Energy Efficiency Project Analysis for Supermarkets and Arenas Clean Energy Project Analysis Course

1. Energy Efficiency Project Analysisfor Supermarkets and Arenas Clean Energy Project Analysis Course

2. Objectives • Review basics of advanced refrigeration systems & energy efficiency measures for supermarkets and arenas • Illustrate key considerationsinenergy efficiency project analysis for supermarkets and arenas • Introduce RETScreen® Energy EfficientArena & Supermarket Project Model

3. Ice Rink and Bleachers Supermarket Interior What do energy efficiency measures & advanced refrigeration systems provide? • Refrigeration and cooling in supermarkets and arenas • Space, ventilation air, and water heating; dehumidification …but also… • Reduced energy consumption • Reduced power demand charges • Reduced refrigerant leaks • Reduced greenhouse gas emission • Reduced maintenance costs • Improved comfort Photo Credit: Regos Photography/Andrus Architecture

4. Supermarkets:Background • Among most energy-intensive commercial buildings • 5,000 MWh-eq/year for electricity in large supermarket (>1,000 m2) • Over 5,000 large supermarkets in Canada • Refrigeration accounts for 50% of energy costs; lighting, 25% • $150,000/year for refrigeration in large supermarket • Energy costs are ~1% of sales • But this is approximately same as store profit margin! • Conventionally have very high refrigerant charges • Average store has 1,300 kg of refrigerant • Long piping runs result in leakage of 10 to 30% of charge per year • Synthetic refrigerants are potent greenhouse gases (GHG) • Can have over 3,000 times the effect of CO2

5. Arenas: Background • Typical arena in Canada: • ~ 1,500 MWh-eq/year consumption • ~ $100,000/year energy cost • Major consumer of energy • 2,300 skating rinks in Canada • 1,300 curling rinks in Canada • Conventionally have high refrigerant charges • Average arena has 500 kg of refrigerant • Open compressor results in significant leakage • Synthetic refrigerants: potent greenhouse gases • Can have over 3,000 times the effect of CO2 Energy Consumption for Typical Arena in Canada

6. The building as a system • Supermarkets and arenas are systems with purchased energy inputs… • Electricity, natural gas, etc., • …that satisfy simultaneous heating and refrigeration loads… • …in proximate warm and cold zones.

7. Heating and refrigeration loads • Influenced by… • Gains/losses through building envelope • Gains/losses in ventilation fresh and exhaust air (sensible + latent) • Gains from occupants (sensible + latent) • Gains from equipment (e.g. lighting) • Gains/losses in mass flows (e.g. hot water down drain, ice making) • Gains/lossesthrough floor • Solar gains • …and heat transfer from heated to cooled areas!

8. Where are improvements possible? • Control according to activity & environmental conditions • Reduce heat transfer from warm to cold zones • Reduce unwanted gains and losses • Process integration: transfer heat from cold to warm zones • Use heat rejected by refrigerationsystems to satisfy heat loads • Improve HVAC&R equipment efficiency • Reduce refrigerant charge and leakage • Major reduction in greenhouse gases

9. Review of vapour-compression refrigeration cycle

10. Supermarkets and Arenas:Problem: Heat transfer from warm to cool zones • Heat draining from warm zones to cold zones accounts for majority of refrigeration load • Majority of heat dumped to outside air by condenser • Heating system must make up for some of this rejected heat • Heat rejected by refrigeration system generally exceeds heating load Typical Canadian skating rinkheating load and heat rejected by refrigeration system, by month

11. Measures for Supermarkets and Arenas: Process Integration makes use of heat rejected by refrigeration system • Capture rejected heat in a secondary loop • Secondary loop facilitates heat distribution • Desuperheater at outlet of compressor • Recovers up to 15% of rejected heat– good for hot water • Further heat recovery before condenser • Heat can be used for space, ventilation air, and water heating • Heat pumps raise temperature of heat from secondary loop as necessary • Excess heat can be… • Stored for later use • Heat under ice rink slab • Snow pit melting • Export to nearby buildings • Sidewalk, parking lot, street heating • Dump any surplus to outside air

