Small Commercial Business Energy Audits Recognizing and addressing the special requirements of the small business market segment.
Class 7 Class 7: Refrigeration Fundamentals The Vapor-compression cycle Factors that affect energy efficiency Basic equipment for the V-C cycle Metrics for refrigeration efficiency
Class 7 Reading Assignment Review
Class 7 Change of State: physical basis of the vapor-compression refrigeration cycle Heat absorbed from environment when change from Solid to liquid Liquid to gas (evaporation) Heat released to the environment when change from Gas to liquid Liquid to solid (freezing)
Class 7 Vapor-Compression Cycle
Class 7 Another view of the V-C Cycle
Class 7 V-C Cycle Reversed: The Heat Pump Outside coil becomes the evaporator, indoor coil the condenser Heat is drawn from the outside and boosted in temperature for heating inside
Class 7 Refrigerants A substance that changes from liquid to gas to liquid at known (and useful) temperature & pressure conditions. Liquid-to-gas change absorbs heat (cools) Gas-to-liquid releases heat Many substances can be used as refrigerants but can pose various hazards.
Class 7 Refrigerants are regulated Refrigerant releases are harmful to the atmosphere. Working with refrigerants is regulated and must be performed by a properly certified technician. Refrigerant safety: http://epa.gov/ozone/snap/refrigerants/safety.html Stationary refrigeration and air-conditioning regulations: http://epa.gov/ozone/title6/608/index.html Phaseout of ozone-depleting substances: http://epa.gov/ozone/title6/phaseout/index.html
Class 7 V-C Cycle Components Compressor Hermetic (sealed) Piston Staged multiple compressors Expansion device Fixed orifice Modulating valve
V-C Cycle Components Class 7 Condenser Air-cooled Water-cooled Evaporative
V-C Cycle Components Class 7 Evaporator Coil inside of refrigerator Refrigerated cabinet Inside coil of room AC unit Mini-split room element
V-C Cycle Class 7 Components: Simulation Exercise Test your knowledge of how the v-c cycle works using SIMUAIR, a simulation application. SIMUAIR simulates two generic versions of light-commercial air conditions systems and provides animated mechanical and electrical schematic diagrams of the system in real time.
Class 7 Refrigeration Efficiency Operating Conditions can significantly affect refrigeration efficiency Refrigerant Charge Air flows Coil Cleanliness
Class 7 Refrigeration Efficiency Under-charge is very common Should be checked regularly by a qualified technician Source; Proctor Engineering
Class 7 Refrigeration Efficiency Operating Conditions can significantly affect refrigeration efficiency Refrigerant Charge Air flows Coil Cleanliness DISCUSSION: HOW WILL THIS KNOWLEDGE AFFECT YOUR PRACTICE IN THE FIELD?
Small Commercial Business Energy Audits Recognizing and addressing the special requirements of the small business market segment.
