis allows the operator to identify relationships between energy use and other variables

By setting seasonal patterns, energy use in a given month not fitting the pattern signals that change in either building activity or energy efficiency has occurred.

Potential problems (equipment failures, inefficiencies, etc.) can then be pinpointed and remedied.

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Energy Accounting

Reasons for Energy Accounting• Track & account for utility costs• Benchmarking performance• Identify savings potential• Justify capital expenditures• See results of conservation• Gaining management support• Detect increased consumption• Identify billing errors

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Energy Accounting Steps1. Determine energy supply2. Collect and organize building utility and physical data3. Calculate initial building performance indicators4. Analyze and account for energy consumption trends

Organize Utility & Building Data- Data Organization

• By building• By meters or sub-meters• By fuel type

- Accounting Methods• Manual accounting• Data tracking spreadsheets• Energy Accounting software

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Collecting and Assembling Data

Common Inputs • Fuel consumption (in kWh, therms, gallons)• Electric demand, kW• Costs, $• All sources converted to BTUs if needed• Totals

As we saw in our energy data class when we collect data the best place to organize it is with a spreadsheet, entering the data oto a spreadsheet to help us see and work with the data.

Depending on the story we want to tell we can use the spreadsheet to manipulate the data.

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Collecting and Assembling DataBuilding Areas • Calculating square footage

• Gross vs. net in company data• Tenant spaces with sub-meters

• Densities – why measure?• Occupants• Computers, plug-in loads

• Other data attributes• Construction types, +/-• Weather info• Changes in building floorplan or usage

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Visualizing Energy DataGraphing, Plotting, and Trending

EnergyUse

Time

There are a few tools we can use to help us get an easy understanding of the story hidden in the data.

Graphs and charts tell the story graphically

An Energy Use Index (EUI), helps you make comparisons. They use common units that that talk about over all energy use. We are familiar with MPG for cars, for buildings we use BTU/ft2/year.

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Visualizing Energy DataCharts & Graphs of energy use data

• can be generated directly from a spreadsheet

6200

6400

6600

6800

7000

7200

7400

7600

7800

8000

Dollars

Jan Feb Mar Apr

First Quarter Electricity Costs

Energy kWh - 58%

Power factor - 8%Demand kW - 34%

First Quarter Cost Breakdown

Bar ChartPie Chart

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Visualizing Energy Data: Time-Series – Annual Load Profiles

0

10

20

30

40

50

60

70

80

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

kWh

(Tho

usan

ds)

Electricity Consumption

This bar chart and

line graph both

have similar

profiles.

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JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC2000 61,287 48,672 45,146 36,834 26,569 27,507 27,040 26,343 29,271 39,324 40,586 80,039 2001 65,061 55,168 52,281 40,158 35,580 29,225 28,546 30,556 26,189 36,642 50,047 74,104 2002 64,373 62,378 60,180 42,761 33,156 29,631 26,426 32,245 25,921 35,593 48,609 63,817

Baseline 63,574 55,406 52,536 39,918 31,768 28,788 27,337 29,715 27,127 37,186 46,414 72,653

-

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Energ

y Usa

ge (K

WH)

2000 2001 2002 Baseline

3 year Monthly Energy Usage vs Average

Visualizing Energy Data Multi-year usage

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Year-to-Year TrackingData Visualization

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Visualizing Energy Data: Time-series and Historical Events

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Weather-normalization is key to modeling the adjusted baseline

Visualizing Energy Data: Time-series & Concept of a Baseline

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Utilize Weather Normalization

• Recall the use of one period’s weather compared to another (prior class)• Use Degree-days and adjust usage • Adjust usage for number of degree-days • Only some loads are dependent on weather

(heating and cooling)

Let’s look at the Class Exercise (handout)Data Interpretation

16Fuel-Use Profile & End Use Winter Peak vs. Summer SeasonWeather Sensitive vs. Base Load

ENERGY USE RECORDOil, gal $-Oil Gas,therms $-Gas fuel $ KWH KW $-Electricity Total $

Jan 5000 4500 800 560 5060 35000 50 3475 8535Feb 3000 2700 2000 1400 4100 30000 47 3020 7120March 1500 1350 3000 2100 3450 28000 46 2840 6290April 0 0 2000 1400 1400 37000 58 3725 5125May 0 0 1870 1309 1309 42000 64 4210 5519June 0 0 2150 1505 1505 46000 69 5290 6795July 0 0 2000 1400 1400 50000 74 5730 7130Aug 0 0 1780 1246 1246 54000 74 6070 7316Sept 0 0 2100 1470 1470 48000 68 5440 6910Oct 0 0 3500 2450 2450 35000 58 3555 6005Nov 0 0 4300 3010 3010 30000 48 3030 6040Dec 5000 4500 1200 840 5340 32000 46 3180 8520

