How Will Wider Temperature Swings Affect Home Heating and Cooling Demand?

They call it “climate change” for a reason.  While our planet is warming fast, two severe cold-weather outbreaks in the last six weeks remind us that global temperature extremes are heading in opposite directions – both up and down!  Last weekend, Mt. Washington set a new national temperature record for the lowest wind chill ever recorded in the United States – minus 108° F, a meteorological feat not even recorded in Alaska!

We’ll get into what this whipsaw weather means for home heating and cooling in a moment.  But first, think back – just before Christmas – when another Arctic blast tore through our area, with record-high winds that dropped temperatures by more than 50 degrees in just a matter of hours.  Tens of thousands of utility customers in Vermont and New Hampshire lost power for days, just as the holidays were fast approaching.

By New Year’s Eve, however, that polar outbreak seemed just like a bad dream.  The frigid air had beat a hasty retreat, leaving the Upper Valley and most of the eastern United States to bask in one of the warmest Januarys on record.  New Hampshire finished the month a whopping 8.9° F above normal.  The average temperature in Concord was 31.2 degrees, only 0.7° F shy of the warmest January on record.

As February 2023 rolled around, another severe-cold outbreak hit New England that was even more frightening than the one before Christmas.  Daytime temperatures plunged well below zero on Feb. 3-4.  For a time, a swath of -40° F wind chill readings from Burlington, VT, to Bangor, ME, made this the coldest place in all of North America – all the way to the Arctic Circle, where this polar air normally resides.

Fortunately, this second “once-in-a-generation” weather event was also short-lived.  Only days after setting low-temperature records across the Northeast, temperatures rebounded quickly to above-normal readings, restoring the very mild weather pattern that had persisted through all of January.

So, with all of these recent weather gyrations, is our climate really getting warmer – or just becoming more erratic, unpredictable and extreme?  We’ll plot some local, long-term weather trends to help find that answer.  But first, let’s take a quick peek at what’s going on behind the scenes, meteorologically speaking, during these recent cold-weather outbreaks.

All Eyes on the Polar Vortex

Remember the Polar Vortex, that frigid airborne invader from the North?  We posted about it two years ago, when it plunged all the way to Texas, dropping air temperatures 40° F below normal and shutting off most of the Texas grid for nearly a week in February, 2021.  The Polar Vortex that struck New England  last weekend had a similar start, crippling Texas with ice and snow that once again left more than 400,000 utility customers without power. 

Behind the displacement of the Polar Vortex is a buildup of greenhouse gas emissions that has the Arctic climate under siege.  Air temperatures above the Arctic Circle are now rising nearly four times faster than the global average, and polar sea ice is also disappearing fast.  These air and sea forces are converging to allow the Polar Vortex, which normally stays bottled up inside the Arctic Circle, to break free and travel to far-away places where it does not belong.  This January, for example, the Polar Vortex paid an unwelcome  visit to the eastern half of Asia, producing extreme cold that lasted nearly a month as the frigid air mass drifted slowly to the east.

This same topsy-turvy weather pattern also left a pocket of exceptionally warm air over Europe in early January, smashing thousands of high temperature records in Europe to start the new year.  London matched its warmest January low ever recorded, only months after setting its all-time high temperature record of 104° F last July. 

Kinks in the Jet Stream, but not in the Warming Trend

While the exact nature of the Polar Vortex’s  connections to climate change are still under review, the basic scientific principle is that a more-juiced atmosphere is creating larger and more energetic waves in the polar jet stream that’s widening its peaks and troughs as it flows across the Northern Hemisphere.  This undulating current enables the Polar Vortex – usually containing the coldest air in North America – to move well beyond its normal circumpolar limits.  The latest plunges to East Asia, Texas and New England are but the latest examples of its aberrant behavior.

At the same time, January’s corresponding warm spells in Europe and the eastern United States show how persistent the strength of global warming is overall.  While setting some new low-temperature and high wind-speed records, these latest polar outbreaks were at least mercifully short.  Longer-term weather records for our area confirm that the global warming trend is intact – and is, in fact, accelerating.

Temperature Trends in the Upper Valley

Here’s a look at three important charts explaining the longer-term weather patterns in the Upper Valley of Vermont and New Hampshire, using NOAA weather records dating back to 1895.

Annual Average Temperature

Average annual temperatures in Sullivan County, NH (centered around Claremont, Newport), have risen by more than 5 degrees F since 1895… or 1965, however you look at it.  That’s more than twice the average rate of global warming (1.94° F worldwide, including oceans).  The increase in warming in Sullivan County has doubled – from 0.3° F per decade over the 127-year measurement period to 0.6° F per decade in just the last 50 years.  Prevailing trend:  Sullivan County (and New England generally) has one of the fastest-growing warming rates in the nation.  While this is reducing winter heating demand, it also means that summer air conditioning loads are increasing.

