Normalisation & unit conversion

Non-normalized metrics naturally vary according to zone size; larger spaces consume more total energy for thermal conditioning, therefore possibly masking geometry performance effects when compared to spatially similar zones of merely different dimensions.

Energy use and gain metrics can thus be normalized by setting the normalize_per_zone_m2 (1) switch. Normalization will then show metrics per m2 of zone area, allowing in some cases a better understanding of how geometry (say, window area in a zone vs. another one) affects e.g. energy consumption.

Typical report variables are Zone/Sys Sensible Heating & Cooling Rate [W] or Zone Transmitted Solar [W]. Note that when using these output variables in range mode, the reported output is actually in Watt-hours (Wh); setting convert_units (2) to “x / 1000″ divides the input by 1000 to yield kWh- which can then be normalized to give kWh/m2 per zone.

Additional quick conversion modes allow you to convert Joules to Wh and kWh, using a conversion factor of “x * 0.00027″ (actually 0.000277777778, but abbreviated in the GUI) – which can then also be normalized per m2 zone area. The same conversion factor can be used when creating custom variables through the var_expression funtionality; typical EnergyPlus outputs are e.g. Zone Total Internal Latent Gain [J] or Zone Infiltration Sensible Heat Loss [J].

Illuminance (and irradiance,  if you use Daysim in that fashion) have normalization disabled, allowing only for direct point source data to be read and filtered- since technically, the zone m2 values parsed from the E+ file and used for thermal results optimization are not linked to the daylight simulation at all, and would thus produce misleading values.