Connect, Learn and Upgrade

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1 2018 Connect, Learn and Upgrade SPEND THE DAY WITH ENERGY EXPERTS Pegasus AB Best Practices in Chilled Water Optimization and Future Trends Joshua Lewis, CEM, CMVP, Energy Group SNP Technical Services Inc.

2 Educational Goals Describe and characterize DX & Chilled Water systems Discuss individual components of Chilled Water systems and their efficiency & cost impacts Provide a framework for evaluating decisions on new or retrofitted Chilled Water systems Look into the future of Chilled Water in terms of net-zero energy / net-zero carbon Do you know your priorities? Economic (short or long) CO2e Net-zero / Net-zero carbon Innovative / Demonstration

3 There are no absolutely right or wrong answers ONLY CHOICES TO BE CONSIDERED AND EVALUATED TO MEET NEEDS, WANTS, AND DESIRES

4 GOOD CHEAP QUICK PICK 2

5 Life Cycle Cost Analysis Determine the most cost-effective option among alternates (no VE!) Sum of costs, typically discounted to present day (NPV): Purchase Own Operate Maintain Dispose Boundaries and Assumptions of analysis are critical to success Boundaries: Large complicated, Small bias Assumptions: Energy & carbon prices?

6 Background DX Cooling DX = Direct Expansion Refrigerant vapour expansion/compression cycle directly cools the supply air to an occupied space Packaged Systems or Split Systems Advantages include: Less expensive Less infrastructure Targeted installations

7 Background CW Cooling CW = Chilled Water Refrigerant vapour expansion/compression cycle generates cold water that cools the supply air to an occupied space Air cooled or Water cooled systems Advantages include: Less space Contained refrigerant Greater energy efficiency

8 #1 Reason for Chilled Water? Efficiency IPLV is to Chillers what SEER is to DX IPLV assumes 44F loop setpoint Energy efficiency DX: 16 SEER = ~13 EER = ~0.94 kw / Ton CW: kw/ton All-In Value: Chillers + Pumps + Fans NPLV Non-Standard Example: 350 Ton, Air-Cooled Centrifugal (4 circuits) Integrated PLV: kw/ton EER: Typically assumes 55F loop setpoint Also a good indicator if SP varies

9 Example Site - Industrial ~1 million sq. ft contiguous space Nominal production fresh air flow of ~750,000 CFM 19 Hot/Chilled Water units original bldg. ( 94) 24 Gas/DX units L-shaped bldg. expansion ( 99) No known reason for decision Energy + maintenance costs very likely exceeded any initial capital savings Now also facing R-22 obsolescence on the DX units More risk and cost Non-optimal

10 Others Reasons for Chilled Water Reliability and redundancy Virtually unlimited service distance Refrigerant containment Cooling not required in all areas simultaneously Vapour condensation avoidance with loop temp control Is CW perfect? No. Higher initial costs Space requirements

11 Typical System Components Mandatory: Chillers Primary Pumps Distribution Piping Controls & Instrumentation Optional: Cooling Towers + Condenser Pumps Secondary Pumps Free Cooling District Tie-in

12 Chiller Technology Overview The core of the system critical to make the right choice Electrical: Reciprocating, Screw, Scroll, Centrifugal Air or water cooled Natural Gas: Absorption Steam, Hot Water, Exhaust, Direct Fired, Solar (non-fossil) Rotational Reciprocating, Steam & Gas Turbine

13 Chiller Evaluation Parameters Complicated Life cycle cost Ambient temperature Fluid discharge temperature Power source Motor fan type Hot gas bypass Chiller IP rating Noise level COP kw/ton Chiller cooling capacity Internal piping materials Controls Evaporator capacity Number of compressors Service contract and tech availability Evaporator material Type of compressor Global Adjustment Evaporator type Number of refridge. circuits And more.. Condenser material Refrigerant Condenser capacity

14 Electrical Chillers Reciprocating typically small, not often used Screw, Scroll, Centrifugal all can be good choices Starting balance point: < 300T Screw, Scroll. > 300T Centrifugal. Centrifugals can assist in avoiding TSSA regulations related to positive displacement Centrifugals with magnetic bearings have excellent efficiency and reliability with higher initial cost Variable Speed Drives greater part load efficiency IPLV kw / Ton possible Air or Water Cooled

15 Air-Cooled versus Water-Cooled Water-Cooled units are typically more efficient than Air-Cooled but neither is always the right choice Multiple aspects needed to be considered: Efficiency Total system price versus operating cost Site Layout Air-Cooled units require more outdoor space Maintenance & Longevity Water-Cooled units located indoors Water Usage Air-Cooled units avoid water consumption (towers) Chemical Usage Water-Cooled units require more Free Cooling Air-Cooled units have it integrated Operation Water-Cooled risk freezing CTs

16 Natural Gas Chillers - Absorption Generate Cooling with a Heat Source Sources can include: Steam Boiler, CHP, District Hot Water Boiler, CHP, District, Process Exhaust CHP, Process Direct Fired Natural Gas, Biogas Solar No fossil fuel Do you care about GHG emissions? Carbon tax? NG/Electricity $/MMBTU: 7:1 Low Cost

