April, 2002 Energy Audits 1

Heating Degree Days• The difference between the base temperature (balance

point) and the mean ambient temperature for the day• The base or balance point temperature varies by building

type and age of construction. Contributing Variables:– Thermostat setpoint (F°)

– Amount of internal and solar gains (BTU/hr)

– Amount of heat loss (BTU/hr)

• If the mean ambient temperature is above the base temperature, no degree-days are counted

• The number of degree days are totaled for the year

April, 2002 Energy Audits 2

Heating Degree DaysIf the balance point temperature for a building is 65F, how many degree days occur during this week in February? The mean ambient temperatures are provided below.

Answer: 76 F°-day

M T W T F S S

50 54 58 60 56 52 49

How many degree-days if the balance point temperature for the building is 55F?

Answer: 15 F°-day

15 11 7 5 9 13 16

5 1 0 0 0 3 6

April, 2002 Energy Audits 3

Heating Degree Day Comparison

• San Francisco has more heating degree days using a base temperature of 65F°

• Stockton has more heating degree days if the base temperature is 60F°, 57F°, 55F° or 50F°

April, 2002 Energy Audits 4

Sources for Climate/Weather Data

• Data should come from closest weather station

• Degree-day data available from PG&E

• See list in handout for on-line climate sources

April, 2002 Energy Audits 5

Benchmarking Software Programs• Energy Star

– http://www.epa.gov/buildings/label/html/introduction.html

• ARCH– http://gismo.lbl.gov/arch/

April, 2002 Energy Audits 6

Building Documentation• Types of documentation

– As built drawings– Equipment inventory– Submittals/test and balance reports– Controls schedule– Maintenance logs/service requests

• What are you looking for?– The major building loads– Control strategies– Efficiencies of equipment

April, 2002 Energy Audits 7

Site Visit Tasks• Observe building usage patterns

– Occupants– Services– Production

• Verify drawings• Catalog existing equipment

– Lighting– Mechanical– Envelope

• Interviews• Locate electrical distribution panels• Take measurements

April, 2002 Energy Audits 8

Catalog Existing Equipment• System configuration

• Equipment– Type– Quantity– Efficiency

• Controls– Identify schedules (Building Automation System) – Locate other sensors and controls – Locate zone controls

April, 2002 Energy Audits 9

Interviews• Interviews:

– Facility managers

– Facility engineers

– Service contractors

– Custodial staff

– Occupants

• Questions:– Building schedule

– Comfort requirements

– Building Performance/Maintenance issues

– Age of equipment

April, 2002 Energy Audits 10

Interview Form

April, 2002 Energy Audits 11

Site Visit at Night• Identify equipment that is in operation

– Night ventilation– Thermal storage

• Identify areas that are in use• Identify potential phantom loads• Observe/interview custodial crew• Observe/test controls

– Sweeps– Occupancy sensors– Air side economizer

April, 2002 Energy Audits 12

Preliminary Energy Auditor’s Toolkit• Five Senses• Matrix (spreadsheet) for data entry, site plan, notepad & clipboard• Light meter• Flicker checker• Temperature/humidity probe• Calculator• Digital Camera• Simple tool kit

– Measuring tape– Screw drivers– Allen wrenches– Pliers– Crescent wrench– Knife– Flashlight

April, 2002 Energy Audits 13

Equipment Matrix Lighting Circuit Area served No. fixtures Lamp type Lamp/fixture Lamp watts Total watts Control type Schedule Notes

LP-2A,1a Copy room 2x2 2 U' tube (fluor) 0 Switch/sweep off

LP-2A,1a Emily's office 2x2 1 U' tube (fluor) 0 Switch/sweep off

LP-2A,1a Jim's office 2x2 2 U' tube (fluor) 0 Switch/sweep off

LP-2A,1b Copy room cove lighting at wall 1 4' fluor tube 0 Switch/sweep off

LP-2A,1b Emily's office cove lighting at wall 1 4' fluor tube 0 Switch/sweep off

LP-2A,1b Jim's office cove lighting at wall 1 4' fluor tube 0 Switch/sweep off

LP-2A,3c Front office uplighting 4' fluor tube 0 Switch/sweep off

LP-2A,5d Front office uplighting 4' fluor tube 0 Switch/sweep off

LP-2A,7a Hallway recessed cans 4 comp. fluor. 0 24-hr opp

LP-2A,7f Maria's office 2x2 2 U' tube (fluor) 0 Switch/sweep off

LP-2A,7g Maria's office cove lighting at wall 1 4' fluor tube 0 Switch/sweep off

LP-2A,8p Recessed cans at res troom 3 comp. fluor. 0 24-hr opp

LP-2A,10m Model shop 7 4' fluor tube 2 32 448 Switch/sweep off

LP-2A,12a Tech office circuit #1 4' fluor tube 0 Switch/sweep off

LP-2A,12b Tech office circuit #2 4' fluor tube 0 Switch/sweep off

LP-2A,29 Men's 2nd floor res trooms 1 4' fluor tube 1 32 32 Occupancy sensor

LP-2A,29 W omen's 2nd floor res trooms 1 4' fluor tube 1 32 32 Occupancy sensor

LP-2A,29 Electrical closet 2 4' fluor tube 0 Switch

April, 2002 Energy Audits 14

Site plan should include…

• Outline of buildings• Name and location of each building• Year of construction• Size (# of floors and square footage)• North arrow• Location of utility meters• Location of mechanical rooms and equipment• Location of electrical rooms• Room layout with glazing shown

April, 2002 Energy Audits 15

Detailed Energy Auditor’s Toolkit• Everything from the last kit• Power meter• Strobe tachometer• Pressure sensor (manometer)• Balometer/anemometer• Liquid flow meter• Flue gas analyzer• Multimeter• Powder gun• Low-E glass detector

April, 2002 Energy Audits 16

Cost Analysis: Pay Back Period• Calculate cost of retrofit

• Subtract cost of incentive

• Divide by annual energy savings

[retrofit cost ($) - rebate ($)]/[savings ($)/year]

= Payback years

April, 2002 Energy Audits 17

Cost Analysis: Life Cycle Cost• Add to the initial costs of the equipment

– Maintenance costs over the life of the system

– Energy costs over the life of the system

– Disposal/recycling costs

• Other issues include– Embodied energy

– Productivity improvements

– Health impacts

• Efficiencies are considered an investment and should provide a good annual return over product life.

April, 2002 Energy Audits 18

Energy Use: Large Office BuildingSpace Heating

2%

Fan/Pumps15%

Other13%

Office Equipment

14%Space Cooling

14%

Indoor Lighting35%

Outdoor Lighting

6%

Water Heating1%