April, 2002Energy Audits1 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, 2002Energy Audits2 Heating Degree Days If 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 How many degree-days if the balance point temperature for the building is 55F? Answer: 15 F°-day

April, 2002Energy Audits3 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, 2002Energy Audits4 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, 2002Energy Audits5 Benchmarking Software Programs Energy Star – ARCH –

April, 2002Energy Audits6 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, 2002Energy Audits7 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, 2002Energy Audits8 Catalog Existing Equipment System configuration Equipment –Type –Quantity –Efficiency Controls –Identify schedules (Building Automation System) –Locate other sensors and controls –Locate zone controls

April, 2002Energy Audits9 Interviews Interviews: –Facility managers –Facility engineers –Service contractors –Custodial staff –Occupants Questions: –Building schedule –Comfort requirements –Building Performance/Maintenance issues –Age of equipment

April, 2002Energy Audits10 Interview Form

April, 2002Energy Audits11 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, 2002Energy Audits12 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, 2002Energy Audits13 Equipment Matrix

April, 2002Energy Audits14 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, 2002Energy Audits15 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, 2002Energy Audits16 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, 2002Energy Audits17 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, 2002Energy Audits18 Energy Use: Large Office Building