Measurement & Verification

GUIDING THE PATH TO GREEN

Measurement & Verification

Or, how I learned to stop worrying and love the meter


Jeremy R. Poling, PE, LEED AP+BDC

Director of Engineering ServicesTranswestern Sustainability

Services

Speaker Introduction

GUIDING THE PATH TO GREEN• The difference between benchmarking and

retroactive modeling• Cases where modeling can identify problems

that benchmarking will not• The business case for measurement and

verification• How to anticipate the process of calibrated

measurement and verification and steps to a successful outcome

Learning Objectives

GUIDING THE PATH TO GREEN• Simple definition: comparison of one building

against its peers for the purpose of classifying a building as “efficient” or “inefficient”

• Broader definition: using whole-building characteristics and aggregated whole-building energy use to determine the Energy Usage Intensity (EUI) for a particular building. After normalizing that EUI for weather effects and comparison to peers, identify whether the building is a low-energy or high-energy use building per square-foot of floor area.

What is Benchmarking?


Benchmarking Tools

GUIDING THE PATH TO GREEN• Allow portfolio managers to decide between

upgrading one building or another in their portfolio

• Provide a basis for tenant lease transactions (careful!)

• Confirm compliance for incentive programs• Earn certification under programs like LEED and

Green Globes

What can Benchmarking do?

GUIDING THE PATH TO GREEN• Identify where energy is being used in a building• Determine the payback of Energy Conservation

Measures• Teach an operator how to run a building• Teach occupants how to use less energy

What CAN’T Benchmarking do?

GUIDING THE PATH TO GREEN• Typically complies with ASHRAE Standard 14 or

IPMVP (International Performance Measurement and Verification Protocol)

• Uses energy modeling software to describe detailed building characteristics, such as:– Hourly occupancy schedules– Hourly load profiles– Chiller efficiency curves– Economizer operation– System zoning

What is Retroactive Modeling?

GUIDING THE PATH TO GREEN• Compares predicted

energy use against measured energy use using hourly energy data and hourly weather data

• Calibrated to end-use submeters for energy use verification

• Built to answer specific questions about building energy use

What is Retroactive Modeling?

GUIDING THE PATH TO GREEN• At a minimum, all buildings should be

benchmarking energy use monthly as energy bills are received– Develops a habit of accounting for energy use– Depending on location, might be legal

requirement (NYC, San Francisco, Seattle…)• Tools like Energy Star Portfolio Manager typically

allow benchmarking energy AND water use• Modeling will require at least an investment in

intellectual capital, in-house or on a consulting basis and typically a capital investment in metering

Title Bout, Round 1:


Benchmarking wins Round 1, right?

Title Bout, Round 1:

GUIDING THE PATH TO GREEN• After benchmarking, then what?• Studies by large property management firms

report 5%-10% energy savings from real-time metering of energy use

• Most electric utilities charge for demand, including ComEd

• Manufacturing companies use detailed energy metering to qualify the savings from Energy Conservation Measures, particularly those that might impact their processes

Title Bout, Round 2: the KO


Getting to significant energy savings requires detailed study of energy end-use

information

Title Bout, Round 2: the KO

GUIDING THE PATH TO GREEN• Individual submeters for

energy end-uses can be relatively affordable ($1,000 - $5,000 depending on manufacturer and options selected)

• For argument’s sake, at $0.09 per kWh a 100,000 kWh annual energy reduction will pay back in 2 – 6 months

• So what does this actually look like?

Business Case for M&V

GUIDING THE PATH TO GREEN• Example: A 64,000 square foot building with typical

3-lamp, 32-watt T8 fluorescent lighting at the rule-of-thumb spacing of 8 feet on-center has 1,000 lighting fixtures at a ballast input of 86 watts. Lighting is controlled by time-clock. Occupants are in the building 8AM-5PM and housekeeping is finished by 11PM.

• For each hour of lighting use, the building electric meter is hit with 86 kWh. 100,000 kWh represents 1,163 annual hours of lighting use, or approximately 4.65 hours a day for 250 business days per year.

• Sub-metering of lighting energy can identify the hours the building lighting is running.


GUIDING THE PATH TO GREEN• In the previous example, the following Energy

Conservation Measures might be proposed:1. Replacement of 32-watt lamps with 25-watt

lamps for a savings of 19 watts at the ballast input

2. Use of lighting controls to automatically shut off lighting during unoccupied hours

• Which do you choose?


GUIDING THE PATH TO GREEN• In absence of submeters, you might choose ECM

#1. This would require investment in slightly more expensive lamps, but could be accomplished with a payback of around 2-4 years.

• However, if you choose ECM #2, your payback could be 2-6 months. How is that possible?

• Submetering the lighting energy identifies that the building operator set the time clock to keep lighting on for housekeeping when they could use the local override switches instead, saving an average of 5 hours per day.


GUIDING THE PATH TO GREEN• Lighting is the simple case• More complicated situations

will require modeling at some level:1. Chiller replacements2. Boiler replacements3. Envelope retrofits4. Control replacements

• While there are estimating methods and spreadsheet calculators, modeling the building will reduce complexity in calculations


GUIDING THE PATH TO GREEN• New Construction

1. Request segregation of loads by end-use to minimize the number of meters required

2. Utilize an energy model and EUI targets early and often in design for selecting systems so the data exists for verification post-construction

3. Connect real-time meters to the building operator’s computer through a dashboard (visibility = accountability)

4. Keep it Simple

Preparing for M&V

GUIDING THE PATH TO GREEN• Existing Buildings

1. Identify where you already have data (i.e. Occupancy hours through building security badge logging)

2. Identify the big energy end-uses (chillers, lighting, plug loads, etc.)

3. Sub-meter 120V panels as these typically only see plug loads or tenant loads

4. Ask about additional BMS data points, such as energy data from VFDs (many can report voltage and amperage if configured to do so)

Preparing for M&V


5. Obtain real-time utility meter readings at a minimum and connect to the building operator’s computer (repeat: visibility = accountability)

6. Connect new submeters to the same dashboard

7. Educate building occupants on the impact of their energy use (think about the lighting example – if an occupant leaves a room of lights on for an extra hour, the cost can be calculated readily)

Preparing for M&V


8. Consider simple, temporary metering investigations to assist with modeling (i.e. Kill-A-Watt for cubicle)

9. M&V doesn’t have to capture everything – while you might miss something if it isn’t comprehensive, subtractive methods can also be effective

10.Use a “paid from savings” approach: in the example before, if the metering pays back in 6 months whereas the lighting retrofit would have taken 2-3 years to pay back, use a portion of the “additional” 18-30 months of savings to pay for the investigation of additional end-uses

Preparing for M&V

GUIDING THE PATH TO GREEN• Benchmarking usually only gets at whole

building data, measurement & verification strategies, including calibrated simulation, help answer the “what” and “why” questions

• End-use metering can be very affordable and can identify hidden energy problems

• Calibrated simulation will account for additive effects of ECMs in a less complex way than spreadsheet calculations

Conclusions


Questions?

[email protected]

Measurement & Verification

Education

e nm e

e d ap

d ecid e

e ling

love th e

e n id

ility s e rvice s

e n c om