Basic Calculations for Energy Efficiency

Energy Efficiency Training Program 4/11/2011

Agenda and Objectives

□ Basic Concepts and Equations

□ Lighting Calculations – Fixture Wattage, Energy and Cost Savings Calculations

□ Basic Financial Calculations

□ Other Calculations Resources

□ Elements and Examples of Audit Reports

□ Practice

□ Instructions for Group Audits

The Basics – Energy vs. Power

□ Energy – Does work. “If energy was used, work was done.”

□ Power – Rate at which work is done

□ Units of Energy

□ Btu, MMBtu (Heat)

□ kWh (Electric)

□ Therm (Natural Gas)

□ Units of Power

□ BTU/h

□ W, kW, MW

□ Hp

The Basics – Conversion Factors

□1 kWh = 3413 Btus

□1 Therm = 100,000 BTUs

□1 Therm = ?? kWh

□1 HP = 746 W = .746 kW

□1 kW = 3413 Btu/h

The Basics – The Equations

□ Energy = Power x Runtime

kWh = kW x Hours

□ The Energy Savings Equation

kWh Saved = kWhBaseline – kWhRetrofit

So…

kWh Saved = kWBaseline x HrsBaseline– kWRetrofit x HrsRetrofit

If Hours don’t change: kWh Saved = (kWBaseline– kWRetrofit) x Hrs

If kW doesn’t change: kWh Saved = kW x (HrsBaseline– HrsRetrofit)

Lighting Calculations – Fixture Wattages

□ Nominal Wattage of lamps ok for CFL, incandescent

□ For most fixtures, must look up fixture wattage in “the wattage table”

□ http://www.aesc-inc.com/download/spc/2011SPCDocs/UnifiedManual/App%20B%20Standard%20Fixture%20Watts.pdf

Lighting Calculations – Ballast Types

□ Magnetic

□ Standard Magnetic – “Mag - STD”

□ Energy Saving Magnetic – “Mag - ES”

□ Electronic

□ Instant Start (IS), Rapid Start, Program Start (PRS)

□ Premium Ballasts

Lighting Calculations – Ballast Factors

□ The ratio of a lamp’s light output on a particular ballast, compared to the lamp’s rated lamp lumens in the testing environment

□ Reduced Light Output (RLO): ballast factor between ~0.75 and ~0.85

□ Normal Light Output (NLO): ballast factor between ~.87 and 0.95

□ High Light Output (HLO): ballast factor greater than ~.95

Example Calculations

□ Replace Incandescent with CFL

□ Retrofit T12, Magnetic Ballast to T8, Electronic Ballast

□ Install Occupancy Sensor

□ High-bay retrofit with integrated occupancy sensor

Cost Savings

□ PG&E Tariffshttp://www.pge.com/nots/rates/tariffs/electric.shtml

□ Cost Savings = kWh savings x ($/kWh)□ Average or Blended Rate

□ TOU Rates

□ Cost Savings for Example Calculations

Financial Calculations – Simple Payback and ROI

□ Simple Payback□ Simple Payback = (Installed Cost)/(First Year Savings)□ With or Without Rebate□ Simple Payback for this situation?

Spend $200 on a retrofit that saves $50 per year inenergy costsWith a $100 rebate?

□ Return on Investment□ ROI = First Year of Savings/Installed Cost□ ROI of the above situation?

□ Over-simplifies situation, does not take into account all lifecycle benefits or cost of capital. BUT is effective seller if payback is sufficiently short.

Financial Calculations – NPV and IRR

□ NPV =

□ t = the time of the cash flow (years after install)□ n = the time of the project (useful life of the measure in years)□ r = the discount rate (rate of return of an alternative investment or the interest rate of the money

used to finance the project)□ Ct = cash flow at time t (annual savings)

(higher is better, use to choose between mutually exclusive retrofits)

□ Internal Rate of Return (IRR)The IRR is the discount rate for which NPV = 0

(higher is better, use to prioritize retrofits)

□ http://www.energytools.com/calc/EnerEcon.html

More Calculations Resources

□ Energy Star Calculatorshttp://www.energystar.gov/index.cfm?c=bulk_purchasing.bus_purch

asinghttp://www.sba.gov/content/energy-saving-calculators-energy-star

□ Food Service Technology Centerhttp://www.fishnick.com/saveenergy/tools/calculators/

□ Waterhttp://www.fishnick.com/savewater/tools/watercalculator/

□ Motor Masterhttp://www1.eere.energy.gov/industry/bestpractices/software.html

#mm

Communicating Recommendations and

Opportunities – the Report

□ Possible Elements of a Report

□ List of recommendations

□ Estimates of energy and cost savings and emissions reductions

□ Project cost information – materials and labor

□ Available rebates and financing

□ Financial calculations and metrics

Examples of Audit Reports of varying

levels of analysis...

Examples of Audit Reports of varyinglevels of analysis...□ http://www.mnenergysmart.com/documents/Lighting-Audit-CEE-Sample.pdf

□ http://www.mnenergysmart.com/documents/Xcel-Sample-Energy-Analysis-Onsite.pdf

□ http://www.greenchipstocks.com/reportpdfs/example-of-a-home-energy-audit-369.pdf

□ http://www.heat.net.au/home_energy_audits/pdfs/ACTEnergyWise/Example%20Home%20Energy%20Audit%20Report.pdf

□ EETP Example in your binder

Steps for Group Project

1. As a group, pick your two sites

2. Submit to Emily, with contact info

3. Coordinate with Emily on time for audit

4. As a group, create your own report – you pick the format. SBC staff will be available for assistance at announced times.

5. Coordinate with SBC staff for scheduling a time to present the reports to customer.

6. See your binder for these instructions!