If you’re new
here, welcome! To catch you up to speed, our new set of occupants moved in at
the end of August.
This next set
of data compares the home’s performance during unoccupied and occupied months. When
we look at the non-occupancy months from May to July compared to when the pair
of occupants moved in at the end of August, we notice the following:
· Appliance
energy was down 62% during the non-occupancy months, almost entirely due to
having no laundry energy. There also was 115kWh over three months of
refrigerator load, which is about as low as you could ever get since it wasn’t
opened during that time. Thus, 140kWh in three months is about as low as
you can get for appliances with their standby.
· Miscellaneous
loads (other receptacles) still have 112 kWh of energy consumption in three
months. This is lower than last year, but a nontrivial amount of energy for essentially
standby loads and iPad chargers.
· Overall,
we usually have surplus energy in summer months because of the good solar
exposure. Last year we had 1610kWh of surplus and this year there was
2351kWh of surplus.
To
access the data, click Downloads -> Performance Data -> APR ‘20 to
SEPT ‘20 above to download a compressed file. Be sure to review the README file
for a thorough explanation of how to use the Data Viewer and Channel Parser
we’ve built.
Future zero net energy homes could look a lot like the Honda Smart Home US, with renewable energy powering both the home and personal mobility. The home’s design considers all facets of sustainability, including water, materials, occupant health, and energy. Check out what the Honda Smart Home US has taught us about sustainable construction and design.
Greetings
from Honda Smart Home! We hope you are staying healthy and safe.
There
have been a few changes around here since our last blog post. New occupants
moved into the home in September, and as a result, we’ve noticed some
interesting changes in the data. This could be attributed to the fact that the
new occupants are a family of three whereas the previous occupants were two
single people who may have spent more time outside of the home.
In
this six-month data installment, here are some key observations when comparing
the current data set to the data from the same time period a year ago:
·
Lighting energy up 36%
·
Appliance energy up 64%
·
Miscellaneous energy up 75%
·
Two times more hot water use for the master shower
To
check out this next six month data release, which covers October 2019 to March
2020, click Downloads -> Performance Data -> OCT ‘19 to
MARCH ‘20 above to download a compressed file. Be sure to review the
README file for a thorough explanation of how to use the Data Viewer and
Channel Parser we’ve built.
When we launched the Honda Smart Home in 2013 as a “living laboratory,” we knew we were literally breaking new ground with a bevy of environmental technologies, some of them very experimental. Now that we have multiple years of data from the 230+ sensors built into the home along with feedback from three sets of unique occupants, we’ve learned a great deal about how these systems perform in real-world situations. So let me share with you the top five things we’ve learned about the zero-net energy Honda Smart Home.
In the ground beneath Honda Smart Home’s backyard, eight 20-foot deep boreholes allow a geothermal heat pump to harness the ground’s relatively stable thermal sink to heat and cool the home’s floors and ceiling throughout the year. These borehole heat exchangers have been working pretty well. However, their actual capacity is a bit lower than we expected. The dry bores – 2’ diameter by 20’ deep with 250’ of tubing inside – only have a capacity of about 0.2 tons each. Combined with the wet bores, our total capacity is about 1.8 tons, which is below our design target. In retrospect, drilling ten or twelve boreholes would have helped us achieve our desired capacity.
2. Energy Recovery – Free Hot Water
Conventional homes waste a lot of energy by heating water for showering and then sending that water immediately down the drain. Using a drain-heat-recovery unit whenever an occupant is showering, combined with a desuperheater to recover energy from summertime cooling, we’re able to produce more than 30% of our hot water for free. Imagine the energy savings multiplied by 11 million homes in California. That’s a lot of free hot water.
3. Heating and Cooling of Floors – Long Delays
We installed a system to efficiently heat and cool the home’s floors through a system built into the Smart Home’s foundation. This system has not performed as well as expected. The long time delays to heat or cool the floors, combined with the chilly-floor feeling in the summer, make it fairly impractical and one of the least-preferred systems in our home.
4. Pre-Cooling Systems – Finding the Right Balance
Our home does not have a traditional air conditioning system. Instead, we use a few different methods to keep the home a comfortable temperature, especially when occupants come home in the evening. After several iterations, we have settled on pre-cooling the house on summer nights using a combination of a whole-house fan, which pulls outside air into the house through a filter, and individual bath fans, which are typically found in bathrooms but are strategically deployed throughout the Smart Home. Together these fans consume a bit more energy than just a whole house fan but provide a better pressure balance and noise performance.
5. Control Systems – Using More Energy than the Systems they Control?
We have a lot of control systems running in the house for HVAC, lighting, and energy. Last year those loads totaled 1412kWh, which is more than our actual LED lights consumed (they consumed 1121kWh). We anticipated that these systems would use a lot energy, but now we are able to quantify how much. The key point is that “smart” systems need to pay attention to stand-by loads.
