Thank you NickWishing you all a wonderful 2026 with health, purpose, time with friends and peace, Art & Eunice
COP is not a marketing term. It's a straightforward ratio of work output (heat output) compared to work input (electricity). A COP of 2 simply means that for 1 kWh of electricity input, you are outputting 2 kWh of heat energy into the space. If you want to convert it to your "BTU per kWh" metric, just multiply the COP by 3412. It is very important for emissions because COP lets you determine the crossover point where a heat pump is either cheaper or "greener" than using other heating sources, for those that have multiple sources. NEEP has all the data for each model of heat pump at different temperatures, there's no obfuscation going on.
> The production and delivery of the electricity used by the HVAC produces, at the absolute best, twice the amount of carbon as is produced to create BTUs in the home by a gas furnace.
This is roughly correct, though the numbers are actually quite a bit better. But using your numbers, it's why you need a COP of at least 2 (see why COP is so important!) for heat pumps to be competitive with gas heating.
> This calculation assumes 100% efficiency of the HVAC converting kWh to BTUs when that conversion is probably from 95% at 40f but 50% at 10f
This statement does not make sense. what is your reference for "efficiency" here? The COP of 2 at 10f means that it isn't 50% efficient but instead 200% efficient. A heat pump will never be less than 100% efficient at converting electricity into heat, that's the whole point.
> Real world- probably in cold temperatures the modern low temp inverter-based compressor HVACs holistically generate 4 to 6 times the carbon of a modern gas furnace per BTU and the older HVACs are worse.
I and others have presented information showing that this is entirely incorrect. A modern cold climate heat pump, running on the dirtiest electricity you can buy in Lincoln, produces less carbon emissions down to the single digits Fahrenheit, if not lower. At slightly warmer temps near freezing, it's not even close. If you really want to do this comparison, your best bet is probably to compare grams of CO2 per BTU of heat, and I think you'll find that heat pumps are clearly better for the environment both now and in the future as we decarbonize the grid. However, if you do have a dual-source system, you might want to consider using gas at very cold temperatures.
> Sarah’s Kohler gas generator supplying clean electricity set-up lists appropriate efficiency curves ( not COP). It has an approximately 95% efficiency (depends on load) so all her electrical appliances are using electricity creating about a quarter of the carbon of the Lincoln power lines
This is confusing to me. That gas generator is probably not even 30% efficient.
> This is the big argument for solar with batteries.
I agree! I just got solar installed and am a huge proponent of getting batteries installed as well.
Happy to sit down with anyone and discuss all the math about heat pump efficiency in way more detail than anyone can possibly want, it's a hobby of mine :)
Thanks,
Nick
Nick, Just to be clear COP appears to be a marketing way to obfuscate because it doesn’t mean anything in terms of efficiency or emissions The problem with HVACs is they use dirty electricity. The production and delivery of the electricity used by the HVAC produces, at the absolute best, twice the amount of carbon as is produced to create BTUs in the home by a gas furnace. This calculation assumes 100% efficiency of the HVAC converting kWh to BTUs when that conversion is probably from 95% at 40f but 50% at 10f Real world- probably in cold temperatures the modern low temp inverter-based compressor HVACs holistically generate 4 to 6 times the carbon of a modern gas furnace per BTU and the older HVACs are worse.
Sarah’s Kohler gas generator supplying clean electricity set-up lists appropriate efficiency curves ( not COP). It has an approximately 95% efficiency (depends on load) so all her electrical appliances are using electricity creating about a quarter of the carbon of the Lincoln power lines
This is the big argument for solar with batteries. hopefully we did not finance the recycle center installation teamed with Eversource through a PPA and lose most of the economic benefits. As individuals only buy your solar panels. Do not finance or lease. Your payback will be a no -brainer. Whatever you do- the solar panels & installation companies are swamped with work charging high prices before Trump’s year end. Wait until late Spring or early summer and there will be fire sales as they all try to stay in business. The problem with solar is batteries. AI & data centers are trying to grab all the rare-earth materials needed. Trump is typically doing everything wrong with China and they control the rare-earth market
With warm regards, Art +1 978.873.3000
COP is used because it's a lot easier to understand than BTU/kWh. Everyone agrees there may be a point where gas heating emits less carbon than using gas fired electricity to power a cold climate heat pump, but those circumstances are very
rare and over the course of a year the heat pump will have vastly lower emissions, and will only have lower emissions over time as the grid gets greener.
I agree grid reliability isn't amazing in Lincoln with overhead power lines and lots of trees. But a battery and/or a generator is a great emergency backup.
-Nick
Thank you, what a huge benefit to all of us to have Lincoln's CREE group- a wonderful resource for us non-technical older folks
Yes, it is true Mitsubishi’s new inverter-driven compressors (cold temperature HVACs) are an engineering marvel. Their low temperature models even perform much better at high temps than conventional HVACs, and even many stand alone AC units.
