new design tools and controls for loadshifting - with radiant systems … · 2019. 10. 29. ·...
TRANSCRIPT
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New design tools and controls for load-shifting with radiant systems
Paul Raftery, Carlos Duarte, Fred Bauman & Stefano Schiavon
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2 Oct 2019
Acknowledgments
CBEß Stefano Schiavonß Carlos Duarteß Jonathan Woolleyß Jovan Pantelic
EPFLß Caroline Karmann
Taylor Engineeringß Hwakong Cheng
TRC Energy Servicesß Gwelen Paliagaß Jingjuan (Dove) Feng
New Buildings Instituteß Cathy Higgins
ARTIC, Anaheim ↑David Brower, Berkeley ↗SMUD, Sacramento →IDeAs Z2, San Jose ↘Delta HQ, Fremont ↓
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3 Oct 2019
Overview
Objectiveß Develop new controls for high
thermal mass radiant systems
Approachß Interview expertsß Review controls and trend data
from existing buildings ß Develop new controls and
iteratively test in simulation ß Demonstrate in two buildings
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4 Oct 2019
Interviews with designers
ß Interviewed 11 prominent professionals who have designed over 330 radiant cooled buildings
Findingsß Generally a wide diversity of design and
control solutions - reveals opportunities for standardization and improvement
ß Very rarely leverage thermal mass to shift load.
Example results: Radiant zone control device
How do you control radiant zones? #Two position zone valves 6Modulating zone valves 4Pumps with 3-way control valves at the zone 3
Constant speed pump 1Variable speed pump 1
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5 Oct 2019
Trend data from a radiant building (in July)
23 °C 73 °F
27 °C81 °F
Peak building demandPeak electricity pricesWarmest outside temperatures
Noon Noon NoonNoonNoon
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6 Oct 2019
Motivation
How can we help designers benefit from the load shifting potential
of radiant systems?
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7 Oct 2019
Simulation results: Common control strategy
Results from a single zone energy simulation on the cooling design day.
Conditionsß Variable flowß Constant temperature
(18 °C | 64 °F) ß Modulating valves
0.5 °C (1 °F) band
Advantagesß Simple, familiar controls
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8 Oct 2019
Effect of different operating times
Conditionsß Constant temperature
(18 °C | 64 °F)ß Constant flow
(two position valves)ß Constant duration of
operation (9 hours)ß Varying time of operation
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9 Oct 2019
Conditionsß Constant temperature
(18 °C | 64 °F)ß Constant flow
(two position valves)ß Constant duration of
operation (9 hours)ß Varying time of operation
Resultß Can maintain comfort
regardless of time of operation
Effect of different operating times
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10 Oct 2019
Design/operation possibilities: Afternoon shutoff
Conditionsß Constant temperature ß Constant flow (on/off valves)ß Operates during the morning
and early afternoon
Advantagesß More uniform daily comfort
conditionsß Reduces peak energy chargesß Avoids building peak demand
charges
0.9 °C | 1.7 °F
Less variation than simple proportional controller
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11 Oct 2019
Design/operation possibilities: Daytime shutoff
Conditionsß Constant temperature ß Constant flow (on/off valves)ß Operates only during the night
Advantagesß Low energy chargesß No demand chargesß Chilled water plant operates at
night, when dry- and wet-bulb temperatures are lowest
2.2 °C | 3.9 °F
More variation
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12 Oct 2019
Design/operation possibilities: Constant flow
Conditionsß Constant supply temperature 4
°F higher than previous cases: 68 °F (20 °C)
ß Operates 24 hours per day
Advantagesß Low peak plant loadß Small chiller, low initial costß High supply water
temperatures
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13 Oct 2019
Controls for radiant systems
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14 Oct 2019
Overview of the controls (sequences publicly available)
ß First loop responds to slab temperature and controls the radiant zone valve
ß Second control loop adjusts slab setpoint once per day based on previous day’s zone conditions.
ß Choose enabled time period each day. Radiant system is disabled at all other times.
