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A horizontally placed earth heat exchanger system heats the air in winter and cools it in the summer. The airtight, highly insulated shell of the building greatly reduces the required supplemental heating power, which is satisfied by one small boiler. Radiators are not needed in the apartments, and small vents in the suspended ceilings supply fresh air. Filtration systems remove dust, pollen, and bacteria.

Instead of one large, centralized air-conditioning system, there are 24 small systems. The air enters through outside fixed tubes directly to the 24 systems which are placed in separate fire-protection-zones. Incoming air is conditioned then distributed in three-inch (80-millimeter) ducts. Their size required only a shallow six-inch (150-millimeter) plenum over the suspended ceiling, thus reducing the needed floor to floor height. As a result, the building code allowed architects Ludwig Rongen and Andreas Nordhoff to construct three stories instead of two.

With a photovoltaic system, the facility generates much of its own electricity and is able to resell some of it.

Lowered heating cost is not the only advantage of this energy-efficient design. It is common for the elderly residents to wander and to be attracted to windows and their views to the outside. Because the windows are highly insulated, the residents do not suffer from thermal drafts commonly associated with conventional glazing during cold winters.

The compact floor plan adds to the thermal efficiency and is well suited to group living for the 80 residents. The Caritas House is divided into eight apartments each with ten residents. This living structure enables each group to interact as a family. All the daily activities are carried out within the protected bounds of this stable family-group.

For each cluster of two or three such groups, there is a nursing area, day room, assisted-use bathing room, and spaces for other support functions. The positioning of the entrances to each of the apartment group in the living room makes this zone more lively yet enables staff to manage resident movement.

Between 1998 and 2002, the price of oil doubled in Germany, and it is expected to continue to rise. So the architects believe the economic benefit of such low-energy design will become increasingly apparent. In the Caritas House, this benefit is nicely compounded by the improved comfort for elderly residents and their caregivers.

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SUBSCRIPTION SAMPLE The Caritas House is an eldercare center in Moenchengladbach- Neuwerk, Germany, designed by Rongen Architekten. Photo: Rongen Architekten Highly insulated, floor-to-ceiling windows provide daylight without causing thermal drafts. Photo: Rongen Architekten Site plan. Image: Rongen Architekten Ground floor plan. Image: Rongen Architekten Second floor plan. Image: Rongen Architekten The exterior walls are of prefabricated wood sandwich panels except at the ground floor and on the gable walls, where the exterior shell is brick. Photo: Rongen Architekten Decentralized air intake equipment. Photo: Rongen Architekten Corner details. Photo: Rongen Architekten   Click on thumbnail images to view full-size pictures.