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Energy sketch: heat demand and PV yield from the model

Monthly heating demand from the envelope of the model, up to four variants side by side, plus the yield of PV on roof and facade with the shade of the neighbours. An estimate for the conversation, not a certificate.

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The same house three times in a row: morning, midday and afternoon light with different shadows

In short

The VEDUTUM energy sketch computes a monthly balance after EN ISO 13790 from the envelope of the model: exterior walls per storey with windows and doors, roof, floor, ventilation and thermal bridges against the climate of the site from PVGIS. Up to four variants stand side by side, for example existing state and renovation. Modules on the roof and a solar facade get a yearly yield from PVGIS, with the shade of loaded neighbouring buildings and trees. The result is labelled as an estimate throughout, not an energy certificate, and costs no points.

What it gives you

  • Numbers from the same geometry

    Wall areas, windows, roof and floor come from the model that also makes the picture. Change the floor plan and the balance changes.

  • Variants side by side

    Up to four states with their own insulation, windows, ventilation and heating, with demand per square metre and a sentence on where most heat is lost.

  • PV with shading

    Roof and solar facade apart, calculated per direction; neighbouring buildings, trees and terrain block the direct sun.

  • Visible to the client

    If you wish, the share page shows the comparison and the client chooses a variant.

Energy sketch with three variants side by side, loss bars per element and PV yield of roof and facade
Picture from the „Haus Lindenweg“ study. A screenshot of the view follows.

How it works

  1. 01Complete the modelCheck the floor plan, set storeys, heights and roof. The balance reads the envelope from the model.
  2. 02Set the locationWith the address, the sketch loads the climate of the site from PVGIS, once; afterwards it is stored with the project.
  3. 03Add variantsEnter U-values, insulation thickness, window type, ventilation and heating per variant; the next variant takes over the previous one, improved.
  4. 04Place PVSet modules in the “Roof · Solar” tool or choose a solar facade in the facade tool; the yield appears in the sketch.
  5. 05Load the surroundingsWith neighbouring buildings, trees and terrain loaded, the yield includes their shade.
  6. 06ShareTick “Show comparison on the share page” if the client should see the variants.

How the balance works

For each month, losses through walls, roof, floor, windows, doors, thermal bridges and ventilation are set against gains from sun through the windows and internal sources; a utilisation factor based on the thermal mass of the house decides how much of the gain counts. This is the monthly method of EN ISO 13790 and DIN V 4108-6.

The climate comes as a typical meteorological year from PVGIS: irradiation on eight facade directions and the monthly temperatures at the site. A reference band places the result: passive house 15 kWh/(m²a), a detached house from 1969 to 1978 about 182 as built and 90 insulated.

PV on roof and facade

Roof modules count with their tilt and direction per roof face. A solar facade enters as a vertical area: the closed wall minus windows, doors and plinth, 80 % of it covered, with 170 Wp/m². Both assumptions are stated under the result.

With the surroundings loaded, each facade group gets its horizon from neighbouring buildings, trees and terrain; PVGIS blocks the direct sun behind it. Without surroundings, the sketch says that neighbours cast no shade.

Questions and answers

Is the energy sketch an energy certificate?

No. It uses the monthly method with simplified boundary conditions and is labelled as an estimate throughout. An energy certificate follows the rules of the country and is issued by an authorised person.

Does the sketch cost points?

No. Climate and PV yield come from the free PVGIS service, the balance is computed in the browser. Points are only spent on pictures, clips and plan readings.

How accurate is the facade PV yield?

As accurate as its assumptions: vertical modules, 170 Wp/m², 80 % coverage, 14 % system losses, neighbour heights from OpenStreetMap. For the building itself, a specialist plans with the actual product.

Can the client see the variants?

Yes, if you release the comparison for the share page. The variants stand side by side there and the client can choose one; you see the choice in the project.

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Compare variants before drawing them

Upload a floor plan, set the location, enter variants. The sketch costs no points.

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