Tuesday, November 2, 2010

Electric Water

Our electric bill is higher. It was $60/month, its now $90. One difference is that hot water was free in the previous apartment but heated with our own electricity in this apartment.

  • 10 gallons typical laundry-wash load
  • 20 gallons typical dishwasher batch
  • 20 gallons for 10 minutes of shower at 2 gallons per minute. http://ga.water.usgs.gov/edu/sq3.html
  • 1000 gallons per month, 35 gallons a day, is our base case hot water usage
  • 7 gallons of water can be heated from 60'F to 120' by 1 kWhr of electricity http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/houseenergy.html
  • 1 kWhr costs $0.20 in CT ( it was $0.18 in NJ)
  • $30/month is our base case hot water portion for the electric bill ( from 1000 gallons / 6 gallons per kWhr * $0.20 per kWhr )

In the winter, this helps to heat the house and this reduces the heating bill. If we used air-conditioning in the summer, this heat would increase the air-conditioning load, 200 kWhr hot water might add 100 kWhr heat which might add 150 kWhr sur-charge to the air-con.

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