17 Natural Gas Chillers - Rotational Reciprocating Higher efficiency at part load compared to electrical, as low as 30% Heat Recovery - Engine cooling jacket water & exhaust gases for other applications (HVAC, Hot water, ORC) Steam Turbine If superheated steam is available Gas Turbine Rare (CHP) All gas or a mix of electrical and gas to even out energy cost and operational risks Gas is cheap but will it be forever? Economic case NG/CO2e prices, DR, Maintenance

18 Other Chiller Considerations Trim Chiller / Low-Load Chiller Match operational chillers closer to instantaneous system loading Trim / Low-Load unit options, most efficient first (typical): Full-size VSD, Half-size VSD, Half-size fixed speed Heat Recovery Chillers Generate 110F 140F hot water Use heat for space heating, domestic hot water, pool heating need year-round load Lower electrical efficiency will have large impact on decision NG/Electricity $/MMBTU: 7:1

19 Pumps & Distribution Piping Pumps Primary, Secondary, Condenser Boostback Rarely High quality, efficient pumps and motors (Premium) Flow and head should match well to system needs No throttling / triple-duty valves check valves only Inlet strainers recommended large hole diameter Distribution Piping Avoid restrictions, oversizing, and if possible, balancing valves Size for load and system delta-t Insulation!

20 Variable Speed Drives Critical to keep 80 / 50 rule in mind 80% pump flow uses ~50% power Superior energy performance compared to throttling, flow setting, and triple duty valves All system pumps should be VSD driven Other advantages include: Soft-starting reduced surge/hammering Maintenance reduced repairs/longer life DP Chiller & Loop control

21 Common Pump Headers Multiple pumps on common headers Primary, Secondary and Condenser Highly recommended - advantages: Energy efficiency Two or more pumps running slower versus pumps at full speed Reliability Pump failure does not incapacitate other equipment Maintenance Equipment available anytime to service Will have cost impact

22 Primary/Return Bypass Often referred to as a Decoupler loop CW not consumed by loads is blended back into return water Reduces pumping power, optimizes chiller flow Always want to maintain a slightly positive flow (Supply -> Return) Three ways to monitor/control for maximum efficiency: Flow DP Temperature

23 Cooling Towers Consider the options early in design Open (Evaporative) Pros: Efficiency, smaller footprint, initial cost Cons: Water & chemical usage, fouling, maintenance Closed (Heat Exchanger) Pros: Cleanliness, lower water use, integrated FC HX Cons: Higher cost, larger footprint VSDs on CT fans should be standard no 2 speed motors Materials stainless or composite? Fire?

24 Chemical Management Robust chemical program is needed to achieve and maintain efficiency and prevent Legionella Key control variables continuous monitoring: Hardness Chloride Alkalinity ph Conductivity Pre-treatment of make-up make be needed 3 rd party options

25 Filtration Pair with chemicals not an alternative Dirty tubes lead to direct chiller efficiency losses Side steam typically 5% to 15% flow Control: Scale, corrosion, biofilm, dirt, iron oxides, suspended solids Technologies can be combined for maximum efficiency: Vortex Sand Bag / Cartridge Electrostatic / Precipitating Critical on open CTs

26 Load Management Understand your load design around it HVAC Comfort or Process? Humidity? Process Critical or Non-critical? Seasonality Summer or All-year? Baseline versus Variable

27 Valves and End Of Loops Valves 2 way or 3 way? 2 way unless immediate response or mixing is required Incorporate automatic system flush logic on all equipment End of Loops Closed Cheapest, most efficient, risk of stagnation/sediment Open Cheap, lowers efficiency Temp. and/or Pres. Controlled Valve Higher cost, efficient, flexibility PRV Highest cost & maintenance, best installed at pump headers System leg isolation Seasonal

28 Instrumentation Combination of electronic / gauges Typical: Temperature Pressure Differential Pressure Flow Be strategic & cost effective (ex. Inline versus insertion, accuracy) But do not skimp efficiency may suffer Control, monitor, troubleshoot

29 Controls The Importance of Delta-T CW system loop Delta-T has a huge impact on system design, cost, and efficiency: Equipment: Chillers, Loads (Coils/HX), Pump & Piping size Energy: Chiller & Pump energy usage Traditional 10F Modern 15F to 20F Efficiency requires avoiding Low DT Syndrome Causes increased pump / chiller energy usage Hydraulic modelling + controls Delta-T (F) gpm/ton Pump hp

30 Controls Strategies Insist on Demand-Flow operation System is always matching the generation to the demand Demand flow systems have: Variable frequency drives, Pressure/flow sensors, Automatic shutoff vales, Fully integrated controls Demand flow systems constantly monitor kw/ton & optimize: Total flow, Bypass flow, Temperature differentials, Energy usage Differential Pressure control across Chillers barrels & Loop Most chillers can be run at lower flows (~50%) Greater efficiency

