( VAV ) air handling units ( AHUs ) in plant rooms on every floor . A dedicated IT chiller connected to the same network provides cooling to IT-critical areas after hours . Chilled and hot water is circulated by a primary-secondary pumping arrangement , with variable speed pumps efficiently supplying the air handling units with chilled / hot water to meet the thermal demand .
The AHUs draw return air from the office spaces , mix it with minimum fresh air requirements drawn from the façade through dedicated plenums and supply conditioned air to the office areas via insulated galvanised sheet metal ducting and VAV swirl diffusers . To make use of the thermally comfortable ambient conditions often experienced in the Highveld region and at the same time reduce cooling / heating energy , an economy cycle system is utilised . This system introduces full fresh air into plant rooms via motorised damper sets when outside conditions are ideal and require less cooling or heating than return air indoor conditions . The over-pressure fresh air is then bled into the unconditioned multivolume atrium through ceiling louvre / damper combinations to improve ventilation and comfort conditions in the atrium at the same time . Furthermore , carbon dioxide sensors in all return air paths actively monitor CO2 levels in the offices and open fresh air dampers accordingly to ensure a healthy level of CO2 is maintained in all occupied areas .
A supplementary fresh air system pressurises the office access floor with neutral , tempered fresh air which is bled into meeting rooms via floor grilles to meet the higher regulatory fresh air requirements in these areas . The access floor fresh air risers also double as smoke extraction risers in fire state .
Basement ventilation is provided by large vertical extraction fans in vertical shafts with modulating dampers on every level , modulating to maintain minimum levels of carbon monoxide on each parking level . Each extraction fan has a variable speed drive to use only the necessary energy . Furthermore , make-up air is introduced from the upper levels and supplied to all levels below through ramps and a series of dedicated slab cut-outs with mentis grid over , so as to
No . 1 Mutual Place 569