Thriving On Low Carbon

Decarbonizing Homes online class with Fine Homebuilding

I'm going to be teaching a new online class with Fine Homebuilding called Decarbonizing Homes. In 5 modules it covers the process I use to look at an existing home and create a master plan roadmap that optimizes the mix of enclosure upgrades, systems changes, and renewable energy. Please check it out!

COVID-19 and energy use

One of the effects of C-19 on buildings may be increased energy use from higher ventilation rates and in some cases, ultraviolet lamps to inactivate viral particles. Another more personal take is our own energy use in 2020, vs. the previous year. Starting in mid-March we were working from home. In 2019, we used a total of 5,849 kWh. In 2020, that dropped to 4,980 kWh. 2020 was warmer, so we used less heat pump energy. Jill was doing a lot less work-related driving in our Hyundai Ioniq plug-in hybrid, which is mostly electric driving around MV.

The drop in heat pump water heater energy is an artifact of swapping a unit which had some refrigerant leakage, which drove efficiency down, for a new unit. This is despite an increase in gallons of hot water used from 6,111 in 2019 to 8,464 in 2020 (we had a third person living here for a few months). The manufacturer says that the new unit is not more efficient than the old one, yet in 2020 it made hot water at a rate of 0.048 kWh/gallon, which with a 75F lift (50F to 125F) is a net COP of 3.8.

What increased in 2020? Predictably, the range (we cooked more) and lights and plug loads. (Ignore the well pump, I think there is an issue with the SiteSage on this circuit.) So, more hours at home, and less driving, amounted to a our lowest energy use year.

A New Chapter...

It's mid-December 2020, the year from hell for so many. We're about to receive the first messy solid precipitation of the season. Jill and I are doing well in the midst of COVID-19 and managing to work from home (me entirely, she mostly) without annoying each other excessively. I'm about to make another transition - at the end of the month I'm leaving employment at South Mountain Company after 10-1/2 years, and reverting to just consulting.

These past 10-1/2 years have been immensely rewarding. I learned more from SMCers than vice versa (as Yogi Berra said, you can observe a lot just by watching). This community of people is extraordinary in so many ways. Over these years, people have asked me numerous times what motivates me most at South Mountain, and my answer continues to be, I’ve never been in a group where dedication to excellence, and doing the best one can, has been so prevalent. The richness comes from the diversity of what we define as excellence. That diversity leads to differences of opinion about what should be prioritized, but the commitments we bring are the foundation of goodwill that allows us to, together, create something profoundly better than any of us could do alone.

 

Yogi again: when you come to a fork in the road, take it. So, I am.

Observations on variations in energy usage

The morning of the first day of each month is when I read the meters and download another month's worth of circuit data from the SiteSage monitor. I have 39 months of data now. There are some items so consistent that I could move the current transformers to other unmonitored circuits, for example the clothes washer - 0.4 kWh/month, month after month. We apparently aren't substantially dirtier season to season. Then there are the predictable seasonally variable loads - the refrigerator and freezer use more energy in the summer (low 40s each per month) and less in winter (high 20s). Similarly, the heat pump water uses more in the winter when the basement is cooler (low 60Fs) and less in summer as it warms up, while our usage of hot water is remarkably consistent at 14 gallons daily.

Once I gather the data each month, one of the first things I look at is the net energy flow - did we need to import energy from the grid, or did we have a surplus of generation and therefore exported energy? This can vary substantially. Let's look at March, the month just past.Here are the net kWh for each of the four months of March 2014 - 2017:

March 2014 - 29 kWh imported

March 2015 - 48 kWh exported

March 2016 - 216 kWh exported

March 2017 - 53 kWh exported

Quite a variation - what's happening? Well, the big variations are in the weather - how cold and how cloudy was each month? In the table below, all values are kWh except for heating degree days base 65 (HDD65) and the ratio of energy used by the heat pump to the HDD65.

	Used	Generated	Net	Heat pump	Used except heat pump	HDD65	HP kWh/HDD65
Mar-14	565	536	29	343	222	1043	0.33
Mar-15	446	494	-48	247	199	1023	0.24
Mar-16	358	574	-216	150	208	789	0.19
Mar-17	461	514	-53	209	252	1013	0.21

In March 2014, I was still working out the control settings on the heat pump which caused it to cycle to full speed then stop, so the high usage that month is primarily the heat pump. In March 2016, the weather was sunnier than normal, and much warmer - presto, a large net export of energy. Our usage in March 2015 and March 2017 was very similar, as was the solar generation, so the net export numbers were almost the same. The heat pump used less in 2017 for a similar amount of heating demand, and I'm pretty sure this is partially accounted for by Jill building a few fires in the woodstove on cold evenings. Our usage of energy besides the heat pump was up in 2017 over 2015 - no one item stands out, but slightly more use of the range, lights and plug loads, HPWH, and ERV add up.

Over the long haul it tends to average out, but we don't draw too many conclusions from one year's worth of data!

Consumption and generation for 2016

This year total usage here at the house is 3,808 kWh. Of that, 1,037 kWh went into the Fujitsu heat pump; 861 kWh went to the refrigerator and chest freezer; 598 kWh were used for water heating in the heat pump water heater; 176 kWh used in the range, and 164 kWh by the well pump (dry summer, lots of drip irrigation); lights and plug loads totaled 315 kWh. November and December were just a bit colder than the 5 year average, after a very warm winter last year.

The PV system generated 6,309 kWh, for a net export of 2,501 kWh. We really should be driving an electric car!

