Q: Hello, I wondering if I can get some insight on how HomeIQ calculates my energy rating. What is the logic involved?
A: This is a very good question. HomeIQ insights essentially are showing you three metrics:
- "Your ecobee saved you" . This value in percentage is tied directly your equipment runtime and thermostat temperature setbacks you used over the last month. We correlate the two to develop a curve fit model for your home. From this we infer the equipment runtime savings you had, as a percentage, compared to had you set your thermostat at a constant 72 for the month.
- "Your ecobee rating" . This metric is a measure of envelope energy tightness. It's based on data that we gather by monitoring the floating temperature in your house when your equipment shuts off. In this calculation we try to do this when factors like solar radiation are minimal (i.e. overnight) and when there is a large enough temperature swing to get some data certainty. I would be the first to concede that there are a number of factors in a calculation like this and we are continuously trying to find innovative ways to make this calculation better.
- "Your system ran for" . This is strictly a comparison of runtime comparison with other ecobee users by province or state. What you mention about sample population size and potentially using adjoining states is a great one and one we've definitely considered it's just that ecobee users, climates and size varies heavily state by state and to date we don't have a simpler way of approaching this. If you have an idea for how to approach this easily, it would be great to hear. Also, personally speaking I would take this metric as an insight only because different systems (e.g. geothermal versus conventional furnaces) or equipment sizing (e.g. a properly sized furnace versus an oversized one) might have longer runtimes despite overall being much more energy efficient systems. Again, a consideration that we are aware of and are working to factor in.