Measurement & Verification
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Benchmarking provides high-level comparisons of whole-building energy use but cannot identify where energy is used or determine cost-effectiveness of upgrades. Retroactive energy modeling uses submetering and hourly data to calibrate an energy model that can answer these questions. By identifying lighting was used 5 extra hours daily, submetering showed controls could save more than lamp upgrades alone in just a few months. Preparing for measurement and verification involves obtaining operational data, connecting submeters to monitor real-time use, and educating occupants on energy impacts to identify hidden problems and most cost-effective upgrades.
Measurement & Verification
- 1. GUIDING THE PA TH TO G RE E N M e as u re m e nt & Ve rification O r, h ow I le arne d to s top worrying and love th e m e te r
- 2. S p e ake r Introd u ction GUIDING THE PA TH TO G RE E N Je re m y R . P oling, P E , LE E D AP + BD C D ire ctor of E ngine e ring S e rvice s Trans we s te rn S u s tainab ility S e rvice s
- 3. Le arning O b j ctive s e GUIDING THE PA TH TO G RE E N • The d ifference between benchm arking and retroactive m od eling • C ases where m od eling can id entify problem s that benchm arking will not • The business case for m easurem ent and verification • H ow to anticipate the process of calibrated m easurem ent and verification and steps to a successful outcom e
- 4. Wh at is Be nch m arking? GUIDING THE PA TH TO G RE E N • Sim ple d efinition: com parison of one build ing against its peers for the purpose of classifying a build ing as “efficient” or “inefficient” • Broad er d efinition: using whole-build ing characteristics and aggregated whole-build ing energy use to d eterm ine the Energy U sage Intensity (EU I) for a particular build ing. After norm alizing that EU I for weather effects and com parison to peers, id entify whether the build ing is a low-energy or high- energy use build ing per square-foot of floor area.
- 5. Be nch m arking Tools GUIDING THE PA TH TO G RE E N
- 6. Wh at can Be nch m arking d o? GUIDING THE PA TH TO G RE E N • Allow portfolio m anagers to d ecid e between upgrad ing one build ing or another in their portfolio • Provid e a basis for tenant lease transactions (careful!) • C onfirm com pliance for incentive program s • Earn certification und er program s like L EED and Green Globes
- 7. Wh at C AN ’T Be nch m arking d o? GUIDING THE PA TH TO G RE E N • Id entify where energy is being used in a build ing • D eterm ine the payback of Energy C onservation M easures • Teach an operator how to run a build ing • Teach occupants how to use less energy
- 8. Wh at is R e troactive M od e ling? GUIDING THE PA TH TO G RE E N • Typically com plies with ASH RAE Stand ard 1 4 or IPM VP (International Perform ance M easurem ent and Verification Protocol) • U ses energy m od eling software to d escribe d etailed build ing characteristics, such as: – H ourly occupancy sched ules – H ourly load profiles – C hiller efficiency curves – Econom izer operation – System zoning
- 9. Wh at is R e troactive M od e ling? GUIDING THE PA TH TO G RE E N • C om pares pred icted energy use against m easured energy use using hourly energy d ata and hourly weather d ata • C alibrated to end -use subm eters for energy use verification • Built to answer specific questions about build ing energy use
- 10. Title Bou t, R ou nd 1 : GUIDING THE PA TH TO G RE E N • At a m inim um , all build ings should be benchm arking energy use m onthly as energy bills are received – D evelops a habit of accounting for energy use – D epend ing on location, m ight be legal requirem ent (N YC , San Francisco, Seattle… ) • Tools like Energy Star Portfolio M anager typically allow benchm arking energy AN D water use • M od eling will require at least an investm ent in intellectual capital, in-house or on a consulting basis and typically a capital investm ent in m etering
- 11. Title Bou t, R ou nd 1 : GUIDING THE PA TH TO G RE E N Benchm arking wins Round 1 , right?
- 12. Title Bou t, R ou nd 2: th e K O GUIDING THE PA TH TO G RE E N • After benchm arking, then what? • Stud ies by large property m anagem ent firm s report 5% -1 0% energy savings from real-tim e m etering of energy use • M ost electric utilities charge for d em and , includ ing C om Ed • M anufacturing com panies use d etailed energy m etering to qualify the savings from Energy C onservation M easures, particularly those that m ight im pact their processes
- 13. Title Bou t, R ou nd 2: th e K O GUIDING THE PA TH TO G RE E N Getting to significant energy savings requires d etailed stud y of energy end -use inform ation
- 14. Bu s ine s s C as e for M &V GUIDING THE PA TH TO G RE E N • Ind ivid ual subm eters for energy end -uses can be relatively afford able ($1 ,000 - $5,000 d epend ing on m anufacturer and options selected ) • For argum ent’s sake, at $0.09 per kWh a 1 00,000 kWh annual energy red uction will pay back in 2 – 6 m onths • So what d oes this actually look like?
