Electric Vehicles, EVs, Vehicle to House (V2H) and Vehicle to Grid (V2G)

• In 2020 I bought a Tesla model S Long Range

•50,000 miles in 3.5 years. It is our preferred car for long-distance travel

•The Tesla Supercharging network is convenient and reliable. GM & Ford will have access to it in ‘24

•We stop every 150 miles or so (every 2-3 hours) for coffee/stretch & add 100 miles of range in 15 mins. There is NO range anxiety. 360-mile range on full charge.

•It is more comfortable than a BMW 3 series or BMW X5 and has more storage space

•Our son went to university in one trip with his bike on the roof and a passenger

•A Tesla Model S costs about $85k. which is still very expensive. However a Model 3 now costs about $26k after the federal tax credit and new MOR-EV MA rebates. For example: The list price of a new Tesla Model 3 is $37k – $7.5k FTC., – $3.5k MA = $26k which means a lease rate of around $375 a month. A new BMW 3 Series has a list price of $42k. So a new Tesla Model 3 is far cheaper to buy than a BMW 3 series. Also, a new Ford F150 Lightening costs $75k – $7.5k federal tax credit – $7.5k MA = $60k. A new gas-powered F150 is $45k.

•The new BYD Atto3 has a 270m range and is priced at under $20k (not available in US yet, already top selling EV in Sweden). A new Toyota Corolla costs over $20k. 

EVs are now cheaper to buy than gas cars!

•On utility electricity (35c/kWh) I can go to NYC (200 miles) for $18 or $4 at solar-panel rates (8c/kWh). BMW 3 Series at 20 mpg & $4/gallon costs $40. Using electricity from my solar panels, I save $2,700/yr. or about $225/mo. a year on gas. The net present value of this (NPV) @3%=$90k. So the savings on gas are worth more over the lifetime of ownership that what I paid upfront for the Model S which was $85k. You can lease a new Model 3 for a net cost of $150/mo. 

If you subtract the monthly savings on gas (about $225) from the lease rate for Model 3 of about $375 a month you have a net cost to drive of about $150 per month. The cheapest lease I can find for a gas-powered vehicle is $269/month for a Chevrolet Equinox.

EVs are now cheaper to drive than gas cars.!

•I have spent zero on maintenance / servicing of my Tesla Model S in 3.5 years. Except: tires last 20k miles not 40k. 

EVs are now cheaper to buy,  run,  & maintain than gas cars. 

Vehicle to Home and Vehicle to Grid.

V2H (vehicle-to-home) uses your EV to replace your back-up generator

V2G (vehicle-to-grid) uses your EV to reduce peaker-plant usage on the grid

•not useful in MA, because we have no (time of day) TOD electrical tariff (there should be!!). A TOD tariff is where the price of electricity is higher during periods of high demand (usually mid afternoons in summer when people use AC) and lower at night. CA has this type of tariff but MA does not.

V2H is already on Nissan Leaf (with charge station) and Ford F150 Lightening. 

•It will be standard on Teslas in 2025, all GM EVs in 2026, Kia EV9 in 2024

•This could be accelerated by legislation requiring it, but a bill in CA recently failed

My Ford F-150 Lightening has 100kWh of storage (7x a Tesla Powerwall!), it has 4 x 110V outlets in the truck bed. These can run things like: circular saws, lights, refrigerator, microwave, espresso – awesome tailgating/movies! Plus 220V for V2H. 

•It will run my house for 5 days (without the heat pumps), a Powerwall would run it for a day. The F150 Lightening could also charge my Tesla.

•The Ford F150 Lightening costs $75k less $7.5k FTC and $7.5k MA rebate = $60k. Regular Ford F150 is about $45k plus $62k for 7 Powerwalls(=100kWh) = $107k

•The Ford F150 Lightening is a huge battery on 4 wheels.  It is also a very nice truck! It has been on order for 2 years. Don’t get a house battery or new generator – get V2H!

In 2021, I ordered 3 different home batteries (from Generac, Sonnen and EnPhase at about 15kWh each) to go with existing and new solar-panel arrays (this is how you get the SMART MA subsidy for batteries) for our house and two rental properties we own. THIS IS VERY COMPLEX!