Totals 14500 13050 26700 18690 31740 467000 49565 81305

0

1000

2000

3000

4000

5000

6000

1 2 3 4 5 6 7 8 9 10 11 12

PEAK-A

FUEL BASE USE - HOT WATER

PEAK - B

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- A Stacked Bar Chart

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ENERGY USE RECORDOil, gal $-Oil Gas,therms $-Gas fuel $ KWH KW $-Electricity Total $

Jan 5000 4500 800 560 5060 35000 50 3475 8535Feb 3000 2700 2000 1400 4100 30000 47 3020 7120March 1500 1350 3000 2100 3450 28000 46 2840 6290April 0 0 2000 1400 1400 37000 58 3725 5125May 0 0 1870 1309 1309 42000 64 4210 5519June 0 0 2150 1505 1505 46000 69 5290 6795July 0 0 2000 1400 1400 50000 74 5730 7130Aug 0 0 1780 1246 1246 54000 74 6070 7316Sept 0 0 2100 1470 1470 48000 68 5440 6910Oct 0 0 3500 2450 2450 35000 58 3555 6005Nov 0 0 4300 3010 3010 30000 48 3030 6040Dec 5000 4500 1200 840 5340 32000 46 3180 8520

Totals 14500 13050 26700 18690 31740 467000 49565 81305

kWatt-hours /month

Visualizing Energy DataWeather-dependence & End-use allocation

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Building Data AnalysisEnd-use Profiles

End-Use Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec TotalsHeat 20005 12911 11410 5383 1907 198 188 131 208 3524 18095 27273 101,233 Lights 4195 3490 3170 2559 2766 2558 2369 2985 3030 3421 3708 4430 38,681 Receptacles + Computers 3808 3291 3170 2764 3040 2742 2589 2744 2533 2941 2970 2871 35,463 Fans 4779 4441 4462 3845 4895 5393 4894 5184 4415 4607 5573 5998 58,486 DHW 575 484 459 460 499 462 340 379 402 372 400 404 5,236 Compressor 0 0 0 240 480 1680 1680 3000 1720 80 0 0 8,880 Kitchen + Exercise 8229 6916 6692 5042 5207 4104 4004 4203 3937 4635 7880 10129 70,978

Totals 41591 31533 29363 20293 18794 17137 16064 18626 16245 19580 38626 51105 318,957

2000 Annual Consumption

2000 Energy End-Use Breakdown

32%

12%11%

18%

2%

3%

22%

HeatLights Receptacles + ComputersFans DHWCompressorKitchen + Exercise

Goal: Understand how energy is used by building systems

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Visualizing Energy Use :Daily Load Profiles

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Visualizing Energy Use:Daily Load Profile with End-uses

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Load Profile – Actual vs. Required Energy Usage

Consumption: Actual Energy Use

Using Data to Set Goals for Energy Use

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Load Profile – Actual vs. Required Energy Usage

Consumption: Required Energy UseHow much we need vs how much we use.

Using Data to Set Goals for Energy Use

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Building Data Analysis

• Heating System• distribution system• control conditions• hours of operation• envelope

• Ventilation• amount of outside air• night & warm-up operation• exhaust system interaction

• Cooling• distribution system• control conditions• economizer cycles

• Lighting• operation time• lamp efficiency• light levels

• Service Hot Water• temperatures• distribution system

• Pumps & Motors• sizing• energy efficiency• maintenance

Goal: Understand how energy is used by building systems to suggest areas of attention for adjustment

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Characterizing Loads within the Load Profile

• Calculation method• Nameplate data,

quantities, presumed operating hours

• Spreadsheet• Measurement methods

• End-use & sub-metering • Data loggers

• Multi-channels• Multimeters• Light meters

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Energy Use Allocation at System or Equipment: Top-Down or Bottom-Up Allocate energy to end-uses to get a strategic perspective

• Use top-down approach (from energy bills)• AND bottom-up (from equipment)• What you think the equipment is doing must match

up with what the energy bills say is happening

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Energy Use Allocation at

System/Equipment • Applying Herzog • Goal is to get a strategic

view of where your energy is used.

• Where would you focus your attention?

• This table should look familiar: your Table 2?

Herzog, p.77

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Energy Data Feedback

Part of on-going Energy Conservation & Facility Management

Identify Energy Using Equipment

Measure Energy Usage

Evaluate Usage and Operations

Prioritize and Make OperationImprovements

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Energy type unit amount MMBTU $ $ / unit $/MMBTU

Electricity(site value)

kwh

300,000 1,024.2 $47,000 $0.16 / kwh $45.89 / MMBtuNatural Gas therm

45,000 4,500.0 $66,000 $1.47 / therm $14.67 / MMBtu#2 Oil gal

10,000 1,400.0 $26,000 $2.60 / gallon $18.57 / MMBtu

Collecting and Assembling DataEnergy Type Btu $

Oil + Gas 70% 35%

Electric 30% 65%

Summary Tables

Cost per MMBTU

Cost allocation for Fuel or Electricity vs Btu

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Electrical Demand Assessment using Unit Cost