31 Controls Loop Control Variables Three primary loop control variables: Schemes and parameters: Delta-T OAT reset Flow Loop temperature Loop supply temperature Condenser temperature Pick 2 scenario General guidelines: Delta-T: Maximize across chillers (15F to 20F) Multiple loop demand variables Adaptive pump speeds / sequencing Equipment cycling / runtime leveling Flow: Optimize within chiller evap. & cond. operational band Temperature: Higher CW EWTs (loop reset)

32 Free Cooling Using CW in the winter? Free Cooling is mandatory! FC typically available when OAT is 2F less than CW SP Eliminates need to run chillers Can be installed on air or water cooled systems Air Integrated into chillers look for partial mode Water Additional heat exchanger between tower/loop and basin heaters may be needed Water systems Need a cooling tower bypass for smooth transitions Use air-side economizers first before FC on air handling units FC must be automatic

33 Chilled Water Storage Operation: Make excess chilled water during off-peak hours & store it Utilize from storage during peak hours Eliminate need to run some or all chillers in the system CW can be made off-peak for HOEP Savings in reduced GA charges due to lower demand during peaks (Class A Only) Compliments Battery Storage systems Ice storage also possible (new systems) High $$$

34 Chilled Water Storage Tank design &construction is straightforward, off the shelf, from water/wastewater industry Prestressed concrete tanks have longest life Can be located underground cost will increase 50% Majority of cost of CWS is the tank balance is piping, pumps & controls Tank is sized based on Cooling ton/hour of storage desired ton/hour tank can supply 2000 tons cooling for 5 hours

35 Chilled Water Storage Peak demand drop (MW), but total energy usage increases (MWh) due to thermodynamic losses Savings realized in GA and lower average hourly MWh rate CWS projects have no SOE incentives (not efficiency) Not likely eligible for demand response permanent shift Can also be used for increasing the peak cooling capacity of a chilled water system and/or emergency backup Avoid purchasing a new chiller Meet demand if chiller is down

36 R-22 Obsolescence R-22 is being depreciated Similar to R-11 / R-12 phase-out in the 1990s Equipment purchased up to 2010 may contain R-22 Chillers and DX Cost per Pound will be huge expensive leaks Drop in replacements are available, but sacrifice efficiency and reliability Best strategy is to replace equipment with newer high-efficiency models Inventory, plan, execute

37 Current / Future Refrigerants Current R-123, R-134a, R-407C, R-410A, R507A Ozone (ODP) was the original problem Global Warming (GWP) is the new problem Next Phase Outs R-123 (2020 no new equipment, 2030 no new production) R-134a, R-407C, R-410A 2024 no new equipment Future issues are flammability, efficiency, and cost 4 th generation R1234ze & yf, R1233zd

38 District Chilled Water Can often be the efficient and most economical choice If available building load management still critical Conventional, Deep Water, or CHP generation Centralized or distributed could you generate revenue? Benefits: Shared loading improved efficiency No equipment on-site, no refrigerants, no maintenance Reliable, redundant, able to use additional load if expanding facility Overall what is the value prop? Steam/HW

39 Future Trends

40 Chiller Ball Cleaning Automatic tube cleaning with foam balls Keep the insides of the chiller like-new Improved efficiency Extended chiller life Reduced downtime for cleaning Reduced cleaning costs Reduced water treatment / chemicals Environmentally friendly Quick installation on existing systems

41 Net-Zero Energy / Net-Zero Carbon The future of building construction & retrofits 47% of respondents in US/Canada expect to have near zero, net-zero, or energy positive buildings in the next 10 years Survey 2018 Zero National Forum Critical to reduce cooling demand before optimizing CW: Building orientation / Shading Assume no NG Tight building envelope Natural ventilation (outside air / earth labyrinth) CO2 on-demand VAV HVAC control Evaporative cooling Geo

42 Chilled Water with Solar Thermal Every ray of sunlight, puff of air, and ground source on your property can be used or wasted Solar Thermal efficiency can be up to 70% than Solar PV Use the solar heat efficiently for: Heating in the winter Cooling in the summer Domestic or process hot water all-year round Not necessarily the first choice Must be balanced against geoexchange Space/heat/kWh

43 Heat Pump Integration No geoexchange? No carbon? Need heat? Water-Sourced Heat Pumps Electrically driven, integrate into net-zero buildings Pair with Chilled Water system District or local Source with deep-lake cooling water in the winter? Efficiency typically highest when there is simultaneous heating & cooling needs More efficient than Air-Sourced

44 Summary There are no absolutely right or wrong answers - Only choices to be considered and evaluated Chilled Water systems offer the most efficient and economic form of cooling in many cases Evaluate decisions on Life Cycle Cost not Value Engineering CW systems, with and without geoexchange, will be a key part of many net-zero buildings Knowing your priorities will be key in setting direction: Economic (short or long) CO2e Net-zero / Net-zero carbon Innovative / Demonstration

45 Conserving Energy Creates New Revenue Streams THANK YOU FOR YOUR ATTENTION