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Spend some quality time with your thermostat

Uploaded: Jan 10, 2021
When I was looking for a house in Palo Alto about twelve years ago, a friend warned me about high utility rates. I asked my real estate agent about it and she responded with a look that said “Really? That is what you want to be worrying about right now?” Nevertheless, after moving in I’ve been tracking our utility bills and the record tells an interesting story.

I’ve already talked about our efforts to use less electricity, which have been both successful and fun. Water has been a tougher nut to crack, but that will wait for another week. Today’s post is about gas, and I’d say we have been moderately successful in reducing our gas use. I want to relate how it’s gone, hear from you what you’ve tried, and generally encourage all of us to consider some of these ideas. As we experience and learn more about the impacts of climate change, the less comfortable it feels to be burning lots of gas.


Burning gas in a home furnace

Before I begin, though, you may be wondering how much is “lots of gas”. As one frame of reference, half the single family homes in Palo Alto use at most 400 therms a year, or 33 therms a month on average. That is probably around 70 in winter months and 10 in summer. For multi-family households, the number is smaller, with half of households using at most 290 therms a year, or 24 therms a month on average. Average use metrics are higher because of the spread at the high end.


Data for Palo Alto homes from the most recent fiscal year, from the City of Palo Alto Utilities

Since almost all gas use goes towards heating, larger homes and/or leakier homes will use more gas. How does your use compare?

I began home ownership with a whopper of a gas bill. In October of 2009, while wrapping up a remodel before moving in, I got stuck with a $450 gas bill (236 therms) because my contractor opted to turn up the heat to dry the sheetrock mud even though the house had no windows. It worked, but talk about warming the planet…

Once we moved in, with windows in place, our gas bills stabilized and have gradually decreased.


Average monthly gas use over the years for our 2100 sf house

In 2012 I lowered our thermostats one or two degrees, which was not noticeable but reduced our gas use by about 14% to an average of 42.5 therms/month. In mid-2014 I installed a smart thermostat and fine-tuned two others, which reduced our gas use by another 19%. I was more careful about scheduling when we needed heat and reducing heat in different areas of the house at different times of day.

In 2017 I wanted to see if the fine-tuning really made a difference, so I programmed a more liberal schedule where more areas of the house stayed warmer for longer. Those adjustments made a big impact on gas use, as you can see -- a 30% increase -- so I reverted to a more careful schedule. At this point we are down to about 34 therms/month, or right around the median for single-family homes in Palo Alto. Is there more we can be doing? Sure. But first I want to talk about what we’re doing right.

1. Insulation. There is no substitute for good insulation. Our house has a foam roof, insulation in the exterior walls, and good windows. We have a lot of windows, which is not ideal, but at least they are modern windows, professionally installed. Before I moved here, I rented a house in Mountain View for six years that felt more like a tent than a house. It had no insulation anywhere and single-pane windows, so it was freezing in the winter and boiling in the summer. It was a small house, about 1200 sf, with just two small wall heaters, but the gas bills were routinely around $150 a month in the winter, twice what ours are today. The rent was a good deal, though, so I didn’t say anything. One day the landlord informed me that he was going to replace the roof, since he’d come to take a look at the house and noticed the roof was falling down(!). He put up a foam roof and it made a world of difference. Summers stayed cool inside, winters stayed warm and used much less heat. Winter gas bills dropped to around $70. I vowed if I ever had my own house that it would be well insulated.

2. Smart thermostat. You can do a lot with a regular thermostat, but so-called “smart” thermostats offer more flexibility to keep you comfortable while also saving energy. For example, they can adjust the heat automatically based on whether or not you are home. But much more is possible. Just a few days ago, my Nest thermostat began offering an optional “Seasonal Savings” program in which it tweaks energy use in what it hopes are invisible ways and then measures the effect. As Nest describes it: “When Seasonal Savings is adjusting temperatures, the changes it makes are subtle, just a fraction of a degree each day. Over the course of the entire tune-up period, the changes typically add up to about 1F or 1C. The biggest temperature adjustments usually happen while you’re asleep or away, so you may never even notice the changes made by Seasonal Savings.” I love this idea, and it works! (1)


3. Lower the temperature. This is a no brainer, so don’t be afraid to try a lower temperature in the winter. If you don’t like it, you can always bump it up some. The City suggests 68. We found we are comfortable with lower temperatures as long as we wear sweaters and warm socks in the house. Then we fight over the best blankets in the evening when watching TV. (Our dog, unfortunately, likes what I think is the best one.) Good comforters also make it easy to lower night-time temperatures.


