reporting degree days, greenhouse gas, carbon footprint in energycap

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Analysis Track

Understanding and Reporting

Degree Days, Greenhouse Gas,

Carbon Footprint

Presented by Steve Heinz, PE, CEM

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Degree Day Fundamentals

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“Degree Days” is a weather analytic

that is only useful in the context of

building energy consumption.

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Degree days measure how much the

temperature varies from a “balance

point temp” at which a building needs

no heating or cooling.

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Degree Days

Based on dry bulb temperature only

(does not account for humidity, wind,

sunshine, precipitation)

Concept developed in the 1930’s to

estimate residential gas demand

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Degree Days

Used widely today for fuel oil fill-ups.

BPT: NOAA’s selection of 65F as the

“balance point temperature” is a poor

choice for modern non-residential

buildings. 60F is better.

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The average annual temperature in San Diego is 65F.

The average annual temperature in Dallas is 65F.

In Dallas, annual A/C usage is 160% more and annual

heating use is 350% of San Diego. How can that be?

The average annual temperature in Orlando is 72F.

The average annual temperature in Phoenix is 72F.

In Phoenix, annual A/C usage is 63% more and annual

heating use is 100% more than Orlando. Huh?

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Warm days and cool days cancel each

other out when average temperature

is used

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These cities had the same 60F average

temp for two days. Was building energy

usage the same?

High Low Mean HDD CDD

San Diego

Day 1 65 55 60 0 0

Day 2 65 55 60 0 0

Average 60

Denver

Day 1 90 60 75 0 15

Day 2 60 30 45 15 0

Average 60

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Conclusion:

The use of Average Temperature fails

to be a good indicator of heating and

cooling needs.

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MDT (Mean Daily Temperature):

Middle value between daily high and

daily low

Typically it’s the outdoor temperature

at around 11:00 AM

CDD=MDT-BPT (when MDT>BPT)

HDD=BPT-MDT (when MDT<BPT)

DD=0 (when MDT=BPT)

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www.WeatherDataDepot.com

©2013 EnergyCAP, Inc. @energycap www.EnergyCAP.com

www.WeatherDataDepot.com

Yearly comparison report

Charts

Excel and print

Monthly data

FAQs

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How is Weather Used in EnergyCAP?

Building ZIP Code

Weather link to WeatherDataDepot

Calendarization & Normalization

Cost Avoidance

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With weather adjustment, $78 savings

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Without weather adjustment (for

unusually mild winter), $352 savings

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Why not also adjust for humidity,

wind, sunshine, precipitation?

Data is expensive

Many fewer available stations

Huge increase in complexity

Marginal increase in accuracy

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Greenhouse Gas

Fundamentals

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Six gases that have global warming

potential:

Carbon dioxide

methane

nitrous oxide

Chlorofluorocarbons (sulfur

hexafluoride, hydrofluorocarbons,

perfluorocarbons)

©2013 EnergyCAP, Inc. @energycap www.EnergyCAP.com

Greenhouse Gas Fundamentals

Measured in equivalent metric tons of

CO2 (often shown as CO2e)

Metric ton=1,000 kg=2,205 lbs

U.S. national average is 20

mTon/person/yr

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EPA’s eGRID Database

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EPA’s eGRID Database

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EPA GHG Equivalencieswww.epa.gov/cleanenergy/energy-resources/calculator.htm

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EPA GHG Equivalencieswww.epa.gov/cleanenergy/energy-and-you/how-clean.html

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How is GHG Used in EnergyCAP?

Meter

Building and Organizational rollups

GHG Report

Questions

Visit the Ace Place to learn more!

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