Mitsubishi does though obfuscate their efficiency numbers by using this vague COP metric and then give a multiplier in their engineering manuals in a different section, and never ever give the normal efficiency curves for this type of equipment. And it appears
they are intentionally trying to hide the kWh (kilowatt hours- this is half of the charges on your Eversource bill the other half is a "delivery charge") to BTU (British thermal Units or "therms") efficiencies
Mainly, I am most concerned about the unreliable and inefficient Lincoln electricity distribution system. If there is a power outage in a storm no matter how efficient the HVAC is, there is no heat produced. In this last storm one of the
Hive stated they had no electricity for 28 hours and it was not even a big storm. The advantages of gas-fired home furnaces are they are generally not subject to distribution disruption and have a 98% conversion from natural gas to BTUs. That compares with
modern gas-fired CCGT electricity power plants which run at best a 62% gas to kWh conversion rate and then send the electricity down our Lincoln grid which has at best an 8% transmission loss. That means our electricity uses ~2X more gas, generating twice
the carbon, before any HVAC begins to convert the electricity to heat
For the Mitsubishi model MUZ-FH12NAH-1 (one of the best cold temp HVACs) I asked Chat GPT to convert the Mitsubishi published COP numbers to BTU heat delivered per 1kWh:
Outdoor ambient temp (degrees f,) BTU heat /1 kWh
47 15,354 (normal above this)
So I think you can see once you get below 15 degrees Fahrenheit you consume twice the electricity to heat your home ( with 4X the carbon produced) , but the good news is, if you have one of these systems, they continue to heat down to pretty
low temperatures as long as there is electricity.
I should be clear; we have this model of cold temp Mitsubishi mini split installed in our home. It is for an auxiliary room without plumbing and we will be installing US-made 24% efficiency solar panels with batteries (unfortunately using
Chinese precious metals) to power it and charge our Mitsubishi (coincidentally) hybrid car
I am, I guess, particularly sensitive to this matter, because we moved here from Concord, MA where the electricity costs about a third of what it does here in Lincoln and we had one power outage in 16 years that lasted 4 hours. We have
already had 2 outages in a year from a mild storm and a car crash. The old power lines here are badly maintained with trees and bushes hanging all over the lines, but it gives Eversource a license to charge huge delivery bills
Hello All-
Chuck Sizer, a founding member of Lincoln’s CFREE (carbon free residential- everything electric) group and a refrigeration engineer, monitored the coefficiency of performance (CoP) on his Mitsubishi heat pump a few years back when the temperature
dropped to subzero temperatures.
Having been at his house and looked at all of the graphs with watt consumption tied in, I was amazed to see that, as Nick suggests, the CoP was able to shadow the temperatures exactly- meaning there was no increase of cost to provide temperature
per degree with a heat pump; so the efficiency and economy maintained all the way to -5°. Hvac engineer savant Antis Hartmann echoed Nick’s statement about newer systems having a steady CoP all the way down to -15°.
Lincoln is fortunate to have perhaps the most advanced committee reviewing apparatus, legislation and other initiatives towards more environmentally, sustainable and efficient energy with the CFREE group. Their meetings are advertise through
Town’s website and a lot of their information has been posted to YouTube. For any resident consider considering upgrading their heating system, adding solar panels, and/or battery backups, or even considering an EV versus another combustion engine purchase,
please reach out and take advantage of this amazing group of community- minded, locally active (slightly nerdy) individuals who have amassed tremendous amounts of information and insight.
That is unfortunately outdated information. With modern cold climate heat pumps, the heat pumps are more environmentally friendly than natural gas heating at around 15f if you're on the Lincoln basic plan and have a 95% efficient furnace.
If you are on the standard plan, it's *always* more environmentally friendly to run the heat pumps instead of gas. The technology has greatly improved recently. Happy to go over the numbers with anyone if they'd like, I'm a bit proponent of heat pumps.
I do agree about power reliability, but battery backup solutions have gotten a lot better recently as well.
Thank you, Nick,
You are correct that point 1 about the unreliable Lincoln electric grid is the most important
But you might check your HVAC system:
“Areas of the country subjected to temperatures 40 degrees and lower for extended periods are not ideal for a heat pump installation.
Why? Well, as the temperature drops, heat pumps work harder to maintain desired comfort levels. This results in more energy use, driving up your utility bill.
In addition, once the temperature drops below 40 degrees, most heat pump systems lose their heating efficiency and must switch to emergency heat mode, which utilizes electric resistant heat strips that use
more electricity.”
And you are correct, below 0 f. the heat strips are almost useless except to generate huge electric bills. It is like heating your home with non-oil-filled electric space heaters
Also since Massachusetts generally has very efficient gas-fired/generated electricity on our grid, the extra electricity to generate heat from HVACs consumes vastly more green house gases than direct conversion
from gas at our homes
Heating with electricity below 32f is bad for the environment.
With warm regards, wishing all a peaceful and healthy 2026
I'd push back against number 2 in particular. Cold climate heat pumps typically provide full output down to 5f and still operate at -13f. I and many others use heat pumps as a primary method of HVAC and have had no issue even on the coldest
of cold days.
-Nick
Rosemary
Erik Lyons - (978) 621-2642
New business, hard working, local
Do not use HVAC for heating in Lincoln
1. Lincoln’s electric grid is too unreliable (I think Eversource cultivates tree growth over our old fragile power lines)
2. HVACs are not designed for very cold weather which we occasionally have
If you insist on HVACs have a good wood- burning stove in the house
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