12. Measures for Supermarkets:Minimize refrigerant leaks with secondary loops • Refrigeration loads aredistributed around building • Long loops of refrigerant-filled pipingconnect mechanical room to loads and condenser • Leaks in piping and joints account for 50% of supermarket’s greenhouse gasses • Solution: secondary loops onhot and cold sides • Secondary loop with water, glycol mix, brine, CO2, methanol, etc.: not potent GHGs like synthetic refrigerant • Small refrigerant load contained in hermetic unit • Low temperature loads: use autonomous refrigeration sub-units (with low refrigerantcharge) that dump heat tothe secondary loop

13. Measures for Arenas:Minimize refrigerant leaks with secondary loops • Open compressors and high refrigerant charges lead to significantgreenhouse gas emissions • Solution: secondary loops on warm (condenser) side • Small refrigerant loadcontained in hermetic unit • Water or glycol mix in loop: no GHG’s

14. Measures for Supermarkets and Arenas: Tailoring HVAC&R equipment to cold climates • Equipment is conventionally designed for warm climates • Condensers typically operate at high temperature,regardless of the exteriorair temperature • Solution: Permitting condensertemperature to drop duringcold weather improvesefficiency and compressorlongevity • “Floating headpressure” operation • COP can double, (e.g. from 3 to 6) • Reduces usefulness of rejected heat • Must optimize operating temp.

15. Measures for Supermarkets and Arenas: Mechanical/ambient refrigerant subcooling • Conventionally, output of condenser feeds directly into expansion valve • Capacity and efficiency can be improved by cooling liquid exiting condenser totemperatures below condensing temperature(subcooling) • Ambient: cold exterior air or rink snow pit • Mechanical: second refrigeration system • Better than simply removing moreheatfromcondenser– second systemoperates with higher COP

16. Measures for Supermarkets and Arenas: Thermal storage • Storage of rejected heat • Peak demand charges associatedwithheating can be reduced • Short-term: water tanks of 2,000 litres for several hour storage (e.g. night) • Seasonal: underground storage with horizontal/vertical heat exchanger • Arenas can also store“cold” under slab orin reservoir • Reduce peak demand charges by extracting cold from storage during times of peak load • Reduce design capacity of refrigeration equipment • Increase in COP through use of heat pump to produce heat and cooling simultaneously

17. Ice rink with daylighting Measures for Supermarkets and Arenas: Efficient lighting and daylighting • Artificial lighting augments refrigeration loads • Solution: More efficient lighting technologies • Solution: Highly reflective ceilings– reduce lighting needs by 30% • Can be combined with low-e paintsor materials in arenas • Solution: Reduced light intensitywhere permissible • Multi-light level intensity lamps • Vary number of operating lamps • Consider activity and occupancy level • Reduce height of fixtures and ceiling,taking ceiling and wall reflectivityinto consideration • Solution: Natural lighting • Pleasing ambience • Must avoid solar gains, excessive heat losses or gains through windows Photo Credit: Skating Club of San Francisco

18. Measures for Arenas: Ceilings that radiate less heat • Infrared radiation from ceiling: up to 30% of the ice sheet refrigeration load • Ceiling gets hot from space heating, solar gains and artificial lighting • Common materials have high emissivity index (e = 0.80 to 0.95) • Solution: use materials withlow emissivity • Low-e aluminized cloth(e=0.03 to 0.08) • Aluminium-based low-e paint or other low-e paints • Additional Benefits • Reduced condensation • Improved acoustics • Reduce lighting requirements Reflective, Low-e Ceiling Photo Credit: Marius Lavoie, NRCan