• Check your unit cost of electricity. • Is it high compared to others? • If so, you may be incurring a high demand charge

TABLE 1 SUMMARY OF ANNUAL ENERGY USE BY ENERGY TYPE GROSS FLOOR AREA = 125,000 SFFOR THE YEAR SEPT 1, 2009 - AUGUST 31, 2010 UNLESS OTHERWISE NOTED (12)

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

unit QTY MMBTU $ unit cost $/MMBTU BTU / SF $ / SF % of BTU % of Cost

(5)/(3) (5)/(4) (4)/(12)*1,000,000 (5)/(12) (4)/(13) (5)/(14)

Electricity kwh 500,000 1,707 68,750.00$ 0.14$ 40.28$ 13,656 0.55$ 16% 38%

Nat Gas therm 75,000 7,500 82,740.00$ 1.10$ 11.03$ 60,000 0.66$ 72% 46%

Fuel Oil, #__ gallon 6,201.70 868 $20,155.53 3.25$ 23.21$ 6,946 0.16$ 8% 11%

Steam mlb 390.85 391 $7,119.22 18.21$ 18.21$ 3,127 0.06$ 4% 4%

- -$ 0% 0

Total 10,466 178,765 17.08$ 83,729 1.43$ 100% 100%

(13) (14)

NOTES: per million 1. MMBTU of all energy types are calculated at the Site Value kwh 3414 0.003414 kwh2. Building area (SF) is gross square footage, including basement nat gas 100000 0.100 therm

oil, #2 140000 0.140 galoil, #4 145000 0.145 galoil, #6 152500 0.153 gal

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TABLE 1 SUMMARY OF ANNUAL ENERGY USE BY ENERGY TYPE GROSS FLOOR AREA = 125,000 SFFOR THE YEAR SEPT 1, 2009 - AUGUST 31, 2010 UNLESS OTHERWISE NOTED (12)

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

unit QTY MMBTU $ unit cost $/MMBTU BTU / SF $ / SF % of BTU % of Cost

(5)/(3) (5)/(4) (4)/(12)*1,000,000 (5)/(12) (4)/(13) (5)/(14)

Electricity kwh 500,000 1,707 68,750.00$ 0.14$ 40.28$ 13,656 0.55$ 16% 38%

Nat Gas therm 75,000 7,500 82,740.00$ 1.10$ 11.03$ 60,000 0.66$ 72% 46%

Fuel Oil, #__ gallon 6,201.70 868 $20,155.53 3.25$ 23.21$ 6,946 0.16$ 8% 11%

Steam mlb 390.85 391 $7,119.22 18.21$ 18.21$ 3,127 0.06$ 4% 4%

- -$ 0% 0

Total 10,466 178,765 17.08$ 83,729 1.43$ 100% 100%

(13) (14)

NOTES: per million 1. MMBTU of all energy types are calculated at the Site Value kwh 3414 0.003414 kwh2. Building area (SF) is gross square footage, including basement nat gas 100000 0.100 therm

oil, #2 140000 0.140 galoil, #4 145000 0.145 galoil, #6 152500 0.153 gal

Electrical Demand Assessment with Unit Cost

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TABLE 1 SUMMARY OF ANNUAL ENERGY USE BY ENERGY TYPE

GROSS FLOOR AREA = SFFOR ANY 1 YEAR PERIOD - Jan 1 thru Dec 31, 20____ (please write in year)

unit QTY MMBTU $ unit cost ($/kwh, etc.) $/MMBTU MMBTU / SF $ / SF % of BTU % of Cost

Electricity kwh

Nat Gas therm

Fuel Oil, #__ gallon

Steam mlb

other

Total 100%? 100%?

NOTES: unit: BTU/unit: MMBTU/unit: fuel type:

1. MMBTU of all energy types are calculated at the Site Value kWh 3414 0.003414electricity

2. Building area (SF) is gross square footage, including basement therm 100000 0.100nat gas

gal 140000 0.140oil, #2

gal 145000 0.145oil, #4

gal 152500 0.153oil, #6

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TABLE 2 ANNUAL ENERGY USE BY END-USE FUNCTION

FUELS USED default % adjusted % MMBTU MMBTU/SF % of TOTAL MMBTU $ $ / SF % OF TOTAL $

OIL/GAS/STEAM USE

HEATING 70%

HOT WATER 20%

COOKING 10%

OTHER 0%

SUB-TOTAL 100% 100%

ELECTRICITY USE

LIGHTING 45%

MOTORS 25%

COMPUTERS & OFF EQUIP 10%

AC 10%

KITCHEN-REFRIG 10%

HEATING & HOT WATER see Note 1

OTHER 0%

SUB-TOTAL 100% 100%

TOTAL 100% 100%

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Class Review and Assignment• Energy accounting, data sources and data management

• What energy management principles to your facility

• Load profiles and End Use

• Spreadsheets and graphics of energy data

Reading Assignment for Class 14: Herzog, Chap. 4 & 5 (finish)