•I was faced with replacing propane powered back-up generators at all 3 houses

•Would have cost $5k per house plus $500 a year for maintenance/service

•The batteries were about $20k each after installation, none was a Tesla Powerwall

•Powerwall cannot both run the house and charge from solar panels together making it useless during lengthy power outages in winter. It is designed for power arbitrage (CA), not back-up generation (MA)! This can be alleviated if you buy the Tesla inverter. A friend just installed two Powerwalls plus this inverter and it cost $23,500 in MA.

•The batteries+arrays were profitable (5-10% IRR) vs. arrays alone (10-15% IRR)

•A 15kWh battery will run my house (but not the heat pumps) for a day

•Not enough! We have had 3-day power outages at our house

•In late 2021 I ordered the Lightening (with a 100kWh battery = 7 PWs)

•In 2023 I cancelled all 3 battery orders. With V2H on most vehicles by 2025, don’t get a back-up generator or house battery – get V2H!

The V2H and V2G capabilities of EVs are one of the main reasons we need a time of day tariff for electricity in MA. CA has it and it is essential to reducing peaker plant usage on hot summer afternoons as well as saving money by charging your battery at night and using it during the day.

The introduction of this tariff would have a huge impact on greenhouse gas emissions. It would also allow low-income households to reduce their electric bills substantially by, for instance running the dishwasher and clothes dryer (and charging their EVs) at night.

Tesla Model S is our preferred car for long distance travel – there is no range anxiety with the Supercharging network

Our Tesla Model S is our preferred vehicle for driving long distances (like down to NY and NJ) from Dover, MA which is about 200 miles. The Tesla Supercharging network is easy to use, fast, and reliable. We stop about every 150 mile or so for a stretch and cup of coffee and in 15 mins we have added 100 miles of range. There are at least 6 supercharging stations (each with about 8-12 individual chargers) between here and NY/NJ. Only once in 3 years have I found all of the chargers in use when we arrived. A space opened up in 5 mins. I do not have range anxiety in my Tesla and it is cheaper to drive than any gas car. Because I charge it from my solar panels it also has a zero carbon footprint. It is also very comfortable for 5 adults whereas the BMW3 series and X5 (SUV) have back seats that are definitely uncomfortable for 5 adults. Everyone detests being the one who needs to sit in the center seat on the ridge above the transmission. Both Ford and GM have announced that their EVs will be able to use the Tesla Supercharging network “next year” and somehow I doubt it will go smoothly, so yes there may still be some justification for range anxiety in a Ford or GM vehicle, but remember those vehicles can also access all Chargepoint, EVGo and other non-Tesla networks so in practice they will have access to every charging station in the USA.

Scope 1 Scope 2 and scope 3 emissions for houses

Net zero for houses does not include scope 3, just scope 1 (emissions from what you burn on site) and scope 2 (emissions from electricity used on site but generated offsite) less any excess power (measured over the whole year) that you contribute to the grid.

In my opinion scope 3 is a huge and meaningless distraction. If everyone (businesses as well as houses) took care of their scope 1 and scope 2 emissions there would not be any scope 3 emissions.

When you burn the coal for heat you cause scope 1 emissions. When a power station burns it to make electricity that you then use you are generating scope 2 emissions. The only scope 3 emissions you generate by burning coal are emissions generated by mining and transporting it. These are not trivial, but not huge either. If coal mining companies used electric-powered miners and electric powered trains (and both were powered by renewable electricity) their scope 3 emissions would be zero. See what I mean?

Coal will go out of use for one reason and one reason only: cost. It now costs more to generate electricity from coal than to generate it from solar or wind. Energy is the ultimate commodity market. The lowest-cost player wins and winner takes all. It is game over for coal. Oil will follow as EV penetration becomes significant, likely, within the next few years. Natural gas will follow that. Zero carbon is now inevitable. The pace is to be determined, but I believe EVs have now hit the inflection point. Housing is still lagging. 

Massachusetts Electric Vehicle (EV) Subsidies MOR-EV program

Massachusetts just (9/27/23) announced its HUGE new rebates for buying or leasing electric vehicles (EVs).

These new MA EV incentives are huge and are in addition to the Federal tax credits. On cars, the new MA incentive is $3,500 and on trucks (like the F150 Lightening I have on order) it is $7,500. 