19. Simulated Temperature Measures for Arenas:Reduce heat losses from stands • Space heating in stands adds to refrigeration load • Air temperature in spectator stands may be as high as 15 to 18ºC • Typically adds 20% to the refrigeration load • Solutions: • Heat stands with lowtemperature (≤32ºC) radiantflooring system • Use heat rejected by refrigeration system • Slab heating maintains spectator comfort • Reduce temperature in stands during unoccupied periods

20. Measures for Arenas: Optimize ice temperature • Rinks normally maintain ice temperature around –6ºC • Refrigeration load can be reduced by letting ice temperature rise • During figure skating: -3 to -4ºC • During free skating: -2 to -3ºC • During unoccupied periods (e.g. night): -1 to -2ºC • Stop secondary fluid pump during unoccupied periods,and restart only when infrared sensor indicates ice temperature has risen to a preset maximum allowable temperature

21. Piping in slab Measures for Arenas:Reduce refrigerant pumping energy • Ice cooled by secondary fluid circulating in concrete slab • Piping network transports secondary fluid across ice in one directionand then back to header: a two-pass layout • Secondary fluid pump accounts for over15% of the refrigeration system’s totalenergy consumption • Secondary fluid pump’s heat adds torefrigeration loads • Solution: • Reduce secondary fluid flow rateaccordingto schedule/occupancy • Two-speed pump, two pumps, orvariablespeed pump • Piping network that transports fluid fouror more passes through slab allows flowrate to be halved • Affects ice uniformity? Photo Credit: Marius Lavoie, NRCan

22. Pouring of slab Measures for Arenas:Optimize ice and concrete slab thickness • Heat transfer from secondary fluid to ice surface reduced by thick ice and thick layer of concrete above tubes • Lower heat transfer results in higher refrigeration energy consumption • In most arenas, ice 25 to 40 mmthick, but can be as high as 75 mm • In most arenas, ~25 mm of concreteabove embedded tubes • Solution: • During construction or renovation,ensure concrete slab should be≤ 25 mm above tubes • Keep ice thickness at 25 mm, where permitted • In combination with under slab coolstorage, reduces capacity requirements Photo Credit: Marius Lavoie, NRCan

23. Measures for Arenas: Different dehumidification approaches • Dehumidification normally involves stand-alone cooling unit • Heat rejected to ice rink and adds to refrigeration load • Solution: Reject heat from dehumidifier to condenser-side secondary loop of principal refrigeration system • Rejected heat can be used for space heating, etc. • Solution: Desiccant dehumidification system

24. Secondary Loop Supermarkets:Costs of efficiency measures • Depending on measures implemented, 0 to 40% higher initial costs thanconventional systems • A full range of measures costadditional ~$250,000 • Supermarkets oftenrequirepaybacksof 3 years or less • Additional costsmay beoffsetby elimination of combustion heating system Standard DX system Secondary loop system

25. Arenas:Costs of efficiency measures • Major rink renovation every 25 years: ~$700,000 • $175,000 (single pad) or $200,000 (multipad) for efficiency measures • Owners and operators generally wantsimple payback of 5 to 8 years or less • Process integration of heating and refrigeration typically has 3½ year payback in new construction, 5 to 8 years in retrofit Minor Investment Moderate Investment Major Investment Better controls Desuperheater Low-e ceiling Nighttime setbacks Dehumidification Efficient lighting Optimize ice thickness Snow Pit Process integration Power factor correction Cold-climate adaptions Thermal storage

26. Supermarkets:Project considerations • Systems must demonstrate very high reliability • A one day refrigeration system failure is extremely costly in terms of lost revenue and produce • Incorporate advanced refrigeration innovations in new buildings and during major equipment overhauls • Supermarket refrigeration systems overhauled every 8 years on average • In existing supermarkets, new systems may need to be installed and brought on-line while supermarket is operating • Rejected heat from refrigeration system can supply all heat required for supermarket • Elimination of combustion heating systemwithfinancially attractive alternative isa convincing argument

