Mathematicians needed! PiP Charge cost vs Gas

I agree that efficiency and conservation are the first steps, but if you have a moderately sized home it won't save you from hitting the SCE tiers of misery.

The first thing I did when I moved in with my fiance was to change every light in the house to LED. The A/C unit (about 10 years old) is probably the biggest culprit, as my fiance says winter electric bills are closer to $100. Summer bills, however, are approaching $500 and we live in the coastal region of SoCal. A high SEER A/C is in our future as well.

 

Our current home is 3800 ft*ft. We consume ~ 225 kWh a month -- some $25 a month not including hook-up fees. This is about double my other home, but this home is a rental and I am limited in what I can improve.

AC definitely sounds like the first thing to take a look into. In addition to machine maintenance or perhaps replacement, you may find ducting has leaks, the house is leaky, or someone likes to set the thermostat at 41F

Good Luck Hunting

 

I have split units with 21-23 SEER. Our last 3 months (with PiP charging and all my lawn equipments are electric) consumption have been 774, 567 and 583 kWh for July, Aug, Sept.

Our 4 months old baby is at home pretty much 24-7 so those figures are pretty good, I think.

I pay about 18.5 cents per kWh, so it has been $100-$140 for electric.

Temp is going down to 50-60 deg F at night recently and we have been using the split units for heat. We'll see the next month bill.

 

My neighborhood had it's first week of freezing temperatures at night this week and the nearby mountains are snow covered. I let the temperatures in the house passively climb to 68 -70F by late afternoon, and then nadir to 62 - 64 F by early morning. I was complaining to my wife today that the house thermal envelope is rather poor -- but yours sounds downright terrible.

 

I was talking about outside temp. This morning, outside temp was 45 deg F. The first floor was 61 deg F, down from 69 deg last night (unheated for about 6 hours). We slept with 72-74 deg upstairs.

I had to use heated seats (High) in my PiP on this morning commute.

 

Yes, I understood that your comment of 50 - 60F temps was outside. I was comparing to my home, which cools down less despite much cooler outside temps.

The answer might be your two stories -- the average is more reasonable

 

Yup, we have two stories plus attic. It is an old house (1920) but well built. No drafts and feel pretty air tight. The attic doesn't have full insulation so there is room for improvement right there.

I am now curious what kind of house you have with better thermal envelope.

 

If the house has not been updated in terms of insulation and leakiness since 1920, fuggediboutit.

We rent a home built about 20 years ago. It is stucco on frame, and was clearly built with passive solar and cooling in mind, but I'm pretty sure to the standards prevalent at the time in terms of thermal envelope -- meaning pretty damned poor. The windows in particular, although double pane, have frames that would make a reasonable builder of today cringe. It has an attic of sorts under an asphalt shingle roof that I have yet to figure out how to access. Perhaps just a foot or two of space ? I cannot tell if it is insulated.

I am not an engineer or a physicist, so I use Newton's law of heating/cooling loosely to compare home 'U' values. The general idea is that area*temp_gradient is proportional to energy_flux. My home is 3800 ft*ft, and loses about 5 - 7 degrees F overnight to an average temp gradient of 20 degrees F.

 

Plugging in gives me roughly the benefit of a half-liter of gas.

 

Plugging in allows me to get on average 100+MPGe for my 32 mile round trip commute, close to twice a typical Prius' mileage. Those saved liters add up each tankful.

 

You are mixing up gas consumption with fuel economy.

100 MPG you see is the consumption, abbreviated as CONS. If you were to repeat such drive with repeated plugging in, you would go 100 miles with a gallon of gas.

Fuel economy is a bit more tricky to find out. To do that you need to go into EV driving ratio screen and get 4 numbers.

EV miles driven and kWh consumed will give you electricity economy. 33.7kWh is equivalent to a gallon to calculate MPGe.

HV miles and gallons consumed will give you gas economy (MPG).

You can also get the composite fuel economy. Total miles / (gallons + gallon equivalent).

See this thread for example.

 

Just be aware that the gallons consumed is a non-rounded integer (could be 7 gallons or 7.9999 gallons). Over thousands of miles this is, of course, less significant but can lead to substantial miscalculations when dealing with a few hundred miles.

 

Yup, you can divide the miles driven by CONS MPG. That'll give you gallons in decimal.