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Greenbuilt Retrofit Test House

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This document can also be found at https://www.nrel.gov/docs/fy14osti/54009.pdf

One of the homes that was part of Sacramento Municipal Utility District?s (SMUD) Energy
Efficiency Retrofit Demonstration (EERD) project was a 1980?s era home in Fair Oaks, California
, referred to as the Greenbuilt house, as Greenbuilt Construction completed the retrofit
of the home. The home underwent an extensive energy efficiency retrofit with a goal of
achieving a 50% reduction in energy use to demonstrate the potential for other builders and
homeowners in the area. The retrofit measures included installing: ENERGY STAR? appliances; high efficiency lights; roof radiant barrier; additional ceiling and wall insulation; double-pane, low-e windows
; external motorized shading and solar tubes; a 16 SEER/9.75 HSPF heat pump; improved ducts; a whole-house fan; a heat pump water heater (HPWH); integrated collector storage solar water heater (ICS SWH)
; and 3.2 kW of PV. In addition, the home was air sealed to reduce infiltration.

Researchers from the National Renewable Energy Laboratory (NREL) performed short-term tests on the major systems installed as part of the retrofit to ensure that they were performing as expected. The systems evaluated included the space conditioning heat pump, the air handler and ducts, the HPWH, the ICS SWH, and the PV array. Some
ducts were untwisted after testing revealed that two rooms were not getting sufficient airflow. Afterwards, all systems were performing as expected.

In addition to testing to confirm adequate performance of all new systems, NREL was given the
opportunity to use the Greenbuilt house as a laboratory house for a year. The space conditioning
system and home water systems were subjected to a series of tests to determine optimal control
strategies for lowering energy consumption and reducing peak (4:00?7:00 p.m.) energy
consumption during the summer. The different cooling strategies considered included two
different precooling schedules, drawing the external shades during the day and using the whole-
house fan at night, and combinations of those. The most effective strategy for reducing overall
energy consumption was the use of external shades, which cut the daily cooling load by 34% and
reduced the energy use during peak hours by 40%. The different precooling strategies eliminated
the peak load entirely but actually increased daily cooling energy use. The use of shades and the
advanced precooling strategy increased the daily energy use by 5% but eliminated all peak use
and maintained a comfortable home. These results were verified over the entire summer using an
Energy Plus model of the home.

The hot water system was tested in two configurations: the HPWH alone and the ICS solar water
heater paired with the HPWH. Six hot water draw profiles, varying in terms of daily hot water
volume, time of day for hot water use, and the duration of the draws, were imposed on the hot
water system to test their effects on performance. When operating alone in the summer, the
HPWH operated with a COP around 2.2, except for a draw that used a quarter of the averaged
daily hot water usage, which had an average COP of 1.6. The combination of ICS and HPWH
resulted in larger COPs, but also more variability depending on the draw profile. The standard,
hourly draw profile produced the highest COP of 6.4. The quarter volume draw profile had the
lowest COP of 2.8 for the combined system. Relative to a standard electric water heater, the
HPWH operating alone reduced the peak load by 56% and the combined ICS and HPWH system
completely eliminated the peak load.

Citation Formats

paulnorton.net. (2018). Greenbuilt Retrofit Test House [data set]. Retrieved from https://data.openei.org/submissions/4932.
Export Citation to RIS
Norton, Paul, Norton, Paul. Greenbuilt Retrofit Test House. United States: N.p., 27 Aug, 2018. Web. https://data.openei.org/submissions/4932.
Norton, Paul, Norton, Paul. Greenbuilt Retrofit Test House. United States. https://data.openei.org/submissions/4932
Norton, Paul, Norton, Paul. 2018. "Greenbuilt Retrofit Test House". United States. https://data.openei.org/submissions/4932.
@div{oedi_4932, title = {Greenbuilt Retrofit Test House}, author = {Norton, Paul, Norton, Paul.}, abstractNote = {This document can also be found at https://www.nrel.gov/docs/fy14osti/54009.pdf

One of the homes that was part of Sacramento Municipal Utility District?s (SMUD) Energy
Efficiency Retrofit Demonstration (EERD) project was a 1980?s era home in Fair Oaks, California
, referred to as the Greenbuilt house, as Greenbuilt Construction completed the retrofit
of the home. The home underwent an extensive energy efficiency retrofit with a goal of
achieving a 50% reduction in energy use to demonstrate the potential for other builders and
homeowners in the area. The retrofit measures included installing: ENERGY STAR? appliances; high efficiency lights; roof radiant barrier; additional ceiling and wall insulation; double-pane, low-e windows
; external motorized shading and solar tubes; a 16 SEER/9.75 HSPF heat pump; improved ducts; a whole-house fan; a heat pump water heater (HPWH); integrated collector storage solar water heater (ICS SWH)
; and 3.2 kW of PV. In addition, the home was air sealed to reduce infiltration.

Researchers from the National Renewable Energy Laboratory (NREL) performed short-term tests on the major systems installed as part of the retrofit to ensure that they were performing as expected. The systems evaluated included the space conditioning heat pump, the air handler and ducts, the HPWH, the ICS SWH, and the PV array. Some
ducts were untwisted after testing revealed that two rooms were not getting sufficient airflow. Afterwards, all systems were performing as expected.

In addition to testing to confirm adequate performance of all new systems, NREL was given the
opportunity to use the Greenbuilt house as a laboratory house for a year. The space conditioning
system and home water systems were subjected to a series of tests to determine optimal control
strategies for lowering energy consumption and reducing peak (4:00?7:00 p.m.) energy
consumption during the summer. The different cooling strategies considered included two
different precooling schedules, drawing the external shades during the day and using the whole-
house fan at night, and combinations of those. The most effective strategy for reducing overall
energy consumption was the use of external shades, which cut the daily cooling load by 34% and
reduced the energy use during peak hours by 40%. The different precooling strategies eliminated
the peak load entirely but actually increased daily cooling energy use. The use of shades and the
advanced precooling strategy increased the daily energy use by 5% but eliminated all peak use
and maintained a comfortable home. These results were verified over the entire summer using an
Energy Plus model of the home.

The hot water system was tested in two configurations: the HPWH alone and the ICS solar water
heater paired with the HPWH. Six hot water draw profiles, varying in terms of daily hot water
volume, time of day for hot water use, and the duration of the draws, were imposed on the hot
water system to test their effects on performance. When operating alone in the summer, the
HPWH operated with a COP around 2.2, except for a draw that used a quarter of the averaged
daily hot water usage, which had an average COP of 1.6. The combination of ICS and HPWH
resulted in larger COPs, but also more variability depending on the draw profile. The standard,
hourly draw profile produced the highest COP of 6.4. The quarter volume draw profile had the
lowest COP of 2.8 for the combined system. Relative to a standard electric water heater, the
HPWH operating alone reduced the peak load by 56% and the combined ICS and HPWH system
completely eliminated the peak load. }, doi = {}, url = {https://data.openei.org/submissions/4932}, journal = {}, number = , volume = , place = {United States}, year = {2018}, month = {08}}

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Data from Aug 27, 2018

Last updated May 23, 2022

Submitted Aug 27, 2018

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