How about a metric to measure house performance? (Not heating or cooling performance)
I was thinking slope of the temperature profile line for resist delta. I see I can click on the “More info” tab to get this. Could it be added to the “Compare” section to see how it stacks up?
(Mine is slope of 0.0184 for resist delta.)
Lower slope = lower heat flux = better house performance.
I posted another topic for folks to share their temperature profile graphs, but it is harder to evaluate with everyone having different scales.
Also, the Runtime Per Degree Day is not a good comparison tool for my system. I have a variable speed compressor and fan and my system usually runs for long periods of time at 10-20% capacity. I wonder if there is a better metric for measuring cooling performance. This data may not be available from ecobee, but energy usage per square foot per degree or something along those lines would be better.
Adding a vote for this one. Beestat has taught me so much about how our house operates, would love to have this comparison to get a sense of how we compare to others. I think the slope would be a great complement to the balance point chart, or even just the absolute temperature loss at some temperature(s) (32F and 70F?). Thanks again for building an awesome app!
I was thinking about better ways to measure performance and propose a new metric, or at least modifying the current Temperature profile data.
When I go on vacation, I usually set my thermostat to around 76F (my wife keeps at 70F when we are home). This means my temperature profiles look much better during these periods because the delta T between indoor and outdoor temperature are much smaller.
To account for different thermostat settings among users and make a more baseline comparison, perhaps the X axis of the graph should be “Delta T” instead of outside temperature.
I think the same logic applies to the Runtime Per Degree Day metric. Changing the setpoint can drastically affect this metric, but it is not captured in the metric.
The other issue I have with measuring performance of my system is that it has a variable compressor and variable fan. On warm to hot days, my system runs nearly 100% of the time, but at ~20% capacity. So, it is very efficient. However my runtime per degree day for cool is >98% of other homes.
This is challenging because what you need is a third dimension. You can’t completely ignore outdoor temperature, because what would happen is that for most people, the dT value would be within 5°F 100% of the time and looking at the profile would be mostly useless as it would give you the same value if it’s 70°F or 90°F outside. Adding a third dimension would then reduce the number of data points for each outdoor temperature, resulting in worse overall averaging. I think it would also be more difficult for people to read the chart. And frankly, I think the change in the rate of thermal transfer is mostly negligible within 10-15°.
This, on the other hand, is a valid concern. I haven’t given much thought to this yet. Multi-stage systems are fairly easy to represent, but a variable compressor would certainly suffer here. I would have to really re-think the data analysis…and even then I’m not sure how I could do that effectively since the ecobee does not report this data. I only know on/off and which stage. Truly variable systems are not represented well by the data and I’m surprised you’re not using a proprietary communicating thermostat.
Great points…definitely something to consider as we continue to improve compressor design.