Orientation, solar energy transmittance and lambda value
Energy performance certificates are relevant to many new buildings, alterations, sales and lettings in Lower Austria. We prepare certificates for residential and non-residential buildings with the intended use in mind.
A building’s orientation tells you which direction its windows and façades face. This matters because sunlight through south-facing windows can help warm a room in winter, but it can also make it too hot in summer. Good shading makes a difference. The solar energy transmittance (g-value) tells you how much of the sun’s energy passes through the glass into the room. A lower g-value lets in less solar heat; a higher one lets in more. The lambda value describes how easily heat passes through an individual building material. The lower the value, the better that material insulates. What matters in practice is how the glazing, insulation and construction work together.
Building applications and energy figures
The documents required depend on the project and local building rules. A certificate includes heating demand and the overall energy efficiency factor. For new buildings, calculations can also help compare insulation, windows and heating solutions before construction.
Renovation and housing subsidies
Lower Austria offers different subsidy paths for home renovation, including options with and without an energy performance certificate. For major thermal renovations, comparing the building before and after the works is especially useful. Some smaller measures can be documented differently. Where registration is required, the relevant energy certificate database is used.
Information needed
Existing plans, construction details, window specifications and heating and hot-water information. Renovation projects also require a description of the proposed changes. We clarify the correct scope before starting the calculation.
Official information: Lower Austria: owner-occupied home renovation · ZEUS submission information