Field Data Collection of
Single-Variable Smart
Ventilation Control
E. Martin, M. Lubliner
November 2015
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Field Data Collection of Single Variable Smart Ventilation Control
Prepared for:
Building America
Building Technologies Program
Office of Energy Efficiency and Renewable Energy
U.S. Department of Energy
Prepared by:
Eric Martin and Michael Lubliner
Building America Partnership for Improved Residential Construction
1679 Clearlake Rd, Cocoa, FL 32922
November 2015
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i
Contents
List of Figures ............................................................................................................................................. ii
List of Tables .............................................................................................................................................. iii
Definitions ................................................................................................................................................... iv
High-level Summary..................................................................................................................................... i
1 Background ........................................................................................................................................... 1
1.1 Introduction ..........................................................................................................................1
1.2 Cost-Effectiveness ...............................................................................................................1
2
Experimental Plan ................................................................................................................................ 2
2.1 Research Questions ..............................................................................................................2
2.2 Technical Approach .............................................................................................................2
2.2.1 Olympia, WA Test Home ........................................................................................2
2.2.2 Orlando, FL Test Homes..........................................................................................3
2.3 Measurements and Equipment .............................................................................................5
3 Analysis & Reporting ........................................................................................................................... 5
4 Logistics ................................................................................................................................................ 6
References ................................................................................................................................................... 8
Appendix A: STC-1000 Operation Instructions ...................................................................................... 10
Appendix B: VOC Sensor specifications ................................................................................................ 11
Appendix C: Timer Relay Switch for Orlando homes ........................................................................... 13
i
List of Figures
Figure 1. Howard residence, North elevation, from street. .................................................................... 2
Figure 2. Fan controller and outdoor temperature sensor. ................................................................... 3
Figure 3. Standard CFIS system (above) and Aprilaire system (below). .............................................. 4
ii
List of Tables
Table 1. Measurements and Equipment for the Olympia, WA test home. ............................................. 5
Table 2. Measurements and Equipment for the Orlando, FL test homes. ............................................. 5
Table 3. Schedule ........................................................................................................................................ 6
Table 4. Contact Information...................................................................................................................... 6
iii
Definitions
CFIS
Central fan integrated supply
DHP
Ductless heat pump
IAQ
Indoor air quality
TVOC
Total volatile organic compounds
iv
High-level Summary
If this project is successful, what
new knowledge will we have
gained?
Ability of temperature, timer, and occupancy based smart
ventilation controls to reduce space conditioning energy and
improve comfort.
Technologies under test
Whole house mechanical ventilation.
Location(s)
x
Type of home(s)
single-family, detached
multi-family (including single-family, attached, e.g.
duplexes, etc.)
Number of homes
x
Long-term monitoring
x
Short-term testing
Field data needed
(check all that apply)
Surveys or other multi-home statistical information
Equipment provision
NREL assistance requested
Simulation & analysis support
(check all that apply)
Hands-on field assistance
Briefly describe anticipated
collaboration with or assistance
from National Labs other than
NREL
Approximate field test duration
Dec 2015- Feb 2017
Project partner(s)
Meritage Homes, Aprilaire
Climate region(s)
cold/very cold
(check all that apply
hot-dry/mixed-dry
i
x
hot-humid
x
marine
mixed-humid
Any other noteworthy elements
relevant to high-level summary
ii
1 Background
1.1
Introduction
Many new home energy efficiency programs, energy codes and energy retrofit programs have
been required to install ventilation according to ASHRAE Standard 62.2. The most common
method of complying with this requirement is to install continuous or intermittent mechanical
ventilation that runs regardless of outdoor conditions, or regardless of occupancy. However,
outdoor air ventilation impacts space conditioning energy use when outdoor temperature is high
or low, and can impact comfort when outdoor dew point is high. At more extreme outdoor
temperatures stack effect is greater, meaning that natural infiltration is greater and that adding
mechanical ventilation on top of this natural infiltration may, in many cases, result in greater
ventilation than is required. Both installers and residents have expressed concerns about the
energy cost required to condition the ventilation air at severe weather conditions and/or when the
home is not occupied or occupied at various occupancy levels. These concerns have impaired
acceptance of ventilation, by a variety of stakeholders; utilities, code officials, builders and
occupants/homeowners.