Do these changes make a big difference? It’s interesting to look at our experimental “don’t be so careful” 2017 in comparison with 2018.


You can see that our gas use was about 50% higher in the winter months even though the adjustment I made wasn’t huge, just a few hours more of heat in different parts of the house, maybe a degree or two warmer. Our annual gas bill went from $730 in 2017 down to $560 in 2018 when I tightened up the schedule. It pays to spend some quality time with your thermostat.

What next?
Our gas use is still higher than I’d like. There are some things we can do. One is to seal where the wood ceiling planks meet the walls. There is a gap there throughout the house, common in Eichlers, that leaks some heat. This is probably not expensive to do, but I’m not super handy. What kind of caulk? How to apply it properly? So I’ve been sitting on this one.


A gap between the ceiling planks and the wall board lets out warm air.

Another way to reduce gas use would be to use window coverings at night. Someone wrote to me that “I live in the cooler redwoods of La Honda with only a wood burning stove and have found that it is very helpful to close the blinds to keep the heat in!” I think it’s a great idea, but for us it would be expensive (we have lots of big windows) and tedious (closing and reopening them each day), plus I’m not wild about the idea aesthetically. I’m going to pass on this.


Windows are beautiful, but not the best for heat retention.


This photo, courtesy of Palo Alto’s Home Efficiency Genie, shows in purple where the heat is leaving at the ceiling and windows.

The simplest thing we could do that would make a big difference is probably to replace our gas tank hot water heater with a heat pump. I was surprised to see how much gas we use for hot water. Here’s what our gas use looked like last year.


Our only gas use is space heating, water heating, and the stove, and I estimate that our water heater uses about 12 therms a month on average. (When we are out of town the idle water heater uses about one-third of a therm of gas a day, or ten therms a month.) Since we use 34 therms/month total, the water heater is a little more than one-third of our use. While there are some small things we could try to reduce our hot water gas use, like further lowering the temperature or adjusting the recirc timer, our best bet is the heat pump water heater. They work well, but the economics are an interesting story. I’ll be writing more about that option in my next blog post. In the meantime, I’d love to hear what you’ve tried to reduce your gas use, or if you are thinking of trying something this winter. There’s no time like the present!

Notes and References

0. Acterra is celebrating “Veganuary” this month, offering help to anyone who is interested in eating a more plant-based diet. Interest in this is growing rapidly and can make a big difference for the planet. “Even a small shift towards a plant-based diet is impactful when done over time and in concert with others in the community. Omnivores can start as small as Meatless Mondays or maybe try three or four days a week of meat-free eating. January is a perfect month for new beginnings.” says program director Nicole Angiel. Learn more about how Acterra can help you make the changes you are thinking about.

1. Nest ran their "Seasonal Savings" program during the winter of 2017 in southern California with SoCalGas. “Initial results from the energy efficiency pilot program indicate that Nest smart thermostat owners who participated in the program saved an average of 8 percent more on their home heating use this past winter than the average Nest customer without that program. The 8 percent savings, which collectively adds up to about as much natural gas as it would take to dry 2 million loads of laundry, comes on top of the 10-12 percent average savings on home heating and cooling already attributable to Nest thermostats in the United States.” Smart thermostats FTW!

2. One of the reasons it’s harder to analyze and adjust gas use than electricity use is that the measurements are coarse and very variable (e.g., weather dependent). Here are measurements for the last twelve days at our house.


Home gas measurements are coarse and variable.

Current Climate Data (November/December 2020)
Global impacts, US impacts, CO2 metric, Climate dashboard (updated annually)

The year 2020 tied for the warmest year on record. This upwards trend will continue until we zero out our emissions.


This graph shows the annual temperature differential (in C) from 1981-2010 over the years. We are already one degree F over that recent period, and 2.25F over the preindustrial baseline. 2020 ties 2016 for the warmest year on record. (Source: Copernicus Climate Change Service/ECMWF)

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Comments

 +   4 people like this
Posted by Neal, a resident of Community Center,
on Jan 10, 2021 at 10:10 am

Neal is a registered user.

To seal the gap between the ceiling and wood planks I would caulk the gap and then cover it with a narrow strip of wood molding.


