2/19/2014
DCV and Conditioned Energy Recovery
‐Active Fresh Air Control for Passive Living‐
Ben Newell, Alex Long & Ty Newell
Build Equinox
Newell Instruments, Inc.
1103 N High Cross Rd
Urbana, IL 61802
www.buildequinox.com
Demand Control Ventilation (DCV)
•What is it?
•Why do we need it in our homes?
•Introduction to residential DCV fresh air conditioning system characteristics
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Newell Instruments
Two Divisions
Automotive
Appliances
R&D
for Industry
Solutions for a Healthy, Comfortable, and Sustainable Lifestyle
Military Systems
Our solar powered laboratory
Newell Background
‐Renewable Energy
‐Energy Conservation
‐Energy Efficiency
‐Resource Conservation
Grad school 1970’s
Univ of Illinois Solar Lab 1980’s
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2007 Univ of Illinois
Solar Decathlon Team
Located at the
Chicago Center for
Green Technology
…now back home and being refurbished
Objective
Our health, our well‐being and our productivity depend on:
‐Fresh Air
‐Clean Water
‐Nutritious Food
‐Comfort
Constraints
Fresh air, clean water, nutritious food, and comfort must be obtained by sustainable practices if we want these things for future generations
‐Sustainable resources
‐Sustainable energy
‐Sustainable economics
Energy is not the objective
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Equinox House Project
BuildEquinox.com
True “Net Zero” home in Urbana Illinois constructed in 2010
•DCV ventilation system
•8kW solar PV system supplies 100% of house energy plus 100% energy for 6000‐8000miles per year for Ford Focus EV
FocusOnSolar.com
•100% rainwater harvesting system (currently permitted to supply toilet and garden water) for ~40% annual water needs (~10,000 gallons per year)
What About Cost?
Installed cost for solar energy to power 100% of Equinox House energy requirements = $3 per day
(our neighbors average more than twice that with “cheap” utility energy)
Extra insulation cost (~ $20k), offset by building smarter:
‐no natural gas supply = $10k savings
‐no air stratification = no ceiling fans = $2k to $5k savings
‐efficient utility runs = $5k savings
Imported European Modern kitchen cost much more $$
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12 ASHRAE Articles on Sustainable Residence Design
•Wall/roof window design
•Energy to build a house
•Thermal mass
•Lighting & daylighting
•Indoor air quality
•Rainwater harvesting
•Appliances
•Comfort
•Solar energy
BuildEquinox.com
2013‐2014 ASHRAE Presidential theme
Shaping the Next
“…..a critical shift in thinking from a goal of indoor environments that are acceptable to the occupants to those that are truly healthy and productive…” Bill Bahnfleth
2013‐2014 ASHRAE President
February 11, 2014 visit to Equinox House
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Current ASHRAE Debate
• ASHRAE 62.2 (residence ventilation standards committee) ventilation debate
– One group favors higher ventilation as reflected in the current 62.2 – 2013 standards
– Another group advocates reduced pollution generation allowing reduction of ventilation needs
• With DCV systems, no debates are needed
– Ventilate at the level required when required
DCV FRESH AIR Conditioning
What is DCV?
•Demand Controlled Ventilation (DCV) actively senses and manages carbon dioxide and volatile organic compounds (VOC) levels
•“Smart” algorithms can control:
•Heating/cooling/dehumidification
•Energy “recovery”
•Energy efficient defrosting
•“Free” conditioning
•Conditioned air (warm air in winter, cool air in summer) can be delivered to rooms in home
•DCV fresh air conditioning is an alternative to HRV (Heat Recovery Ventilators) and ERV (Energy or Enthalpy Recovery Ventilators)
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History of House Energy
160000
Annual House Energy (kWh) Requirements
•Infiltration 30ACH@50Pa
•No insulation
•Single pane windows
120000
80000
•Infiltration 10ACH@50Pa
•3” insulation
•Storm windows
40000
People Energy
House Energy
•2010 “conventional”
•Infiltration 6ACH@50Pa
•6” insulation
•Energy Star windows
•Respiratory illnesses double over 20 years
•2010 “super”
•Infiltration 0.6ACH@50Pa
•Fresh Air Ventilation
•12” insulation
•Energy Star windows
•People dominated energy loads
0
1920
1950
2010C
2010S
What Do We Want in a House?
Comfort
Healthy Comfort
Sustainable Healthy Comfort Zero Energy Chicken House at our Lab
•Building a “zero energy” house is easy
•A comfortable indoor environment with healthy, fresh air is more important (and more valuable) than energy
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Active Control for Passive Living??
