1 Water and Space Heating Nonresidential HVAC Stakeholder Meeting #2 California Statewide Utility Codes and Standards Program Heschong Mahone Group, Inc. Portland Energy Conservation, Inc. CTG Energetics Taylor Engineering December 9, 2010
2 ACM Update-Water & Space Heating, VRF Summary of current code requirements Typical practice Summary of code change proposals Data/findings Specifics of code change proposals Remaining data collection and analysis Specific stakeholder requests
Current Code Requirements 3 ACM for Hydronic Space Heating Distribution pipe heat loss Different methods for DHW and Hydronic heating pipe loss included in boiler efficiency calculated as AFUE Very limited capabilities of modeling controls Hydronic heating modelling optional capability
Current Code Requirements 4 Standard Design for Hydronic Space Heating Res hydronic heating system compared to central furnace with duct loss Air Dis Table R3-1 Summary of Standard Design HVAC System Proposed Design Standard Design Heating System Cooling System Heating System Cooling System Detailed Specifications Through-the-wall heat pump Gas wall furnace with our without ducts and/or circulation fan Any other electric heat including electric resistance, water source heat pump, etc. Any Any Same equipment as proposed design with no air distribution ducts Same equipment as proposed design with no air distribution ducts Split system AC with air distribution ducts Split system heat pump with air distribution ducts All other gas heating Any Split system air conditioner with gas furnace and air distribution ducts. Equipment efficiency determined by CEC Appliance Efficiency Regulations SEER per Package D Verified refrigerant charge (prescriptive requirement) No credit for sizing No credit for cooling coil airflow No credit for reduced fan power Note: The standard design cooling system is also used for the proposed design if the proposed design has no air conditioning
Current Code Requirements Standard Design for Hydronic Space Heating N Res hydronic heating system compared to 4-pipes fan coil system with duct loss 5
Current Code Requirements 6 VRF technologies not recognized by ACMs Treated as heat pump with minimum compliance efficiency Waived from federal testing requirements
Typical Practice 7 Hydronic heating, including combined hydronic heating, are used in MF and in nonres. Buildings (18% in Low Rise, 7% in High Rise according to PG&E California Multi-Family New Homes program) DHW and hydronic system control technologies are commonly used VRF technologies have relatively low market share; they have high part-load efficiencies and have no duct losses
Code Change Proposal #1 8 Distribution Pipe Heat Loss Hourly pipe heat loss calculation Consistency DHW and Hydronics Space Heating Algorithms for controls Temperature modulation Flow variation Default distribution system layout Hydronic system fuel consumption calculation
Data / Findings PIER DHW Research 9 In-depth understanding of central DHW distribution system based on field performance study of 30+ MF buildings Monitoring of HW & CW flows, temperatures, and pressures; gas flows System controls study and cool down tests System heat balance and energy flow analysis DHW recirculation loop modeling 30% Water Heater Losses Recirculation Loop Losses 30% Branch Losses* Distribution Losses End-Use Energy Include pipe inside and outside of dwelling units
Data / Findings Pipe Heat Loss Model 10 System model includes two heat transfer modes with consideration of transition Pipe heat transfer with HW flow UA, water temp & flow, ambient temp Pipe without HW flow - cool down UA and pipe/water thermal capacity
Data / Findings Model Validation Based on actual building DHW recirculation loop configurations Compare modeled vs. measured HWR Temp, and energy losses 11 1 1 2 2 3 3 4 4 6 5 6 5 7 7 8 12 13 10 11 12 9 8 10 9 11
Data / Findings Model Validation 12 Control type Measured Data (Btu/day) Model Results (Btu/day) %Difference Continuous Pumping Temperature Modulation Timer Demand control 639732 643487 0.6% 633433 616266-2.7% 600803 562822-6.3% 411903 453556 10.1%
