Overall view of the building before construction.
How can we improve thermal insulation and staff comfort ?
Our case study on natural light concerns the renovation of a technical building. Located in the Moselle département, it houses the mechanical workshop and vehicle repair and maintenance store of the département’s technical services.
The project involves total renovation of the roof, with the aim of improving thermal insulation and staff comfort. The client also specifically requested that the roof be flooded with natural light.
Principe
The most important indicator of a building’s ability to let in natural light is the daylight factor (DF). It represents the ratio of natural light entering the building to the amount available outside.
It depends solely on the orientation of the building and its openings. DF is therefore independent of location. Based on a site’s weather data, DF can be used to estimate natural light autonomy in relation to an illumination target. It represents the percentage of time during which the lighting target will be reached in the building.
Study
To achieve the objective of natural lighting inside the building, our experts recommend the installation of :
- 8 Bluevoûtes Therm, size 3×6 m
- 1 Bluevoûte Therm, size 2×5 m
- 3 Bluesteel Therm, size 1.3×1.3 m
The light transmission of the roof-mounted units is 52%. Facade-mounted glazed units have a light transmission of 70%.
Simulation
According to the recommendations and simulation results, natural light from the facades and roof will cover the entire space. The objective of 300 lux for 50% of the time will be largely achieved, over 95% of the surface area.
| Location | |
| Longitude | 0.6° |
| Latitude | 44.2° |
| Current sun position | |
| Elevation | 37° |
| Azimut | 13.6° |
| Natural lighting | |
| Sky type : | CIE type 16 |
| Direct available illuminance : | 34 059 lux |
| Available diffuse illuminance : | 25 175 lux |
| Minimum illuminance : | 747 lux |
| Average received illuminance : | 3061 lux |
| Maximum received illuminance : | 22 824 lux |
| DF minimum : | 1,8% |
| DF medium : | 6,0% |
| DF maximum : | 27,2% |
| Surface area ratio meeting the requirement : | 100% |
Result after work
Several months after completion of the work, the feedback is very positive.
The recommendations of our lighting study have been respected, eliminating the need for artificial lighting for most of the day. In addition, an extra Bluevoûte has been installed in the darker location to achieve a better distribution of natural light in this area.
Finally, the total re-roofing combined with the thermal performance of the installed vaults greatly improved the building’s thermal comfort.
