All of the data on this tab is initially set from the NCM template.
Unlike the NCM template data on the Room Conditions tab, however, aspects of this data may be edited in certain circumstances.
The NCM activity room conditions specify levels and schedules (profiles) for internal gains and (where relevant) electrical consumptions associated with lighting, equipment and occupancy. These gains are automatically set on the Internal Gains tab as a function of the NCM activity.
Lighting gains and consumption, however, are a special case. The NCM activity specifies lighting levels in terms of lux. In the NCM template these are translated to W/m2 using a fixed conversion factor – the Installed Power Density. The value of this factor depends on the activity. It is 3.75 W/m2 per 100 lux for office, storage and industrial spaces and 5.20 W/m2 per 100 lux for other spaces. If the luminous efficacy of the lights in the building differs from the figure assumed in the NCM activity, it is permissible to adjust the lighting power consumption by editing the Installed Power Density.
To do this it is first necessary to un-tick the Template box attached to Design Illuminance. When this is done a parameter ‘NCM Database Illuminance’ appears, together with a Template box that allows the Design Illuminance to be edited to a value derived from a detailed lighting design. In accordance with the rules set out in the Modelling Guide, any value of design illuminance which is less than the database illuminance must be replaced by the latter value, and the interface imposes this condition automatically.
In the ‘lux’ input mode the Luminaire Efficacy is derived using geometry-related rules set out in the Modelling Guide, and the Light Output Ratio (the ratio of Luminaire efficacy to Lamp Efficacy) is editable. The Luminaire and Lamp efficacies are output to BRUKL and appear on the compliance report.
Another way to adjust the Installed Power Density is by setting Input mode to Inference. This allows the lighting properties to be inferred from a Lamp Type. The Lamp Type may also be left Unset, in which case a Lamp Efficacy and Light Output Ratio can be entered by hand.
Ticking the check box labelled ‘NCM simple lighting control’ activates NCM simple lighting control, the details of which are documented in section 5.3 of this guide under the heading ‘NCM lighting data dialog’.
It is also possible to simulate lighting control using a Dimming Profile which has been defined using a formula profile linking the lighting level to room daylight illuminance values calculated by Radiance.