On a new Tesla Model 3, which lists for $37,000, the net price is now $26,000. A new Toyota Corolla is $22,000. Corolla’s cost about $4,000 in maintenance in the first 10 years. The Model 3 will cost nothing.  So, including maintenance the Tesla Model 3 and the Toyota Corolla cost the same. The Tesla Model 3 will save about $800 a year on gas (even when charged at todays very high electricity prices) compared to the Corolla. So, over its first 10 years, the Tesla Model 3 is now about $8,000 cheaper than a Toyota Corolla. The Tesla Model 3 will save far more money if it is charged from rooftop solar panels on your house which can generate electricity for about 5-8c/kWh compared to our local utilities which charge about 40c/kWh. On our solar electricity, I can travel the 200 miles from Dover, MA to New York City for about $4. They Greyhound costs $26, is uncomfortable and spews CO2 and pollution every mile of the way.

The internal combustion powered the advances in the last century. Thank you for all you have done for civilization internal combustion engines, but it now game over and time to move on. Solar, heat pumps and EVs. Plus insulation and triple-pane windows on your house. That is the recipe for getting to net zero.

This is the inflection point we have been working so hard to reach! Congrats to all who have been involved in creating both the federal (IRA) act and the MA one. This is a huge victory for us and the planet!

What incentives are available through MOR-EV?
As of August 8, 2023, MOR-EV has added new incentives for EVs:

  • A $3,500 rebate for the purchase or lease of a new electric car with a total MSRP of up to $55,000 or a used electric car with final sales price up to $40,000.
  • A $7,500 rebate for the purchase or lease of a new electric truck with a total MSRP of up to $80,000.
  • An additional rebate of $1,500 for people who participate in certain income-qualified programs.

Biotechnology – The Technology of Increased Human Lifespan

Longevity. Increasing lifespan. Biotechnology. Stem Cells. Revolutions in medicine, agriculture and sanitation increased the human population to 8 billion and increased human lifespan from 30 years to 80 years in only the last 150 years.
Biotechnology the technology of life.

Webinar by David Green (who founded two biotech companies, was CEO of both and took both public on NASDAQ) on how medical, sanitary and agricultural revolutions led to 8 billion humans on Earth and a fifty-year increase in human lifespan in just the last 150 years. Will the trend continue and will your grandchildren live to 150?

This webinar was created for students at Dover-Sherborn High School in March 2023. It is available on YouTube by clicking here: https://youtu.be/jsQ7KueGicg

In addition to founding and being CEO of two biotech companies, both of which he took public on NASDAQ, David Green cut his home’s carbon emissions to zero and is making a 15% return on his investments in heat pumps, insulation, triple-pane windows and solar panels. You can read about his experience on this website.

You can download the slides for my presentation here:

Zero Carbon for a house for rent

Q: This question is about renting out a property that is zero carbon.

I saw that you have rental properties that are zero carbon. How did you get those to work financially? I’d like to create a zero carbon rentals, and the ways I can imagine getting it to work financially:

1. Include electricity in the rent (charging enough to pay off the solar panels, heat pumps in a reasonable period). The drawback there is it doesn’t incentivize energy conservation, unless there was a cap at e.g., #### kwHr/month on average (the first one I’d convert to such a rental is the home I’m living in, so I’ll have a pretty good understanding of energy usage).

2. Charge a premium because it’s a net zero house, but they still pay the electric bills.

3. Charge a monthly fee (e.g., “a climate-friendly house” fee, and educate them about how they recover some of those costs with reduced electric bills) such that the heat pump and solar electric system pay for themselves in e.g., 10 years.

I live in a state that doesn’t do much to incentivize zero carbon, but fortunately my city (Columbia, Missouri) has both net metering, and rebates and low-interest loans (3-5% for 5-10 years) for heat pumps, energy efficiency measures, and solar electric.

I would appreciate any perspective you can share.

A:

Hi Terry, neither of my rental properties is zero carbon, at least not yet. 

The first one is almost impossible to insulate due to having brick walls with no cavity and very nice old oak paneling on the inside. We have added triple-pane windows, some insulation in the basement, heat pumps and a 25kW array. It is still not at net zero. I am waiting for a wall injection system that drills through the mortar rather than the bricks before I can insulate it without having to either drill the bricks (which is prohibitively expensive) or take off the oak panels. It is probably about 70% of the way there. We charge market-rate rent for the place (I found I could not charge any premium for bring “green” though I do think it creates a preference at the market price) but I add the solar production to the electricity consumption from the grid and charge the tenant for this. I am making solar electricity at around 10c/kWh and I am selling it to the tenant at utility rates currently around 40c/kWh and long term perhaps 25c/kWh. I sell the tenant about 20k kWh a year which at 15c/kWh is $3,000 a year which is about a 5% increase in the rent. So I do get paid something, but probably not enough to justify all the investment. However the value of the house has gone up considerably and I think I would get my investment back if we sold it. Academic research strongly supports this conclusion. 

