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Heat loss guide

Heat loss formula guide: inputs before equations

Formula debates are secondary when survey inputs are weak. Strong evidence reduces rework and protects install schedules.

4.7/5 on Trustpilot · report and organised photos in the portal on completion · EPC by next morning in the standard flow.

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Guide

Input quality standards that matter most

The basic heat loss relationship is simple; the risk is in the inputs. A clean survey makes each assumption visible enough for the next person to challenge or approve.

What strong looks like

Capture standards

  • Room-by-room dimensions and construction context
  • Evidence-backed assumptions instead of defaults
  • Explicit recording of unknowns requiring follow-up
  • Clear outputs usable by office and design teams
Where time is lost

Where teams lose time

  • Inputs too weak to support defensible outputs
  • Unclear assumptions hidden inside spreadsheets
  • Rework after teams discover gaps in the report
Why it helps

Why teams use Vertex

  • Clearer reports for office and design
  • Faster quoting with less chasing
  • Install teams start with clearer site context
  • Portal visibility across teams and roles
Method

What the formula needs before it is useful

Room heat loss is driven by fabric loss, ventilation loss, temperature difference, and room dimensions. The formula is only useful when the survey data behind those parts is reliable.

Fabric

Walls, roof, floor, doors, and glazing

The survey should show where U-value assumptions came from, whether insulation evidence exists, and which areas need conservative assumptions because proof is missing.

Rooms

Dimensions and heated spaces

Room boundaries, ceiling heights, open-plan areas, extensions, and unheated adjoining spaces need to be clear. A small input error can change the emitter or heat pump conversation.

Assumptions

What gets challenged later

Ventilation, design temperature, room target temperature, fabric assumptions, and unknown areas should be recorded in the report rather than hidden in a spreadsheet.

Related guides

Related pages and proof

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