 +   4 people like this
Posted by Tom, a resident of Menlo Park,
on Jan 10, 2021 at 11:12 am

Tom is a registered user.

Great post and I salute you as a fellow home energy scientist! You're doing well to entice more folks into this interesting field (or hobby).

I agree that some big gas savings will come from replacing the fossil water heater with a heat pump water heater. Also we find those water recirculation loops loose a lot of heat that makes water heaters work harder. A control system using either an occupancy sensor that only turns on the pump when someone enters the bathroom or kitchen can cut the loop heat loss dramatically. Or a push button that runs the pump for a minute each time you push it would save even more with fewer starts per day.
Since we turned off the gas furnace in our 2 adult 2200 sqft home a couple of years ago we've been trying different electrification experiments. The first 2 years we used plug-in resistance space heaters turned on in whatever room one of us was in. That was hot and cold. Then for a couple of years we've been enjoying a $400 plug-in window heat pump to heat the upstairs. That's been more comfy and also gave us heat wave cooling as a new luxury. This recent year we installed a small (intentionally undersized as an experiment) DIY mini-split $1600 Mr. Cool brand heat pump that heats and cools most of the house if I'm patient. If I'm impatient I can also fire up a resistance space heater near me while the mini split focuses on catching up with replacing the heat I lost while I had it dialed back too far overnight. Heat pumps are great at maintaining comfortable quiet heat around the clock where the air temperature and all the surfaces our bodies radiate heat toward come into balance. But they are not as powerful as my old fossil fired rocket of a gas furnace for lurching the air temperature up and over the surface temperatures and starting an oscillating wobble toward noisy comfort. My heat pump averages 400 Watts of electric draw, but this chilly morning (36F outside) I set it to "turbo mode" and it's drawing 1,100 Watts to rewarm the house from 64 toward 70F. It's putting out about 3000 Watts of warmth so that's double or triple the output of typical resistance space heaters but 1/6 the output of my old furnace that would lurch on for 1/6 of the minutes of each hour.
Now that I've tried them, I really like heat pumps for both water heating and space conditioning.


 +   1 person likes this
Posted by Jennifer, a resident of another community,
on Jan 10, 2021 at 12:07 pm

Jennifer is a registered user.

"There is no substitute for good insulation" is so true. We never turn on our heater because our house never gets cold. Even when it's in the low 30s overnight, our large house is 68-70 degrees early in the morning. Saves a lot of money on our gas/electric bill.


 +   2 people like this
Posted by David Coale, a resident of Barron Park,
on Jan 10, 2021 at 12:47 pm

David Coale is a registered user.

Thanks for another good article. I have an Eichler type house and did seal up the holes in the tongue and grove roof decking. I did remove the trim and used a clear silicone caulking. This worked quite well. Now my home is pretty well sealed up, as tight as it should be without requiring active ventilation as determined by the Palo Alto home Genie energy audit. This is a great energy audit that everyone should take advantage of: Web Link and is well worth it!

On measuring the gas use, you can actually measure the gas use very accurately with the standard gas meter. While the main numbers on your gas meter are cubic feet X 100, there are two smaller rotary dials that measure 2 cubic feet and ½ cubic feet of gas use. Using these meters I was able to figure out gas use very closely and found that the pilot lights use in my house was 73 therms per year. This was for an older oven and stove, the water heater and an older gas wall heater. This is about two months of gas use! Now I make sure to turn off the gas wall heater all the way in the late spring and re-light it in the late fall when is it needed again. I look forward to replacing the older oven and gas stove along with the gas wall heater in the next few years.



 +   1 person likes this
Posted by David Coale, a resident of Barron Park,
on Jan 10, 2021 at 12:49 pm

David Coale is a registered user.

PS, on sealing up the house, I also did blow-in insulation in the walls and foam sealant on the house plumbing. This made the biggest difference.


 +  Like this comment
Posted by Sherry Listgarten, a Mountain View Online blogger,
on Jan 10, 2021 at 6:15 pm

Sherry Listgarten is a registered user.

Interesting and informative comments, thanks!

One thing I want to emphasize is that while some people love to tinker with home energy use, ALL OF US can look at a meter a few times and tune a thermostat, and it's an easy way to save money and help the planet. It's a great job for kids, I think, who really care about our future. They can make a difference and boss around their household at the same time...