On our other rental property we are making progress but it is still a long way off. We are just about to replace the HVAC system ( the furnace broke and the AC units are 25-years old) and are considering geothermal. At a minimum we will do ASHP. The attic needs insulating and draft sealing but I have not done it yet due to dampness in the basement. If I draft seal it now I will just get mold in the attic. Hence I need to put a sump pump in the basement first. This is coming this month.  I already have installed a heat-pump hot water tank which is doing a nice job of dehumidifying the basement. This house is too shaded, and the roof lines too chopped up, for solar. Hence I have bought 12,000 kWh a year from an installer of big solar arrays in MA. In MA, the net-metering law allows you to transfer excess credits to other meters. There is now a whole industry doing this because it is highly profitable. You generate zero-carbon electricity from utility-scale solar arrays at about 5c/kWh and sell it at a 12% discount to utility rates or about 35c/kWh. That’s a fat profit!

This second house is not currently rented. I doubt I can get a premium for the “low carbon” status. I might be able to once it is finished and has zero-carbon status. I have no doubt I would get my money back if I sold it with zero carbon emissions and zero utility bills. I think I could get a rent premium once it is there because of the zero utility bills. The utility bills are about $12k a year and that would represent a 12% premium to market rent. 

I hope this helps. Please let me know how you get on with zero carbon rentals!

Heat pumps insulation triple glazed windows and solar panels Zero Carbon Home author David Green
Cut your carbon emissions and utility bills to zero, I have done it
How David Green, the "Green Guru" cut his home's carbon emissions and utility bills to zero by adding heat pumps, insulation, triple-pane windows and solar panels to make a 15% return on investment.
How David Green, the “Green Guru” cut his home’s carbon emissions and utility bills to zero by adding heat pumps, insulation, triple-pane windows and solar panels to make a 15% return on investment.
How David Green, the "Green Guru" cut his home's carbon emissions and utility bills to zero by adding heat pumps, insulation, triple-pane windows and solar panels to make a 15% return on investment. David Green is the author of the books Zero Carbon Home and Zero Carbon Pool. He is also the author and presenter of the webinar Zero Carbon, Zero Bills. He is recognized as the "Green Guru" for his expertise in energy efficiency, profitable ways to cut carbon emissions and save money, and the design of houses for net-zero living.
How David Green, the “Green Guru” cut his home’s carbon emissions and utility bills to zero by adding heat pumps, insulation, triple-pane windows and solar panels to make a 15% return on investment. David Green is the author of the books Zero Carbon Home and Zero Carbon Pool. He is also the author and presenter of the webinar Zero Carbon, Zero Bills. He is recognized as the “Green Guru” for his expertise in energy efficiency, profitable ways to cut carbon emissions and save money, and the design of houses for net-zero living.
Book energy efficiency Zero Carbon Home 2020 edition front cove. Profitable ways to cut your home's carbon emissions and bills. How to get a net-zero-carbon house. By Green Guru David Green.
Zero Carbon Home paperback book front cover

Useful links:

The Easiest Way to Calculate Your Home’s Carbon Footprint:https://greenzerocarbonhome.com/2018/07/what-is-the-carbon-footprint-of-natural-gas-heating-oil-propane-and-coal/

Written Answers to over 300 Questions about Zero Carbon Homes:https://greenzerocarbonhome.com/webinar-questions-and-answers/

Finance and Net Zero Energy Terms explained: https://greenzerocarbonhome.com/energy-and-finance-terms-explained/

Zero Carbon Home Website Home Page:                https://greenzerocarbonhome.com

Database of State Incentive for Renewable Energy (DSIRE) https://www.dsireusa.org

Published articles on Zero Carbon and Net Zero Energy:

Department of Energy, EnergySage, “Zero Carbon Home”https://www.energysage.com/project/7230/zero-carbon-home/

Zero Energy Project, “My Zero Energy Retrofit beats my 401k”https://zeroenergyproject.org/2018/09/23/my-zero-energy-retrofit-beats-my-401k/

Cool Effect, “Mr. Green’s Zero Carbon Home”         https://www.cooleffect.org/content/news/green-testimonial?utm_source=Cool_Effect_CRM&utm_medium=EMAIL&utm_campaign=20180814Engage_Testimonial&utm_content=green_CTA

