I must admit that I am still having trouble getting my head around this idea. But the arithmetic is fairly simple: an 80% reduction in carbon emissions simply can’t be achieved without drastic cutbacks in residential natural gas use. In the residential sector, natural gas burned on site is responsible for about one quarter of carbon emissions. We can use carbon-free electricity generated by wind and solar to power the refrigerators, lights, TVs, and computers but that leaves the gas-fired furnaces, water heaters, stoves, and clothes dryers sticking out like carbon sore thumbs. We are already testing technologies for capturing and sequestering the river of CO2 emanating from a huge gas or coal power plant, but there’s no economic technology even on the horizon to capture the trickle of CO2 emanating from a home’s furnace flue. So we need to talk about electrification.

For me, electrification runs counter to everything I have learned (and advocated): making heat with electricity is really expensive, gas heat is more economical over the life of the device, and never select electric heat if you can avoid it. Some regions have even enshrined this philosophy into their codes, requiring builders to obtain special exemptions for permission to install electric heating equipment. Worse, electrification must begin during a period of exceptionally low gas prices when heating with gas is economically attractive. We need to start talking—and acting—about it soon or else we’ll be saddled with homes served by equipment that they can’t use (or perhaps only at an unacceptable cost). People often speak of “stranded assets” like non-operational nuclear power plants, but a gas furnace, clothes dryer, or other polluting devices can become a stranded asset, too. This is occurring with diesel cars in Paris, France. Diesel emissions have become such a problem that the mayor banned their use after 2020. Current owners of diesel cars are stuck with a stranded asset.

Timing is critical to avoid backward steps in carbon emissions. If electrification begins today, it would be powered by dirty coal in some regions, much cleaner natural gas and nuclear in other regions, and a little renewables. That’s not the outcome we want. America’s electricity supply structure is diverse, so perhaps electrification in a region should begin only when renewables generate more than 50% of the electricity. A half renewables grid may seem far in the future, but actually it means that a few regions in North America need to start considering code changes today.

How does electrification translate into practical things, like outfitting a new home or the next retrofit? It means installing electric appliances in new homes and, in existing homes, possibly replacing gas appliances when they wear out. It does not mean the return of resistance heat. Instead, you will see a lot more heat pump water heaters; indeed, there will be very efficient (and quiet) heat pumps embedded in all sorts of devices.

In the meantime, reducing the need for heat—hot water, hot air—should of course be the first goal. Insulation and hot water conservation will make the conversion more economical because smaller equipment can handle the loads. Truly sealing homes becomes easier—and cheaper—when combustion is eliminated inside the building envelope.

The transition to all-electric homes is going to be controversial, complicated, and expensive. New technologies and conservation can lower the costs but, ultimately, some difficult political decisions will determine the direction and rate of this transition. In the long run, electrification also needs to be economically attractive. And perhaps what I find difficult to wrap my head around today will become obvious in a few years.

- Alan Meier

This editorial originally appeared in the May/June issue of Home Energy Magazine

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Comment by Hans Joachim Preiss on May 15, 2015 at 8:36pm

Alan, similar to cars going all-electric, removing combustion appliances from homes is inevitable. A few thoughts:

  • Bringing the NACH down and reducing infiltration is significantly easier if there are no chimneys or other vents for combustion appliances.
  • Many combustion appliances are never properly commissioned, never adjusted for altitude, gas pressure, the CO dialed in, or serviced regularly, and therefore not running as efficient as they could. 
  • No combustion equipment, no gas leak, and zero chance of CO poisoning.
  • Contaminants leaking from combustion equipment are one major source of poor indoor air quality, and an all-electric home would have a zero chance of back drafting. 
  • Achieving net-zero is a lot easier with an all-electric home, as all you have to do is watch your meter to know if you're on the right track. No therm to kWh conversion.
  • As you wouldn't convert a gasoline car to all-electric, simply replacing a furnace with a heat pump would not provide any savings. This only makes sense in high performance new homes or deep energy retrofit existing homes.
  • If consumers were able to pick their electricity provider and decide what 'pollution grade' of electricity they buy, there would be real competition and market transformation would happen a lot quicker. 
  • The introduction of the Tesla battery certainly has a lot more people thinking about how their home is powered, and how it might be powered tomorrow.