@Neal/@David -- re the gap between ceiling planks and wallboard, the suggestion I heard that made sense to me was to seal it from the outside. That way the inside would stay as-is, and it wouldn't be visible. A painter for example could do it. It just seems to me like you'd need a ton of caulk and a really big "bead" or whatever. Ugh, I'm not a construction person.

@Tom -- I think the approach of turning off your gas and then figuring out how to deal with it is underrated. You quickly get rid of a lot of emissions, you are forced to try things (even simple things like electric resistance), and you appreciate them more. Thanks for the description of the various things you are trying...

@Jennifer, interesting! Where does your heat come from? Is it a passive house? Something like Amory Lovin's house?

@David, that's really interesting about the pilot lights, and more generally using the finer dials on the meter. I also suspect our furnace uses gas even when it's not "on". I'll have to look at this more.

Anyway, thanks for the comments and suggestions!


 +  Like this comment
Posted by KOhlson, a resident of Old Palo Alto,
on Jan 10, 2021 at 6:49 pm

KOhlson is a registered user.

Another great post - thanks.

We have a 19 year old furnace, and it is pilot free. I think that was pretty common/required at that time. I thought 19 years was pretty old - who would have one older? - and then my neighbor asked me to light her 2 (!) floor heater pilots in early December.

My suggestion for gap sealing is to find a handyman or local service company who knows Eichlers - they will probably be better informed on what to do. In my experience, if you wanted to learn how to use a caulking gun and a case of silicone, you have done it by now.

Good advice we got from our contractor when moving into our house 25 years ago, when I complained how hot it was upstairs. Insulate first. It may be all you need. Even if you get a/c, you wouldn't want it to work against uninsulated space.


 +  Like this comment
Posted by Jennifer, a resident of another community,
on Jan 10, 2021 at 9:40 pm

Jennifer is a registered user.

Sherry -- Our home isn't a passive house. I had never heard of that. When we bought our home new we were told that it was "well-insulated" and it would save on A/C and heating costs. We run the A/C occasionally, but we've never needed our heater!


 +  Like this comment
Posted by Sherry Listgarten, a Mountain View Online blogger,
on Jan 11, 2021 at 12:35 pm

Sherry Listgarten is a registered user.

Here is a comment from someone who has done many home energy inspections in Palo Alto.

"Most houses have lots of leakage associated with attics and crawl spaces. And forced air duct systems typically have about 25% efficiency loss through leakage. (Eichlers don't have these issues.)

Most homes have fewer windows than Eichlers, and I think it would be helpful to let people know that window coverings can be effective in lowering heating costs. It does require action and behavioral effort but one important message (zero cost) with windows coverings is opening curtains during the day to let sun in during winter and close them at night to keep the cold out. And that can be reversely applicable in summer for keeping sun out in the daytime. The DOE has a nice, high level explanation on how window treatments can help with efficiency: https://www.energy.gov/energysaver/energy-efficient-window-attachments."


 +  Like this comment
Posted by Jim P, a resident of Greendell/Walnut Grove,
on Jan 13, 2021 at 12:41 pm

Jim P is a registered user.

Thanks, Sherry, for the article and to readers for their comments. We moved into our 2200 sf Eichler in Palo Alto 49 years ago. The in-floor heating had failed and a previous owner had installed resistive electrical baseboard heaters. At some point we installed a gas fireplace insert and a couple of wall-panel gas heaters. We installed a foam roof, sealed the wall/roof intersection, and installed window coverings. We removed most of the resistive heaters and did not heat the bedrooms. We installed a timer-controlled hot water circulation system. After it runs for 2 minutes, we have hot water in the shower in 6 seconds. We did the Genie's energy audit and found that our house is a little too tight wrt outside air entering. Last year we removed all wall heaters, turned off the gas fireplace insert, and installed a seven-unit mini-split heat pump system. We use gas only for the stove top and water heater. We'll know after the winter if we are saving any money, but our winter gas bill is close to our summer gas bill.


 +  Like this comment
Posted by Sherry Listgarten, a Mountain View Online blogger,
on Jan 13, 2021 at 9:27 pm

Sherry Listgarten is a registered user.

@Jim, wow. That is a super interesting evolution, really sensibly done. I have to say, if I ever got to the point where my winter gas bill was like my summer gas bill, and my summer water bill was like my winter water bill, I'd be in heaven...


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