Each point is one day: mean heat output against mean room minus outside temperature. Hover over a point for details, click to open the power view for that day. The slope of the fit line is the heat loss in W/K.

• Fit: the balance point is where the fit line reaches zero heat. Days below the balance point are mostly water heating and standby, so the fit excludes them and refits until the balance point settles. Days more than 2.5 standard errors from the line are also excluded.
• Design outside and Room: set the design ΔT for the heat demand estimate.
• Use as room T: replaces measured room temperature with the Room value. Used automatically when there is no room temperature feed. Useful when the feed is not representative of the whole house.
• Min ΔT: optional, excludes mild days before the fit.
• Min quality: percentage of the day with heat meter data. Days with gaps under-count heat and are excluded. Applies with the daily pre-processor enabled.
• Split by: heating season runs July to June. Solar splits days into three equal groups by solar generation, from the optional solar feed.

Notes on the estimate:

• Heat comes from the mode selected above the chart. All includes water heating. For a typical 100 m² house the extra heat for water heating is similar to the reduction from internal gains, so All is often a good approximation of the building heat loss. Space gives a lower figure.
• Estimate is mean output over a day at the design temperature, not peak output within the day.
• Range is an 80% prediction interval: 8 out of 10 days are expected to fall within it. A design temperature colder than any recorded day is an extrapolation.