Home Electrification 2: Plug-in replacements, power outages, and more

These videos always remind me of one of my favorite "oldie" sitcoms from the late 60's. Makes perfect sense. :) https://www.youtube.com/watch?v=WGPMadwqPKQ

why not have both?

Peter Vanusanik

TL:DR if your electricity is not renewable, and you live somewhere that regularly gets below freezing in the winter, you would have a lower carbon footprint with a high efficiency natural gas water heater than you would with a heat pump. Heat pump water heaters are great, in the right areas. Unfortunately in areas that regularly get below 32 degrees in the winter they are terrible. Natural gas water heaters are up to 98% efficient. The COP of one of these is 1-4, or 100%-400% efficient at turning electricity into warm water (through absorbing outside heat). However, the power plants are only 40-50% efficient at turning natural gas into heat. Add to that, whenever you take a shower you will be kicking in the backup elements, with an efficiency of about 98%. So, the average efficiency of your electricity will probably be less than 150% using power from natural gas that is converted to electricity at about 50% efficiency. So, you end up with a natural gas to hot water efficiency of about 75%, compared to as much as 98% with a natural gas water heater,

Interesting idea. I started crunching numbers because I thought that the fridge moves way less heat energy (and a modern, reasonably efficient one does), but it's not off by as much as I thought. Heating 85 litres of water by 40 degrees centigrade needs 4 kWh of heat energy. I guess this should be sufficient for 2 adults per day. A modern fridge uses less than 1 kWh of electric energy per day, but let's make it 1 kWh. Since it is a heat pump, it should move around 3 times that energy in heat. So we would have about 2 to 3 kWh of heat from the fridge to put into the water. Having a huge tank coupled to your fridge and connected to your water distribution may not be feasible in most homes. On the other hand, you can just put your fridge (or freezer) in the same basement room as the water heater and at least gain some advantage. Especially if the cold air from the water heater passes over the refrigerator's radiator at the back.

Dr. Bjoern Bieber

Hi again. I love the concept of a heat pump HWH. What if you built a small "room" in the attic with vents to the next floor down. In and out vents. Warm air rises, and cool air falls. Yes, you have to pump water up there, but you don't really have to comeing down. In the summer, it acts as an extra cooling vent for your top floor. In the winter, vent to the outside. I think that's a cool idea.

Mike Bird

Hybrid water heater is a box that heats inside and cools outside. Refrigerator is a box that cools inside and heats outside. Why are these not one system?

Nitron F117