1935 GE Globe Top Refrigerator:
•Manual “on‐off” switch
•10 minutes per day checking and switching = 8 workdays per year (~$1600 labor value)
•Poor control = poor food quality and poor energy efficiency
•Food spoilage, sickness, loss nutritional value
•Modern refrigerator uses $30‐40/yr energy for storing $4000‐$8000/yr of food
Other Examples:
•Manual laundry vs automatic
•Manual dishwashing vs automatic
•Manual hot water vs automatic hot water
•Manual house comfort vs automatic
Our goal is to automatically maintain a high quality indoor air environment in an energy efficient manner
Carbon Dioxide (CO2) Impairs Cognitive Performance
Strongly impairs: Initiative, Information Utilization, Breath of Approach, and Basic Strategy
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Value of Fresh Air
25,000 sqft facility with constant ventilation
120 Employees
Annual Utility ~ $88,000/yr
Annual Payroll ~$6,000,000/yr
Constant ventilation air flow
•Fresh air control would increase employee productivity by $750,000/year by reducing CO2
•1% drop in productivity ~$60,000 per year
•Additional benefit through reduced sick days not included
•Annual utility cost ($88,000/yr) is unaffected
Humans are more valuable than energy!
Active sensing and control of ventilation air flow
CO2 and VOC [ppm]
Pollutant Variation in Homes is Complex
2500
CO2 Sensor
VOC Sensor
2000
1500
1000
500
3/8 12:00 AM
2/26 12:00 AM
2/16 12:00 AM
2/6 12:00 AM
1/27 12:00 AM
1/17 12:00 AM
1/7 12:00 AM
12/28 12:00 AM
0
•Either CO2 or VOCs may dominate a home’s pollutants •Constant ventilation flow = too much or too little air
•Even “good” VOCs (chicken soup) should be flushed to avoid odor absorption
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CO2 Concentration ‐ Constant Flow Venting
<10cfm per person results in all air > 1000ppm CO2
~20cfm per person average air = 1000ppm CO2
100
Data from actual homes
and buildings
% Time
80
60
co2<1000
1000<co2<2000
40
co2>2000
20
0
0
10
20
30
40
50
60
70
80
Ventilation per person (cfm/person)
Indoor Air Quality
Poor indoor air quality impacts:
•Health
•Human Performance
But, how do you know if your air stinks?
Molds, etc
Infiltration
Pesticides, dust, pollen
CO2
Exfiltration
VOC
Germs
H2O
Filtered Ventilation
radon
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Air Quality
% People Dissatisfaction with Odors
You can wait until others tell you it stinks….
45
40
35
30
25
20
High levels of carbon dioxide correlate with
• Increased spread of contagious diseases
•Drowsiness
•Headaches
•Inability to concentrate
15
10
5
0
0
1000
2000
Average Carbon Dioxide and VOC (ppm)
3000
Or, You Can Measure and Control It
Two Factors Affect Air Quality
Pollution generation rates
Fresh air flow rate
DCV control screen photo from Denver PH
FRESH IN
STALE Out
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Concept and initial results presented at 2008 Passive House Conference (Duluth MN)
DCV Development
Laboratory and Field Tests
2008 to current
Three UL certifications:
‐Energy Recovery
‐Heat Pump
‐Power electronics component
UL Certification 2012
DCV
Fresh Air Supply/Exhaust Air
Preferred Duct Design
Exhaust Return from “Wet” Areas
(6 inch diameter typical, uninsulated)
Fresh Air Supply to Living Areas
(6 inch diameter typical, insulated)
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Balance Ventilation Fans
2.5
Panasonic FV Fan Series with 100 feet of Duct
FV10
Pressure Drop ("H2O)
2
•0.5 Watts per cfm
(total fan power)
•Balanced ventilation
FV20
FV30
1.5
FV40
4" duct
1
5" duct
6" duct
0.5
8" duct
10" duct
0
0
200
400
Air Flow (cfm)
600
•Annual fan energy depends on occupancy
•1 person* vent ~ 80kWh/yr
•2 persons vent ~ 160kWh/yr
•4 persons vent ~ 320kWh/yr
* 12 hours/day occupancy per occupant assumed
Cooling Ventilation Mode
•Cools and dehumidifies when beneficial, exchanging energy between fresh air stream and exhaust air stream
•When “fresh air” is nicer than indoor air, maximizes fresh air similar to opening the windows….except it knows to close them when it isn’t so nice
•Unlike an open window, the air is filtered as desired
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Cooling Recirculation Mode
•Additional cooling and dehumidification capacity when desired through recirculation mode….helps maintain uniform air quality and comfort conditions
•Can decide whether the DCV provides as much as it can, or whether it operates only at a level of treating the fresh air
•Equinox House uses DCV and 1 ton mini‐split combo
•Mini‐split AC primarily needed for high occupancy time and exceptionally warm/humid weather
Heating Ventilation/Recirculation Modes
Similar to cooling:
•Heats fresh air when beneficial
•Can provide additional heat if desired through recirculation unifying air quality and comfort
•Energy recovery from frost (during cold weather, 30% of energy exchange is latent)
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DCV Controls
Master Controller
‐secure wireless
(non‐internet)
‐color touchscreen
Remote Vent Switch (battery free)
‐ Optional – kitchen, baths, etc
Full Internet control and monitoring
How Much Ventilation Is Needed?
•Impact of house size?
•Negligible
•Furnishings?
•Important
•People?