What’s Next
These are just some of the top takeaways, but really we’re learning new things about the home everyday. Technology development is never a straight line: there are stops and starts, breakthroughs and setbacks. We’ve seen our share of both, but of course that’s what is to be expected in a living laboratory. Overall, the Honda Smart Home continues to provide us a unique opportunity to do real-world experiments and gradually improve our approach to designing zero-carbon homes of the future.
If you’d like to check out the latest data sets collected from the operation of the Smart Home, click on the “Downloads” tab above.
Our new occupants have been enjoying their zero-carbon
lifestyle in the Honda Smart Home. Since the pair moved in, lighting, HVAC, MEL and appliance use have all been down a bit, as you’d expect with fewer people in the home.
Check out the next six month data release,
which covers October 2018 to March 2019. As always, we’re here to answer any
questions you may have. Feel free to email us at hondasmarthome@hna.honda.com.
To access the data, click
Downloads -> Performance Data -> OCT ‘18 to MARCH ‘19 above to
download a compressed file. Be sure to review the README file for a thorough
explanation of how to use the Data Viewer and Channel Parser we’ve built.
I was recently contacted by a group of middle school students from Dublin, Ohio about a cool idea for water conservation. They developed a water
catcher device that uses a special mesh to capture moisture from the air and use it to water home gardens.
The students wanted to test their prototype in a more drought-prone climate, so we worked together to install the device at the house. Check out this video for the full story.
For those of you who have been following our progress, you know that
we’ve been publishing our data for four years now. I’m happy to post our latest
files. I hope these help you with your own projects and research, and as
always, please feel free to email us with questions at hondasmarthome@hna.honda.com.
As we continue looking for new ways to improve the performance of the home’s
technologies, we’ve been running some HVAC experiments over the last several
months. You may notice the effect of these experiments when checking out the
latest data set.
To review
the data, click Downloads -> Performance Data -> APRIL ‘18 to
SEPT ‘18 above to download a compressed file. Be sure to review the
README file for a thorough explanation of how to use the Data Viewer and
Channel Parser we’ve built.
In
the ground beneath Honda Smart Home’s backyard, eight 20-foot deep boreholes
allow a geothermal heat pump to harness the ground’s relatively stable thermal
sink to heat and cool the home’s floors and ceiling throughout the
year. As part of the mission to bring value to sustainable homes of the
future, we asked Frontier Energy (formerly Davis Energy Group) to evaluate the ground
loop performance tied to the heat pump at the home over the period of January
2016 through December 2016. Here are three key findings:
Total
system efficiency
The seasonal Coefficient of
Performance (COP) for the entire system is measured to be 4.1 in heating,
versus 3.5 in cooling. The lower cooling
efficiency correlates to elevated temperatures for the ground loop return
during the summer.
Comparison to a
hypothetical air-source heat pump (ASHP)
If we imagine swapping our geothermal heat pump
for an air-source heat pump, this analysis shows that the total efficiency of
an air source system should be pretty similar.
Of course, if we were to design new systems today we would optimize
them, but in this simplified analysis we don’t see much difference in energy
performance.
Wet bore versus dry
bore performance and temperature profiles
The dry bores have an average capacity of about
0.2 tons each, which is lower than our original estimate during the design
phase. While conductivity within the
bore is improved with the wet bore design, resulting in a larger ground loop
temperature split, the wet bore doesn’t transfer heat as well from the bore to
the surrounding soil as the dry bore does. It appears that the plastic casing
acts as an insulator between the water and the neighboring soil, likely as a
result of air pockets around the corrugated plastic shell, keeping heat in the
water of the wet bore.
For detailed analysis
from Frontier Energy, check out the full report in the Downloads section of the site (Downloads -> Resources -> Ground Loop Performance).
Spring is here, and you know what that means–it’s time for the next six month data release!
To access the data, click Downloads -> Performance Data -> OCT ‘17 to MARCH ‘18 above to download a compressed file. Be sure to review the README file for a thorough explanation of how to use the Data Viewer and Channel Parser we’ve built.
A key learning from this data set is the improved performance
of the HVAC system. The six-month data collected between April and September
2016 showed 2084 kWh for the heat pump plus 246 kWh for the fans. During that
same time period in 2017, we measured 1650 kWh for the heat pump with 391 kWh for
the fans. By adjusting the logic and using outside air more aggressively, we
achieved a 12% energy spend reduction.
To check out the rest of the data, click Downloads ->
Performance Data -> APRIL ‘17 to SEPT ‘17 above to download a compressed
file with all of the data. Make sure to check out the README file for a
thorough explanation of how to use the Data Viewer and Channel Parser we’ve
built.
