Answer first
Do not assume a house must be brought to new-build insulation standards first. Do calculate the current heat loss honestly and identify low-disruption measures that improve comfort or change equipment sizing.
Air sealing must preserve deliberate ventilation. Blocked vents and uncontrolled moisture are not energy upgrades, so fabric changes should be appropriate to the building.
Heat-loss inputs should reflect the home being surveyed
View sourceA suitable system can maintain consistent temperatures
View sourceThe 742-home trial included varied British property types
View sourceGet a heat-loss survey for the home you actually have
Tell FLO about the property and current heating. A survey turns the general guidance into a room-by-room design and written quote for the complete system.
Draughts add heat loss and discomfort
Uncontrolled air movement carries warmed air out and brings colder air in. Occupants can also feel uncomfortable beside leaks even when the thermostat reports an acceptable average.
The room heat-loss calculation includes ventilation and infiltration assumptions. Exposed rooms, chimneys, suspended floors and leaky doors deserve specific attention.
Design for the home that exists
A heat pump, emitters and pipework must meet the calculated design load. Ignoring leakage creates undersizing; assuming every future upgrade is complete can create the same error.
If insulation or draught work is firmly planned, ask the designer to show current and post-improvement cases and make the sequencing explicit.
Start with proportionate fabric measures
Loft insulation, appropriate floor measures, door and window seals and safe treatment of unused openings can reduce demand. Heritage and solid-wall buildings need moisture-aware advice.
Ventilation for combustion appliances, bathrooms and indoor air quality must not be removed casually. Heat retention and healthy air are designed together.
Comfort depends on emitters as well as capacity
A unit large enough on paper can still disappoint if one exposed room lacks radiator output or flow. Room-by-room emitter selection is therefore essential.
The written proposal should show design temperatures and identify fabric assumptions, so the homeowner knows what comfort has been priced.
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Questions people also ask
Must I insulate everything before getting a heat pump?+
No, but the current heat loss and sensible planned improvements should be considered.
Will a larger heat pump solve draughts?+
It may cover more load, but it does not remove cold air movement or guarantee balanced room comfort.
Can I seal every vent?+
No. Purpose-provided ventilation and building-moisture requirements need proper assessment.
Evidence used for this answer
Figures are explained in context and links go to the independent source. Prices, tariffs, scheme rules and standards can change, so check the source again before making a financial or technical decision.
- MCS heat-pump design standardTechnical requirements for heat loss, equipment selection, domestic hot water and system design.
- Home Energy Scotland: heat pumpsCurrent Scottish guidance on typical costs, savings, lifespan, comfort and combining a heat pump with solar panels.
- Energy Systems Catapult: home surveys and installation reportEvidence from 742 installations, including radiators, cylinders, survey constraints and typical installation duration.
- MCS domestic heat-pump guideConsumer guidance covering design, installation, controls, handover and maintenance.