4.9 Mountain hut in Langtang National Park, Nepal

The main points:
In spite of its sophisticated design the building does not fully fulfill expectations, because:
· the system of heating air by a passive solar collector is not efficient enough;
· the users are generally careless about heat conservation and do not close doors.

This house was built in 1979, at an altitude of 4000-m. The southern elevation is fully glazed, consisting of 1/3rd windows and of 2/3rd solar collectors as a solar wall for space heating. Because of the severe climate at this altitude (below zero) the collectors were designed as air heaters.

Other climatic design features were also applied:

· Curved south front for wind protection
· Buffer zones on east and west side
· built-in to the slope on the north side

Experience has shown that the concept was not fully successful:

· The human factor was not sufficiently considered; for instance the outer doors were never closed.
· Mice had blocked the air-ducts with rice which they collect and store in the inaccessible parts of the ducts.
· The efficiency of air-heating compared to water-heating systems is low.