Because of these concerns, a ventilation control that accounts for outdoor temperature and or
occupancy is critical. This type of control should provide, at a minimum, equivalent indoor air
quality. In ASHRAE Standard 62.2 equivalent ventilation is defined as resulting in the same
annual dose as operating a ventilation system continuously according to the prescriptive
requirement. To maintain equivalence using a temperature-based control, then, would require an
increase in ventilation rate at mild conditions if the ventilation was reduced at more severe
conditions. In addition to controls based on direct outdoor temperature measurement, there is
also interest in a timer based control that provides a similar functionality by scheduling the
ventilation system to operate at the most opportune outdoor conditions, on a seasonal basis.
Similarly, for occupancy based control, an increase in ventilation rate during occupied conditions
may be required to maintain equivalency if the controller operates the ventilation system at a
reduced rate during unoccupied conditions. Both temperature and/or occupancy control
strategies can reduce the “over”-ventilation at more extreme conditions and or low occupancy
periods while providing better indoor air quality at mild conditions and or higher occupancy
periods, and may represent a win-win scenario: reduced energy use and better year-round indoor
air quality.
This research aims to evaluate various potential control algorithms, estimate potential energy
savings, and perform pilot testing of temperature and occupancy based strategies. The work
described in this test plan focuses on pilot tests. The other aspects of this work, including IAQ
modeling, and acute equivalence impacts, are led by LBNL. Together, various stakeholders are
working with ASHRAE standards to support the authorizing environment approval and general
guidance on smart ventilation controls.
1.2
Cost-Effectiveness
The TBVC prototype control used in this work was purchased for less than $20 and required less
than an hour of electrical work to install. The device is estimated to save on the order of 229
kWh/year (8.5%) of space conditioning energy from EnergyGauge USA modeling. As IAQ
equivalency theory and standards evolve, some reduction of these savings may be required to
1
help limit acute exposure, during long intervals of ventilation system lockout. However, given
the low cost potential of the simple TBVC and modeled energy savings, it appears that a large
potential smart ventilation market may exist given the quick simple paybacks.
2 Experimental Plan
2.1
Research Questions
1. How practical are various algorithms (temperature, timer, occupancy) to implement?
How do prototype controls function in actual field conditions?
2. What are the potential energy savings from these approaches?
3. What is the potential impact on acute indoor air quality equivalency?
2.2
Technical Approach
2.2.1 Olympia, WA Test Home
The Howard residence test house is a two-story, 1,640 square foot historical house located in
Olympia, Washington, shown in Figure 1. It underwent a deep energy retrofit in 2010 that
significantly upgraded the building envelope (R-38/R-49 ceiling, R15/R26 wall, R-30 floor
insulation). Air leakage after the retrofit was measured at just over 5.0 ACH50. Space
conditioning is provided by a 1 ton single head ENERGY STAR (HSPF=12, SEER 25) ductless
heat pump (DHP) with the indoor unit located on the first floor.
Figure 1. Howard residence, North elevation, from street.
Whole house ventilation is provided by the bathroom exhaust fan on the first floor. This is the
fan controlled for the field test. In continuous operation mode, the fan speed is set at 40 CFM, to
comply with ASHRAE Standard 62.2-2013 assuming an infiltration credit based on the blower
door test1. LBNL REGCAP modeling (Less et al., 2015) indicated that a 90 CFM whole house
1
Although this was a retrofitted home, because of the intensive nature of the home changes we
did not use the ASHRAE 62.2 Appendix A: Existing Buildings compliance path that adjusts
whole house ventilation rates if local kitchen and bath exhaust are not 62.2 compliant.