27. Arenas:Project considerations • Incorporate advanced refrigeration innovations in new buildings and during major equipment overhauls • Arena refrigeration systems overhauled on 25 year basis (30 to 40% of Canadian rinks presently operating beyond projected life span) • Many arenas close for 1 to 2 months per year when retrofits can be done • Rejected heat from refrigeration system is three times heating energy requirement on annual basis • But for short periods in winter heat load may exceed reject heat • Reduction in power demand charges can bea significant source of annual cost savings • In some provinces, power demand charges accountfor 40% of electricity invoices

28. Supermarket Entrance Vegetable Display Example: Quebec, Canada Repentigny supermarket • Refrigeration systems reject heatto two secondary loops • Medium temperature refrigeration system loop provides up to 250 kW of space and air heating • Low temperature loop provides up to 220 kW ofheat to heat pumps (2nd function: air conditioners) • Desuperheater meets hot water needs • Medium temperature cold side secondary loop used to subcool low temperature refrigerant by 30ºC at output of condenser • Evaporator (cold) side secondary loops • Condenser temperature/pressure floats according to building heating requirement and outdoor air temperature

29. Supermarket Interior Example: Quebec, CanadaRepentigny supermarket (results) • No boiler or backup heating installed! • All heating provided by waste heat from refrigeration system • Energy consumption reducedby 20% • On-going monitoring • GHG emission reduction of 75% anticipated • Due to reduced natural gas consumption and reduced refrigerant leaks • Minimal commissioning: system functionedwell from start • No problems since April 2004

30. Val-des-Monts Recreational Ice Rink Example: Quebec, Canada Val-des-Monts recreational ice rink • Heat rejected by refrigeration system recovered in secondary loop • Radiant floor heating (stands and space heating)reduces refrigeration load • Service hot water and resurfacing hot water(with heat pump) • Under slab heating • Snow pit melting • Excess heat to nearby community centre • Thermal storage • Short term: 2,000 litre water tank for heat • Short term: Under pad storage for cold • Seasonal: Horizontal loop underground • Circulation of secondary coolant in five-passrather thantwo-pass configuration • Six cascaded 3 hp pumps achieve variablesecondary coolant flow rates as required • Floating condenser pressure • Low emissivity ceiling • Efficient lighting (10.5 kW vs 25 kW) Photo Credit: Marius Lavoie, NRCan

31. Example: Quebec, CanadaVal-des-Monts recreational ice rink (results) • 60% reduction in energy compared with model building code reference rink • 50% reduction in power demand compared with average rink • Power demand and energy savings of $60,000 annually • Greater than 90% reduction in GHG emissions • Mainly due to reduced refrigerant leaksachieved with sealed units andsecondaryloops • Refrigerant charge of 36 kg(vs 500 kg in typical system) • Refrigerant with no impact on ozone layer • Autumn start-up andend-of-season shut downrequire no special skills (where permitted) • Exceptional comfort for spectators

32. RETScreen®Energy Efficient Arena & Supermarket Project Model • Calculates energy savings, life-cyclecosts andgreenhouse gasemissions reductions • For supermarkets & ice rinks • Process integration (waste heat recovery) • Secondary loops to reduce refrigerant losses • Lighting and ceiling improvements • Floating condenser pressure • Ice and concrete slab thickness • Other efficiency measures • Also includes: • Multiple currencies, unit switch, and user tools

33. Conclusions • Cost-effective energy efficiency measures, as well as improvements to refrigeration systems in supermarkets and arenas, can greatly reduce energy consumption and greenhouse gas (GHG) emissions • Through process integration, heat rejected by refrigeration system can satisfy most or all of supermarket/arena heating load and, in certain cases, eliminate fossil-fuel combustion heating systems • RETScreen® calculates energy savings and greenhouse gas emission reductions for a wide range of energy efficiency measures for supermarkets and ice rinks • RETScreen® provides significant preliminary feasibility study cost savings

34. Questions? Energy Efficiency Project Analysisfor Supermarkets and Arenas Module RETScreen® International Clean Energy Project Analysis Course For further information please visit the RETScreen Website at www.retscreen.net