Green Energy Times, “My Zero Energy Pool is a Great Investment!” http://www.greenenergytimes.org/wp-content/uploads/2019/05/GET_May-2019.pdf

Published Presentations on Zero Carbon Zero Bills:

To see a 3-minute interview of David Green by NBC Boston anchor Joy Lim Nakrin, please click here:TV interview

To see a 20-minute TED talk at Harvard Business School, please click here: TED Talk

You can watch a recorded version of my Zero Carbon, Zero Bills webinar here: Zero Carbon, Zero Bills Webinar

Reviews of my “Zero Carbon, Zero Bills” webinar included, “Minute-for-minute, point-for-point, one of the best webinars I have ever attended. Thank you!”, “David is a true inspiration and asset to our community. He inspired us to get solar panels and a new front door”, “This is like a masterclass in ZeroCarbon”, “Thank you soooo much for the sensible advice and your fabulous resources!!” and, although this next comment is a little flowery, it does express the sentiment of many other comments, “Your contribution to Greening America is great and will probably help our survival as a species a bit longer than expected”.

How big is a ton of carbon dioxide (CO2) / visualizing a ton of CO2

A ton of CO2 gas is huge. It would fill a cube about 27′ (9 meters) on a side. That cube would be as tall as a telephone pole. One ton is the weight of about half a car. In other words, a car weighs about 2 tons.

The carbon footprint of each house in the US varies considerably depending on the location of the house and its size. The following charts show some of this variation. They are taken from, “Goldstein B, Gounaridis D, Newell JP. The carbon footprint of household energy use in the United States. Proc Natl Acad Sci U S A. 2020 Aug 11;117(32):19122-19130. doi: 10.1073/pnas.1922205117. Epub 2020 Jul 20. PMID: 32690718; PMCID: PMC7431053. Which is available here: https://pubmed.ncbi.nlm.nih.gov/32690718/

Useful links:

The Easiest Way to Calculate Your Home’s Carbon Footprint:https://greenzerocarbonhome.com/2018/07/what-is-the-carbon-footprint-of-natural-gas-heating-oil-propane-and-coal/

Written Answers to over 300 Questions about Zero Carbon Homes:https://greenzerocarbonhome.com/webinar-questions-and-answers/

Finance and Net Zero Energy Terms explained: https://greenzerocarbonhome.com/energy-and-finance-terms-explained/

Zero Carbon Home Website Home Page:                https://greenzerocarbonhome.com

Database of State Incentive for Renewable Energy (DSIRE) https://www.dsireusa.org

Published articles on Zero Carbon and Net Zero Energy:

Department of Energy, EnergySage, “Zero Carbon Home”https://www.energysage.com/project/7230/zero-carbon-home/

Zero Energy Project, “My Zero Energy Retrofit beats my 401k”https://zeroenergyproject.org/2018/09/23/my-zero-energy-retrofit-beats-my-401k/

Cool Effect, “Mr. Green’s Zero Carbon Home”         https://www.cooleffect.org/content/news/green-testimonial?utm_source=Cool_Effect_CRM&utm_medium=EMAIL&utm_campaign=20180814Engage_Testimonial&utm_content=green_CTA

Green Energy Times, “My Zero Energy Pool is a Great Investment!” http://www.greenenergytimes.org/wp-content/uploads/2019/05/GET_May-2019.pdf

Published Presentations on Zero Carbon Zero Bills:

To see a 3-minute interview of David Green by NBC Boston anchor Joy Lim Nakrin, please click here:TV interview

To see a 20-minute TED talk at Harvard Business School, please click here: TED Talk

You can watch a recorded version of my Zero Carbon, Zero Bills webinar here: Zero Carbon, Zero Bills Webinar

Reviews of my “Zero Carbon, Zero Bills” webinar included, “Minute-for-minute, point-for-point, one of the best webinars I have ever attended. Thank you!”, “David is a true inspiration and asset to our community. He inspired us to get solar panels and a new front door”, “This is like a masterclass in ZeroCarbon”, “Thank you soooo much for the sensible advice and your fabulous resources!!” and, although this next comment is a little flowery, it does express the sentiment of many other comments, “Your contribution to Greening America is great and will probably help our survival as a species a bit longer than expected”.

How to evaluate proposals from solar panel installers

I have too many demands on my time to be able to review this proposal unless you are willing to hire me for which I charge $250 an hour. 

