What problem does bananzia solve?
A small housing cooperative in Leeds uses bananzia as a weekly heat-pump review, not a general energy audit. The problem it targets is specific: a heat pump can switch on its backup immersion heater during a cold snap, run for 40 minutes, and leave no obvious trace on a monthly bill. In one terrace of six homes, that hidden boost added 11 kWh of electricity over three days while indoor temperatures stayed flat.
The cause is usually controls, not hardware. Weather-compensation curves set too high, or a temporary “boost” mode left active, push the system to use resistance heat when the outdoor unit could still handle the load. The cooperative’s volunteer log—nicknamed bananzia—records meter reads beside outdoor temperature so the mismatch becomes visible before the bill arrives.
Why does the waste go unnoticed?
Most households see heat-pump data only through a supplier portal that updates daily or monthly. That delay hides short bursts of auxiliary heat, which are exactly the events bananzia is designed to catch. A 15-minute immersion boost can cost more than an hour of normal compressor running because resistance heat has a coefficient of performance near 1.0, while the heat pump may run at 2.8 to 3.5 in mild cold.
The practical result is a bill that looks vaguely “high” without a clear cause. By the time the statement arrives, the weather has changed and the evidence is gone. A weekly log keeps the context: outdoor temperature, thermostat setting, and the heat pump’s operating mode at the same moment.
How does the bananzia routine work?
The routine is deliberately low-tech, which is why it survives busy weeks. It takes about six minutes and uses the same three signals every time.
- Read the electricity meter and heat meter at the same time each week, ideally before the morning hot-water cycle.
- Record the outdoor temperature and thermostat setpoint from a phone weather app and the wall controller.
- Check the backup heater status in the controller’s event log; note any immersion or auxiliary run longer than 15 minutes.
On a wet Tuesday in February, the Leeds volunteer spotted a 22-minute immersion run at 4°C outdoor temperature. The heat pump was set to “comfort” with a 50°C flow limit, so the controller called for backup heat instead of letting the compressor work longer. Lowering the flow limit to 45°C and locking out the immersion above 2°C removed the spike within two days.
What should a first-time bananzia log include?
Keep the fields narrow enough to compare week to week. A useful first log has date and time, outdoor temperature, indoor temperature, electricity kWh, heat delivered kWh, controller mode, and any boost or immersion runtime. Ignore single-day noise; read the seven-day trend. If electricity use rises while outdoor temperature is stable, check the backup heater first, then the hot-water schedule.
The takeaway is that bananzia works because it turns a vague winter bill into a small, repeatable observation. It does not require a smart meter dashboard or a technician visit; it requires one consistent reading and the discipline to compare it with the weather.