> as lemmas

1844 D. B. Reid Illustr. Theory & Pract. Ventilation ii. iii. 121 Plenum ventilation..can be sustained only by the constant use of machinery.

1852 Lancet 6 Mar. 253/2 Ventilation by the plenum method implies that the fresh air is blown or driven into the apartment to be ventilated, and the impure air thus forced out.

1888 J. A. Ewing in Encycl. Brit. XXIV. 160/2 A broad distinction may be drawn between what are sometimes called vacuum and plenum methods of artificial ventilation.

1894 J. Keith Houses of Parl.: Rep. Heating & Ventilation 3 The action of the Plenum fan..in blowing in the fresh air upwards through the grated floor of the Chamber.

1903 Architect 24 Apr. 276/2 The ventilation of the hospital was secured by natural, as opposed to artificial, means, such as that usually called the Plenum system.

1934 H. M. Vernon Princ. Heating & Ventilation ix. 177 A comparison of some thousands of observations made in factories ventilated by plenum air and by natural means showed very little defect of humidity in the plenum factories.

1978 Ld. Drogheda Double Harness xiii. 143 We had allowed for proper air conditioning... Instead we installed a horrible thing called plenum ventilation, which warmed the air in winter, filling the offices with smuts..but failing to cool it in summer.

1995 R. Fellows Edwardian Archit. iii. 71/2 North Yorkshire County Hall..used fans to force warm air into the council chamber through a plenum system.