In general though, look for:

  1. Panels made by companies you recognize (like Panasonic, LG, Sunpower, and I just bought Solaria) so they have the staying power to honor the 25 year warranty. Don’t go with cheap panels from no-name companies many of which are Chinese. 
  2. A 25-year panel power production warranty that allows you to make a claim based on the data in the app – avoid the warranties that require you to get the panel inspected. 
  3. A 10-year “total energy per year from the entire array” warranty from the installer
  4. A 10-year roof penetration warranty if there are roof penetrations. If you have a flat roof get a quote for a ballasted system. If you have a standing-seam metal roof, great, the panels clamp onto the seams, if you have slate or shingles forget a roof mount and look at either ground mount or suppliers like NexAmp or community source aggregation in your town. 
  5. Get the NPV, IRR and payback periods for the investment. Be wary of inflation calculations higher than 3% as they inflate the returns. Electricity prices (which determine your avoided cost or cost savings) are currently astronomical (almost 50c/kWh) because of the war in Ukraine and are likely to come down. I am currently using 25c/kWh plus 3% annual inflation in my projections. 
  6. Barring these numbers (which are not easy to do properly) look for the cost per kWh over the guaranteed life of the panels. Calculate this by taking the net cost of the array (after tax breaks and subsidies) and dividing it by the guaranteed kWh produced per year, multiplied by 25 years. This should come out somewhere between 8-12c per kWh. The lower the better.  Even the high end is a 50% discount to my 25c/kWh long term estimate for electricity prices and is by far the cheapest way to get electricity. 
  7. If the cost differences and warranty differences are small, trust your gut and go with the installer you feel most comfortable with. 

I hope this helps!

David Green – the “Green Guru”

Heat pumps insulation triple glazed windows and solar panels Zero Carbon Home author David Green
Cut your carbon emissions and utility bills to zero, I have done it
Book energy efficiency Zero Carbon Home 2020 edition front cove. Profitable ways to cut your home's carbon emissions and bills. How to get a net-zero-carbon house. By Green Guru David Green.
Zero Carbon Home paperback book front cover

The highly-acclaimed book “Zero Carbon Home”

How David Green, the "Green Guru" cut his home's utility bills to zero by adding heat pumps, insulation, triple-pane windows and solar panels to make a 15% return on investment. David Green is the author of the books Zero Carbon Home and Zero Carbon Pool. He is also the author and presenter of the webinar Zero Carbon, Zero Bills. He is recognized as the "Green Guru" for his expertise in energy efficiency, profitable ways to cut carbon emissions and save money, and the design of houses for net-zero living.
Cutting carbon footprint

How we cut our home’s carbon emissions to zero

How David Green, the "Green Guru" cut his home's carbon emissions and utility bills to zero by adding heat pumps, insulation, triple-pane windows and solar panels to make a 15% return on investment.
How David Green, the “Green Guru” cut his home’s carbon emissions and utility bills to zero by adding heat pumps, insulation, triple-pane windows and solar panels to make a 15% return on investment.

Useful links:

The Easiest Way to Calculate Your Home’s Carbon Footprint:https://greenzerocarbonhome.com/2018/07/what-is-the-carbon-footprint-of-natural-gas-heating-oil-propane-and-coal/

Written Answers to over 300 Questions about Zero Carbon Homes:https://greenzerocarbonhome.com/webinar-questions-and-answers/

Finance and Net Zero Energy Terms explained: https://greenzerocarbonhome.com/energy-and-finance-terms-explained/

Zero Carbon Home Website Home Page:                https://greenzerocarbonhome.com

Database of State Incentive for Renewable Energy (DSIRE) https://www.dsireusa.org

Published articles on Zero Carbon and Net Zero Energy:

Department of Energy, EnergySage, “Zero Carbon Home”https://www.energysage.com/project/7230/zero-carbon-home/

Zero Energy Project, “My Zero Energy Retrofit beats my 401k”https://zeroenergyproject.org/2018/09/23/my-zero-energy-retrofit-beats-my-401k/

Cool Effect, “Mr. Green’s Zero Carbon Home”         https://www.cooleffect.org/content/news/green-testimonial?utm_source=Cool_Effect_CRM&utm_medium=EMAIL&utm_campaign=20180814Engage_Testimonial&utm_content=green_CTA

