reporting degree days, greenhouse gas, carbon footprint in energycap

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

Analysis Track

Understanding and Reporting

Degree Days, Greenhouse Gas,

Carbon Footprint

Presented by Steve Heinz, PE, CEM


Degree Day Fundamentals


“Degree Days” is a weather analytic

that is only useful in the context of

building energy consumption.


Degree days measure how much the

temperature varies from a “balance

point temp” at which a building needs

no heating or cooling.


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


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.


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?

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

Warm days and cool days cancel each

other out when average temperature

is used


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


Conclusion:

The use of Average Temperature fails

to be a good indicator of heating and

cooling needs.


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)


www.WeatherDataDepot.com


www.WeatherDataDepot.com

Yearly comparison report

Charts

Excel and print

Monthly data

FAQs


How is Weather Used in EnergyCAP?

Building ZIP Code

Weather link to WeatherDataDepot

Calendarization & Normalization

Cost Avoidance


With weather adjustment, $78 savings


Without weather adjustment (for

unusually mild winter), $352 savings


Why not also adjust for humidity,

wind, sunshine, precipitation?

Data is expensive

Many fewer available stations

Huge increase in complexity

Marginal increase in accuracy


Greenhouse Gas

Fundamentals


Six gases that have global warming

potential:

Carbon dioxide

methane

nitrous oxide

Chlorofluorocarbons (sulfur

hexafluoride, hydrofluorocarbons,

perfluorocarbons)


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


EPA’s eGRID Database


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


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


How is GHG Used in EnergyCAP?

Meter

Building and Organizational rollups

GHG Report

Questions

Visit the Ace Place to learn more!


reporting degree days, greenhouse gas, carbon footprint in energycap

Technology

energycap catalyst

day fundamentals2013

average annual temperature

use of average temperature

daily temperature

outdoor temperature

annual heating use

balance point temperature