Cooling Degree Days

Cooling degree days measure how hot the temperature is on a given day relative to a mean daily temperature of 65° F.  (For example, a hot day with an 80° F mean temperature triggers 15 degrees of cooling demand, or 15 CDD.)  At the start of the measurement period in 1895, Grafton County, NH, accumulated only 100 CDD all year.  That figure now tops 250 CDD in some recent years, for an average rate of increase of 5.77 CDD per decade over the entire measurement period – and an 18.04 CDD per decade since 1972.  Prevailing trend:  Days and nights are getting warmer, faster – spurring more demand for room and home air conditioning systems even in this northern part of New Hampshire!

Annual Minimum Temperature

Annual minimum temperature (AMT) measures how cold the daily low temperature is as an average over the course of a year.  With global warming, winter has become the fastest-warming season in New England (as in most of the Northern Hemisphere).  In Windsor County, VT, the AMT has gone from a few degrees below freezing (28.8° F in 1895) to mainly above freezing since 2000 (33° F AMT in 2022).  Like the other examples, this warming trend has accelerated – from 0.3 AMT per decade since 1895 to 0.7 AMT per decade in the last 50 years.  Prevailing trend:  Rising minimum temperatures are curbing winter heating demand and creating a better operating environment for electric heat pumps as a replacement for fossil-fuel furnaces and conventional air conditioners.

Two Cheers for Heat Pumps 

In prior posts, we discussed how heat pumps are becoming a critical building block to electrify everything in your home.  Now, in Vermont, state legislators are making a second attempt to hasten this energy transition away from fossil-fueled heating systems, which still provide 70% of home heating in Vermont.  

The “Affordable Heat Act,” as this bill is known, is now up for reconsideration.  Its adoption would establish a credit-trading system to move home heating providers away from high-emitting carbon fuel sources to lower-emitting ones like biofuels, renewable natural gas, advanced wood heating systems (like pellet stoves) and, most of all, electric heat pumps.  In the long run, implementation of this “clean heat standard” is projected to save Vermonters $6.4 billion in avoided fuel costs and reduce climate emissions 34% by 2030.  

This bill is not without its critics, however.  In the absence of decarbonizing the grid, they point out that such a move would simply raise demand for gas-fired electricity to power heat pumps drawing from the New England power pool.  

The up-front costs of achieving these clean heat goals are also considerable.  By 2030, Vermont’s Agency of Natural Resources estimates that 145,000 heat pumps will need to be installed at a cost of $725 million, along with 125,000 heat pump hot water heaters for another $375 million, to help meet the state’s ambitious decarbonization goals.  Moreover, another $890 million needs to be spent to weatherize 85,000 Vermont homes to make them better insulated and more energy-efficient.  

Vermont ANR Secretary Julie Moore recently told lawmakers that these estimates are “really rough” and could be off by a factor of two.  Altogether, she said, it could cost about $1.2 billion to make the necessary home-heating improvements in Vermont, which could raise the corresponding price of home heating by the equivalent of about 70 cents per gallon for those who heat with kerosene, heating oil or propane.  

(These estimates include federal funding that’s available to offset some of these household expenses. The Inflation Reduction Act provides residential tax credits of up to $8,000 for air-source heat pumps and up to $1,500 for heat pump water heaters.)

Clean Heat Standard – Take Two 

In Vermont’s last legislative session, Gov. Phil Scott (R) vetoed the first attempt at a clean-heat bill, and a subsequent override attempt failed by a single vote.  Chances for the bill’s passage have increased now that Democrats have secured veto-proof margins in both houses of the Vermont legislature.  

As this policy debate continues, the recent – if erratic – warming trend in New England does make one thing perfectly clear:  Electric heat pumps are gaining a better natural environment in which to operate here in New England.

Here’s why:

• Air-source heat pumps can be built to maintain their operating efficiency in cold climates until outside temperatures drop below minus 10° F.  In January 2023, the average minimum temperature in our region wasn’t even close to falling below zero!  In fact, the average low temperature of 24.1° F (as measured in Concord, NH) was the highest on record in January, and no below-zero took place between the start of winter on Dec. 22 and the strike by the Polar Vortex on Feb. 3-4.  
• Meanwhile, as summertime temperatures continue to climb, heat waves are gripping our region with increasing frequency and intensity.  This warming trend also plays to heat pumps’ advantage, since in their dual-operating capacity, they can cool homes just as efficiently as they heat them.
• Finally, as detailed in a separate post, a Solaflect Tracker can operate an air-source heat pump to heat and cool a typical single-family home for only about $7 a month.  And a Tracker running a heat pump water heater can produce more than $4,000 in net energy savings over the appliance’s projected 13-year lifespan.  
• And the Tracker’s solar panels, by the way, are warrantied for 25 years! 

Solaflect Energy is your trusted home energy management partner.  We help you install clean and affordable solar electricity for a more resilient and climate-friendly future.  For more information email us, or call (802) 649-3700.  Working together, the power is in our hands to make a difference!