Class 8 Class 8: Refrigeration EE Types of refrigeration systems & equipment Grocery refrigeration applications & measures Conditions to look for
Class 8 Reading Assignment Review Let s consider a successful program
Class 8 Grocery Refrig Stats Overall Grocery Energy Use Profile Refrigeration Energy Use Breakdown Refrigeration 57%
Class 7 Intro to commercial refrigeration equipment Refrigerated cabinets (reach-in, roll-in) Refrigerated storage rooms (walk-in coolers and freezers, meat processing rooms, wrapped meat storage) Food freezers Display refrigerators (open and closed) Dairy Meat Produce Frozen food/ice cream Refrigerated vending machines (closed-front, glass-front) Ice machines Other (blast chillers and blast freezers, prep tables)
Typical Refrigerated Cabinet Temperatures Refrigerated cabinets Medium-temperature (33 to 41 F) Low-temperature (-10 to 10 F) Display refrigerators Medium-temperature (0 to 40 F) Low-temperature (-40 to 0 F) Walk-in coolers/freezers Medium-temperature (-10 to 30 F) Low-temperature (-20 to -10 F)
Temperature Requirements for food storage Source: 2010 ASHRAE Handbook Refrigeration 21.9
Class 8 Refrigeration Types Self-contained/Standalone VS. Centralized/Remote (ie. Multiplex DX)
Class 8 Self-contained Refrig Units CLOSED DISPLAY CLOSED REACH-IN TYPES OF UNITS, COMMON TERMS OPEN MULTI-DECK OPEN DISPLAY OPEN COFFIN
Class 8 Remote (DX) Refrig Equipment OPEN MULTI-DECK OPEN DISPLAY REACH-IN (ie. CLOSED) MULTI-DECK WALK-IN COOLER OPEN COFFIN REACH-IN MULTIDECK OPEN MULTI-DECK
Class 8 DX System Diagram
Class 8 Advanced Remote Systems
Refrigeration: Simulation Exercise Class 8 Test your knowledge of how a supermarket refrigeration system works using SIMUMKT, a simulation application. SIMUMKT simulates a typical parallel-type multi-evaporator supermarket refrigeration system, and provides animated mechanical and electrical schematic diagrams of the system in real time.
Class 8 Grocery EE - Overview Basic Maintenance & Behavioral Equipment replacement Lower tech measures Higher tech measures Advanced/ extensive measures
Class 8 Basic Maintenance for EE Maintenance Behavioral Clean coils 2x/year Keep doors shut! Replace door gaskets when seal is bad Load items quickly Annual technician servicing Check temp settings
Class 7 Factors that Affect Energy Efficiency in commercial refrigeration Suction pressure groups Cooling load and heat sources Store ambient effect (temperature, humidity, movement of surrounding air) Equipment selection Refrigerator construction Refrigerator sizing Refrigerant selection Refrigerant lines Temperature requirements Cleaning and sanitizing equipment Maintenance and operation
Interaction Between Refrigeration and A/C Systems The ambient store environment temperature and humidity makes a significant difference to the load on refrigerated display cabinets. Humidity in ambient air causes condensation and heat release when it enters the colder cabinet. Then electric anti-sweat heaters turn on.
Class 8 Equipment Upgrades Up to 35% energy savings As short as 1.3 year payback NYSERDA Incentives: ENERGY STAR qualified reach-in glass door refrigerators ENERGY STAR qualified reach-in solid door refrigerators ENERGY STAR qualified reach-in solid door freezers <19 ft³ = $125 19-30 ft³ = $150 31-60 ft³ = $200 61-90 ft³ = $300 <19 ft³ = $75 19-30 ft³ = $100 31-60 ft³ = $150 61-90 ft³ = $225 <19 ft³ = $100 19-30 ft³ = $200 31-60 ft³ = $325 61-90 ft³ = $500
Class 8 Measures: Low-tech CFL lighting in walk-in coolers/freezers. Automatic door closers on walk-in coolers/freezers.
Class 8 Measures: Low-tech Strip Curtains on walk-in coolers/freezers and display cases. Night covers on display cases.
Class 8 Measures: Low-tech Insulate suction lines (for remote condensers)
Class 8 Measures: Medium tech LED case lighting
Class 8 Measures: Medium tech Anti-sweat heater controls
Class 8 Measures: Medium tech Electronically commutated motors & motor controllers
Class 8 Measures: Medium tech Smart defrost controllers
Class 8 Measures: Advanced Floating head/floating suction pressure control
Class 8 Measures: Advanced Glass door retrofit
Class 8 Refrigeration Recap Grocery refrigeration is very energy intensive, with significant financial savings potential Few pre-qualified incentives exist, may add complexity to projects Energy savings range from basic maintenance to advanced retrofits The more in-depth the retrofit, the more effect on the rest of the system (ie. compressors, condensers) Some measures are applicable to standalone equipment AND remote, some only to remote
Small Commercial Business Energy Audits Recognizing and addressing the special requirements of the small business market segment.