- 15. Bu s ine s s C as e for M &V GUIDING THE PA TH TO G RE E N • Exam ple: A 64,000 square foot build ing with typical 3-lam p, 32-watt T8 fluorescent lighting at the rule-of-thum b spacing of 8 feet on-center has 1 ,000 lighting fixtures at a ballast input of 86 watts. L ighting is controlled by tim e-clock. O ccupants are in the build ing 8AM -5PM and housekeeping is finished by 1 1 PM . • For each hour of lighting use, the build ing electric m eter is hit with 86 kWh. 1 00,000 kWh represents 1 ,1 63 annual hours of lighting use, or approxim ately 4.65 hours a d ay for 250 business d ays per year. • Sub-metering of lighting energy can identify the hours the building lighting is running.
- 16. Bu s ine s s C as e for M &V GUIDING THE PA TH TO G RE E N • In the previous exam ple, the following Energy C onservation M easures m ight be proposed : 1. Replacem ent of 32-watt lam ps with 25-watt lam ps for a savings of 1 9 watts at the ballast input 2. U se of lighting controls to autom atically shut off lighting d uring unoccupied hours • Which d o you choose?
- 17. Bu s ine s s C as e for M &V GUIDING THE PA TH TO G RE E N • In absence of subm eters, you m ight choose EC M #1 . This would require investm ent in slightly m ore expensive lam ps, but could be accom plished with a payback of around 2-4 years. • H owever, if you choose EC M #2, your payback could be 2-6 m onths. H ow is that possible? • Subm etering the lighting energy id entifies that the build ing operator set the tim e clock to keep lighting on for housekeeping when they could use the local overrid e switches instead , saving an average of 5 hours per d ay.
- 18. Bu s ine s s C as e for M &V GUIDING THE PA TH TO G RE E N • L ighting is the sim ple case • M ore com plicated situations will require m od eling at som e level: 1. C hiller replacem ents 2. Boiler replacem ents 3. Envelope retrofits 4. C ontrol replacem ents • While there are estim ating m ethod s and spread sheet calculators, m od eling the build ing will red uce com plexity in calculations
- 19. P re p aring for M &V GUIDING THE PA TH TO G RE E N • N ew C onstruction 1. Request segregation of load s by end -use to m inim ize the num ber of m eters required 2. U tilize an energy m od el and EU I targets early and often in d esign for selecting system s so the d ata exists for verification post-construction 3. C onnect real-tim e m eters to the build ing operator’s com puter through a d ashboard (visibility = accountability) 4. K eep it Sim ple
- 20. P re p aring for M &V GUIDING THE PA TH TO G RE E N • Existing Build ings 1. Id entify where you alread y have d ata (i.e. O ccupancy hours through build ing security bad ge logging) 2. Id entify the big energy end -uses (chillers, lighting, plug load s, etc.) 3. Sub-m eter 1 20V panels as these typically only see plug load s or tenant load s 4. Ask about ad d itional BM S d ata points, such as energy d ata from VFD s (m any can report voltage and am perage if configured to d o so)
- 21. P re p aring for M &V GUIDING THE PA TH TO G RE E N • Existing Build ings 1. O btain real-tim e utility m eter read ings at a m inim um and connect to the build ing operator’s com puter (repeat: visibility = accountability) 2. C onnect new subm eters to the sam e d ashboard 3. Ed ucate build ing occupants on the im pact of their energy use (think about the lighting exam ple – if an occupant leaves a room of lights on for an extra hour, the cost can be calculated read ily)
- 22. P re p aring for M &V GUIDING THE PA TH TO G RE E N • Existing Build ings 1. C onsid er sim ple, tem porary m etering investigations to assist with m od eling (i.e. K ill-A-Watt for cubicle) 2. M & V d oesn’t have to capture everything – while you m ight m iss som ething if it isn’t com prehensive, subtractive m ethod s can also be effective 3. U se a “paid from savings” approach: in the exam ple before, if the m etering pays back in 6 m onths whereas the lighting retrofit would have taken 2-3 years to pay back, use a portion of the “ad d itional” 1 8-30 m onths of savings to pay for the investigation of ad d itional end - uses
- 23. C onclu s ions GUIDING THE PA TH TO G RE E N • Benchm arking usually only gets at whole build ing d ata, m easurem ent & verification strategies, includ ing calibrated sim ulation, help answer the “what” and “why” questions • End -use m etering can be very afford able and can id entify hid d en energy problem s • C alibrated sim ulation will account for ad d itive effects of EC M s in a less com plex way than spread sheet calculations
- 24. GUIDING THE PA TH TO G RE E N Q u e s tions ? j re m y.p oling@ trans we s te rn.ne t e