Case study: NAC Houthalen-Helchteren

Revolutionary design requires customisation

The New Administrative Centre (NAC) in Houthalen-Helchteren is recorded as one of the most sustainable public buildings in Belgium. The bold design reconciles energy-efficiency with maximum functionality for staff and visitors. This requires customisation, also with respect to lighting. Tom Daniëls, senior account manager at ETAP, provides text and clarification.

The New Administrative Centre (NAC) in Houthalen-Helchteren was designed by architectural firm Holistic Architecture 50│5 from Hasselt and realised by THV Mandala. The building fits into the rezoning project for the municipality's former mine sites. Despite its bold futuristic design, it perfectly blends into the environment. The austere geometric shapes seamlessly fit in with the site's natural wavy surface. Since the entire building is covered by a living roof, from a distance the structure looks more like a green space than an administrative centre. The NAC was inaugurated in September 2012.

Functional and sustainable
But the striking design does not prevent functionality, quite the contrary. The building houses the various municipal administrative services, OCMW (social services), library and police in a single location. The municipality's residents effortlessly find their way to all services from the spacious central foyer.
In the design a lot of attention was paid to sustainability. In terms of heat-insulation and energy efficiency the building scores a lot higher than the required, legal standards and is one of the most sustainable administrative buildings in Belgium. Nothing was left to chance. For example, for heating and cooling, concrete core activation is used, whereby all pipes are integrated into the concrete supporting structure. Therefore the system heats or cools the spaces through the ceiling – comparable to under-floor heating systems in houses.

Customisation required
The concrete core activation immediately posed the necessary challenges for the lighting installation. “Since there are no false ceilings, there is no room for traditional recessed luminaires,” Tom Daniëls explains. “Therefore we had to rely on suspended and surface-mounted luminaires in any case. Since the latter are visually more apparent than recessed luminaires, it was also critical that they fit in with the existing architectural components both in terms of design and volume. In addition, the request was also made to integrate the smoke detectors into the luminaires. Therefore ETAP designed a series of tailored luminaires, based on our R6 and Kardó luminaires, but in a bigger size. Our downlights were also slightly adjusted for the project with the integration of a K9 LED module for emergency lighting.”

ETAP delivered the luminaires for the lighting of all offices, staircases and underground car park. “Our lighting solutions perfectly fit into the building's philosophy – maximum yield with minimum consumption,” says Tom Daniëls. “The installed power only amounted to 1.60 W/m²/100 lux in the open-plan offices and 1.85 to 1.97W/m²/100 lux in the individual offices. Motion detection and daylight control further reduce consumption.”

In the office lighting the focus was also on working comfort – aluminium reflectors provide high visual comfort and minimum loss of contrast on the employees' screens. “In this way, with our lighting solutions we made a significant contribution to the designers' ultimate goals – a building that pulls out all the stops, both in terms of sustainability and functionality,” Tom Daniëls concludes.

Project sheet

- Library and offices: 1,000 1.5-m light line segments / 280 D22 downlights

- Library and hall: 180 D14 downlights

- Stairway halls: 80 R8

- Emergency lighting: 500 K1, K2 and K9 / ESM Web

- Car park: 400 E62

Holistic Architecture 50│5
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