Specifics of Code Change Proposals Distribution pipe heat loss Existing DHW ACM 13 Hourly Adjusted Recovery Load Hourly Standard End Use Distribution Loss Multiplier Solar Savings Multiplier Hourly Recirculation Distri. Loss Hourly Jacket Loss Implement monthly variation Inside dwelling unit: Proposed Improvement DLM k =1 + (SDLM k -1)*DSM k DSM k =1 for MF SSM k should be applied to HRDL k as well; however, it depends on how SSF is rated Recirculation Loop Plumbing layout based on building geometry HW Draw patterns; or HW flow rates for hydronic heating HW temp: 135F for HW; vary for hydronic heating & Control Branch Depend on HSEU k should be a multiplier to HSEU k Modify DLM k to include heat loss from branches outside of dwelling unit
Specifics of Code Change Proposals Proposed Recirculation Distribution Pipe Heat Loss Assess hourly average pipe temperature to calculate heat loss - Replace the table of UL with explicit calculation 14 Hourly average water temperature for pipe section, n Hourly ambient temperature for pipe section, n Average pipe temperature is weighted between two modes, which depend on control schedule Weighting factor depending on control schedule Average water temperature during pump-off period Each control strategy has a 24-hour schedule Average water temperature during pump-on period
Specifics of Code Change Proposals Continuous Pumping Hour p Pump off Time T S T S With cont. monitoring p TIMER Pump off Time T S p DEMAND CONTROL Pump off Time T S p TEMPERATURE MODULATION Pump off Time T S T S With cont. monitoring 15 1 1 2 135 0 0 110 110 2 1 3 135 0 0 110 110 3 1 4 135 0 0 110 110 4 1 5 135 0 0 110 110 5 1 6 135 0 0 120 120 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 1 1 135 0 0 120 120
Specifics of Code Change Proposals Current ACM requires user input of pipe length for three pipe sections Proposed changes Supply and return each has three sections Unconditioned, conditioned, (semi-conditioned), underground, Return pipes behave dramatically different from supply pipes under controls ACM generate default system layout to check/adjust user input (details to be discussed after ACM algorithms) 16 Boiler Room Supply Return n=1 n=2 n=3 n=6 n=5 n=4 CA Hydronics Utilities 2013 heating Title and 24 Stakeholder Central DHW Meeting ACM update for Proposed Code Changes 12/13/2010
Specifics of Code Change Proposals Recirculation Distribution System Pipe Layout 17 USER INPUT Building Story, floor area Number of apartment/guest room Boiler room Location Number of Loops Supply and Return Loop section locations and length Use user input Reasonable Input Validation Adjust user input Unreasonable ACM Generate Default Loop Configuration Recirculation loop path Branch length and number Pipe diameters (Follow UPC) Pipe insulation thickness High Rise Low Rise Recirculation pipes at different levels All recirculation pipes in the same level Calculate Default Pipe Length
Specifics of Code Change Proposals 50 Section #1 10 Uncondition ed Space- Bottom Level Section #1 User Inputs A 100 2 stories 2 loops Supply Recirculation Pipe Section #2 Section #3 30 / Conditione d Space- Bottom LeveL / Return Recirculation Pipe Section #2 Section #3 Example 1: Low Rise Generate ACM Default Total Length < 85% of ACM Default? No Keep user input Yes Adjust user input 50 ACM Default Loop 1 Loop 2 100 A Supply Return Loop 1 35 ft 35 ft Loop 2 35 ft 35 ft Total 140 ft Branch number / length 18 30 Conditioned Space- Bottom Level 10 / Unconditio ned Space- Bottom LeveL / Option 1: Increase total length to ACM default Option 2: Increase branch length
Specifics of Code Change Proposals User Inputs Example 2: High Rise Generate ACM Default ACM Default Ceiling level 3 19 Section #1 10 Uncondition ed Space- Bottom Level Section #1 30 4 stories / 2 loops Supply Recirculation Pipe Section #2 Section #3 30 / Conditione d Space- Middle Level / Return Recirculation Pipe Section #2 Section #3 10 / Total Length < 85% of ACM Default? No Keep user input Yes Adjust user input Loop 1 Loop 2 A Supply Ceiling level 2 Return Loop 1 80 ft 80 ft Loop 2 80 ft 80 ft Total 320 ft Branch number / length Conditioned Space-Top Level Uncondition ed Space- Bottom Level / Option 1: Increase total length to ACM default Option 2: Increase branch length
Specifics of Code Change Proposals Default Pipe Sizing Based on IAPMO Uniform Plumbing Code Maximum water velocity limit of 5 ft/s determines sizing # of Dwelling Units Line Size 1 0.75 2 1 3 4 1.25 5 7 1.5 8 20 2 21 42 2.5 43 67 3 68 100 3.5 101 144 4 20