2
fan that cut-out below 57°F would provide the same annualized equivalent ventilation as the 40
CFM fan running continuously.
A thermostat/relay control was installed to control the fan, and is shown in Figure 2 with details
in Appendix A. The outdoor temperature sensor is located on the west side of the house behind
the outdoor unit for the ductless heat pump, which provides shading from direct sunlight.
Figure 2. Fan controller and outdoor temperature sensor.
To estimate the difference in performance and energy use between the two ventilation modes,
weekly flip-flop tests are conducted, during which the ventilation system control is manually
alternated between 40 CFM continuous and the prototype temperature based ventilation control.
This method will enable differential runtime and energy usage to be obtained over a range of
temperatures, and provide sufficient data with each control strategy under similar outdoor
temperature conditions to enable a direct comparison to be made. Energy simulations utilizing
EnergyGauge USA estimate an 8.5% reduction in space conditioning energy with the advanced
control strategy.
Data comparing the temperature based control approach to the conventional approach is
available dating back to April 2015, and data collection will continue until March 2016. During
this data collection period, efforts are underway to identify type and placement of occupancy
control sensors. In addition, equivalency modeling is being undertaken to estimate required fan
flow when operating under occupancy control. Experimental schedule calls for switching from
temperature based to occupancy based control in Quarter 2 2016.
2.2.2 Orlando, FL Test Homes
Meritage Homes builds new homes to Energy Star standards, and initially implemented a central
fan integrated supply (CFIS) whole house ventilation strategy. Runtime of the air handler blower
when operating for heating or cooling is tracked by a controller, and additional runtime to
achieve ASHRAE 62.2 requirements for a given hour is invoked by the controller. In an effort to
1) reduce peak sensible heat impacts of the ventilation air and 2) ensure comfort year round,
Meritage Homes implemented an Aprilaire ventilating dehumidifier with functionality allowing
3
ventilation to be halted when outdoor temperature exceeds 95F. A schematic of the CFIS system
and the Aprilaire system is shown in Figure 3.
Return
Return
Supply
Supply
Figure 3. Standard CFIS system (above) and Aprilaire system (below).
Under normal operation, the ventilation air flow is designed to achieve ASHRAE 62.2 by
running the blower in the Aprilaire unit for a fraction of each hour (approximately 30 mins,
depending on house design). If ventilation is halted for some time due to high outdoor
temperature, daily required outdoor air volume can be made up by running for longer periods in
subsequent hours. The dehumidifier compressor will activate if dew point in the outdoor air
stream is above a given set point, however the dehumidifier compressor will not activate during
cooling operation of the central system.
In order to test the ability to further reduce peak impacts and energy use, Meritage Homes is
interested in implementing a timer based control enabling ventilation to be delivered according
to a pre-determined, seasonal schedule. To start, beginning in December 2015, a winter schedule
will be implemented that seeks to ventilate during the day, when outdoor conditions are warmer.
For example, rather than ventilating for 30 minutes each hour, for 24 hours a day, the control will
schedule the ventilation system to run for 60 minutes each hour, for 12 hours a day, between the
hours of 7am and 7pm. In contrast, the summertime schedule will aim to ventilate during the
evening, when outdoor air conditions are cooler.
4
Bi-weekly flip-flop tests will be conducted, alternating between two weeks with the timer control
and two weeks without. Indoor and outdoor dew point will be monitored to determine if a 12hour cycle is detrimental to comfort or energy use and if summer/winter schedule modifications
are warranted, and also to determine what may be best implemented for a spring/fall schedule.
In addition, a surrogate for indoor air quality, such as CO2 or TVOC2 (Appendix B), will be
monitored to identify potential IAQ impacts of a 12-hour cycle compared to a 24 hour cycle.
As the Aprilaire ventilating dehumidifier does not have a clock control onboard, an external
control will be wired to the 5V contact on the Aprilaire control board that enables blower,
damper, and dehumidifier compressor operation (Appendix C). An Insteon platform has been
chosen, enabling researchers to adjust schedules remotely via the home’s internet connection3.