Green Energy Times, “My Zero Energy Pool is a Great Investment!” http://www.greenenergytimes.org/wp-content/uploads/2019/05/GET_May-2019.pdf

Published Presentations on Zero Carbon Zero Bills:

To see a 3-minute interview of David Green by NBC Boston anchor Joy Lim Nakrin, please click here:TV interview

To see a 20-minute TED talk at Harvard Business School, please click here: TED Talk

You can watch a recorded version of my Zero Carbon, Zero Bills webinar here: Zero Carbon, Zero Bills Webinar

Reviews of my “Zero Carbon, Zero Bills” webinar included, “Minute-for-minute, point-for-point, one of the best webinars I have ever attended. Thank you!”, “David is a true inspiration and asset to our community. He inspired us to get solar panels and a new front door”, “This is like a masterclass in ZeroCarbon”, “Thank you soooo much for the sensible advice and your fabulous resources!!” and, although this next comment is a little flowery, it does express the sentiment of many other comments, “Your contribution to Greening America is great and will probably help our survival as a species a bit longer than expected”.

Choosing double pane vs triple pane windows

Question by email:

Hi Mr. Green,

We want to get triple pane, as you advise. I am looking at Pella and Harvey to keep costs down). However, I am confused as to whether I should trade the R rating advantage and drop to a double pane to improve the SHGC and VT ratings for the Southern facing windows. (I live in Boston Metro-West). 

Right now, all the triple panes are coming in at:

 U of .21-.23, SHGC .23-.24, and VLT .40-.43 

 If I go double pane I get:

 U .28, SHGC .28 and VLT .53. 

So, is the loss in U a good trade off for an increase in solar passivity and light for South facing windows? Your book spoke to this, but I seem stuck with the numbers I am getting, which differ from your options.

Also, Harvey had a triple pane casement half price from Pella, but its VLT  of .33 instead of .43. —  Is .33 noticeably darker?

Thanks for the advise. 

My answer:

I think the difference in SHGC is modest and not a big deal in this decision. Installing an arbor with deciduous plants over it on the south side will provide much more difference than the SHGC difference. The arbor/plants will provide shade in summer and not shade in the winter so the winter sun warms your house. An overhand of 3’ at approx 9’ high does the same thing. Hence arbor plus triple glazed is a better combination. Alternatively a semi-transparent curtain will have a similar effect in rejecting some of the summer sun. This will be far more effective than the small difference in SHGC.

VLT is 0.33 is definitely noticeable from 0.43. See the pictures of windows with different VLTs in the book on page 116. The VT is written on the glass and varies from 0.57 (top left) to 0.53 bottom right. These are all considerably brighter than 0.43. I estimate that 0.43 will look quite dark and noticeably green and the 0.33 will look something like a car window. I suggest getting samples from the manufacturer before deciding.

I hope this helps!

David Green – the “Green Guru”

Useful links:

The Easiest Way to Calculate Your Home’s Carbon Footprint:https://greenzerocarbonhome.com/2018/07/what-is-the-carbon-footprint-of-natural-gas-heating-oil-propane-and-coal/

Written Answers to over 300 Questions about Zero Carbon Homes:https://greenzerocarbonhome.com/webinar-questions-and-answers/

Finance and Net Zero Energy Terms explained: https://greenzerocarbonhome.com/energy-and-finance-terms-explained/

Zero Carbon Home Website Home Page:                https://greenzerocarbonhome.com

Database of State Incentive for Renewable Energy (DSIRE) https://www.dsireusa.org

Published articles on Zero Carbon and Net Zero Energy:

Department of Energy, EnergySage, “Zero Carbon Home”https://www.energysage.com/project/7230/zero-carbon-home/

Zero Energy Project, “My Zero Energy Retrofit beats my 401k”https://zeroenergyproject.org/2018/09/23/my-zero-energy-retrofit-beats-my-401k/

Cool Effect, “Mr. Green’s Zero Carbon Home”         https://www.cooleffect.org/content/news/green-testimonial?utm_source=Cool_Effect_CRM&utm_medium=EMAIL&utm_campaign=20180814Engage_Testimonial&utm_content=green_CTA

Green Energy Times, “My Zero Energy Pool is a Great Investment!” http://www.greenenergytimes.org/wp-content/uploads/2019/05/GET_May-2019.pdf

Published Presentations on Zero Carbon Zero Bills:

To see a 3-minute interview of David Green by NBC Boston anchor Joy Lim Nakrin, please click here:TV interview

