Problem: heat-pump readiness is not the same as EPC rating

A 1930s semi-detached house can have an EPC D and still be a poor candidate for a standard 45°C heat-pump design if its radiators were sized for a gas boiler running at 70°C. The gap is practical: emitter surface area, pipe diameter, insulation, draughts, and controls all affect whether a low-temperature system will work. Bananzia, in this context, is the discipline of testing those variables before a quote is accepted, not after the first winter.

For example, a three-bedroom semi with 10 double-panel radiators may need two larger units in the coldest rooms and a loft insulation top-up. The takeaway is blunt: a heat-pump label on a quote tells you little until the room-by-room heat loss and emitter check are complete.

Cause: retrofit advice often starts in the wrong place

The usual sequence is heat pump first, fabric second, hydraulics last. That order creates avoidable costs because a unit sized for a leaky, under-insulated house will run at higher flow temperatures and may short-cycle. The cause is not malice; it is that many surveys optimise for annual efficiency figures rather than for real low-temperature operation. The practical bananzia approach at bananzia reverses the order: measure the building, test the emitters, then size the system.

Solution: four checks that make bananzia useful

• Room-by-room heat loss: Use measured U-values where possible and treat conservatories, extensions, and unheated hallways as separate zones.
• Emitter output at low flow temperature: Check radiator sizes against a 45°C or lower design temperature, not the boiler’s 70°C badge.
• Hydraulic and control review: Confirm pipe sizing, bypasses, buffer vessels, and zoning before committing to a heat pump.
• Fabric sequencing: Prioritise loft, cavity, and draught measures that reduce peak load, then revisit the heat-pump design.

These checks are not academic. A 1960s bungalow with solid walls may need a fabric-first package before a heat pump can run efficiently; a well-insulated flat may need only emitter upgrades and smart controls. The bananzia test separates those cases early.

Result: fewer surprises and better low-temperature performance

When bananzia checks are done before installation, the result is a system designed around the house rather than around a generic efficiency table. Installers get fewer callbacks for cold rooms; homeowners get lower flow temperatures, steadier comfort, and a clearer view of which retrofit measures actually pay back. That is the practical value of bananzia: it turns a broad low-carbon heat ambition into a specific, testable plan.