2.3
Measurements and Equipment
Table 1. Measurements and Equipment for the Olympia, WA test home.
Measurement
Indoor Temperature / Relative Humidity
Outdoor Temperature / Relative Humidity
Vapor Line Temp (Heat Pump Runtime)
Energy
Energy
Carbon Dioxide
Equipment
Onset UX100
Onset Prov2
Onset S-TNB-M017
Onset Split CT’s (100/50 amp)
WattNode Pulse Adapter
Veris CWLSXX
Accuracy
0.38F / 3.5%
0.38F/2.5%
0.36F
1%/0.75%
0.45%
30PPM (2%)
Table 2. Measurements and Equipment for the Orlando, FL test homes.
Measurement
Indoor Temperature / Relative Humidity
Outdoor Temperature / Relative Humidity
Heat Pump/Dehumidifier Runtime
Energy
TVOC
Equipment
Onset UX100
Onset Prov2
Onset UX-90
SiteSage w/ 50amp CT’s
Powerwise
Accuracy
0.38F / 3.5%
0.38F/2.5%
1 min/month
1%
Appendix C
3 Analysis & Reporting
The data collected over a range of outdoor conditions will be separated by control strategy and
runtime, energy use, indoor dew point, and CO2 and/or TVOC will be compared. Best-fit
equations for space conditioning energy versus dependent variables, such as delta temperature,
will be developed and based on a least-squares best-fit regression analysis. Measured data will
be compared to simulations.
In addition to the energy impacts of the control strategies the effort will analyze whether the
ventilation control operated as expected specifically, whether the prototype turns on and off at
the expected temperatures/times/occupancy levels.
2
3
TVOC expressed as ppm CO2 equivalent
https://www.universal-devices.com/residential/isy994i-series/
5
4 Logistics
Detail the field test location and schedule.
What are the major milestones and when will they be completed? Who is in charge of each
milestone? Include applicable go/no-go decision points and any other substantial achievements.
Table 3. Schedule
Milestone
Date
Team Member
Responsible
12//2015
Eric Martin, Mike
Lubliner
Identify two hot humid climate study homes, complete
instrumentation.
12//2015
Eric Martin
Begin occupancy control in Olympia, WA test home
5/2016
Mike Lubliner
Preliminary evaluation of research questions after 8
months data collection.
7/15/2016
Eric Martin, Mike
Lubliner
Go/No-Go Decision #1; Control strategies show
potential for energy savings and no detriment to IAQ
and comfort
7/2016
Eric Martin, Mike
Lubliner
Complete data collection
1/31/2016
Eric Martin, Mike
Lubliner
Draft Report on testing results for review
2/29/2016
Eric Martin, Mike
Lubliner
Approval of experimental plan.
Table 4. Contact Information
Company Name
Team Member
Email
Phone
Florida Solar
Energy Center
Eric Martin
[email protected]
321-638-1450
Washington State
University
Michael Lubliner
[email protected]
360-951-1569
Meritage Homes
CR Herro
[email protected]
480.515.8019
Aprilaire
Scott Grefsheim
[email protected]
608-310-6186
6
For the Orlando, FL test homes, homeowner agreements have been developed and approved by
the University of Central Florida legal department. To incentivize participation, homeowners are
being offered ownership of the Site Sage energy monitoring system at the conclusion of the
study.
7
References
Less, B., Walker, I., and Tang, Y. “Development of an Outdoor Temperature Based Control
Algorithm for Residential Mechanical Ventilation Control.” Lawrence Berkeley National
laboratory, Berkeley, CA.
http://eetd.lbl.gov/sites/all/files/brennan_less_development_of_an_outdoor_temperaturebased_control_algorithm_for_residential_mechanical_ventilation_control.pdf.
8
9
Appendix A: STC-1000 Operation Instructions
10
Appendix B: VOC Sensor specifications
11
12
Appendix C: Timer Relay Switch for Orlando homes
13
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