•Extremely important
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NI Lab; Urbana IL
3 Employees
4400sqft; 3ACH50
Setpoint = 1100ppm
Equinox House; Urbana IL
2 Occupants
2100sqft; 0.6ACH50
Setpoint = 900ppm
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Gable House; Champaign IL
No Occupants
500sqft; 0.6ACH50
Setpoint = 1100ppm
Denver Passive House
2 Occupants
4000sqft; 0.5ACH50
Setpoint = 1050ppm
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Vermont Residence
4 Occupants
2000sqft; 1‐2ACH50
Setpoint = 2000ppm
MH1 – Vermont
Model Home
1000sqft; 1ACH50
Setpoint = 1000ppm
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MH2 – Vermont
1 Occupant
1000sqft; 1ACH50
Setpoint = 1000ppm
MH4 – Vermont
3 Occupants
1000sqft; 1ACH50
Setpoint = 1000ppm
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Energy & Moisture Impacts
How does a DCV’s energy characteristics compare to basic HRV and ERV systems?
How is house moisture affected?
DCV Fresh Air Heating Data
Total CERV Power
~200cfm air flow
‐Gross heat = 4.1kW
(35.5F to 100.2F)
‐Net heat = 2.1kW
(67.2F to 100.2F)
Exhaust Air from Inside, 67.2F
Room Temperature & Humidity
(21C = 70F)
Exhaust Air to Outside, 36.7F
“Vent Heat”
Conditioned Fresh Air to Inside, 100.2F
Fresh Air from Outside, 35.5F
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Equinox House Monthly Energy (kWh)
Jan 2012 – Dec 2012
Equinox 2012 Electrical Energy Usage (kWh)
RainPump
Dishwasher
ClothesDryer
HPWH
Heat PumpAC
1200
1000
KitchRecept
MainLight
Fridge
EV
Cooktop
DblOven
Sub‐Panel
CERV
Equinox House
800
600
400
200
FocusOnSolar.com
Dec‐12
Nov‐12
Oct‐12
Sep‐12
Aug‐12
Jul‐12
Jun‐12
May‐12
Apr‐12
Mar‐12
Feb‐12
Jan‐12
0
Summer Moisture – Equinox House
Condensate Summer 2011
900
CERV Summer 2011
800
HPWH Summer 2011
•800 liters of water removed from house to maintain humidity less than 60‐65%rh
•Mini‐split highest capacity
•DCV system and heat pump water heater contribute significant amounts
Dehum Summer 2011
600
Total Water Summer 2011
500
400
300
200
100
10/24/2011
10/4/2011
9/14/2011
8/25/2011
8/5/2011
7/16/2011
6/26/2011
6/6/2011
5/17/2011
0
4/27/2011
Condensate (liters)
700
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Winter Moisture – Equinox House
2011‐12 Winter HPWH Condensate and CERV Defrost
450
HPWH Winter 2011/12
CERV Defrost Winter 2011/12
350
450 liters of DCV condensate ~300kWh of heat input to house
300
250
200
150
100
50
5/21/2012
4/1/2012
2/11/2012
12/23/2011
11/3/2011
0
9/14/2011
Condensate or Defrost (liters)
400
Is the Highest HRV Efficiency
Always Best?
Example House
•4 Occupants
•Denver
•2000sqft
•R48 walls and roof
•Heat pump & AC
•200W base electric
•50W/person electric
•Heat Pump Water Heater
•200sqft S window
•50sqft E & W windows
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Annual Electric (kWh) vs
HRV Efficiency
12000
ZEROs™ simulation model results
10000
8000
6000
4000
2000
HRV Efficiency
CERV
Opt
0
10
20
30
40
50
60
70
80
90
0
DCV controls know when it is “nicer” outside than inside and knows when it is more energy efficient to ventilate
Optimal HRV Efficiency
•Only 3 months (Jan, Feb, Dec) benefit from the highest HRV efficiency
•Other months benefit from outdoor air without energy exchange
•DCV system knows when it is “nicer” outside than inside
100
Optimal HRV Efficiency
90
80
70
60
50
40
30
20
10
0
1
2
3
4
5
6
7
8
9
10
11
12
Month (January = 1)
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DCV/HRV/ERV
10000
•2000sqft home
Urbana 4 People •0.6ACH@50Pa
Urbana 2 People •R48 wall/roof
•DCV pollution setpoints
(CO2 and VOC) = 900ppm
•HRV = 90% with 0.7W/cfm; 120cfm
9000
•ERV = 80% heat and 60% moisture with 0.7W/cfm, 120cfm
8000
•NOTE: HRV & ERV results assume someone knows how to properly control ventilation air flow
7000
6000
•No HRV/ERV pre‐heat frost prevention assumed
5000
CERV
HRV
ERV
Annual Energy Trends – DCV/HRV/ERV
Each case will vary by house design, occupancy and location
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Thank you!
DCV fresh air conditioning is an energy efficient means to ensure a healthy indoor environment under the highly varying conditions in a home
•Automated monitoring frees occupants from continual adjustment and programming of a home’s ventilation schedule
•Active sensing and control of carbon dioxide and VOCs maintains excellent indoor air quality in an energy efficient manner
•Conditioned air delivered throughout a home improves overall house comfort
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