A Metric Like MPG for Houses

Like MPG, we need a metric for houses that uses things that people understand. People use gallons, and drive miles. That the genius of the metric. But HERS Index? Its meaningless without customer outreach programs. We need to find a metric, like mpg, that uses things in the house that people understand, or could be expected to understand easily.

People understand consequences. We all have to endure them. The 2 things in life that we all can’t do without: time and money. I propose dollars per day as a potential metric for housing energy performance. ZNE houses target $1/day (about $350 per year). A 2200 CFA, 2-story house in southern California (houses that we have brought down to $1/day, such as Meritage Sierra Crest) might use $6 per day ($2200 per year). Just the fees for connectivity are about $0.30 per day. MPG tends to range from 20 mpg to 30 mpg. People are OK with that spread. <20 is bad. >30 is good. With Dollars Per Day (DPD) it will range from perhaps 0.5 DPD to 6 DPD for new homes, and larger for older homes. This is a smaller spread, but perhaps if DPD were given in increments of 0.5 it would create the illusion of a larger spread (0.5, 1, 1.5, 2, … 6). We wouldn’t need any customer training, other than what a “normal” house uses.

15 years ago, if I asked John Doe off the street what a “kilowatt hour” was, I surmise they would be confused. Back then, it was just an electrical bill. No one knew what the metrics that the utilities used to determine the bill. People just looked at the dollar amount, and paid it. Same with the gas bill. But today, everyone knows what kWh are. The various energy efficiency outreach programs have made sure that people understand electrical bills are metered in kWh. This has not happened yet with therms. Basically no one knows what the gas companies use to determine their bill, they just pay it. Sound familiar? Its just like with kWh. Make a public outreach program. “Don’t be a therm bum!” Et cetera. Then we could have houses sold using the same metrics energy nerds use to talk about houses: kWh/yr, therms/yr, and peak draw. Now our typical 2200 CFA, 2-story house in SoCal is sold with the label: 4000/200/2 (kWh per year/therms per year/peak kW draw). This not only captures annual performance, but peak performance as well. However, it would require years of customer training, just like with kWh.