Class 9 Class 9: Air-Conditioning SC responsibility for AC Typical AC Equipment based on the Vapor-Compression cycle Room units Rooftop units Efficiency Measures and Programmatic Approach
Class 9 Reading Assignment Review Let s consider a successful program as described in the reading
Class 9 SC Responsibility for AC How can you tell if the client is responsible for their air-conditioning? If it is his/her responsibility, how can you know how much air-conditioning costs during the summer months and as a part of the client s total energy expense? How would knowing the answers to these questions affect your field work?
Class 9 Types of AC Systems The V-C cycle components can be variously configured and assembled
Types of AC Systems Unitary An integrated packaged unit is located in the conditioned space Ducted Cooled air is delivered from a packaged unit, often located on a rooftop (RTU) Direct Expansion ( DX ) Evaporator is located in the conditioned space Central Chiller Chilled water is delivered
Types of AC Systems - Unitary Room units Essentially same as familiar residential unit but in larger sizes Also PTAC - packaged terminal AC plug into wall - usually on SC electric meter Relatively low efficiency and limited control
Types of AC Systems - Unitary EER rated Easy to replace inefficient old units Add control capability for Better temperature regulation Networked control Demand-limiting and Demand Response
Class 7 Terminology for AC Efficiency 1 ton = 12,000 btu 1 kw = 3,410 btu Watts = amps x volts (single phase unit), AxVx1.73 (for 3-phase) Energy Efficiency Ratio (EER) = Refrigeration effect (Btu cooling) / input in watts 1 kw/ton = 12,000 / 1,000 = EER of 12.5 kw/ton = 12,000 / 500 = EER of 24 EER of 6 = 12,000/ 2,000, ie 2 kw/ton Coefficient of Performance (COP) = Refrigeration effect / input in btu 1 kw/ton = 12,000/3,410 = COP of 3.5
Class 7 AC Efficiency: Practice Let s work some practice calculations for energy savings from improved EER or COP Assume a 20 ton system that operates 1,500 hours per year. The existing system has a EER of 8 and we want to replace it with a unit that has an EER of 12. Calculate the savings, first in KW, then in KWH Do the same calculation as above but the new unit is rated as having a COP of 5. Calculate the savings, first in KW, then in KWH.
Types of AC Systems - Ducted Air delivered from a packaged unit located on a rooftop, mechanical room or closet Conditioned air, including ventilation, delivered through ductwork Usually on tenant meter but not always
Types of AC Systems - Ducted Lets take a closer look at typical packaged Rooftop units (RTU) components and function
Types of AC Systems - Ducted Economizer Enables use of outside air instead of running compressor Major energy savings in shoulder seasons Damper operation is often not functioning
Types of AC Systems - Ducted Outside Air Control flip-side of economizer control use minimum OA when heating, mechanically cooling How can this be monitored? Damper positions Watch out for leaky dampers Flow across dampers is not linear with position RA / MA / OA temperatures (more accurate)
Types of AC Systems - Ducted Optimized Start-Stop See if OA dampers can be programmed to close fully during unoccupied periods If so, close OA dampers after occupancy hours Keep OA dampers closed during morning pre-occupancy start-up. This may require re-programming of the controlled start-up sequence.
Types of AC Systems - Ductless DX Refrigerant piping is run to evaporator in conditioned space from remote condenser and compressor split, mini-split, multi-split
Types of AC Systems - Ductless DX VFR The latest, greatest thing - Variable Flow Refrigerant (VFR) Multi-zone with efficiency features Variable frequency compressor control Simultaneous heating & cooling with heat recovery
Program Approaches Maintenance & Adjustment Tune-up Favored for AHU and RTU Replacement equipment Useful for unitary equipment Full systems when renovations planned
Program Approaches Maintenance & Adjustment Tune Up How does this kind of program work? Pre-qualified trade ally provides defined scope of service
EXERCISE: Review of EE for AC units