Net Zero: The All-Electric Home

Posted by on March 21st, 2016 in Uncategorized Comments Disabled

by Jessica Steely

Exploring heat pump and induction cook-top technologies

Once upon a time there was a dream to have homes make all their own energy, a true demonstration of personal responsibility. The phrase coined to represent this objective was that a home would be Net Zero Energy. As one can imagine, the harvesting and refinement of gas was not a task the average homeowner could accomplish easily, so the all-electric home gained popularity. The resulting demand of new electric technology to replace older gas appliances became abundant and innovation was employed.

Here in California, this dream has come in the form of mandates; Net Zero Energy homes are becoming a reality. Due to the increased market demand, the efficient electric technologies long utilized around the world are now available at a feasible price in our local markets. Two of these innovations that Semmes & Co. includes regularly in homes are Heat Pumps and Induction Cooking.

THE HEAT PUMP

The basic principles of a heat pump go back to ancient vernacular architecture. It’s efficient because instead of heat creation, it simply transfers heat from one place to another. In our modern application we are using two basic methods of heat transfer, air-to-air and air-to-water. Heat in the ambient air (outside of the conditioned space), is extracted and concentrated to heat the air or water. This process can also be reversed to provide cooling. The air-to-air unit replaces our traditional forced air unit and air conditioner. The air-to-water pump replaces our traditional hot water heaters. These systems are up to three times more efficient as their gas or electric counterparts.

See below a video with a simple illustration of how an air-to-water unit works:

Benefits:

  • Efficiency: They are up three times more efficient than their gas or electric counterparts.
  • Sustainability: Enables all electric and net zero homes.
  • Secondary Cooling: They are going to cool and dehumidify the space they are placed within. The warmer that space, the better their performance.
  • Versatility: The air-to-air units can be used in ducted or non-ducted applications.
  • Continued innovation: Newer technology is under development in the compressors. Look for a scroll compressor as opposed to a piston compressor. It is even more efficient and it’s quieter.

Considerations:

  • Noise: The compressor can be a little noisy so you want to place the unit somewhere where sound will not be an issue.
  • Cold climate: Today’s models are more advanced but still, if there is not enough heat in the air for the unit to extract, a backup heater will need to come on. These backup heaters are typically electric but models with gas backups exist.
  • Space: These units typically need about 1000 cubic feet of volume from which to pull the heat from surrounding air. Garages and large attic spaces tend to be the favorite location for placement.
  • Recovery time: Like other electric water heaters, the air-to-water unit can be a little slower to make hot water, so going with an 80 gallon unit tends to be the safe way to go.
  • Cost: The air-to-air units tend to run about twice the cost of standard units and the air-to-air types are adding about 50% to the cost. The return on investment is still good however it should be estimated on a case by case basis.
  • Off grid: When you are making your own power off grid or are on a limited sized meter in a grid tie application it may be cost prohibitive to go all electric. Assessing this balance is an important part of the process.

THE INDUCTION COOK-TOP

I hear it all the time, “I would go all electric, but I simply don’t want to give up my gas cook-top”. While it is true that the old time electric stove-tops were slow to respond and somewhat dangerous with their lasting residual heat, there is a new electric option that appears to be alleviating all of these issues: Induction Cook-tops. The technology is based on magnetic induction as opposed to the traditional thermal conduction. They are extremely efficient as there is significantly less heat lost to the surrounding air. It provides instant heat control like a gas burner and the surface is immediately cool to the touch when the pan is removed. They are making their presence known in the appliance world.

Watch the video on this website for a simple illustration of how induction works:

Screen shot 2016-03-21 at 4.39.03 PM

Benefits:

  • Controls: Specific settings allow you to modulate temperatures instantly over the heat as with a gas cook-top but with calibrated measurements for more exact control. Often 18 settings within low to high zones.
  • Speed: On the highest setting water will boil in nearly a quarter of the time as on a gas cook-top. Think 2.5 minutes vs. 9 minutes.
  • Efficiency: There is no waste heat distributed to ambient surrounding air.
  • Safety: The surface of the induction cook-top, even when turned on, will not be hot enough to burn hands when the pan is removed.

Considerations:

  • Pots and pans: The surface of the cookware that is in contact with the cook-top must be made of ferrous metal. Cast iron and stainless steel are best.
  • Durability of cook-tops: The ceramic and glass tops can scratch relatively easily and it has been known for melting aluminum foil into the surface. There is also the concern that when an induction cook-top has a problem, you will not be able to use it, as opposed to striking a match to light a problem igniter on a gas unit.
  • Sound levels: There is an internal cooling fan that may be heard. Also some pots may make a small hum when on high settings if the cookware has any loose parts.
  • Pacemakers: There are certain scenarios where some types and implantation methods can be impacted when exposed to induction technology. Though the threat is minimal, you will want to speak with your physician.
  • Cost: These units tend to be slightly more expensive than the low end gas and electric models on the market. However they are comparably priced with nicer middle or high-end models.

Being part of a team focused on increasing the performance of a home is rewarding as we constantly get to deal with the cutting edge of technology and performance of these machines. If you want to discuss the implementation of this equipment in your home, give us a call and we would enjoy a conversation.