This winter I'm re-doing experiments I did last winter, with (I hope) better set-ups. I'm measuring the effectiveness of the Zehnder ComfoAir 200 ERV at recovering heat from the exhaust air and putting it into the supply air. And I'm logging pressure difference between the basement and outdoors, as well as outdoor temperature, and attempting to find correlation with radon levels.

Deep Energy Retrofit Online Course starts Sept 12th!

I'm teaching a 10 week in-depth course for professionals who are serious about transformative energy upgrades to residential and commercial buildings. We'll cover the pertinent building science, techniques for superinsulating foundations, walls, windows, and roofs, appropriate mechanical systems. There will be a weekly in-depth case study as well. Please join us, and pass this on to anyone who might benefit. Here's the link:

Deep Energy Retrofits Online Course

I'm teaching a 10 week in-depth course for professionals who are serious about transformative energy upgrades to residential and commercial buildings. We'll cover the pertinent building science, techniques for superinsulating foundations, walls, windows, and roofs, appropriate mechanical systems. There will be a weekly in-depth case study as well. Please join us, and pass this on to anyone who might benefit. Here's the link:

Deep Energy Retrofits Online Course

Great video on a Deep Energy Retrofit to Net Positive Energy

My friend John Livermore is multi-talented, and enlisted his 17 year old daughter and his stepson as well to produce a tremendously clever and fun 10 minute video on how they transformed their 70s raised ranch from an energy hog to a net energy producer, shrinking their carbon footprint to a fraction of its initial size. Full disclosure: I was one of the participants.

Check it out here

Deep Energy Retrofits of Historic Buildings

Here is a PDF of my talk today at the RISD Architecture Dept. Tomorrow we look at the retrofit possibilities at their 50,000 ft2, 1848 building, the Bayard Ewing Building. Download Historic Buildings RISD 2016

Deep Energy Retrofit Online Course starts Sept 14th!

I'm teaching a 10 week in-depth course for professionals who are serious about transformative energy upgrades to residential and commercial buildings. We'll cover the pertinent building science, techniques for superinsulating foundations, walls, windows, and roofs, appropriate mechanical systems. There will be a weekly in-depth case study as well. Please join us, and pass this on to anyone who might benefit. Here's the link:

Deep Energy Retrofits Online Course

Retrofits vs. Reductions

I’m excited because I’ve been putting together a new online course on Deep Energy Retrofits (DER). More so than the course I teach on Zero Net Energy Homes, it’s focused on the multiple approaches and techniques for taking the diverse building stock we have and transforming it – not just from the standpoint of energy use, but also upgrading comfort, health and safety, and durability – because so much of our building stock is plagued with deficiencies. Retrofits fix the issues with the building asset and saving energy almost ends up as a desirable byproduct. There are so many different buildings and conditions, and therefore solutions, so the DER course is based on case studies and we show many approaches people have chosen to implement.

 If energy saving is the principal goal, it’s important to look carefully at the choices the occupants make. Energy in buildings goes to more than heating and cooling, which are the main loads that retrofits target. Over forty percent of primary energy in US homes goes to non-thermal loads. Once we superinsulate a house in New England, energy for heating, once the largest load by a comfortable margin, may become the smallest load amongst heating, domestic hot water (DHW), and plug loads/lighting/appliance loads (PLA). To get to truly low energy performance then requires focus on DHW and PLA.

 With motivated occupants, it’s possible to get deep energy reductions without DERs.  People can do a moderate weatherization on a house, then install a point source heater such as a single zone minisplit heat pump to keep the most-used part of the house comfortable. The rest of the house runs cooler and the main heating system stays off until the outdoor conditions get severe. Lots of savings have been demonstrated in this approach. Couple that with LED lighting replacement in high use fixtures; great low flow showerheads like the Delta H2OKinetic; a horizontal axis washer; and depending on the household size, perhaps a heat pump water heater. Replace the dryer with a drying rack and a clothesline. Make a concerted attempt to keep appliances and entertainment stuff off when not using it. Hunt down phantom loads. 

 Combine all of the above and the total outlay might be $10-20,000 and the energy saved might equal or even exceed what a second household might achieve that goes the whole enchilada and does a DER, if that second household is much less conscious of their DHW and PLA usage, and heats the whole retrofitted house to comfort temperatures. I definitely see DER households using a pretty wide range of energy per person. The climate doesn’t care how we each reduce our consumption, just that we do. Of course a motivated, conserving  household in a DER will have the lowest energy usage of all, but if a household is committed to reducing their carbon emissions, they needn’t spend six figures to get there. What the DER gets that the targeted weatherization, behavior-based deep energy reduction strategy may not is relief from the non-energy deficiencies – ice dams, pest infestations, water issues, mold, etc., and true comfort. The cost of remediating those defects shouldn’t have to be paid for solely by the energy savings that accrue.

 I live in a zero net energy DER after previously weatherizing a pretty good house and also reaching zero net energy. I like the second house a lot better, because of its superior comfort and air quality. But I spent a lot more money to get there, and the total energy performance isn’t much better, because DHW and PLA usage is pretty similar. The DER uses less energy for heating at an even 70F setpoint than the pretty good house used with some temperature setback and letting parts of the house get cooler. I hope to live in this retrofitted house for a long time, and it’s worth it to me to have spent what I did to get a house my wife and I are so pleased to inhabit. I’m just not fooling myself that I needed a DER to achieve deep energy reductions, if that was my only goal.

 To learn more about the transformative possibilities of Deep Energy retrofits, please join me starting September 14^th in the ten week online course – check it out at Deep Energy Retrofit online course

Photo courtesy Janice and Steve Kurkoski