When it is required to predict the local mean age of air, the calculations are often carried out assuming that there is no recirculation that is that all of the supply air is fresh. However, local mean age values will be greater than in the fresh air case when some of the exhaust air is recirculated. This paper examines and discusses the effect of recirculation and shows that, for many systems the increase in local mean age due to recirculation can be calculated by means of an elementary analysis that leads to a simple algebraic expression.

Nearly 20 years after it was ordered by Parliament, the f'.230 million parliamentary building is ready to welcome its inmates: 200-odd constituency MPs and their staff. Does the building's controversial luxury extend to the engineering services?

Experimental studies on natural smoke filling in an atrium induced by a liquid pool fire up to 1.6 MW were carried out. The new full-scale burning facility, the PolyU/USTC Atrium constructed at Hefei in China, was used. Five sets of hot smoke tests with diesel pool fires of 2 x 2 m placed on the floor were carried out. All openings were closed, except leaving a small vertical vent of 0.2 m high for supplying fresh air. Transient variations on the mass of the burning fuel, the vertical temperature distributions and the smoke layer interface heights were measured.

Even when the hills have soaked up the rain and the lush green grass is bent flat in the wind, the Great Glasshouse in Wales can still offer a Mediterranean haven. But how do you create and service such an environment?