Data / Findings - Branch Model 21 SDLM expand current ACM formula to include heat loss from all branches and twigs SDLM has two components; correlate both to HSEU k Pipe heat loss during usage = (GPH k /Num branch ) Cp T branch T branch = 0.25F [Insulated Pipe] or 1F [Uninsulated Pipe] Water waste = Num Wait Cp (f wait Vol branch ) (T supply,branch -T coldwater ) Num Wait : to be determined based on NREL HW draw event tool f wait : multiplier reflecting the effects of flow mixing + extra waiting
Specifics of Code Change Proposals For hydronic heating, pipe loss in conditioned spaces contributes to space heating Only consider pipe loss in unconditioned space Return pipe starting temperature: 22 Temperature and flow controls can be modeled similar to DHW controls Supply T S,end Conditioned Space HourlyLoad T R,start Return
Proposed Existing Water & Spacing Heating, VRF Specifics of Code Change Proposals Hydronic system fuel consumption calculation Water heater efficiency Effective AFUE: Accounting for pipe losses AFUE: Boiler/water heater efficiency converted in AFUE PL: Hourly pipe loss rate, calculated based on annual estimates using heat transfer equation RI: rated input of the gas water heater 23 Water heater gas consumption FurnFuel: Hourly water heater/boiler gas consumption NetHLoad: Hourly space heating load Hourly distribution pipe loss rate, calculated with the new methodology
Code Change Proposal #2 24 Space Heating Standard Design for Gas Heating Air Dis Table R3-1 Summary of Standard Design HVAC System Proposed Design Standard Design Heating System Cooling System Heating System Cooling System Detailed Specifications Through-the-wall heat pump Gas wall furnace with our without ducts and/or circulation fan Any other electric heat including electric resistance, water source heat pump, etc. Any Any Same equipment as proposed design with no air distribution ducts Same equipment as proposed design with no air distribution ducts Split system AC with air distribution ducts Split system heat pump with air distribution ducts All other gas heating Any Split system air conditioner with gas furnace and air distribution ducts. Equipment efficiency determined by CEC Appliance Efficiency Regulations SEER per Package D Verified refrigerant charge (prescriptive requirement) No credit for sizing No credit for cooling coil airflow No credit for reduced fan power Note: The standard design cooling system is also used for the proposed design if the proposed design has no air conditioning Proposed Design Standard Design Gas wall furnace with or without ducts and/or circulation fan Hydronic Heating All other gas heating Current Same equipment as proposed design w/o air distribution ducts Split system air conditioner with gas furnace and air distribution ducts. Proposed Fan assisted wall furnace w/o air distribution ducts Standard design hydronic system (TBD, w/o air distribution duct loss) Same as current
Data / Findings Potential Standard Designs Central System hydronic heating with baseboard/radiator - no ventilation/no fan hydronic heating with baseboard/radiator w/ fan assisted circulation - no ventilation/no fan hydronic heating with baseboard/radiator - 2 pipe fan-coil system for AC hydronic heating with baseboard/radiator - 4 pipe fan-coil system Combined hydronic heating - pipe and WH efficiency RTU/split AC system with central furnace Distributed system Fan assisted furnace Gravity based furnace 25
Data / Findings Standard Designs 26 Central DHW distribution plumbing designs baseline distribution system design Distributed systems : Fan Wall furnace
Code Change Proposal #3 27 Introduce VRF modelling capability in ACM Validate manufacturer proposed models
Data / Findings VRF 28 VRF model developed by EnergySoft for: Mitsubishi Daikin Sanyo LG Proposed Compliance Option submitted by manufacturers VRF model can be validated by certified test data using AHRI 1230
Remaining Data Collection and Analysis 29 Pipe distribution heat loss Refine branch heat loss model Perform energy savings analysis Hydronic heating standard design Survey hydronic heating design practices Cost effectiveness study of different design options Cost effectiveness study of fan-type wall furnace vs. gravity-type wall furnace Market penetration study of hydronic heating, combined hydronic heating, and wall furnace heating systems VRF validation procedure
Specific Stakeholder Requests 30 Hydronic heating system design practice Market penetration of wall furnace and hydronics heating, including combined hydronics Test Data from VRF manufacturers
31 Water & Space Heating, VRF? QUESTIONS & COMMENTS