Cheers
Hans

Comment by Graham Irwin on May 7, 2015 at 7:44pm

As we move toward more and more renewable energy in the grid, storage will be a key issue. The biggest challenge is providing renewable energy in winter, when solar energy is lowest. Not coincidentally, that's also when heating demand is highest (i.e. "It's cold outside because it's winter. It's winter because there's not much sun!") There are a number of parallel efforts afoot for long-term (seasonal) energy storage, including solar synthetic natural gas: http://greenbuildingelements.com/2015/04/24/first-us-power-to-gas-p... It could well be that the current natural gas grid becomes a distribution system for renewable energy. Conventional natural gas is solar-derived as well, but over the course of millions of years and much less efficiently...

In terms of analyzing the environmental impact of natural gas vs. electric, it is really about the source, not site, energy, as Brennan points out. Here's another neat illustration of what's he's getting at: http://www.sfgate.com/business/article/Benefit-of-electric-cars-fou...

Comment by John Nicholas on May 5, 2015 at 8:09pm

Electrification for heating is bad.   Nope!

Electric Resistance heating is not efficient. Nope!  The Yellow Energy Guide Label from the FTC says 100% on an Electric Furnace.

Gas furnace (mine) is only 97% efficient.

In 2012 I choose to use an ASHP as my primary heating and cooling source. (CZ4).  I left off the emergency and back up electric resistance strips, for the gas furnace.

The ASHP has a COP of 3 to move heat from the outside at 50°F inside my house.  That is 300% efficient.  Plenty of heat outside at 40 - 50° F.  Using energy to move heat is much more efficient than consuming energy to create heat.  How much heat in 50°F outside? More than inside your refrigerator at 40°F when it kicks on and moves the heat outside to keep the food cold.

Comment by David Eakin on May 5, 2015 at 5:11pm

Alan, it's not the source of the energy that's important - it's the amount of energy used that matters. If you reduce your energy loads (whatever they may be) you will be generating less carbon emissions (wherever they may be produced). Without dramatically reducing energy loads (by mandating much more efficient structures in addition to appliances, transportation and electronic devices) you just end up with an expensive switch from one form of energy to another with negligible carbon emission reduction. A switch that the general buying public will not pursue because it makes no (economic) sense to them. Renewable energy is all well and good, but there are business models behind them so the energy is not likely to be low-cost. Drastically lower energy use and lots more environmentally friendly energy sources become much more economically viable - maybe without creating any more of them.

Comment by Brennan Less on May 5, 2015 at 3:30pm

In case this is useful for anyone, I have calculated the 2010 carbon emissions per unit of delivered electricity (lbs./kWh) for each state in the U.S. (based on eGRID data). The map below of the US highlights states where a best-in-class heatpump can meet or beat carbon emissions from an efficient gas appliance. These emissions are compared with those of a 95% efficient, on-site gas heater (gas emissions are 0.399 lbs./kWh) in order to assess the heat pump equipment efficiencies required to break-even with natural gas in terms of carbon emissions. Holding all else constant (e.g., insulation levels, airtightness, ducts), in those states highlighted in green, a high performance air-source heat pump (<10 HSPF) can at least break-even with a 95% efficient gas heater (and often do much better). Yellow states require best-in-class heat pumps (such as those listed in the Energy Star Most Efficient list) in order to break-even. In red states, no currently available air-source heat pump can break-even with a 95% efficient gas heater, given federal performance ratings.

Comment by Ben Thompson on May 5, 2015 at 2:30pm

Alan, super important discussion you have started. I work a lot with multifamily rehabs and I'm recommending elimination of all gas appliances inside of building envelopes. That's seems the obvious first step. Heat pumps are getting better and better, especially for mild climates. As you point out, air sealing and insulation is key to reducing loads, and becomes much easier without combustion appliances to worry about. I think the primary cause for failure of 'whole house' utility rebate programs is due to issues around combustion appliance safety. Get rid of combustion appliances and the problem goes away. Of course IAQ and indoor moisture control must still be considered. - Ben Thompson

Comment by Barbara Smith on May 5, 2015 at 1:50pm

Good points.

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