DALEC - Day- and Artificial Light with Energy Calculation

In the course of DALEC an online concept evaluation tool for architects, building engineers, lighting designers and building owners was developed. Although easy to use, the software accounts for the complex thermal and light processes in buildings and allows a simple evaluation of heating, cooling and electric lighting loads. Not only energy, but also user behavior were considered (e.g. in terms of glare protection) and visual and thermal comfort were evaluated. This novel and innovative, holistic approach makes sustainable and energy efficient building design possible for new buildings as well as refurbishment.

Short Description




Starting point / motivation

The design significantly influences the energy demand of a building. In particular the facade system defines both daylighting and solar gains in the building. The latter might reduce heating loads in winter, but can also lead to overheating in summer.

Depending on the amount of daylight in the building interior, electric lighting has to be added. This in turn means electricity demand as well as an additional internal gain that might lead to increased cooling loads. Thus, a realistic evaluation of façade and electric lighting systems has to be done with a combined lighting and thermal simulation. Moreover, the comfort for the user in the building has to be taken into account already in the early design stage.

For example manually controlled glare protection affects the thermal behavior and thus the energy demand of the building. With existing software tools such a holistic building evaluation approach is not possible at the moment.

Contents and goals

In the previous project K-Licht the consortium could develop a software prototype that allows for these interdependencies. Based on this knowledge an online tool was developed; it is practical, easy to use and allows an energy efficient building design with short calculation times.


The project contained the following steps:

  • Improvement of the calculation method and practicability
    The existing method of a room by room evaluation will be extended to whole buildings and halls (industry, sports, …).

    The implementation of additional electric lighting controls (e.g. maintenance control) allows the calculation of realistic lighting scenarios.

    With additional data interfaces users are able to import own weather data, daylighting and artificial lighting systems.

  • Definition of comfort criteria
    With a newly developed evaluation scheme the visual and thermal comfort are assessed and analyzed. Comfort-wise critical building designs can thus quickly be excluded (quality traffic lights).

  • Improvement of evaluations
    With the implementation of design comparisons as well as an “optimizer” the user shall easily and quickly find the best building design for the investigated location.

  • Validation and improvement of user interface
    The DALEC tool will be validated against advanced scientific simulation methods and user feedback will be considered for further developments.

Expected results

With these tasks a unique building design evaluation tool was created that allows exact and fast results in an early design stage for new buildings and refurbishments.

As no specific know-how is needed for using the tool, the target group includes architects, building engineers, lighting designers and building owners. The software accounts for the complex thermal and light processes in buildings and allows a simple and fast evaluation of heating, cooling and electric lighting loads.

The elaborated business plan guarantees continuity of the development even after the project end helping the consortium to keep their innovation leading role at the market and in the scientific community.

Project Partners

Project management

Bert Junghans, Zumtobel Lighting GmbH

Project or cooperation partners

  • Bartenbach GmbH

  • Universität Innsbruck

Contact Address

Zumtobel Lighting GmbH
Schweizerstrasse 30
A-6851 Dornbirn
Tel.: +43 5572 390 187
E-Mail: bert.junghans@zumtobelgroup.com
Web: www.zumtobelgroup.com
Current website of the project: http://dalec.zumtobel.com/