ß Heating or cooling mode separated by at least one day
ß Supplemental zone cooling/heating systems:ß Prioritizes radiant systemß Limits systems operating in opposing
heating/cooling modes on the same day
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Zone valve controller Slab
Slab temp
Zone loads
Error
Slabsetpoint
Proportional controller
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+
Comfortsetpoint
Error
Peak daily air temp
Preferred: Pulsed flowAlternate: Open/close
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15 Oct 2019
Example cooling day operation from field study demonstration
ErrorIndoor air max
Reset slab SP atend of occupied hours
Indoor airSlabSlab setpointManifold valve
Comfort boundsSafety factor
Occupied periodEnabled period
80
75
70Te
mpe
ratu
re[°
F]
Off
On
0:00 6:00 12:00 18:00 0:00 0:006:00 12:00 18:00
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16 Oct 2019
Example thermal comfort comparison in one zone
8 16Hour
Baseline Intervention
8 16
78°F
70°F
Daily air temperature profiles
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17 Oct 2019
Example thermal comfort comparison in one zone
0.94°F
0.47°F
Average day-to-day variability
Intervention
8 16 8 16
78°F
70°F
Hour
Baseline
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18 Oct 2019
8 16 8 16
78°F
70°F
Example thermal comfort comparison in one zone
12.3% 0.6%
InterventionExceedance percentage of total occupied hours
Hour
Baseline
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19 Oct 2019
Sacramento Municipal Utility District East Campus Operations Center (SMUD)
ß Five story, 200K ft2
ß LEED Platinumß Low WWR and well shadedß Single tenant; 900 occupantsß Sacramento, CA
ß Cooling season weathersummary 2017-2019ß Max: 111°F ß Daily averages
• Mean: 74°F | Range: 30°F• Day-to-day variability: 2.7°F
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20 Oct 2019
Baseline Intervention
Group A and B zones cool whenever
needed during the day or night
Group A zones cool only from morning to early
afternoon
Group B zones cool only during the night
ß Baseline: May – Nov 2017ß Controls implemented in Siemens
Apogee systemß Split zones into two groupsß Intervention: May – Nov 2018ß Compared results
Tested new control sequences
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21 Oct 2019
SMUD radiant system thermal comfort performance in all zones
Variability: 0.42°FGroup A: 0.46°FGroup B: 0.35°FExceedance: 8.9%
Variability: 0.29°FGroup A: 0.28°FGroup B: 0.30°FExceedance: 1.1%
Baseline Intervention
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22 Oct 2019
SMUD radiant system zone performance
Radiant system operationß Proxy for pump consumptionß Actuated far less timeß Daily average ON time
• Baseline: 2-4 hours• Intervention: 0.5 - 1 hour
ß Some days does not turn on at allMorning &Afternoon
Night
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23 Oct 2019
Resources
Please share, use and give us feedback.
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24 Oct 2019
Free webtool (steady-state performance): radiant.cbe.berkeley.edu
Applications:ß Heating and coolingß Floor and ceiling systemsß Radiant systems with and without
insulation and/or surface coveringsß Metric and I-P units
Calculates:ß Steady-state capacity (ISO 11855)ß Number of circuits, pipe length and
pressure drop
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25 Oct 2019
Free webtool (transient performance): radiant.cbe.berkeley.edu
ß Transient results from over 2.5 million simulations
ß 13 user selectable design parameters incl. time and duration of operation
Outputsß 24-hour cooling day
design valuesß Surface heat fluxß Hydronic heat capacityß Operative temperature
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26 Oct 2019
Controls publicly available in resources: radiant.cbe.berkeley.edu
ß Sequences of operation available
ß English language, editable Word document
ß Can be implemented in existing automation systems
ß EnergyPlus examples available
ß Available as a measure in OpenStudio
Resources
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27 Oct 2019
Design concept leveraging thermal storage
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28 Oct 2019
Example design concept leveraging thermal mass
Daytime (45-60 °F water)
Night-time (60-68 °F water)
ß All-electric: Air (or ground) source heat pump for heating and cooling
ß Dedicated outside air system (DOAS) and radiant can operate at different times and different temperatures, using the same heat pump
ß Reduced design capacityß Closed circuit cooling
tower (fluid cooler) for economizer operation
80-90% of annual radiant cooling
~50% of annual DOAS cooling
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29 Oct 2019
Closing remarks
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30 Oct 2019
Annual grid greenhouse gas emissions
Source: Recurve.
When solar panels generate power.
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31 Oct 2019
Need for energy storage
ß Getting the storage we need to make the grid renewable is a huge challenge.
ß Storing energy in concrete is as cheap and easy as it’s going to get.
Source: Recurve.
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32 Oct 2019
New HVAC designs should leverage inherent thermal storage
in buildings.
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33 Oct 2019
Questions?
Paul [email protected]
New design tools and controls for load-shifting with radiant systemsAcknowledgments OverviewInterviews with designersTrend data from a radiant building (in July)Motivation��How can we help designers �benefit from the load shifting potential�of radiant systems?�Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12��Controls for radiant systemsOverview of the controls (sequences publicly available)Example cooling day operation from field study demonstrationExample thermal comfort comparison in one zoneExample thermal comfort comparison in one zoneExample thermal comfort comparison in one zoneSacramento Municipal Utility District East Campus Operations Center (SMUD)Tested new control sequencesSMUD radiant system thermal comfort performance in all zonesSMUD radiant system zone performance�Resources��Please share, use and give us feedback.Free webtool (steady-state performance): radiant.cbe.berkeley.eduFree webtool (transient performance): radiant.cbe.berkeley.eduControls publicly available in resources: radiant.cbe.berkeley.edu��Design concept leveraging thermal storage��Slide Number 28Closing remarksSlide Number 30Slide Number 31��New HVAC designs should �leverage inherent thermal storage�in buildings.��Questions?