Building energy audit for practical renovation questions

What can this assessment tell you?

It can show which entered envelope components make the largest estimated contribution to heat loss, which inputs are uncertain, and which measures are worth comparing before renovation. It can also place heating, ventilation and energy-consumption information beside the envelope record instead of treating them as separate decisions.

• Walls, roof or attic, floors and foundations
• Windows and doors, including entered areas and U-values
• Thermal transmittance (U-values) from recognised material layers
• Ventilation and air-change assumptions
• Heating-system and available energy-consumption context
• Renovation-oriented comparisons and a generated assessment report

How the building envelope affects heat loss

Heat loss through a building element depends primarily on its area, thermal transmittance (U-value), and the temperature difference represented by the selected heating-degree-day climate data. The tool uses entered walls, roof, floors, foundations, windows and doors to calculate indicative component contributions.

A low U-value generally means less heat transfer through the modelled element. It does not prove that insulation is continuous or that junctions, thermal bridges, workmanship and air leakage are satisfactory; those require project-specific inspection or analysis.

Use the result to prepare the next technical question

A high estimated contribution is a reason to verify the assembly, dimensions or system interaction—not a diagnosis of a defect. Compare alternatives using the same documented assumptions, then use the report to decide whether drawings, bills, an on-site survey, thermography or professional design work is needed.

Ventilation matters alongside insulation and airtightness. Reducing envelope losses can change indoor humidity and air-change needs, while heating equipment should be considered against the demand after envelope improvements.

Preliminary assessment, official audit and certificate are different

Energy-audit.eu is a preliminary digital planning tool. It does not issue an official or legal energy audit, an energy performance certificate, or a compliance decision.

Use a certified audit, certificate, site survey or professional engineering design where local law, finance, procurement or technical risk requires one.

Start a building energy assessment

Create a preliminary record of the envelope, systems and energy-use information you already have.