To see a 20-minute TED talk at Harvard Business School, please click here: TED Talk

You can watch a recorded version of my Zero Carbon, Zero Bills webinar here: Zero Carbon, Zero Bills Webinar

Reviews of my “Zero Carbon, Zero Bills” webinar included, “Minute-for-minute, point-for-point, one of the best webinars I have ever attended. Thank you!”, “David is a true inspiration and asset to our community. He inspired us to get solar panels and a new front door”, “This is like a masterclass in ZeroCarbon”, “Thank you soooo much for the sensible advice and your fabulous resources!!” and, although this next comment is a little flowery, it does express the sentiment of many other comments, “Your contribution to Greening America is great and will probably help our survival as a species a bit longer than expected”.

Heat pumps insulation triple glazed windows and solar panels Zero Carbon Home author David Green
Cut your carbon emissions and utility bills to zero, I have done it
Book energy efficiency Zero Carbon Home 2020 edition front cove. Profitable ways to cut your home's carbon emissions and bills. How to get a net-zero-carbon house. By Green Guru David Green.
Zero Carbon Home paperback book front cover

Q: What are the options for getting renewable electricity from my utility?

There are several options in MA to going fully renewable with your electricity. It is a matter of cost. From lowest cost to highest cost, these are:

  1. The first option is rooftop solar with a reasonably sunny roof (like my house), about 5-8c/kWh, by far the cheapest option for 100% renewable electricity. Even roofs in half shade (like my garage) can produce electricity at 12c/kWh.
  2. Even with a no-cash-down solar lease (or power purchase agreement) the cost is around 13c/kWh. A huge discount to the Eversource or National Grid basic rate at 29c/kWh.
  3. Move to one of the towns (Wellesley, Littleton, Boxborough etc.) that have a Municipal Light and Power (MLP) source of electricity. Often around 18c/kWh and many offer 100% renewable options, usually for a slight premium.
  4. NexAmp offers a 12% discount to the Eversource basic rate (the R1 rate, now 29c/kWh, so the NexAmp price is around 26c/kWh) for 100% solar, 100% generated in MA. There is currently a waiting list. There are other suppliers than NexAmp but the others offer a 10% discount. This is accomplished via the z-metering provision of the net-metering law that allows the generator of renewable energy to sell the credits to other people with electricity meters. You end up getting two bills each month, one from Eversource (net of the credits from NexAmp) and one from NexAmp for the credits. The two net to a 12% discount to the ES basic rate. 
  5. If you switch to heating with primarily heat pumps (you can still have a backup fossil fuel furnace) you can ask ES for the R4 rate which is for electric heating. R4 is about 1.5c below R1. This is regardless of whether you have solar or not. This does not cut your carbon emissions from the electricity you buy, but you are now not emitting carbon from burning a fossil fuel to heat your house. Effectively this is like buying electricity that is about 60% generated from renewable sources because your carbon emissions will drop about 60% due to the efficiency of a heat pump compared to a fossil-fuel furnace.
  6. Community choice aggregation offered through a town usually offers several options with a basic rate (ISO NE grid carbon emissions), a 50% renewable mix and a 100% renewable mix. The 100% renewable mix is usually more than basic rate but this is highly dependent of rates at the time the town bids out the contract.
  7. ES offers greener options through various generators for the supply portion of your current bill. I do not know current pricing but it used to be about 5-6c/kWh  more expensive than basic rate for 100% solar, so say 35-36c/kWh

To read more about the “Fab Four” of heat pumps, insulation, triple-glazed windows and solar panels (which is how I got my house to a zero carbon footprint and also zero utility bills) please click here:

https://greenzerocarbonhome.com

To watch a YouTube recording of my free “Zero Carbon, Zero Bills” webinar (it is 45 mins of me presenting then 45 mins of Q&A) please click here:

To watch a TED talk version that I gave at Harvard Business School, please click here:

To read written answers to over 300 questions that have been asked on my webinars, please click here:

To read more about David Green who is the author of the book “Zero Carbon Home” and the “Zero Carbon, Zero Bills” webinar, and who is both a bit of an energy geek (BS in physics from Oxford University) and a finance nerd (MBA from Harvard Business School), please click here:

David Green, who has a BA in physics from Oxford University and an MBA from Harvard Business School, and who is the author of the book “Zero Carbon Home” and the webinar, “Zero Carbon, Zero Bills”