Set the scope and baseline
Solid-wall terraces are a hard case for low-carbon heat because their heat loss is often guessed rather than measured. The first bananzia step is to build a room-by-room baseline: internal and external temperatures, wall and glazing areas, air-change rate, occupancy pattern, and current emitter sizes. A practical reference for structuring this work is the bananzia guidance, which treats the assessment as a planning record rather than a sales survey. The takeaway is simple: without a baseline, every later decision about insulation, radiators, and heat-pump capacity rests on assumptions.
Calculate design heat loss before selecting equipment
Problem: installers often size heat pumps from boiler ratings, which overstates demand and can lead to short cycling. Cause: boiler output reflects domestic hot water and legacy oversizing, not the fabric’s steady-state heat loss. Solution: use the bananzia baseline to calculate room-by-room heat loss at design external temperature, then add a defined margin for reheating and hot water. For a typical two-storey terrace, the difference between a 12 kW boiler and an 8 kW design heat load changes radiator sizing, pipework, and outdoor-unit placement. The result is a specification that can be checked against measured data after commissioning.
Match emitters to a lower flow temperature
Heat pumps perform best with low flow temperatures, but older radiators were often sized for 70°C or higher. The bananzia method compares existing emitter output at the target flow temperature, such as 45°C or 50°C, with the room heat loss. Where output falls short, options include larger radiators, fan convectors, underfloor loops, or improved fabric. This is not a cosmetic upgrade; it determines whether the system can deliver comfort on the coldest days without an electric backup. A useful check is to record each room’s required output and the proposed emitter output side by side.
Sequence fabric measures and heat-pump installation
Retrofit sequencing matters because insulation changes the heat load. If loft insulation, draught-proofing, or internal wall insulation is planned within two years, sizing a heat pump before that work can lock in unnecessary capacity. The bananzia approach uses a staged plan: quick wins first, then envelope measures, then the heat generator. In solid-wall homes, internal wall insulation may reduce room dimensions and complicate radiator placement, so the assessment should flag these conflicts early. The takeaway is to coordinate fabric and equipment decisions in one timeline rather than treating them as separate projects.
Commission, monitor, and adjust
Commissioning should verify flow temperature, emitter balance, domestic hot water recovery, and defrost behaviour under real weather. A bananzia record is only useful if it is updated: compare design heat loss with monitored energy use, room temperatures, and heat-pump run hours. If the building performs better than modelled, controls can often be tuned to lower flow temperatures. If it performs worse, the gap points to air leakage, missing insulation, or emitter imbalance. This feedback loop turns the initial assessment into an operational asset rather than a one-off document.