A Picopod was evaluated for its thermal performance (its ability to maintain a comfort temperature and the running cost). Frequent measurements of electricity consumption (supplying the pod heater) and the outside air temperature were recorded over several days and nights in April 2021. The standard building industry methodology (using independently recorded degree day measurements) was applied to establish the straight line relationship between energy consumption and the external air temperature (while a comfort temperature of 21C was maintained by the thermostatically controlled heater).
The plot below records internal (orange) and external (blue) temperatures. It shows that despite external swings between zero and 25C, the heater was keeping the pod temperature very stable.
The graph below shows how heating energy needs rise the colder the temperature outside.
This is the relationship that is used to establish energy consumption for a given degree day value.
Degree days are simply a measure of the amount of time the outside was colder than the 21C of the heated pod.
(The R squared value being very close to unity indicates that the equation accurately models the pod’s thermal performance)
The pod is located in North East Fife, Scotland where the weather is influenced by cool Arctic and Northern Continental Europe air flows.
It is oriented to face North so does not enjoy solar gain through the double glazed doors.
Measurements were taken over four days when the outside air temperature (blue line) swung between zero and twenty+ values and an average well under ten C .
Daily consumption was around four Kwhrs to maintain the pod at 21C 24 hours per day. W
We may reasonably consume less than half this value had we restricted heating to eight or twelve hours per day to reflect a more common occupancy pattern.
An annual heating requirement for this structure would likely have been between 500 and 1000 Kwhrs over the year (to May 2021) and considerably less if it was oriented to the East or West.
In a cool, Eastern coastal Scottish location this Rumipod in the year to May 2021 would have cost very little to run.